Mysterious rear end "clunk" noise

[Magoo1222]

Reposted from general Tech section to S-Chassis section.

Hey guys, for the past few months Ive been tearing my hair out trying to find the source of a horrible drivetrain noise that showed up after putting my car back together for the second time after installing Energy Suspension poly bushings (subframe bushings + all rear arm knuckle bushings) and GKTech rear arms.

Basically, whenever I let out the clutch in gear (more notably a higher gear, low RPM) something is making a horrible knocking noise from the rear end, slightly louder on the passenger side. The noise can be exaggerated by holding the e-brake to bog the car to the point of stalling. The noise is still present with both axles completely removed.

Things that have been tried to solve this include:
New rubber trans mount
Competition Clutch "White Bunny" setup
1 piece Z1 Motorsports driveshaft
New diff side bearings (all internals cleaned and inspected, backlash and preload are perfect)
2 New Car-Quest pass side axles with new circlips for the stub shafts

At this point, I have zero idea what else could be causing this noise. Below are a few videos I took of the car, as well as pertaining info. ANY HELP IS COMPLETELY APPRECIATED!!

https://www.youtube.com/watch?v=IT0q5K29q-s

https://www.youtube.com/watch?v=b8IFY-yfqko

In the second half of this video, I hold the brake to exaggerate the noise
https://www.youtube.com/watch?v=m94LYGPW4go&feature=youtu.be


Relevant car info:
1991 240sx SE hatch
stock rebuilt KA24DE, stock rebuilt transmission (no issues after rebuild)
Competition Clutch "White Bunny" upgrade
z1 motorsports 1 piece steel driveshaft
OEM VLSD rebuilt with Timken side bearings
OEM driver side axle, Car Quest pass side axle (twice)
fortune auto 500 coilovers
full GKTech suspension arm kit with HICAS delete converted to conventional toe arms
full Energy Suspension poly arm and subframe bushings

[Magoo1222]

Anyone have any ideas?

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[lunchmeat]

Jeebus that sounds bad. I'd start removing driveline parts one at a time, checking for excessive play. Sounds like it's coming from the diff to me.

[Magoo1222]

I completely tore the diff apart, cleaned and inspected everything last night. No abnormal wear. No broken or missing parts, no discoloration. Ring and pinion backlash is perfect withing FSM spec, ring tooth pattern is spot on

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[tuzzio]

Are your e-brake cables touching your drive shaft..

[Magoo1222]

No, brake cables are secured in the factory brackets. It is definitely a mechanical metal on metal "clunk"

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[cotbu]

I agree with the differential.
I can hear it actually. For you to rule it out unbolt the driveshaft from the diff. And test it out, if the sound is still there it definitely not the diff. And I'm wrong
Or you could put a screw driver to the differential and get the same or better results.

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[Magoo1222]

As a side note, the noise resonates really loud inside the car and can be felt through the floor. I'm 99% sure it's nothing forward of the diff as the clutch is brand new, and trans is a fresh rebuild (I actually pulled the tailshaft housing off to check the output shaft bearing last week, everything is tight and solid)

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[cotbu]

It's the diff, not that the backlash is wrong or instalation. But it sounds like it's been shimmed. Can you turn the output shafts separately of one another? By hand?

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[Magoo1222]

No, the output shafts don't spin separately unless one shaft is removed. It worked perfectly before I dropped the subframe out to change the bushings, but all I did with the diff was paint it

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[kruked]

I'm wondering if the ears on the output shaft(s) are hitting the floor pan.

[jumboflan]

maybe you did mount the subframe back right after the subframe bushings. did the umpkin line up?to subfrme cross member?

[Agamemnon]

Have you tried using another diff? You can typically find an open diff locally for cheap.

[Magoo1222]

Unfortunately I live in a pretty desolate location when it comes to local used parts, so I don't have access to a known good diff

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[Magoo1222]

Update on OG problem:

After completely disassembling the differential, thoroughly cleaning, inspecting, and reassembling, I bolted it back into the car. Without either axle installed, I ran the car in gear, low and behold, the original noise is gone, replaced with more of an "annoying" vibration/rattle sound. Im thinking the issue may be with diff alignment on the subframe? Im not sure.

I reassembled everything, and took the car up and down the road, other than a slight rattle upon takeoff, the only noticeable noise now is the pass. rear wheel bearing (which I noticed was on its way out during disassembly).

So I have a new Moog unit ordered and on the way. I will update after I get that problem sorted. Not quite sure what changed the noise, but I wont question it haha.

[DiscountPirate]

Did you confirm the driveshaft is not part of the issue? Does it have U joints that could be loose or some type of misalignment, It sounds like you ruled out the shafts, and you went over the diff. It's hard to tell from videos but the sound reminds me of lightweight flywheel chatter. It seems that the sound did not coincide with revs so most likely is some kind of vibrational resonance thing somewhere in the back end.

[Magoo1222]

Did you confirm the driveshaft is not part of the issue? Does it have U joints that could be loose or some type of misalignment, It sounds like you ruled out the shafts, and you went over the diff. It's hard to tell from videos but the sound reminds me of lightweight flywheel chatter. It seems that the sound did not coincide with revs so most likely is some kind of vibrational resonance thing somewhere in the back end.
The driveshaft was the first thing I replaced, first by replacing the carrier bearing, and then with a 1 piece Z1 Motorsport driveshaft.

After driving the car a few miles, the only noise I can now hear is the pass rear wheel bearing

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[Mrodriguez124578]

I have a question. And I am new to this website, but I was thinking about welding my Differential and was wondering about the whole breaking Axles thing. If as of right now I run a 17x10 245/45/r17 in the rear, will that cause my rear Axles to break after a while or would I be okay?

[zenkicpe]

I have a question. And I am new to this website, but I was thinking about welding my Differential and was wondering about the whole breaking Axles thing. If as of right now I run a 17x10 245/45/r17 in the rear, will that cause my rear Axles to break after a while or would I be okay?


:picardfp:

[alexusbailey_s13]

I have a similar issue going on. My sounds like a binding noise when Im slowing down. It just started today. No matter if Im in gear or in neutral. It seems like its coming from the center console or passenger side when the noise is made.

Car -
95 S14 Zenki
SR20DE
Z32 LSD
And other shit.