Driveshaft clunk in reverse on first drive

[New recaros]

Yeah I understand that but that isn’t always the case either.

Ford would have engineered out that clunk, what ever it is.

 

[Old-Raptor-guy]

The hubs actually do engage for a short time, on first start up 1/4 mile I believe. longer when cold I believe. Let me go open the service manual

 

[Reaper308]

Ford would have engineered out that clunk, what ever it is.

Ok I will give you that 98% of the time the engineer who designed what ever component we are talking about, engineered it to work in conjunction with the rest of the components of said vehicle. But I also understand that they have a boss that is looking at cost verse reward when designing said component. “Will this component do its job and not fail, to then cause us to spend more money in repairs to fix that failure, if so then let’s spend some more on the front side to increase reliability of the component”. However if your telling me that the engineer was 100% thrilled with what was put out and they couldn’t have designed something more robust, that would handle more load or endurance than what they ended up going with due to cost then I am going to have to disagree. I do agree sometimes and probably most times using an inferior aftermarket product causes more trouble than good. But there are probably a good number of fabricators on this site that do their homework and either purchase from a very reputable aftermarket supplier or fab their own stuff to increase the ability of our trucks and aren’t doing this in anyway to cause more problems and are actually improving on the engineering the original Ford engineers wish they could have done if not for the bean counters tight strings. Now does that mean it’s always perfect right off the bat, no sir you sometimes have to mod as you go, to fit the need. Just my 2 cents!

 

[Sig Fanboy]

I used to have a very slight clunk, in reverse, on initial start up. I thought possible it was play in rear shock bushing but never really found out what it was, so mostly ignored it. I’ve since added FFR rear shocks and Deavers, the clunk is gone.All I got

 

[Old-Raptor-guy]

Ok I will give you that 98% of the time the engineer who designed what ever component we are talking about, engineered it to work in conjunction with the rest of the components of said vehicle. But I also understand that they have a boss that is looking at cost verse reward when designing said component. “Will this component do its job and not fail, to then cause us to spend more money in repairs to fix that failure, if so then let’s spend some more on the front side to increase reliability of the component”. However if your telling me that the engineer was 100% thrilled with what was put out and they couldn’t have designed something more robust, that would handle more load or endurance than what they ended up going with due to cost then I am going to have to disagree. I do agree sometimes and probably most times using an inferior aftermarket product causes more trouble than good. But there are probably a good number of fabricators on this site that do their homework and either purchase from a very reputable aftermarket supplier or fab their own stuff to increase the ability of our trucks and aren’t doing this in anyway to cause more problems and are actually improving on the engineering the original Ford engineers wish they could have done if not for the bean counters tight strings. Now does that mean it’s always perfect right off the bat, no sir you sometimes have to mod as you go, to fit the need. Just my 2 cents!

You understand that Bean counters have more say than engineering.

I knew (have not talk to him in about 12 years) one of the head engineers on the 6.0 powerstroke. He told me how the bean counters vetoed 2 items on the 6.0. #1 a VGT position sensor. #2 fuel pressure sensor.

Bean counters said it would add $167 to the price of the engine.

By 2010 it was proven that the inclusion of both sensors would have saved $870 per engine in warranty cost.

Since 2008 pretty much all diesels have had those sensors.

In 2005 when the new mustang came out the engineering team had looked at independent rear suspension but the bean counters said NO it would add $197 per vehicle. But......... by 2011 it was determined that keeping the solid axle had actually added $378 per car because by 2006 the machinery/tooling to make the solid axle was worn out and FORD had to invest $$$$$ in machinery to keep old technology vs switching to new tech (independent rear suspension) & new machinery at the same time.

 

[New recaros]

You understand that Bean counters have more say than engineering.

I knew (have not talk to him in about 12 years) one of the head engineers on the 6.0 powerstroke. He told me how the bean counters vetoed 2 items on the 6.0. #1 a VGT position sensor. #2 fuel pressure sensor.

Bean counters said it would add $167 to the price of the engine.

By 2010 it was proven that the inclusion of both sensors would have saved $870 per engine in warranty cost.

Since 2008 pretty much all diesels have had those sensors.

In 2005 when the new mustang came out the engineering team had looked at independent rear suspension but the bean counters said NO it would add $197 per vehicle. But......... by 2011 it was determined that keeping the solid axle had actually added $378 per car because by 2006 the machinery/tooling to make the solid axle was worn out and FORD had to invest $$$$$ in machinery to keep old technology vs switching to new tech (independent rear suspension) & new machinery at the same time.

In your power stroke case and the mustang case the VP or whom ever was tasked with selling the additional costs per vehicle did a poor job of identifying the consequences of not adding the suggested changes. What you stated shows Ford did engineer it correctly, but the consequences of failure was not identified. Mistakes happen and bean counter do get their way. Usually there is a trade off, they give you a fixed gross vehicle cost and you don’t get all you want. But clunking would have been fixed. I am not saying Denver or whomever is inferior, I am sure better in many ways. It just not engineered to be 100% compatible and sometimes requires additional parts to work.
I have been through many maintenance and design schools and training. Probably the best was mcs2 which is what keep airplanes flying.
Ever wonder that possibility Ford tried springs like Devers and ran into the same issue and their fix was the design they have?

 

[Old-Raptor-guy]

IWE operation per the service manual:

The IWE system uses a vacuum solenoid and vacuum actuated hubs to engage or disengage the front wheel hubs from the front half shafts.


When the 4WD system is in 2WD (2H) mode, the TCCM supplies a ground path to the IWE solenoid to apply engine vacuum to the IWEs thus disengaging the front hubs from the front half shafts. To maintain vacuum during all modes of engine operation, a one way vacuum check valve and a vacuum reservoir are positioned between the vacuum source and the IWE solenoid.


When operating in any 4WD mode, the TCCM does not supply the ground path to the IWE solenoid. Vacuum is not applied to the IWE . An internal spring keeps the IWE clutch ring engaging the front hub and the front half shaft.


The TCCM has two startup strategies that affect IWE operation after initial key cycle:

• When ambient temperature is below 32 F (0 C), the IWE engage after initial key cycle and a driven gear is selected. The hubs stay engaged regardless of a 4x4 mode change for approximately 2 miles (3km). Once the set distance has been achieved, the IWE disengage (if the vehicle is in 2WD (2H)). Distance traveled resets only if the temperature is below calibrated threshold and another key cycle occurs or if customer shifts to Park (P) and back to a driven gear within the same key cycle. The TCCM uses this strategy to warm up the front axle in cold temperatures to improve driveline synchronization.

• When ambient temperature is above 32 F (0 C), the IWE engage after the initial key cycle and a driven gear is selected. The hubs stay engaged regardless of a 4x4 mode change for approximately 0.5 miles (0.8km). Engagement only occurs once per key cycle and is not reset when shifting between Park (P) and Drive (D). The TCCM uses this strategy to delay vacuum use until vacuum-intensive engine startup has completed and sufficient vacuum is available to fully disengage the IWE .