Diagnosing drive train clunk (renamed thread).

[HoosierDaddy]

I have some play in the drive train causing a clunk as the slack is taken up or released. Probably either a U/CV joint or in the pumpkin. Easiest way to reproduce is by letting the clutch in or out while coasting.

The dealer called to say they couldn't work on it because it had an aftermarket clutch. When I told them it had the original factory clutch they then said I need to reinstall the factory shifter before they could diagnose.

I was not pleased and contacted the Service Manager. He got back saying it was miscommunication between the tech and the service writer. Mgr says the tech just wanted the writer to call me and ask if I had an aftermarket clutch because they couldn't go forward if I did. No real explanation about the shifter statement. But the mgr seemed genuinely interested in getting things right.

A little later, I got a call saying the diff was "bad" and they were putting me in Mustang loaner until its fixed. I went down and they had my 2016 GT PP on a lift with the trans and diff both drained. It seems they drained the trans because they noticed more than normal vibration thru the shift knob. I explained that was because the MGW shifter is trans mounted instead of body mounted.

Moving to the rear, they showed me that if they turned one wheel the other didn't move and concluded the diff was bad and drained it in preparation for replacing it.

I posted in the drivetrain forum to ask just how a Torsen should behave in that situation since I don't know. But I do know that a Torsen does behave differently than a clutch type in some situations and wonder if this is one of them.

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[Schwerin]

I took my car to Ford to get a rear main seal fixed, it was leaking. They fixed it... for about a year when it started to leak again. I took it back and they call me up letting me know they would have to replace it again. I asked if it was a common issue. They said it was not, who ever I took it to before just had done a shoddy job. At which point I said, "Well that would be you, in fact I even have the paperwork with your name on it." He just kinda stuttered and said they would get it fixed.

 

[el-guapin]

That SUX!.. Hate when they attempt to cover up faulty eq or shady work done at their shop!!.. And according to Buzz A. , we never went to the moon!

 

[Anthony 05 GT]

That SUX!.. Hate when they attempt to cover up faulty eq or shady work done at their shop!!.. And according to Buzz A. , we never went to the moon!

https://www.snopes.com/fact-check/moony-tunes/

https://www.metro.us/news/the-moon-landing-was-fake-truth-buzz-aldrin

 

[carter2980]

Took mine is for the same sound/symptom. Its been there over a month and the only thing they came back with recently was that the 2nd and 4th gear synchros were bad....

 

[HoosierDaddy]

Took mine is for the same sound/symptom. Its been there over a month and the only thing they came back with recently was that the 2nd and 4th gear synchros were bad....

I'm pretty sure I have a different issue and the clunk may not even be a problem. It just felt like there was more slack than when new and when the slack was taken up or relieved is exactly when the clunk was felt. I can easily live with it if its normal and not a sign of something about to fail. When on the lift they showed me the slack at every joint between trans and wheel and said it was normal. None of the individual joints slack seemed worrisome, but what do I know? I would be interested in how many total degrees of slack from trans to wheel is "okay".

And I did not mention before that they said neither the trans or diff fluid had any metal in it when they drained it. I don't believe that literally since some would be normal but that they meant nothing unusual. But I observed the actual fluid they drained and did not see any metal flakes on the surface. Which adds to my confusion about the bad diff diagnosis. If you know the components of a Torsen, it is comprised solely of shafts and constantly messing gears. And there are basically 3 sets of them to spread the load. For the life of me, I can't imagine any way a Torsen can "fail" without a lot of really big chunks of metal laying loose and it sounding like hell when turned. When I spun one rear wheel on a lift after they drained the fluid, it spun freely with no hangs or noise.

 

[HoosierDaddy]

https://www.snopes.com/fact-check/moony-tunes/

https://www.metro.us/news/the-moon-landing-was-fake-truth-buzz-aldrin

Thanks for the links. LoL. And if anyone was wondering why @el-guapin and @Anthony 05 GT posted anything about the moon landing, it was in reference to something in my original post that I later removed due to it being too much sarcasm even for me.

 

[carter2980]

Yeah I was confused by what my tech had said the issue was because it had nothing to do with the sound I was hearing coming from what seem to be slack in the driveshaft whenever I presss the clutch in while coasting. Ford just sent out a service engineer to look more into it today so I’ll have to give the rundown to him now.

 

[HoosierDaddy]

Yeah I was confused by what my tech had said the issue was because it had nothing to do with the sound I was hearing coming from what seem to be slack in the driveshaft whenever I presss the clutch in while coasting. Ford just sent out a service engineer to look more into it today so I’ll have to give the rundown to him now.

My clunk (more felt than heard) does occur when coasting and pressing or releasing the clutch and seemed to me likely to much play in a U/CV jount or in the diff. Will be interested in what your's turns out to be. I could have the same thing going on.

 

[HoosierDaddy]

Glad to report Ford told the dealer the diff is fine. I'm picking up the car today.

Too bad they drained my BC fluids to look for metal in the trans and diff. Guess I need to order another kit. Probably will wait until summer to install the diff fluid. Might as well get some use out of the Ford stuff.

 

[carter2980]

Haha the same thing happened to me, I had just put BG in it right before I brought it in. Good to know they gave you the all clear.

 

[jasonstang]

My clunk (more felt than heard) does occur when coasting and pressing or releasing the clutch and seemed to me likely to much play in a U/CV jount or in the diff. Will be interested in what your's turns out to be. I could have the same thing going on.

Nothing you can do just sloppy tolerance.

 

[carter2980]

Indeed.

 

[HoosierDaddy]

Well it was worth it just to watch the dash cam recordings. Thankfully no car abuse, but the dialogs between the techs while driving and working on the lift were classic. Closest thing to risk of the car was when they drove past the construction site for another car dealer that was breaking ground and apparently had the press and the Cardinal cheerleaders there. You could almost feel the Tech's heart rate go up as the car drifted ever so slightly out of its lane. If you are of the Cheers generation, think Cliff Clavin when a beautiful woman walks into the bar. LoL

 

[NvrFinished]

The clunking is normal. The main culprit is the larger backlash setting that is required for the Torsen differential. Everyone has the clunk, some more than others. A one piece driveshaft reduced the clunking noise for me, but it's not the reason I installed it. Another option that someone did was take his car to a driveline shop and have them adjust the backlash. They were able to reduce the backlash some. It reduced the clunk noticeably, but it's still there.

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