Clunk in the rear after lowering

stang_gang

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Hey guys so recently I lowered my mustang with
Koni orange shock and struts
ford performance lowering springs
bmr adjustable panhard bar

But now I've been faced with this annoying clunk at low speeds while going down my drive way or some smaller bumps. I've retorqued all the bolts with weight on the suspension and I feel like it does it less. I also have gear whine from the back that I didn't have before too. Any suggestions on what I should do?
 

stkjock

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are the LCA/UCA stock?

sounds like you need to be able to adjust the pinon angle
 

stang_gang

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are the LCA/UCA stock?

sounds like you need to be able to adjust the pinon angle
yes stock uca and lca.

I figured the gear whine was from the pinion angle. But the clink i can’t figure it out

I torqued the Panhard Bar to 129 ft/lbs, end links to 90 ft/lbs, and lower shock bolts to 90 ft/lbs.
 
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pass1over

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I've been chasing a clunk in the rear of my car since I lowered it 6 years ago. Two different upper arms, sway bar end links, and bushings, torqued and retorqued everything multiple times. I only hear it when going down my bumpy rock/offroad driveway. I've just learned to live with it/turn the radio up.
 

stang_gang

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So the advice is to deal with the clunk but the gear whine isn't normal right?
 

rocky61201

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Did you install shorter jounce bumpers or at least cut yours down? Cutting an inch off the top of the jounce bumper is the easiest thing to do and it's free. You can probably get both of them off, cut them, and re-install them in less than 30 min.
 

01yellerCobra

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Could they be caused by the same thing? Maybe the clunk you're hearing has to do with the driveshaft angle. Have you checked the U joints and carrier bearing? If you still have the stock two piece set up.
 

stang_gang

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Did you install shorter jounce bumpers or at least cut yours down? Cutting an inch off the top of the jounce bumper is the easiest thing to do and it's free. You can probably get both of them off, cut them, and re-install them in less than 30 min.
No I haven’t yet, should I?
 

Mustang dog

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Have a look at the differential bushing. If it is torn and allowing the UCA to come into contact with it. Or the pinion angle is off and that is causing the contact.
 

bl817

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the gear whine was there previously but not noticeable account your stock panhard bar had rubber bushings. your new panhard bar has poly bushing that transmit the axle whine thru to the body and hence your hearing it more. also as mentioned above, if you lower your car with stock UCA and LCA, you are twisting the already old and worn out stock rubber bushings. also as mentioned above, my car clunks since I lowered it and replaced everything out back (BMR UCA mount, RTR UCA, JM LCA, JM adj panhard bar, poly bushings top to bottom). I wouldn't worry about the pinion angle much, it should still be within tolerance and your not going to be able to change it until you get adjustable control arms. good luck
 

stang_gang

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the gear whine was there previously but not noticeable account your stock panhard bar had rubber bushings. your new panhard bar has poly bushing that transmit the axle whine thru to the body and hence your hearing it more. also as mentioned above, if you lower your car with stock UCA and LCA, you are twisting the already old and worn out stock rubber bushings. also as mentioned above, my car clunks since I lowered it and replaced everything out back (BMR UCA mount, RTR UCA, JM LCA, JM adj panhard bar, poly bushings top to bottom). I wouldn't worry about the pinion angle much, it should still be within tolerance and your not going to be able to change it until you get adjustable control arms. good luck
I just bought a adjustable UCA and plan to install it this week. I'll let you know if it gets rid of the whine if it doesn't then I guess I will be looking at a Diff rebuild? I don't really know how to deal with gear whine so I'll probably be paying for a shop to do it.
 

bl817

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I think your missing the point of me saying that your panhard bar has poly bushings and is transferring the noise thru to the cabin. your rear diff is fine, always has been. its always been making that noise. the adjustable UCA is a good add but it will also (probably) have poly bushings or at least some that are harder than the stock rubber bushings, it will also add to the diff whine in the cabin. a better upgrade for the 05-09 cars is the 11-14 UCA and UCA mount. the later ones are about 1" longer and have more range of adjustment. they are however not interchangeable. you cannot use a 05-09 UCA with a 11-14 UCA mount and vice versa. good luck
 

stang_gang

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I think your missing the point of me saying that your panhard bar has poly bushings and is transferring the noise thru to the cabin. your rear diff is fine, always has been. its always been making that noise. the adjustable UCA is a good add but it will also (probably) have poly bushings or at least some that are harder than the stock rubber bushings, it will also add to the diff whine in the cabin. a better upgrade for the 05-09 cars is the 11-14 UCA and UCA mount. the later ones are about 1" longer and have more range of adjustment. they are however not interchangeable. you cannot use a 05-09 UCA with a 11-14 UCA mount and vice versa. good luck
I get your point and I don’t disagree that it might be that. From your own personal experience do you hear a whining as well in your own car?
 

1950StangJump$

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OP, my suspension is fully stock, though I do plan on going the BRM route with UCA, LCAs, panhard, shocks/struts, etc this summer. I recently had JPC install a Magnum XL and 4.10s. The first set of 4.10s whined. Eventually, they put more in a set that fixed the noise. But, here is my point:

When discussing the whine with the owner (who was great), the first thing he asked was whether I had aftermarket UCA and/or LCAs. He said EXACTLY what bl817 wrote above -- those items will enhance "normal" gear whine that you didn't know was there before. Told me they put a UCA on a GT500 once, and the owner later paid them to put it back to stock because the gear whine started transmitting through the cabin and it bothered him. The stock UCA had masked it.

Ford puts lots of money into developing suspension and drivetrain combos that the general public will tolerate. Every piece has give and take. With every change, you risk unintended consequences.

You MIGHT be able to have new gears installed and hide the sound even with the aftermarket suspension pieces, but it will be a crapshoot -- you will have to get lucky and get perfectly cut gears (there are tolerances) and a perfect install. The chances of that happening get smaller depending on how aggressive the gears are (e.g. 3.73s are more likely to be noisy than 3.15s). And you will roll those dice at a cost of $200 for gears and $500-$600 install costs.
 

1950StangJump$

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a better upgrade for the 05-09 cars is the 11-14 UCA and UCA mount. the later ones are about 1" longer and have more range of adjustment. they are however not interchangeable. you cannot use a 05-09 UCA with a 11-14 UCA mount and vice versa. good luck

I thought I saw a BMR install video for the 05-09 UCA where they referenced that you could use the 11-14 set, but that you had to go to Ford and purchase a different bolt? I also think, but can't remember, the benefit was less noise transmitting through the 11-14 model. Maybe I'm remembering that wrong . . .
 

Yoyo1

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I got a 2008 GT. I have been PLAGUED with clunking noise but finally figured all out. After installing Ford Racing lowering P springs and jounce bumper stops, Billstein HD shock and struts, SR double adj panhard bar, GT500 strut mounts, Moog inner tie rod and sway bar end links, and OPR outer tie rods got clunks. Very noticeable but only when backing out driveway. Soon progressed to sounding like rear end was going to clunking drop out, whether backing out or driving forward at any speed hitting any rough paving! Turned out to be UCA differential bushing. Replaced with BMR rear LCA, UCA and frame mount, and BMR diff bushing. NAPA auto will cut out the old bushing for cheap. Stuck all on and clunk gone. After a few road track sessions back again. This time clunking when turning left at really slow speeds only. I found out GT500 strut mounts were defective and caused this clunk. Replaced it and clunk gone. Also replaced front sway bar bushings to poly bushings. Now only slight clunk again going slow backing out of driveway which is from the SR brand panhard bar, due to heims joint. I can live with that one. If its more a rattle only check and adjust your axlebacks, my Pypes Bomb gets loose easy and causes rattle. Hope that helped.
 
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bl817

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I noticed the change in noise when I installed the PH bar and control arms. I installed the prothane motor mounts and those are very stiff, they also added some noise. my exhaust (Bassani AB) are louder than stock but not annoyingly so, they cover most the noise. I don't mind the noise very much because I put these parts on for the sole purpose of getting it to the track (HDPE) very soon.
 

pass1over

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The chances of that happening get smaller depending on how aggressive the gears are (e.g. 3.73s are more likely to be noisy than 3.15s).

dont know if the OP ever said what gears he's running, but I was thinking about this omw into work this morning. I have 3.73s and yes, they do whine a bit, but it's normal
 

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