AlbertaRaptor
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Axle hop explanation and a cheap cure
I started a thread asking about other brands of leaf springs that may eliminate the rear lift block without the expense of certain replacement leaf springs such as the deaver springs.
Now I just want to make clear that I am not trying to say that any spring company is over priced or that they are not the best solution for the 25% of the raptor owners that demand the very best "money is no object" solution to our rear suspension issues.
I want to say that there are 75% of us Raptor owners that may not need those springs and I've done a ton of research to back up what I'm about to write. Please feel free to do the same and contribute to this thread.
The ideas, theories and real world solution I am to write come from 25 years personal experience in suspension systems and although the Raptor is new to me the basics of a leaf spring suspension is all relatively the same for the last 100 years.
Our first thing to understand is what is wheel hop? Wheel hop is uncontrolled up and down motion of our axle and more than a few factors on a Raptor come into play here but the basic facts on this are found by understanding that tall tires and huge torque make this issue very apparent. Do a quick math equation and you'll notice something right off....
Here is an example of torque multiplication when you compare a 1970 LS6 SS454 Chevelle to a Raptor:
500lbs of torque at 3200 rpm multiplied through a turbo 400 transmission with a 2:48 first gear ratio to a 4:10 final rear axle ratio
500x2.48x4.10= 5084lbs of torque
math freaks and true rodders will argue torque converter multiplication, tire heights etc, but I'm just trying to show what we are dealing with in simplistic easy to understand terms
here is a 2011 Shelby GT 500
510lbs of torque at 4250 rpm 2:97 first gear ratio with 3:73 rear gears = 5649 ft lbs of torque
2011 Raptor 434 ft lbs at 4500 4:17 first gear ratio and 4:10 final drive
434x4.17x4.10 equals an amazing 7421 ft lbs of torque!
So our fist issue is we have massive torque, the second is we have heavy tires and the truck itself is heavy.
Which leads us to our next issue and that is axle wrap
Axle wrap is uncontrolled pinion angle changes which causes the spring to "wrap" or bend out of it's original shape exactly like this:
When you combine the massive torque we have in a truck that wants to be sitting still due to its heavy weight and then throw in tall heavy tires to boot? We bend those rear leaf springs up like a pretzel especially when we sit our leaf springs on a lift block that acts as a fulcrum enabling the actual torque at the wheel to multiply through lever action and further bend the leaf springs.
So Deaver and National spring came up with perfect kick ass springs to fix this situation and they work great by using some technology that has been around for 41 years.
I mention 41 years because Chrysler of all people came up with a solution around 1970 to combate the axle wrap and hop that they experienced in their muscle cars. They designed the "super stock spring" which used more leaves, thinner metal and they stacked the springs closer to the front eyelet so that the axle couldn't wrap.These in conjunction with a pinion snubber are all it takes to hook up the best mopars without any ladder bar or traction bar usage....which leads me to the next point.
If you look at the two major players in our spring supply you will notice that the springs are thinner, they are longer so they reach closer to the eyelets of the leaf and they are clamped tight to resist the sliding of the leaves within the pack.....in other words they are kind of preloaded....
Now go look at your factory springs and note two things right off the bat:
Spring leaf layers that leave large gaps to the front eyelets. 3 inches on the secondary leaf and 17 inches on the lower leaf. You will also notice that our leaf clamp which comes from the factor has a gap of 3/8's of an inch for play which allows our leaves to arch at different rates which exagerates the axle wrap I explained....it basically leaves the main leaf to control all axle wrap by itself......**** poor idea when dealing with almost 8000 ft lbs of torque.
So now the cheaper solution:
I live near Edmonton Alberta Canada and like 99% of you reading this post there are local spring shops that can do cold metal re-arching of your factory springs....call and ask around, these places are everywhere.
Before anyone freaks out, this process has been done since the creation of the leaf spring, yes it will eventually sag...so will my springs anyways so who cares lol. The truth is the process will not last any less time than the factory spring can maintain its original strength anyways, because we aren't going to leave it all up to the factor main leaf.
We are changing the design...just a bit...just enough to fix this problem.
You add a secondary main leaf, an add a leaf if you will, be it one that is added to supliment the main leaf though. Does this add a harshness to the ride? no actually. Long leaf materials allow full flex and for most guys doing a top perch front spring adjustment it balances out the rear to match that ride quality.
The top spring is cold arched to match the amount of lift you ask for or to equalize the two sides of the truck so that you are starting out at an even level side to side...if you are leaving your truck at stock height.
For my choice I am raising the rear of the truck one inch higher than the front after the top perch adjustment so I have just a bit of difference front to rear.
The secondary spring that is added now will be located length wise to be about an inch from the front eyelet and the rear of the spring will stagger about an inch further towards the rear than your existing second factory leaf as that leaf will now become the third leaf.
What this does is it gives double the resistance to axle wrap than the factory springs are as is. I say double because the leaves are now going to be clamped tight, like the national, like the deaver, like any other decent non factory spring has been since the late 60's.
This means adding about 3/8's to 1/2 inch of height to the factory spring. Even guys that want the ****** diaper pre runner look can probably live with 1/2 an inch.
You cannot remove the lift block with this fix, but if you add the same thickness leaf as the main leaf you will not have axle wrap. If you eliminate axle wrap you don't change pinion angles. If you don't change pinion angles you do not have axle hop.
A cold re-arch with an added second leaf, staggered to provide support for the factory main leaf, tightly clamped together to work as a single unit will fix the problem.
Up here in Canada we just bend over and hold onto the edge of the desk when we ask prices on this custom work.
My quote including the 3 hours labor to remove and re-install my leafs is $700
Any leaf you buy will cost three hours labor to install unless you do it yourself. So for me thats $300 of that $700.
$400 to get my height levelled side to side with re-arch, new secondary leaf, new u-bolts ( a must for safety ) and additional clamping the factory never had is an absolute bargain compared to $1400-$1500 for new leafs.
For ME and I'm guessing 10,000 other owners, this is a viable solution without the use of traction bars etc.
I'm doing the top perch this week, I'm looking at the re-arch in the beginning of Feb. I will post pictures by the 10th of February I promise.
Jeff
p/s If you have the money buy the deavers or the National springs, they are the best solution
Jeff
I started a thread asking about other brands of leaf springs that may eliminate the rear lift block without the expense of certain replacement leaf springs such as the deaver springs.
Now I just want to make clear that I am not trying to say that any spring company is over priced or that they are not the best solution for the 25% of the raptor owners that demand the very best "money is no object" solution to our rear suspension issues.
I want to say that there are 75% of us Raptor owners that may not need those springs and I've done a ton of research to back up what I'm about to write. Please feel free to do the same and contribute to this thread.
The ideas, theories and real world solution I am to write come from 25 years personal experience in suspension systems and although the Raptor is new to me the basics of a leaf spring suspension is all relatively the same for the last 100 years.
Our first thing to understand is what is wheel hop? Wheel hop is uncontrolled up and down motion of our axle and more than a few factors on a Raptor come into play here but the basic facts on this are found by understanding that tall tires and huge torque make this issue very apparent. Do a quick math equation and you'll notice something right off....
Here is an example of torque multiplication when you compare a 1970 LS6 SS454 Chevelle to a Raptor:
500lbs of torque at 3200 rpm multiplied through a turbo 400 transmission with a 2:48 first gear ratio to a 4:10 final rear axle ratio
500x2.48x4.10= 5084lbs of torque
math freaks and true rodders will argue torque converter multiplication, tire heights etc, but I'm just trying to show what we are dealing with in simplistic easy to understand terms
here is a 2011 Shelby GT 500
510lbs of torque at 4250 rpm 2:97 first gear ratio with 3:73 rear gears = 5649 ft lbs of torque
2011 Raptor 434 ft lbs at 4500 4:17 first gear ratio and 4:10 final drive
434x4.17x4.10 equals an amazing 7421 ft lbs of torque!
So our fist issue is we have massive torque, the second is we have heavy tires and the truck itself is heavy.
Which leads us to our next issue and that is axle wrap
Axle wrap is uncontrolled pinion angle changes which causes the spring to "wrap" or bend out of it's original shape exactly like this:
When you combine the massive torque we have in a truck that wants to be sitting still due to its heavy weight and then throw in tall heavy tires to boot? We bend those rear leaf springs up like a pretzel especially when we sit our leaf springs on a lift block that acts as a fulcrum enabling the actual torque at the wheel to multiply through lever action and further bend the leaf springs.
So Deaver and National spring came up with perfect kick ass springs to fix this situation and they work great by using some technology that has been around for 41 years.
I mention 41 years because Chrysler of all people came up with a solution around 1970 to combate the axle wrap and hop that they experienced in their muscle cars. They designed the "super stock spring" which used more leaves, thinner metal and they stacked the springs closer to the front eyelet so that the axle couldn't wrap.These in conjunction with a pinion snubber are all it takes to hook up the best mopars without any ladder bar or traction bar usage....which leads me to the next point.
If you look at the two major players in our spring supply you will notice that the springs are thinner, they are longer so they reach closer to the eyelets of the leaf and they are clamped tight to resist the sliding of the leaves within the pack.....in other words they are kind of preloaded....
Now go look at your factory springs and note two things right off the bat:
Spring leaf layers that leave large gaps to the front eyelets. 3 inches on the secondary leaf and 17 inches on the lower leaf. You will also notice that our leaf clamp which comes from the factor has a gap of 3/8's of an inch for play which allows our leaves to arch at different rates which exagerates the axle wrap I explained....it basically leaves the main leaf to control all axle wrap by itself......**** poor idea when dealing with almost 8000 ft lbs of torque.
So now the cheaper solution:
I live near Edmonton Alberta Canada and like 99% of you reading this post there are local spring shops that can do cold metal re-arching of your factory springs....call and ask around, these places are everywhere.
Before anyone freaks out, this process has been done since the creation of the leaf spring, yes it will eventually sag...so will my springs anyways so who cares lol. The truth is the process will not last any less time than the factory spring can maintain its original strength anyways, because we aren't going to leave it all up to the factor main leaf.
We are changing the design...just a bit...just enough to fix this problem.
You add a secondary main leaf, an add a leaf if you will, be it one that is added to supliment the main leaf though. Does this add a harshness to the ride? no actually. Long leaf materials allow full flex and for most guys doing a top perch front spring adjustment it balances out the rear to match that ride quality.
The top spring is cold arched to match the amount of lift you ask for or to equalize the two sides of the truck so that you are starting out at an even level side to side...if you are leaving your truck at stock height.
For my choice I am raising the rear of the truck one inch higher than the front after the top perch adjustment so I have just a bit of difference front to rear.
The secondary spring that is added now will be located length wise to be about an inch from the front eyelet and the rear of the spring will stagger about an inch further towards the rear than your existing second factory leaf as that leaf will now become the third leaf.
What this does is it gives double the resistance to axle wrap than the factory springs are as is. I say double because the leaves are now going to be clamped tight, like the national, like the deaver, like any other decent non factory spring has been since the late 60's.
This means adding about 3/8's to 1/2 inch of height to the factory spring. Even guys that want the ****** diaper pre runner look can probably live with 1/2 an inch.
You cannot remove the lift block with this fix, but if you add the same thickness leaf as the main leaf you will not have axle wrap. If you eliminate axle wrap you don't change pinion angles. If you don't change pinion angles you do not have axle hop.
A cold re-arch with an added second leaf, staggered to provide support for the factory main leaf, tightly clamped together to work as a single unit will fix the problem.
Up here in Canada we just bend over and hold onto the edge of the desk when we ask prices on this custom work.
My quote including the 3 hours labor to remove and re-install my leafs is $700
Any leaf you buy will cost three hours labor to install unless you do it yourself. So for me thats $300 of that $700.
$400 to get my height levelled side to side with re-arch, new secondary leaf, new u-bolts ( a must for safety ) and additional clamping the factory never had is an absolute bargain compared to $1400-$1500 for new leafs.
For ME and I'm guessing 10,000 other owners, this is a viable solution without the use of traction bars etc.
I'm doing the top perch this week, I'm looking at the re-arch in the beginning of Feb. I will post pictures by the 10th of February I promise.
Jeff
p/s If you have the money buy the deavers or the National springs, they are the best solution
Jeff
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