Rear End Creaking… Stumped

[nickpiper12]

Coming up on 15 years of ownership, having sorted through literally everything on this car, but I am officially stumped.

Combo of failed wheel bearing/diff last year, led to a complete refresh of the rear end. Fresh Drexler with every bearing/race/seal replicated plus new 4.10 R&P. Every ball joint/bushing/etc. JRZ’s rebuilt with new bearings/seals. Thought that would cover everything… but here we are 🤡

Old noises in video below. Yikes.

https://youtube.com/shorts/Ur2SAfcfH-I?si=8EZzORIa7mFKuQrs

New creak/“noise” in video below. Occurs upon accel/decel. Usually the worst when starting to move. Barely can hear in gears 4-6. Nothing over bumps/suspension activity. Nothing in corners/turning. Car feels fantastic on both street and track.

https://youtube.com/shorts/ckIGz3sK2-8?si=ZeGRtb-fvH5JZKjz

So far I’ve investigated the following:

Diff - I have opened it up already to investigate, plus 2 fluid changes after break in. Nothing out of the ordinary. There’s a chance the actual Drexler LSD unit is bad, but I’m not too sure that is the case.

Driveshaft - New CV joint. CSB and Guibo are still fresh.

Torque check - The obvious. All bolts are torqued to spec.

Sway Bar removal - For testing purposes I have removed. No change.

RTAB/UCA bearings - RTAB’s seem to move freely, but is this too much play? Would assume this noise would occur over bumps if the bearings were toast. The UCA arms have GC inner monoballs, which does raise the question can these be ran without a divorced spring? Currently running a true rear.

https://youtube.com/shorts/kfLmPrsuzJo?si=NyCdtoE_ck8xz-cj

Any insight is appreciated!

[discoelk]

What subframe bushings are in the car? Aluminum, poly, stock?

I had a similar creak with aluminum PBM subframe "bushings" which were slip fit on the original install. Retaining compound on the bushing/subframe interface resolved it.

My car has stock interior and Vincebar with gusset cups. No damage to the RACP.

[nickpiper12]

What subframe bushings are in the car? Aluminum, poly, stock?

I had a similar creak with aluminum PBM subframe "bushings" which were slip fit on the original install. Retaining compound on the bushing/subframe interface resolved it.

My car has stock interior and Vincebar with gusset cups. No damage to the RACP.

Solid Turners. Those have been installed for probably almost 10 years so highly unlikely it would be those. I refinished the welded underside plates also so no cracks in the floor, etc.

I may try greasing the inner monoballs on the UCA's. Maybe some sort of binding occurring. Not a ton of info regarding them to begin with.

The noise definitely resonates through the cage, and my exhaust is quiet enough to hear everything with no back seat.

[fattycharged]

So I actually have a very very similar sound in mine and after pulling everything apart to do some reinforcements, I found a cracked weld on an upright forward of the driver side passenger seat (not sure what to call it). I'll shoot you a photo of exactly where, but I'd be surprised if that were it with the half cage, but I've been surprised before.

[D-O]

Were all the control arms etc in the rear torqued at ride height and fully loaded?

[nickpiper12]

So I actually have a very very similar sound in mine and after pulling everything apart to do some reinforcements, I found a cracked weld on an upright forward of the driver side passenger seat (not sure what to call it). I'll shoot you a photo of exactly where, but I'd be surprised if that were it with the half cage, but I've been surprised before.

Would be interested to see. It has seemingly become louder over time, so I'm leaning towards maybe a RTAB bearing replacement, or needing to grease the inner control arm bearings.

[nickpiper12]

Were all the control arms etc in the rear torqued at ride height and fully loaded?

Absolutely. That was the first thing I double checked.

[Theraqa]

Mine creaks too when one wheel is higher than other, like when im slowly parking car in garage, my car is low and i have to go up in angle, also i have noticed this after i completly restored subframe, including all new subframe bushing, guibo, welded subframe with turner plates, and i do have x brace installed which is pretty much welded to strut tower, i might even cut and remove my x brace and install yurkan one

[fattycharged]

Absolutely. That was the first thing I double checked.

Aren't you running sphericals?


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[nickpiper12]

Aren't you running sphericals?


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Correct, so torquing at fully loaded position does not technically matter. I still do it out of habit, however.

There is not a lot of info regarding the UCA inner sphericals. I’m running a true rear on the JRZ’s as well, so that arm has quite a bit of freedom without the divorced spring in place.

[fattycharged]

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[Jarvis]

I have this exact same sound. I don’t remember hearing it as soon as I did a full subframe reinforcement kit. I went with the entire CMP kit. Top side reinforcement beams for the top front and top rear also…. Sounds like it’s coming from the passenger side.

[bmwfnatic]

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Going to have to check this area on my car now lol…

[nickpiper12]

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Trying to figure out where this is…

[Kdubski]

I've had failed OEM strut mounts in rear make me think the frame is tearing off. Check that