Clunk from the Driveshaft... I think

[notfastenuf]

Let me preface this by saying, I've swapped a lot of the suspension in the past month and by all means, expect a decent amount of NVH. It's happened before on other Cobras, it happens now. I get it.

Recently installed...
FFRP springs, d-specs, Eibach Sways, J&M adjustable PHB and UCA, and LCAs and a Metco UCA mount. All installed with decent ease. I still have the stock d/s.

I am having some clunking emanating from the rear end when I'm going easy on the gas - it happens most frequently going from reverse to first but can happen between other gears as well - clunk, as in just once when it occurs. I can without a doubt say everything has been torqued and retorqued - everything has been checked. So I thought it may have been the driveshaft... stock - ended up finding the thread below and from his description, thought that was it.

http://www.svtperformance.com/forums/shelby-gt500-150/714414-rear-end-clunk.html

Got under it today and all the bolts where tight, at least the ones I could get to - only 9k miles and I've never removed the driveshaft. There is however significant play in the driveshaft - meaning, I'm able to rotate it some, probably 5 degrees - is that normal in these cars? Is there a companion flange farther up that buts against the transmission and if so, can I get to this easily?

I think the warranty is good till October so I'm about to run it up there, but wanted to check here first. Anything else I'm missing? And is the dealer going to tell me to kick rocks because of the mods on the suspension? Thanks guys.

 

[Proto]

Check for witness marks. I had the same identical problem and it turned out to be the UCA adjustment nuts, worked themselves finger loose. Doubt it's the driveshaft to be honest. I drag the car frequently, and stuff just gets loose sometimes.

 

[cbarile]

As stated above i had the exact same thing happen. My upper control arm bracket bolts loosened up and had the clunk reverse to first.

 

[brian70068]

http://www.svtperformance.com/forums/shelby-gt500-150/714414-rear-end-clunk.html my car was doing the samething I thought it was one of my control arms but it was the driveshaft

 

[lkatya]

UCA bracket, those fuggers are tuff.

 

[notfastenuf]

UCA bracket, those fuggers are tuff.

sorry, should have mentioned it was happening before the UCA mount install.

 

[notfastenuf]

http://www.svtperformance.com/forums/shelby-gt500-150/714414-rear-end-clunk.html my car was doing the samething I thought it was one of my control arms but it was the driveshaft

Did the dealership take care of it for you?

 

[Proto]

in for an update

 

[notfastenuf]

in for an update

taking it on Monday morning - read a couple threads over at GT500 forums that alluded to it being in the rear-end itself. Will report back. The tech looking at it has an '10 or '11 GT500 and knows his SVTs from what I've been told - was referred to him from another member here.

 

[inyadreems]

taking it on Monday morning - read a couple threads over at GT500 forums that alluded to it being in the rear-end itself. Will report back. The tech looking at it has an '10 or '11 GT500 and knows his SVTs from what I've been told - was referred to him from another member here.

Hey, I am in the same boat, what was the outcome? Did you solve the "clunk" problem yet?

 

[notfastenuf]

Hey, I am in the same boat, what was the outcome? Did you solve the "clunk" problem yet?

Sorry took so long to get back. I spent about 30 minutes with the tech in the afternoon after picking it up. He drove it in the morning and essentially he said it came down to NVH - tech stated the parts were torqued fine and setup correctly. It wasn't the driveshaft, pinion angle is fine.

Essentially the 'clunk' comes at tip-in and resinates through the gears in the pumpkin. Why? I don't know - he doesn't know; but when he's cracked them open before, the rear ends have been fine - he was aware of the issue with rear end parts upgrades. He did say that he's seen a couple guys change their gears for another ratio and the problem went away. Again, why would that matter if mine was setup correctly? He thought the noise was directly related to the harsher parts installed that removed any cusioning in the rear. I totally can buy this, but why is it not so on every GT500 from this gen? That is what I don't get. If it's a J&M thing, I'll gladly ditch them, but I know there are guys on here with similar setups that don't have the problem. I tend not to think it's a brand issue but maybe I'll try a Metco setup in the future.

Thoughts welcome.

 

[inyadreems]

UPDATE:

Clunk is not UCA. Took UCA and mount out of the car and torqued UCA on a vice. It was NOT torqued to 129 ft lbs. Retorqued everything again for the third time and still have the noise. My bud has 2 Shelby's and one is heavily modified. The drivetrain play and noise seem to be more in my car then in his. My gear lash is set 12 thousandths , the factory range is 8-12 thousandths. The only thing else to try is disassembling the rear and setting the gear lash at 8 thousandths. I seem to remember a post in which a GT500 owner swapped out his gears for 3.73's and the clunk went away, maybe because the gear lash was set closer to 8 thousandths.

Maybe I get get the dealer to adjust the gear lash to 8 thousandths and see if that solves the "clunk".

 

[me32]

That's way too much. That rear has too much play. I don't like to see any 8.8 gear setup more than 9 thousandths. Idea is .006-.008

 

[manOwar]

It's the pinion angle...

 

[Robertt305]

I say pinion angle... And mechanic can say it's fine but I would measure it myself to make sure.

I was off 2 degrees and getting all types of crazy noises.