gbrown27
Full Access Member
I wish i had that kind of money to do that
Had some new Progressive rate Spring made
- Thread starter Johnny
- Start date
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Mil T
Full Access Member
I'm curious Johnny if you took into account any modified shock work that someone may do on the stock shocks. I'm assuming that your springs are meant only for factory stock shock valving etc. use? If that is the case will a person be able to make changes to the shock valving etc. with new pistons or shims or new shafts with different valving holes etc. to create a better off road operation? There is a lot that can be done with the stock shocks. There are people around that know how to set them up well and for little money. $75 to $100 for a rebuild and they know how to revalve and or change parts to make a much better off road performance shock. Changeing the perch postion will make a difference in how the shocks will perform with the type of revalving etc. AND spring that you have on the shock.
Just wondering if you have accounted for this possibility?
Mil T
Just wondering if you have accounted for this possibility?
Mil T
INI
Full Access Member
its about time someone did this....I had this idea for a long time...just couldn't find the right avenue to present it....in fact i just talked to someone about this the other day.....
Good Job Johnny. would love to hear the results.
Fox makes ok Stock Raptor shocks but not so great springs..in fact pretty sure Fox doesn't "make" the springs anyways....might be outsourced to a Chinese company
when we wanted to change our race cars suspension the first thing we would do was bring out 5-10 different Eibach Coils and adjust the spring rate and pre-load setting on the coil overs. It was a easy and simple adjustment that really changed offroad "tuning"
When the Spring compresses it completely changes the rate at with you have rebound....modern shocks try and adjust to this but if you could have best of both worlds then your good.
*EDIT*after some research there is a fairly large company making a "kit" now and should be available as a possible option in 2013.
lets hold our breath.
here is some good coil reading for us nerds.
What is Spring Rate?
Spring rate refers to the amount of weight needed to compress a spring an inch (Example:500# per inch) To understand and properly check a spring for rate you need to know the factors that determine the rate of the spring. Fortunately, there are only three things that affect spring rate, so there's not that much to remember!
1. Wire diameter. This affects rate since greater diameter wire is stronger than lesser diameter wire. So, when wire diameter is increased, spring rate increases.
2. Mean diameter of spring. Mean diameter is the overall outside diameter of the spring less one wire diameter. When mean diameter increases, the spring rate decreases.
3. Active coils. Determination of the number of active coils varies according to spring design. Count the total coils minus two for springs with both ends closed (includes all AFCOILS). Count the total coils minus one for springs with one end closed and one end open. As the number of active coils increases, the spring rate decreases.
If a spring's rate is linear (most racing springs have linear rates) its rate is not affected by the load put onto the spring. For example, a linear rate spring rated at 500#/inch will compress 1" when a 500# weight is placed onto the spring. If another 500 pound weight is put onto the spring the spring will compress another inch. At this point the load on the spring has increased to 1000 pounds. The rate of the spring, however, remains constant at 500#/inch.
If the load put onto a spring increases the rate of the spring, the spring is said to have a progressive rate. Progressive rate springs are sometimes used on torque arms to absorb engine torque. Keep in mind that the load (or preload) put onto a progressive rate spring can greatly increase the rate of the spring.
Typically, progressive rate springs are made by varying the spacing between the springs' active coils. During compression the close coils bottom out and deaden. This reduces the amount of active coils and spring rate increases as a result.
Springs that are designed to include coils of different diameter or are wound using a tapered wire will also produce a progressive rate.
Most coil springs are actually progressive to some degree -- as we will learn later!
Dynamics of Coil Springs:
There are basically three different spring designs presently used in race cars. They are:
TYPE I: Closed and ground on both ends (Coil-overs and rear conventional springs are this type).
TYPE II: Closed both ends but ground one end only (Conventional front springs are normally this type).
TYPE III: Closed and ground on one end and open on the other end (Similar to a conventional spring that has been cut).
The 3 springs types are used in different situations and provide different effects to rate. Since the designs are so varied, it only follows that the dynamics of each design are also varied (more later). You must remember, however, the only factors that affect spring rate are wire diameter, mean diameter, number of active coils.
How Spring Rates Change Dynamically:
Keep in mind that as a coil spring compresses, the inactive (dead) end coils gradually contact adjacent, active coils. The contact causes the active coils to deaden which increases the rate of the spring. The rate creep that results usually stops after the first inch of spring travel and does not appear again until spring travel approaches coil bind. Generally speaking, this type of rate creep is of little consequence with springs softer than approximately 500#/inch. When you use springs stiffer than 500#/inch rate creep becomes more pronounced.
It is important for you to realize that springs will pick up rate during compression. Consequently, the rate marked on a spring can differ from the rate as seen by the chassis. This is especially true whenever a spring manufacturer rates springs based on the first inch of compression.
Example: A racer replaced a 720# coil-over spring with a 750# Afcoil. The racer believed he had stiffened his right front spring, however, the chassis behaved as though he had gone to a softer spring. Upon rating both springs, he found that the 720# spring was rated for its first inch of travel (720# in.) and produced a much higher (780# in.) rate for its second inch where it actually operated on the race car. Because Afcoils are designed to give their nominal rate closest to their actual working range of travel (this particular 750 spring rated 735# in. for its first inch of travel and 755# in. for its second inch), this racer actually softened up his race car even though the spring rate markings indicated the opposite! Rate creep can become even more complex and more difficult to monitor for racers using conventional type front coil springs designed with an open end coil(type 3). The lower control arms used with conventional springs typically incorporate a stepped helix spring seat built to an SAE specification (.720" of step). The helix seat was designed into lower control arms to insure consistent installation of the spring. Keep in mind that any rotation of the spring affects the actual installed rate of the spring.
Unless racing springs used for this type of application are designed with one end coil that closely matches the lower arm helix spring seat, a serious amount of rate creep can result. To minimize this type of rate creep, a conventional front spring should be wound with its bottom end closed so that it sits squarely in the helix seat. No active coil should touch the seat (just like the original production spring for which the control arm was designed -Type 2 spring).
When built in this manner, a coil springÂs only contact with the lower control arm is through an inactive (dead) coil (just like the spring's contact with the weight jack). Consequently, as the spring compresses, the number of active coils in the spring is not affected by the lower control arm. Therefore the spring's rate remains constant throughout normal suspension travel. Some rate creep still occurs due to contact between the dead end coils and the adjacent active coils as was explained earlier, but the amount of rate creep is miniscule compared to the rate creep produced by an open end coil spring. All AFCOILS, designed for use with stock lower control arms, are built in this manner.
If a spring has an open end coil(type #3), the open end coil is active but gradually deadens as the lower control arm moves against the spring. A considerable increase in spring rate occurs until the open end coil is completely seated in the helix.
For example, during a test a 1500# open end coil spring gained 464 lbs. of rate after 2 inches of spring travel. By comparison, a 1300# Afcoil (closed end coil spring) gained only 48 lbs. of rate after the same travel.
Further testing of a series of open end coil springs produced rate creep so inconsistent that at some points of spring travel the springs did not remain in the same rate order of softest to stiffest! It would be very difficult to make predictable handling adjustments using springs that exhibit such inconsistencies!
Keep in mind that any load change to an open end coil spring (via static weight, wedge, chassis roll, bumps, etc.) usually causes the spring's rate to change and, consequently, handling to change. If you are using open end coil springs you should chart their rates from static loaded height to fully loaded height weight(in one inch increments). You should compare this information before making spring changes. By now you should realize the importance of using springs that are designed to keep rate creep to a minimum.
What is Spring Stress?
As was pointed out earlier, the rate of a spring is determined by its diameter, the number of its active coils, and the diameter of its wire. Since most racing springs are built to a fixed diameter, a spring designer must decide on the diameter of wire and the correct number of active coils needed to produce the desired rate.
If the designer chooses a smaller than normal diameter of wire (which tends to soften rate), he will have to compensate by using fewer active coils (which tends to stiffen rate) to achieve the desired rate. There are two possible reasons for a spring designer to use a smaller than normal wire diameter for a specific rate spring:
1. The ideal diameter wire may not be made and using the next larger wire (which requires more active coils) would produce a spring with insufficient spacing between its coils. This could cause the spring to bind during normal operation.
2. Cost could be the prime consideration and by using a smaller diameter wire and fewer coils (shortening the length of wire used) material cost is reduced. Unfortunately, many racing springs are built this way and these springs can cause a multitude of problems for the chassis tuner that we will cover.
Many racers mistakenly believe extra spacing between the coils of a spring indicates a preferable spring. While a spring must have sufficient stroke capacity it also must have sufficient material to absorb the load put onto it. If the spring's material is not sufficient for the load put onto the spring, the material will become over-stressed and the spring will take a set (lose height). Handling, of course, is affected and the reason is not always apparent to the racer unless he pays close attention to his springs.
Example: A typical asphalt late model set-up calls for a tremendous amount of load on the left rear spring (upwards to 600 pounds more weight than on the right rear spring). When the chassis sees normal spring travel, the cumulative load on the left rear spring produces a tremendous amount of stress in the spring. If the spring does not have sufficient material to handle the stress (as many don't), it will take a set (as many do) and the car will lose crossweight and tend to become loose off the corner. Excessive spacing between the coils of a spring is usually an indicator of a potential problem with spring stress.
Stress Consideration in Spring Design
Many times, because of the long stroke requirements for certain rates of racing springs, material strength must be sacrificed to achieve significant stroke. Couple this with the fact that the ideal wire diameter is not always made and you can see why some springs have a real potential to take a set. We have seen some brands of springs lose as much as 15/16" of free height during normal operation. To eliminate any set from occurring at the race track, it is good manufacturing policy to pre-set (press to solid height) all racing springs during their manufacture.
If done correctly, pre-setting will generally eliminate any potential for additional set, even when springs are designed with smaller than ideal wire. Shot-peening will further enhance a spring's durability. It should be pointed out that all Afcoils are pre-set and shot-peened during manufacture.
What if a Spring "Sets"?
When a spring takes a set it will normally stabilize at its new height. The rate effectively remains the same since no appreciable changes have been made to any of the three factors that determine the spring's rate. Other than creating a need to readjust the chassis (to restore the original set-up and ride heights) the spring should provide satisfactory performance. It is not uncommon for even well designed and properly manufactured springs to settle up to 1% of their free height. It needs to be pointed out, however, that in cases where a poorly designed spring is subject to extreme over-stressing, the spring's height may not stabilize. The spring may continue to change height (both shortening and lengthening) as the spring is worked. As a result, the set-up on the race car changes every time the spring's height changes. This can cause major chassis tuning headaches!
Monitor your Springs:
We recommend that you monitor the free heights of your springs on a regular basis. This is so important that some Indycar teams measure their springs' heights to the thousandth of an inch. Be sure to always measure height at the same point on the end coils(mark your springs to indicate the measuring point). You should suspect that a spring is setting whenever wheel weights continually change. Under no circumstances should springs be used that change more than 2% in height or do not stabilize in height. AFCOILS are guaranteed to maintain their free heights to within 2% forever!
At the least you should inspect all springs for free height changes after racing on a very rough track or if your race car was involved in a wreck. By now, you should realize there is much more chance for a spring to change its height than its rate. Consequently, you should spend your time monitoring your springs' free heights and not their rates!
What is Coil Bind?
Coil bind occurs whenever a spring is compressed and one or more of the springs active coils contacts another coil. The rate of the spring increases whenever a coil binds since the bound coil or coils are no longer active(this changes one of the three rate-determining factors). Of course, handling is affected whenever a coil binds. If the spring is compressed to solid height (all coils touching) during suspension movement, the suspension will cease to work. You can, and should, check for evidence of coil bind by examining the finish between the active coils. If any coils have bound the finish between them will show contact marks that appear as though they were drawn with a lead pencil. Normally any spring that is binding should be replaced with a taller spring. Be aware, however, there are racing springs on the market that are built with wire that is heavier than what's needed. These springs will coil bind before others that are built with the proper size wire.
Under very extreme conditions, coil binding can cause a spring to unwind slightly. This can cause the mean diameter of the spring to increase and reduce rate of the spring. You should realize that the potential for coil bind is increased whenever short springs are used. Always match the spring to the job.
Why Springs Bow:
Springs that have lengths greater than 4 times their diameter will have a natural tendency to bow when loaded. Consequently, tall springs tend to bow more than short springs, and small diameter springs tend to bow more than large diameter springs. Generally, the more a spring is compressed the more it will tend to bow. Keep in mind the rate of a spring will increase if an active coil rubs another part of the race car. Here are some tips to minimize bowing:
• Use correctly fitting coil-over hardware or install weight jack assemblies so that the spring mounting surfaces are kept as parallel as possible during suspension travel..
• Use springs that do not lean excessively (when positioned on a flat surface). This indicates that the ends are ground parallel to each other. This reduces the tendency for a spring to bow. You should check both ends.
• If a coil-over spring is rubbing the shock, try reversing the spring so the bowed part of the spring is around the shaft where there's more clearance.
• Use coil-over springs that have straight sides rather than an hour glass shape. This maximizes the clearance between the shock and spring.
• Use springs that are wound straight. You can roll the spring on a flat surface to check for straightness.
• The new AFCO XCS coil-over springs were developed specifically to eliminate bowing and shock hardware interference problems.
There are special manufacturing techniques that help to keep bow to a minimum. AFCOILS are built for minimum bow under all racing conditions.
Spring Checkers:
Unfortunately, we know of no reasonably priced spring checker that will accurately measure a spring for rate. We have tested most brands of checkers and cannot give recommendation to any. However, there are steps and procedures that can increase the reliability of the spring rate checkers commonly sold to racers. The accuracy of a spring checker should be monitored. This can be done through the use of a checking spring. A checking spring can be any spring that has been accurately rated at one inch (or smaller) increments up to a load close to the total capacity of the checker. It is important that the free length of the checking spring remain constant. The rates given by the checker can be compared to the known rates of the checking spring (at each increment of compression). Any rate discrepancies between the checker and the checking spring should be noted and taken into consideration when checking for rates of other springs.
AFCO can provide checking springs for this purpose. The repeatability of a spring rate checker should also be monitored. Simply put an old spring in your checker and preload it to at least 20 lbs. Then compress the spring and note gauge readings at 1" increments (or less) for the next three or four inches of spring travel. Tag the spring with this information and use it occasionally to check for repeatability. Make sure the free height of the spring remains constant. Do not use the spring if any change in free height occurs. A checking spring can also be used to check for repeatability. A rate checker should consistently repeat rates to within 2.5%.
Some Final Points on the use of Spring Rate Checkers:
• Preload Afcoil closed end conventional front springs 1/2". Coil-over and conventional rear springs should be preloaded 1".
• Always use similar preloads when checking different brands of springs. It's best to preload springs to a height equal to their loaded height (as installed in the race car) before checking for rate. This simulates what the race car sees for spring rate.
• Use a dial indicator to measure travel.
• Take dial indicator readings as close to the spring's center line as possible. Readings taken very far from the springs center may not allow for any rocking of the spring seat which distorts the actual amount of spring travel.
• Realize travel indicated stiff springs can flex the framework and fixtures of portable checkers. Consequently, the spring compresses less than its indicated & the rate shows softer than actual.
• The dial indicator should hold steady whenever rate readings are being taken. If the indicator moves, suspect the units framework is flexing or there is a problem with the units jacking device.
• Checkers equipped with load cells tend to be much more accurate than checkers equipped with hydraulic gauges.
• Avoid checkers that allow the spring seats to rock in any manner or amount.
• Always use the proper spring seats.
• When using a helix type spring seat make sure the spring is positioned against the stop in the helix.
Good Job Johnny. would love to hear the results.
Fox makes ok Stock Raptor shocks but not so great springs..in fact pretty sure Fox doesn't "make" the springs anyways....might be outsourced to a Chinese company
when we wanted to change our race cars suspension the first thing we would do was bring out 5-10 different Eibach Coils and adjust the spring rate and pre-load setting on the coil overs. It was a easy and simple adjustment that really changed offroad "tuning"
When the Spring compresses it completely changes the rate at with you have rebound....modern shocks try and adjust to this but if you could have best of both worlds then your good.
*EDIT*after some research there is a fairly large company making a "kit" now and should be available as a possible option in 2013.
lets hold our breath.
here is some good coil reading for us nerds.
What is Spring Rate?
Spring rate refers to the amount of weight needed to compress a spring an inch (Example:500# per inch) To understand and properly check a spring for rate you need to know the factors that determine the rate of the spring. Fortunately, there are only three things that affect spring rate, so there's not that much to remember!
1. Wire diameter. This affects rate since greater diameter wire is stronger than lesser diameter wire. So, when wire diameter is increased, spring rate increases.
2. Mean diameter of spring. Mean diameter is the overall outside diameter of the spring less one wire diameter. When mean diameter increases, the spring rate decreases.
3. Active coils. Determination of the number of active coils varies according to spring design. Count the total coils minus two for springs with both ends closed (includes all AFCOILS). Count the total coils minus one for springs with one end closed and one end open. As the number of active coils increases, the spring rate decreases.
If a spring's rate is linear (most racing springs have linear rates) its rate is not affected by the load put onto the spring. For example, a linear rate spring rated at 500#/inch will compress 1" when a 500# weight is placed onto the spring. If another 500 pound weight is put onto the spring the spring will compress another inch. At this point the load on the spring has increased to 1000 pounds. The rate of the spring, however, remains constant at 500#/inch.
If the load put onto a spring increases the rate of the spring, the spring is said to have a progressive rate. Progressive rate springs are sometimes used on torque arms to absorb engine torque. Keep in mind that the load (or preload) put onto a progressive rate spring can greatly increase the rate of the spring.
Typically, progressive rate springs are made by varying the spacing between the springs' active coils. During compression the close coils bottom out and deaden. This reduces the amount of active coils and spring rate increases as a result.
Springs that are designed to include coils of different diameter or are wound using a tapered wire will also produce a progressive rate.
Most coil springs are actually progressive to some degree -- as we will learn later!
Dynamics of Coil Springs:
There are basically three different spring designs presently used in race cars. They are:
TYPE I: Closed and ground on both ends (Coil-overs and rear conventional springs are this type).
TYPE II: Closed both ends but ground one end only (Conventional front springs are normally this type).
TYPE III: Closed and ground on one end and open on the other end (Similar to a conventional spring that has been cut).
The 3 springs types are used in different situations and provide different effects to rate. Since the designs are so varied, it only follows that the dynamics of each design are also varied (more later). You must remember, however, the only factors that affect spring rate are wire diameter, mean diameter, number of active coils.
How Spring Rates Change Dynamically:
Keep in mind that as a coil spring compresses, the inactive (dead) end coils gradually contact adjacent, active coils. The contact causes the active coils to deaden which increases the rate of the spring. The rate creep that results usually stops after the first inch of spring travel and does not appear again until spring travel approaches coil bind. Generally speaking, this type of rate creep is of little consequence with springs softer than approximately 500#/inch. When you use springs stiffer than 500#/inch rate creep becomes more pronounced.
It is important for you to realize that springs will pick up rate during compression. Consequently, the rate marked on a spring can differ from the rate as seen by the chassis. This is especially true whenever a spring manufacturer rates springs based on the first inch of compression.
Example: A racer replaced a 720# coil-over spring with a 750# Afcoil. The racer believed he had stiffened his right front spring, however, the chassis behaved as though he had gone to a softer spring. Upon rating both springs, he found that the 720# spring was rated for its first inch of travel (720# in.) and produced a much higher (780# in.) rate for its second inch where it actually operated on the race car. Because Afcoils are designed to give their nominal rate closest to their actual working range of travel (this particular 750 spring rated 735# in. for its first inch of travel and 755# in. for its second inch), this racer actually softened up his race car even though the spring rate markings indicated the opposite! Rate creep can become even more complex and more difficult to monitor for racers using conventional type front coil springs designed with an open end coil(type 3). The lower control arms used with conventional springs typically incorporate a stepped helix spring seat built to an SAE specification (.720" of step). The helix seat was designed into lower control arms to insure consistent installation of the spring. Keep in mind that any rotation of the spring affects the actual installed rate of the spring.
Unless racing springs used for this type of application are designed with one end coil that closely matches the lower arm helix spring seat, a serious amount of rate creep can result. To minimize this type of rate creep, a conventional front spring should be wound with its bottom end closed so that it sits squarely in the helix seat. No active coil should touch the seat (just like the original production spring for which the control arm was designed -Type 2 spring).
When built in this manner, a coil springÂs only contact with the lower control arm is through an inactive (dead) coil (just like the spring's contact with the weight jack). Consequently, as the spring compresses, the number of active coils in the spring is not affected by the lower control arm. Therefore the spring's rate remains constant throughout normal suspension travel. Some rate creep still occurs due to contact between the dead end coils and the adjacent active coils as was explained earlier, but the amount of rate creep is miniscule compared to the rate creep produced by an open end coil spring. All AFCOILS, designed for use with stock lower control arms, are built in this manner.
If a spring has an open end coil(type #3), the open end coil is active but gradually deadens as the lower control arm moves against the spring. A considerable increase in spring rate occurs until the open end coil is completely seated in the helix.
For example, during a test a 1500# open end coil spring gained 464 lbs. of rate after 2 inches of spring travel. By comparison, a 1300# Afcoil (closed end coil spring) gained only 48 lbs. of rate after the same travel.
Further testing of a series of open end coil springs produced rate creep so inconsistent that at some points of spring travel the springs did not remain in the same rate order of softest to stiffest! It would be very difficult to make predictable handling adjustments using springs that exhibit such inconsistencies!
Keep in mind that any load change to an open end coil spring (via static weight, wedge, chassis roll, bumps, etc.) usually causes the spring's rate to change and, consequently, handling to change. If you are using open end coil springs you should chart their rates from static loaded height to fully loaded height weight(in one inch increments). You should compare this information before making spring changes. By now you should realize the importance of using springs that are designed to keep rate creep to a minimum.
What is Spring Stress?
As was pointed out earlier, the rate of a spring is determined by its diameter, the number of its active coils, and the diameter of its wire. Since most racing springs are built to a fixed diameter, a spring designer must decide on the diameter of wire and the correct number of active coils needed to produce the desired rate.
If the designer chooses a smaller than normal diameter of wire (which tends to soften rate), he will have to compensate by using fewer active coils (which tends to stiffen rate) to achieve the desired rate. There are two possible reasons for a spring designer to use a smaller than normal wire diameter for a specific rate spring:
1. The ideal diameter wire may not be made and using the next larger wire (which requires more active coils) would produce a spring with insufficient spacing between its coils. This could cause the spring to bind during normal operation.
2. Cost could be the prime consideration and by using a smaller diameter wire and fewer coils (shortening the length of wire used) material cost is reduced. Unfortunately, many racing springs are built this way and these springs can cause a multitude of problems for the chassis tuner that we will cover.
Many racers mistakenly believe extra spacing between the coils of a spring indicates a preferable spring. While a spring must have sufficient stroke capacity it also must have sufficient material to absorb the load put onto it. If the spring's material is not sufficient for the load put onto the spring, the material will become over-stressed and the spring will take a set (lose height). Handling, of course, is affected and the reason is not always apparent to the racer unless he pays close attention to his springs.
Example: A typical asphalt late model set-up calls for a tremendous amount of load on the left rear spring (upwards to 600 pounds more weight than on the right rear spring). When the chassis sees normal spring travel, the cumulative load on the left rear spring produces a tremendous amount of stress in the spring. If the spring does not have sufficient material to handle the stress (as many don't), it will take a set (as many do) and the car will lose crossweight and tend to become loose off the corner. Excessive spacing between the coils of a spring is usually an indicator of a potential problem with spring stress.
Stress Consideration in Spring Design
Many times, because of the long stroke requirements for certain rates of racing springs, material strength must be sacrificed to achieve significant stroke. Couple this with the fact that the ideal wire diameter is not always made and you can see why some springs have a real potential to take a set. We have seen some brands of springs lose as much as 15/16" of free height during normal operation. To eliminate any set from occurring at the race track, it is good manufacturing policy to pre-set (press to solid height) all racing springs during their manufacture.
If done correctly, pre-setting will generally eliminate any potential for additional set, even when springs are designed with smaller than ideal wire. Shot-peening will further enhance a spring's durability. It should be pointed out that all Afcoils are pre-set and shot-peened during manufacture.
What if a Spring "Sets"?
When a spring takes a set it will normally stabilize at its new height. The rate effectively remains the same since no appreciable changes have been made to any of the three factors that determine the spring's rate. Other than creating a need to readjust the chassis (to restore the original set-up and ride heights) the spring should provide satisfactory performance. It is not uncommon for even well designed and properly manufactured springs to settle up to 1% of their free height. It needs to be pointed out, however, that in cases where a poorly designed spring is subject to extreme over-stressing, the spring's height may not stabilize. The spring may continue to change height (both shortening and lengthening) as the spring is worked. As a result, the set-up on the race car changes every time the spring's height changes. This can cause major chassis tuning headaches!
Monitor your Springs:
We recommend that you monitor the free heights of your springs on a regular basis. This is so important that some Indycar teams measure their springs' heights to the thousandth of an inch. Be sure to always measure height at the same point on the end coils(mark your springs to indicate the measuring point). You should suspect that a spring is setting whenever wheel weights continually change. Under no circumstances should springs be used that change more than 2% in height or do not stabilize in height. AFCOILS are guaranteed to maintain their free heights to within 2% forever!
At the least you should inspect all springs for free height changes after racing on a very rough track or if your race car was involved in a wreck. By now, you should realize there is much more chance for a spring to change its height than its rate. Consequently, you should spend your time monitoring your springs' free heights and not their rates!
What is Coil Bind?
Coil bind occurs whenever a spring is compressed and one or more of the springs active coils contacts another coil. The rate of the spring increases whenever a coil binds since the bound coil or coils are no longer active(this changes one of the three rate-determining factors). Of course, handling is affected whenever a coil binds. If the spring is compressed to solid height (all coils touching) during suspension movement, the suspension will cease to work. You can, and should, check for evidence of coil bind by examining the finish between the active coils. If any coils have bound the finish between them will show contact marks that appear as though they were drawn with a lead pencil. Normally any spring that is binding should be replaced with a taller spring. Be aware, however, there are racing springs on the market that are built with wire that is heavier than what's needed. These springs will coil bind before others that are built with the proper size wire.
Under very extreme conditions, coil binding can cause a spring to unwind slightly. This can cause the mean diameter of the spring to increase and reduce rate of the spring. You should realize that the potential for coil bind is increased whenever short springs are used. Always match the spring to the job.
Why Springs Bow:
Springs that have lengths greater than 4 times their diameter will have a natural tendency to bow when loaded. Consequently, tall springs tend to bow more than short springs, and small diameter springs tend to bow more than large diameter springs. Generally, the more a spring is compressed the more it will tend to bow. Keep in mind the rate of a spring will increase if an active coil rubs another part of the race car. Here are some tips to minimize bowing:
• Use correctly fitting coil-over hardware or install weight jack assemblies so that the spring mounting surfaces are kept as parallel as possible during suspension travel..
• Use springs that do not lean excessively (when positioned on a flat surface). This indicates that the ends are ground parallel to each other. This reduces the tendency for a spring to bow. You should check both ends.
• If a coil-over spring is rubbing the shock, try reversing the spring so the bowed part of the spring is around the shaft where there's more clearance.
• Use coil-over springs that have straight sides rather than an hour glass shape. This maximizes the clearance between the shock and spring.
• Use springs that are wound straight. You can roll the spring on a flat surface to check for straightness.
• The new AFCO XCS coil-over springs were developed specifically to eliminate bowing and shock hardware interference problems.
There are special manufacturing techniques that help to keep bow to a minimum. AFCOILS are built for minimum bow under all racing conditions.
Spring Checkers:
Unfortunately, we know of no reasonably priced spring checker that will accurately measure a spring for rate. We have tested most brands of checkers and cannot give recommendation to any. However, there are steps and procedures that can increase the reliability of the spring rate checkers commonly sold to racers. The accuracy of a spring checker should be monitored. This can be done through the use of a checking spring. A checking spring can be any spring that has been accurately rated at one inch (or smaller) increments up to a load close to the total capacity of the checker. It is important that the free length of the checking spring remain constant. The rates given by the checker can be compared to the known rates of the checking spring (at each increment of compression). Any rate discrepancies between the checker and the checking spring should be noted and taken into consideration when checking for rates of other springs.
AFCO can provide checking springs for this purpose. The repeatability of a spring rate checker should also be monitored. Simply put an old spring in your checker and preload it to at least 20 lbs. Then compress the spring and note gauge readings at 1" increments (or less) for the next three or four inches of spring travel. Tag the spring with this information and use it occasionally to check for repeatability. Make sure the free height of the spring remains constant. Do not use the spring if any change in free height occurs. A checking spring can also be used to check for repeatability. A rate checker should consistently repeat rates to within 2.5%.
Some Final Points on the use of Spring Rate Checkers:
• Preload Afcoil closed end conventional front springs 1/2". Coil-over and conventional rear springs should be preloaded 1".
• Always use similar preloads when checking different brands of springs. It's best to preload springs to a height equal to their loaded height (as installed in the race car) before checking for rate. This simulates what the race car sees for spring rate.
• Use a dial indicator to measure travel.
• Take dial indicator readings as close to the spring's center line as possible. Readings taken very far from the springs center may not allow for any rocking of the spring seat which distorts the actual amount of spring travel.
• Realize travel indicated stiff springs can flex the framework and fixtures of portable checkers. Consequently, the spring compresses less than its indicated & the rate shows softer than actual.
• The dial indicator should hold steady whenever rate readings are being taken. If the indicator moves, suspect the units framework is flexing or there is a problem with the units jacking device.
• Checkers equipped with load cells tend to be much more accurate than checkers equipped with hydraulic gauges.
• Avoid checkers that allow the spring seats to rock in any manner or amount.
• Always use the proper spring seats.
• When using a helix type spring seat make sure the spring is positioned against the stop in the helix.
INI
Full Access Member
More Reading for Shock and Coil Nerds like myself.
Modes of Travel, Ride Height, Suspension Height, & Wheel Travel
Now that we have basic understanding of suspension components and their function, let’s cover a some key suspension terms and definitions. These definitions, and indeed this entire article, is unapologetically written assuming the vehicle has solid axles installed at both front and rear of the vehicle. Unless otherwise specifically mentioned to the contrary, you should read this article assuming we're discussing solid axle suspensions.
Travel: In the strictest sense, travel is just the movement or motion of some component of the suspension, or of the suspension as a whole. All moving components of the suspension have their own travel, thus we have wheel travel, spring travel, shock travel, and suspension travel.
We can speak of either "total" travel, meaning the entire range of motion from one extreme to another - e.g. "total wheel travel"; or we can speak of some portion of travel -e.g. "up-travel"
If we're talking about only some portion of travel, we qualify it in one of two ways:
If we're talking about the wheels or suspension as a whole we describe it by direction - e.g. up-travel or down-travel; or
If we're talking about the shocks or springs, we describe it by the effect on the component - e.g. shock compression.
If we're talking about the travel of the shocks or springs we have:
Compression: Travel of the spring or shock that occurs as it gets shorter. Spring compression is also known as deflection, crush, displacement from free length, or simply, displacement.
Rebound: Travel of the spring or shock that occurs as it gets longer. Also known as extension.
If we're talking about the travel of the wheels or suspension as a whole, before we qualify the direction of the travel, we must first distinguish the "mode" of travel. There are three modes of travel, distinguished by how the wheels and chassis are moving relative to one-another. They are:
Ride: The vertical travel that occurs when both wheels on an axle move together the same distance at the same time, relative to the chassis. If both wheels on a solid axle hit a speed-bump at the same time the resulting wheel or suspension travel would be ride travel. During ride travel, the axle remains parallel to the ground and both wheels on that axle remain, more or less, perpendicular to the ground. Sometimes ride is also called heave. Ride travel can be subdivided into:
Compression / Up-travel / Bump - terms that describe the ride travel that occurs when the wheels get closer to the chassis.
Rebound / Down-travel / Droop - terms that describe the ride travel that occurs when the wheels get farther away from the chassis.
Flex: The suspension travel that occurs when one wheel on an axle moves closer to the chassis and the other wheel on that axle moves farther away from the chassis. During flex the wheels on the other axle move in the same direction as their diagonal opposites. In other words, if you stuff the right front wheel, you also stuff the left rear wheel, while the other two wheels droop. Also known as warp travel or articulation. Flex travel can be subdivided into:
Compression / Up-travel / Bump / Jounce / Stuff - terms that describe the motion of the wheels that get closer to the chassis.
Rebound / Down-travel / Droop - terms that describe the motion of the wheels that get farther away from the chassis.
Roll: Roll is the motion that occurs when all four wheels remain more or less fixed in position and the chassis moves relative to the wheels. In roll, the chassis pivots about an imaginary longitudinal axis in such a way that it gets closer to the wheels on one side of the vehicle, and farther away from the wheels on the opposite side. Also known as body-roll or sway, roll is generally an unwanted motion that is related to, but not the same as, flex.
The following diagrams should help clarify the different modes of travel:
Ride Travel.
Axle remains parallel to the ground as it travels vertically.
Flex Travel.
Rear axle shown. Front axle will be articulating in opposite direction.
Roll.
Note distinction between flex and roll.
In flex, wheels at opposite corners are doing the same thing (both getting closer too, or farther away from, the chassis).
Whilst in roll, wheels on the same side are doing the same thing (both getting closer to, or father away from, the chassis).
You may be wondering about the distinction between wheel travel and suspension travel. The terms are very closely related and often used interchangeably. However, there is a distinction worth noting:
Wheel travel generally refers to the motion of one wheel on an axle, and can be used to describe that motion either with or without springs / shocks installed.
Suspension travel generally refers to the motion of both wheels on an axle, and is only ever used to describe the motion with springs / shocks installed.
For example, wheel travel can have two different "values":
- a theoretical maximum value, in both ride and flex modes, that is limited by link geometry, driveline angles, and tire to chassis / body clearance; and
- an actual installed value, measured or calculated with the springs and shocks (and bumpstops and limit straps) installed.
In contrast, suspension travel, meaning the motion of the entire suspension as a whole, has only an actual installed value measured or calculated with the springs and shocks (and bumpstops and limit straps) installed.
Clearly many of these travel terms are interchangeable and may be used in more than one context. Care is required when both reading and writing so that confusion may be eliminated or at least reduced to a minimum. With regards to this article, I shall attempt, as far as possible, to stick to the following conventions:
Referring to shock travel - compression & rebound
Referring to spring travel - compression / deflection & rebound
Referring to ride travel - bump & droop
Referring to flex - bump & droop
Oscillation: Oscillation is a back-and-forth motion. A spring compressing and rebounding is an example of oscillation.
Force: A force is simply a push or a pull. When we apply a force to something, we push it or pull it. Force = Mass times Acceleration. Load is synonymous – when something experiences a load, it has a force applied to it. Weight is a particular load or force, it is the mass of an object multiplied by the acceleration due to gravity, measured in pounds.
An Important Note on Ride Travel
Ride travel is the simplest mode of travel to model and to understand. Modeling the suspension in terms of ride travel forms the basis for understanding shock and spring geometry. Once we have a firm grasp of the basics, we can then move on to modelling and design in the other modes of travel, which are more complicated. For this reason, Part 1 of the Coilover Bible is written primarily with ride travel in mind, unless otherwise specified.
Ride Height (RH)
The height of the chassis or frame above the ground, measured in inches when the vehicle is at static rest - i.e. sitting still on level ground.
Ride height is a fundamental component of vehicle design and is arrived at through careful consideration of the compromises between ground clearance, suspension travel, and stability.
Suspension Height (SH)
The position in the suspension's travel where the vehicle sits at ride height, expressed as the amount of droop travel available from static rest, quantified by either:
the number of inches of available droop, or
the percentage of total suspension travel that is available for droop.
In the latter case, the following examples illustrate the concept:
Suspension Height 0% = suspension at full droop. No more droop available.
Suspension height 50% = suspension in the middle of its travel. Equal amounts of droop and bump available.
Suspension height 100% = suspension at full compression. No bump available.
Suspension height for high speed desert applications usually varies from 30% to 50%. Suspension height for slow speed rockcrawler applications usually varies from 50% to 70%.
Wheel Travel (WT)
The total vertical travel of the wheel as the wheel goes from full droop to full bump. Can be expressed for ride travel or flex travel, with values often varying between the two. In this article we shall concern ourselves with wheel travel in ride mode, and discuss other modes in later issues. Wheel travel is a separate value for front and rear axles, although these values can be equal.
There are two "values" for wheel travel – “max theoretical” and “actual installed”.
Maximum theoretical wheel travel is measured with shocks and springs disconnected. It is limited by link geometry, tire to body clearance, or steering and driveshaft bind.
Actual installed wheel travel is the wheel travel achieved by the complete, installed suspension, including shocks, springs, limit straps and bumpstops.
To measure wheel travel:
Support the vehicle chassis with a lift or jack-stands so that the sprung weight is not on the suspension.
Working on one axle at a time, remove the shocks, springs, and any anti-roll bar if installed (for measurement of "max theoretical" wheel travel only).
In ride travel mode, bring the axle (i.e. both wheels) to full droop, measure from the floor to the centre of the wheel hub, and note the distance.
In ride travel mode, bring the axle (i.e. both wheels) to full bump, measure from the floor to the centre of the wheel hub, and note the distance.
Make sure that no suspension link binds with wheels turned to full left and full right. Also check that the desired tire to body clearance is maintained, check all other components (brake components, brake lines, wires, sensors, drive-axles, drive-shafts, CV joints, U-joints and etc.) to make sure they can function properly and that there are no clearance issues.
The difference between the two noted distances is the wheel travel.
Droop Travel (DT)
The amount of wheel travel, measured from static rest, available for suspension droop. May be expressed as a length, in inches, or as a percentage of total available wheel travel. When expressed as a percentage of total available wheel travel, it is known as suspension height.
Droop travel is also known as down travel, droop, or rebound travel,
Bump Travel (BT)
The amount of wheel travel, measured from static rest, available for bump, or compression. May be expressed as a length, in inches, or as a percentage of total available wheel travel. Equal to total wheel travel minus droop travel (suspension height).
Modes of Travel, Ride Height, Suspension Height, & Wheel Travel
Now that we have basic understanding of suspension components and their function, let’s cover a some key suspension terms and definitions. These definitions, and indeed this entire article, is unapologetically written assuming the vehicle has solid axles installed at both front and rear of the vehicle. Unless otherwise specifically mentioned to the contrary, you should read this article assuming we're discussing solid axle suspensions.
Travel: In the strictest sense, travel is just the movement or motion of some component of the suspension, or of the suspension as a whole. All moving components of the suspension have their own travel, thus we have wheel travel, spring travel, shock travel, and suspension travel.
We can speak of either "total" travel, meaning the entire range of motion from one extreme to another - e.g. "total wheel travel"; or we can speak of some portion of travel -e.g. "up-travel"
If we're talking about only some portion of travel, we qualify it in one of two ways:
If we're talking about the wheels or suspension as a whole we describe it by direction - e.g. up-travel or down-travel; or
If we're talking about the shocks or springs, we describe it by the effect on the component - e.g. shock compression.
If we're talking about the travel of the shocks or springs we have:
Compression: Travel of the spring or shock that occurs as it gets shorter. Spring compression is also known as deflection, crush, displacement from free length, or simply, displacement.
Rebound: Travel of the spring or shock that occurs as it gets longer. Also known as extension.
If we're talking about the travel of the wheels or suspension as a whole, before we qualify the direction of the travel, we must first distinguish the "mode" of travel. There are three modes of travel, distinguished by how the wheels and chassis are moving relative to one-another. They are:
Ride: The vertical travel that occurs when both wheels on an axle move together the same distance at the same time, relative to the chassis. If both wheels on a solid axle hit a speed-bump at the same time the resulting wheel or suspension travel would be ride travel. During ride travel, the axle remains parallel to the ground and both wheels on that axle remain, more or less, perpendicular to the ground. Sometimes ride is also called heave. Ride travel can be subdivided into:
Compression / Up-travel / Bump - terms that describe the ride travel that occurs when the wheels get closer to the chassis.
Rebound / Down-travel / Droop - terms that describe the ride travel that occurs when the wheels get farther away from the chassis.
Flex: The suspension travel that occurs when one wheel on an axle moves closer to the chassis and the other wheel on that axle moves farther away from the chassis. During flex the wheels on the other axle move in the same direction as their diagonal opposites. In other words, if you stuff the right front wheel, you also stuff the left rear wheel, while the other two wheels droop. Also known as warp travel or articulation. Flex travel can be subdivided into:
Compression / Up-travel / Bump / Jounce / Stuff - terms that describe the motion of the wheels that get closer to the chassis.
Rebound / Down-travel / Droop - terms that describe the motion of the wheels that get farther away from the chassis.
Roll: Roll is the motion that occurs when all four wheels remain more or less fixed in position and the chassis moves relative to the wheels. In roll, the chassis pivots about an imaginary longitudinal axis in such a way that it gets closer to the wheels on one side of the vehicle, and farther away from the wheels on the opposite side. Also known as body-roll or sway, roll is generally an unwanted motion that is related to, but not the same as, flex.
The following diagrams should help clarify the different modes of travel:
Ride Travel.
Axle remains parallel to the ground as it travels vertically.
Flex Travel.
Rear axle shown. Front axle will be articulating in opposite direction.
Roll.
Note distinction between flex and roll.
In flex, wheels at opposite corners are doing the same thing (both getting closer too, or farther away from, the chassis).
Whilst in roll, wheels on the same side are doing the same thing (both getting closer to, or father away from, the chassis).
You may be wondering about the distinction between wheel travel and suspension travel. The terms are very closely related and often used interchangeably. However, there is a distinction worth noting:
Wheel travel generally refers to the motion of one wheel on an axle, and can be used to describe that motion either with or without springs / shocks installed.
Suspension travel generally refers to the motion of both wheels on an axle, and is only ever used to describe the motion with springs / shocks installed.
For example, wheel travel can have two different "values":
- a theoretical maximum value, in both ride and flex modes, that is limited by link geometry, driveline angles, and tire to chassis / body clearance; and
- an actual installed value, measured or calculated with the springs and shocks (and bumpstops and limit straps) installed.
In contrast, suspension travel, meaning the motion of the entire suspension as a whole, has only an actual installed value measured or calculated with the springs and shocks (and bumpstops and limit straps) installed.
Clearly many of these travel terms are interchangeable and may be used in more than one context. Care is required when both reading and writing so that confusion may be eliminated or at least reduced to a minimum. With regards to this article, I shall attempt, as far as possible, to stick to the following conventions:
Referring to shock travel - compression & rebound
Referring to spring travel - compression / deflection & rebound
Referring to ride travel - bump & droop
Referring to flex - bump & droop
Oscillation: Oscillation is a back-and-forth motion. A spring compressing and rebounding is an example of oscillation.
Force: A force is simply a push or a pull. When we apply a force to something, we push it or pull it. Force = Mass times Acceleration. Load is synonymous – when something experiences a load, it has a force applied to it. Weight is a particular load or force, it is the mass of an object multiplied by the acceleration due to gravity, measured in pounds.
An Important Note on Ride Travel
Ride travel is the simplest mode of travel to model and to understand. Modeling the suspension in terms of ride travel forms the basis for understanding shock and spring geometry. Once we have a firm grasp of the basics, we can then move on to modelling and design in the other modes of travel, which are more complicated. For this reason, Part 1 of the Coilover Bible is written primarily with ride travel in mind, unless otherwise specified.
Ride Height (RH)
The height of the chassis or frame above the ground, measured in inches when the vehicle is at static rest - i.e. sitting still on level ground.
Ride height is a fundamental component of vehicle design and is arrived at through careful consideration of the compromises between ground clearance, suspension travel, and stability.
Suspension Height (SH)
The position in the suspension's travel where the vehicle sits at ride height, expressed as the amount of droop travel available from static rest, quantified by either:
the number of inches of available droop, or
the percentage of total suspension travel that is available for droop.
In the latter case, the following examples illustrate the concept:
Suspension Height 0% = suspension at full droop. No more droop available.
Suspension height 50% = suspension in the middle of its travel. Equal amounts of droop and bump available.
Suspension height 100% = suspension at full compression. No bump available.
Suspension height for high speed desert applications usually varies from 30% to 50%. Suspension height for slow speed rockcrawler applications usually varies from 50% to 70%.
Wheel Travel (WT)
The total vertical travel of the wheel as the wheel goes from full droop to full bump. Can be expressed for ride travel or flex travel, with values often varying between the two. In this article we shall concern ourselves with wheel travel in ride mode, and discuss other modes in later issues. Wheel travel is a separate value for front and rear axles, although these values can be equal.
There are two "values" for wheel travel – “max theoretical” and “actual installed”.
Maximum theoretical wheel travel is measured with shocks and springs disconnected. It is limited by link geometry, tire to body clearance, or steering and driveshaft bind.
Actual installed wheel travel is the wheel travel achieved by the complete, installed suspension, including shocks, springs, limit straps and bumpstops.
To measure wheel travel:
Support the vehicle chassis with a lift or jack-stands so that the sprung weight is not on the suspension.
Working on one axle at a time, remove the shocks, springs, and any anti-roll bar if installed (for measurement of "max theoretical" wheel travel only).
In ride travel mode, bring the axle (i.e. both wheels) to full droop, measure from the floor to the centre of the wheel hub, and note the distance.
In ride travel mode, bring the axle (i.e. both wheels) to full bump, measure from the floor to the centre of the wheel hub, and note the distance.
Make sure that no suspension link binds with wheels turned to full left and full right. Also check that the desired tire to body clearance is maintained, check all other components (brake components, brake lines, wires, sensors, drive-axles, drive-shafts, CV joints, U-joints and etc.) to make sure they can function properly and that there are no clearance issues.
The difference between the two noted distances is the wheel travel.
Droop Travel (DT)
The amount of wheel travel, measured from static rest, available for suspension droop. May be expressed as a length, in inches, or as a percentage of total available wheel travel. When expressed as a percentage of total available wheel travel, it is known as suspension height.
Droop travel is also known as down travel, droop, or rebound travel,
Bump Travel (BT)
The amount of wheel travel, measured from static rest, available for bump, or compression. May be expressed as a length, in inches, or as a percentage of total available wheel travel. Equal to total wheel travel minus droop travel (suspension height).
Attachments
gbrown27
Full Access Member
bump
Johnny
Full Access Member
im checking on the springs still havnt got a shipping update but should be anyday
---------- Post added at 11:11 AM ---------- Previous post was at 11:10 AM ----------
No they are made for stock shocks
---------- Post added at 11:11 AM ---------- Previous post was at 11:10 AM ----------
No they are made for stock shocks
gbrown27
Full Access Member
Any ideas on pricing?
Yukon Joe
FRF Addict
heres the other spring installed in the top perch
Completely off topic, but what is the push bar on the front of the blue raptor?
Thanks,
Yukon Joe
Buffalo Run Support Raptor
http://www.fordraptorforum.com/showthread.php?p=364119
gbrown27
Full Access Member
Any updates on pricing? also, how do these ride on and off road compared to stock?
gbrown27
Full Access Member
its between these and icon 3.0's. i need a price so i can decide within the next week
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