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TBirdJKC
08-10-2017, 12:18 PM
I have a loud clunk from the rear of the car anytime I take off moderately hard, back up and then move forward, or go over large dips/bumps. It sounds like someone whacking the trunk pan with a rubber mallet.

The suspension is all new: Vogtnland 1.6" drop springs, Air Lift 1000 bags, poly spring cups, SCUI nylon composite bushings in the knuckles and LCA's, newer NOS Motorcraft inner UCA bushings, new Timkin wheel bearings and hub nuts, shorter sway bar end links with poly bushings.

The subframe bushings look great, not a spot of rust or rot on the car, including the body to subframe brackets that commonly rot out.

The diff bushings are original rubber from 93, but look like there in good shape (originally what I suspected the clunk was from, I plan on replacing them when I get some time anyway). The 3.27 TL rear end is from my old 95 LX and has had a very hard life from when it was new. It has 115,000 on it and I just noticed the pinion seal is seeping a bit. I had it open about 10,000 miles ago to inspect it before swapping it in and everything, including the original clutches, looked great and was nice and tight. Seems to be functioning properly.

Nothing under the car has any abnormal play. It drives great. Anyone have any ideas on what it could be or something I missed checking?

SCarSC
08-10-2017, 12:21 PM
I have something similar happening... mine guessing u joints but I don't know.

KMT
08-10-2017, 12:53 PM
Anyone have any ideas on what it could be or something I missed checking?

I chased a similar issue for a long time, and didn't find anything* obvious/abnormal, including a lack of body cracks, hung up moving parts, loose lug nuts, u-joints, half-shafts, etc. etc.. Installed red poly bushings (old were flat/wedge shaped)...no change, so now I just tell myself it's the diff plates locking/unlocking, doing their job as normal. Among the usual suspects, I made sure the fluid was up, w/fresh OEM diff additive.

* I did have a minor snout seal leak that stopped when I allowed the oil level to settle w/the plug out for a while.

TbirdSCFan
08-10-2017, 06:01 PM
Check your exhaust hanger rubber straps. :)

sam jones
08-10-2017, 08:13 PM
Good afternoon


The differential bushing is what I would check. This is what I do. Remove and swap bushing (top to bottom). Re-torque and look for a deformed and or unusually flatten bushings.

TBirdJKC
08-10-2017, 09:08 PM
I have something similar happening... mine guessing u joints but I don't know.

My u joints are also new heavy duty spicers.


Check your exhaust hanger rubber straps. :)

Exhaust is good and not contacting anything.


Good afternoon


The differential bushing is what I would check. This is what I do. Remove and swap bushing (top to bottom). Re-torque and look for a deformed and or unusually flatten bushings.

Sounds like a plan! I'll report back on the results.