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Another UCA "clunk" thread


inyadreems
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Before I explain, 2 things: Not looking to make this a debate on which UCA's or LCA's are better than the next one and in no way shape or form is this negative post about the manufacturer.

 

After doing research on TS and GT500 I decided to purchase the J&M Non-Adj UCA, LCA's and Adj Panhard Bar (street versions) for my 2010 GT500 to eliminate my wheel hop. My car is mostly spiritedly driven on the street.

 

 

My Ford SVT tech did the install. All J&M directions were precisely followed. The pinion angle was within spec and the rear centered to Ford specs. (Note the car is NOT lowered, stock wheels and tires and stock suspension, we reused the original bolts, anti-clunking bushings and lubed all parts very well). The wheel hop is gone and the car takes off nice and straight while spinning but I developed a clunking noise coming from the rear when on and off the gas while in gear and sometimes over bumps.

 

After talking to Brian at Hotparts, I took my car back to the dealer and the tech went over every bolt re-torqueing them to specs, but the noise is still there. Nothing seems loose; there are no scorch marks on any of the suspension parts that would indicate movement. With the car on the lift and the tech underneath you can hear the noise inside the car when engaging the clutch/gears, but you don't hear it underneath the car. The noise gets louder when the back seat is removed but the UCA mount bolt is torqued and tight. I drove the car with the backseat out and the tech in the passenger seat holding the bolt underneath the seat and there is no movement or play from the bolt. We also lightly used a pry bar on the suspension parts and no noise or movement.

 

Anyone one have a clue what it could be?

 

 

Edited by inyadreems
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Just two ideas that come off the top of my head, are rear gears making noise- backlash and runout clearances. However, more likely it could be bushing noise from the UCA or LCAs. Even if the bolt is tight, there could be too much clearance between the circumference of the bolt and the circumference of the bushing sleeve.

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Thanx for the replies:

 

"Even if the bolt is tight, there could be too much clearance between the circumference of the bolt and the circumference of the bushing sleeve"

 

The anti clunking bushings are suppose to take up the slop with the bolt on the mount.

Anti-Clunk.jpg

 

"I would go with the bolt to sleeve clearance , you mentioned you re-used the original bolts . Check to see if the ones that were supplied have a larger dia."

No bolts were supplied with the J&M UCA.

Edited by inyadreems
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The anti-clunk bushings on my 08 GT500 with the J&M non-adjustible UCA work without incident. Yes, I hear more rear-end noise but no clunking to speak of. I am purplexed by your issue.

 

 

Yes I hear more rear end noise too and plan to dynamat underneath the rear seat to keep the noise out of the engine compartment. This noise is specifically heard when driving while in a any gear and getting on or off the throttle.

 

I guess I should check the bushing in the rear. 07-2937 Where did you get a poly bushing for the rear? or did you use a rubber?

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I have also heard of this problem to my dismay. I think it is a shame. Could it be too much clearance inside the new bushing sleeve and the stock bolt? The anti-clunk bushings take up the slop between the control arm and the bolt but not the sleeve.

Edited by Secondo
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I have also heard of this problem to my dismay. I think it is a shame. Could it be too much clearance inside the new bushing sleeve and the stock bolt? The anti-clunk bushings take up the slop between the control arm and the bolt but not the sleeve.

 

 

Yeah I was thinking that too. I am going to have the Tech talk to J&M and see if they can figure it out.

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My Ford SVT tech did the install. All J&M directions were precisely followed. The pinion angle was within spec and the rear centered to Ford specs. (Note the car is NOT lowered, stock wheels and tires and stock suspension, we reused the original bolts, anti-clunking bushings and lubed all parts very well). The wheel hop is gone and the car takes off nice and straight while spinning but I developed a clunking noise coming from the rear when on and off the gas while in gear and sometimes over bumps.

Anyone one have a clue what it could be?

 

 

I had the same exact symptom when I put my Roush UCA and adjustable UCA bracket on my '10 GT500. When I hit a bump or went from accell to decell (and vice versa). My driveway is inclined slightly uphill into my garage and if I let the car roll back a little then hit the brake, I'd get the clunk.

 

My first suspicion was my UCA bracket. I pulled the rear seat and got out my torque wrench. I checked the torque spec (I THINK it was 130 lb/ft) and applied it to the bolt under the seat (ease of access).

 

DAMN! What *I* thought was tight wasn't nearly as tight as what Roush thought was tight. I torqued it to spec then jacked up the rear of the car and checked the other two bolts. SAME THING. I *thought* I had them TIGHT....they were nowhere near as tight as they should have been.

 

Once I torqued the UCA bracket bolts to spec, NO MORE CLUNK.

 

I will say that I also torqued the two cross bolts to spec "while I was there" (the two on either end of the UCA) but I don't believe either one of them was significant.

 

It's easy to check, at least the one under the seat. I have a Snap-On "click type" 1/2 drive torqe wrench that's at least 1-1/2 ft. long and I had to put some OOMPH on it to get it to spec., which is why I *thought* I had it tight just using my ratchet.

 

That may or may not be your problem but it's easy enough to check and since you are describing my very same symptoms, I'd start there.

 

 

HTH,

Phill

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I had the same exact symptom when I put my Roush UCA and adjustable UCA bracket on my '10 GT500. When I hit a bump or went from accell to decell (and vice versa). My driveway is inclined slightly uphill into my garage and if I let the car roll back a little then hit the brake, I'd get the clunk.

 

My first suspicion was my UCA bracket. I pulled the rear seat and got out my torque wrench. I checked the torque spec (I THINK it was 130 lb/ft) and applied it to the bolt under the seat (ease of access).

 

DAMN! What *I* thought was tight wasn't nearly as tight as what Roush thought was tight. I torqued it to spec then jacked up the rear of the car and checked the other two bolts. SAME THING. I *thought* I had them TIGHT....they were nowhere near as tight as they should have been.

 

Once I torqued the UCA bracket bolts to spec, NO MORE CLUNK.

 

I will say that I also torqued the two cross bolts to spec "while I was there" (the two on either end of the UCA) but I don't believe either one of them was significant.

 

It's easy to check, at least the one under the seat. I have a Snap-On "click type" 1/2 drive torqe wrench that's at least 1-1/2 ft. long and I had to put some OOMPH on it to get it to spec., which is why I *thought* I had it tight just using my ratchet.

 

That may or may not be your problem but it's easy enough to check and since you are describing my very same symptoms, I'd start there.

 

 

HTH,

Phill

 

 

Phil, thanx for the reply. I have had the Ford Tech torque all the bolts to factory specs twice already. I am waiting for the weather to clear up so my buds and I can toy around with it and see if we can isolate the problem.

 

Question: My rear was not centered to Ford Specs with the stock pan hard bar. We centered the rear to specs with the J&M APHB. Does anyone think the centering of the rear has thrown off the driveshaft, pinion angle or backlash??

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Question: My rear was not centered to Ford Specs with the stock pan hard bar. We centered the rear to specs with the J&M APHB. Does anyone think the centering of the rear has thrown off the driveshaft, pinion angle or backlash??

 

 

No.

 

It can NOT change the backlash as that is a function of pinion depth and ring gear location (from side to side in the diff case).

 

It won't change the pinion angle in the sense that we all speak of (pinion nose-verticle plane vs horizontal plane) but it could change the side angle. Having said that, if the rear alxe is off enough to adversely affect the side angle you'd have one tire sticking out the side of the car.

 

I used a Shelby (BMR) adjustable panhard bar to center my rear axle and my noise is gone (once I located the culprit).

 

It doesn't matter what brand panhard bar (or relocator) you use, centered is centered.

 

Did you use a string and plumb bob to center it with? Just hold the string on the edge of the fenderwell lip and measure the distance from it to the nearest point on the tire sidewall. Mine ended up with the small lip on the tire being *exactly* plumb with the fender lip, both sides.

 

 

HTH,

Phill

Edited by 2010KonaBlueGT
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No.

 

It can NOT change the backlash as that is a function of pinion depth and ring gear location (from side to side in the diff case).

 

It won't change the pinion angle in the sense that we all speak of (pinion nose-verticle plain vs horizontal plain) but it could change the side angle. Having said that, if the rear alxe is off enough to adversely affect the side angle you'd have one tire sticking out the side of the car.

 

I used a Shelby (BMR) adjustable panhard bar to center my rear axle and my noise is gone (once I located the culprit).

 

It doesn't matter what brand panhard bar (or relocator) you use, centered is centered.

 

Did you use a string and plumb bob to center it with? Just hold the string on the edge of the fenderwell lip and measure the distance from it to the nearest point on the tire sidewall. Mine ended up with the small lip on the tire being *exactly* plumb with the fender lip, both sides.

 

 

HTH,

Phill

 

Yes we used a string and plumb bob to center it. I will see if I can figure it out this weekend.

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  • 2 months later...

Today we found the culprit. When u turn the drive shaft manually left and right it makes a "clunking noise". Took the diff cover off and no metal shavings at all, gears look perfect, lash was within Ford spec (12,000), clutch paks and spider gears look good. The pinion angle was checked and it was within Ford spec also (-2). Put the cover back and refilled with RP and friction modifier. All work has been performed by an SVT mechanic.

 

Any idea what it could be? Could it be the pinion angle?

 

Thanx

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Today we found the culprit. When u turn the drive shaft manually left and right it makes a "clunking noise". Took the diff cover off and no metal shavings at all, gears look perfect, lash was within Ford spec (12,000), clutch paks and spider gears look good. The pinion angle was checked and it was within Ford spec also (-2). Put the cover back and refilled with RP and friction modifier. All work has been performed by an SVT mechanic.

 

Any idea what it could be? Could it be the pinion angle?

 

Thanx

 

The clunking could be comming from your adjustable panhard rod mount on the passenger side. The bolt hole is excessive on some of the cars, the design of the stock PHR works but the aftermarket rod may be moving just enough to cause the clunk. I had this problem on my 07 and corrected it by having a steel washer welded to the mount hole. It's worth a look.

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The clunking could be comming from your adjustable panhard rod mount on the passenger side. The bolt hole is excessive on some of the cars, the design of the stock PHR works but the aftermarket rod may be moving just enough to cause the clunk. I had this problem on my 07 and corrected it by having a steel washer welded to the mount hole. It's worth a look.

 

 

Ok thanx, will do.

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  • 7 months later...

When you replaced the UCA mounting bracket? I had an UCA arm put on but did not know to replace the mounting bracket as well. Within a month of driving I started having the same symptoms you describe, everything was tight as you describe but yet I still had the clunk. After a little research I bought the UCA arm mounting bracket and replcaaed the stock one and the noise was gone. The stock one was not bent and all bushings looked good. My suggestion would be to get the mounting bracket ( http://www.google.com/imgres?imgurl=http://www.lethalperformance.com/images/medium/UCM002_MED.jpg&imgrefurl=http://www.lethalperformance.com/suspension-control-arms-upper-control-arms-bmr-fabrication-c-8485_9440_9447_9448_9449/bmr-2011-2012-shelby-gt500-upper-control-arm-mount-p-33224&h=409&w=525&sz=69&tbnid=4dDsEGwHhzvn_M:&tbnh=97&tbnw=125&zoom=1&docid=5lsG-9bcNlMBLM&sa=X&ei=gO9OT8C-HIrj0QGxuLm2DQ&ved=0CKIBEPUBMA4 ) if you have not already replaced it. Like I said all bolts were tightened to spec and still had noise with stock part. Good luck and reply with what you find.

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