Constant Cluncking Noise from Rear End....

[Ramius83]

Ok, here is the deal. I have an RB26DETT in my S14. About 5 months ago, I installed a NISMO Limited Slip Diff. into the car. I have done about 20 or so passes at the drag strip, using slicks, running as low as 12.06, so the car does move pretty well. The LSD had the NISMO synthetic oil in it for a while, and about a month ago, I switched to Redline Heavy-duty Shockproof oil.

Well, about 2 months ago, I started having some problems with the 240. When I am turning the car out of a parking lot, pulling out of my driveway, executing a left/right hand turn, the rear end of the car makes a constant clunking noise. It mainly only does it when I have some gas applied to the pedal, but it is constant. If there is no gas applied and I just coast a turn, the clunking is not there.

So, what do we all think it is? I can probably rule out the driveshaft universal joint. If that was to be bad, it would make a single clunck here and there, not a constant cluncking. I have a set of rear subframe spacers, so it is not the rear end pounding against the body. etc etc

I am more or less leaning towards the diff or the axles being bad. I don't really know why the diff would go bad so fast. Now I think it may be the axles because the chassis (excluding the engine/transmission/driveline) has over 186k miles on it. The axles are original. And with going to the drag strip, maybe the axles have gone bad. Anyone have any insight into this? Thanks all for your help.

[MdaddyS]

Sounds familiar to mine, has me stumped.

Sounds like a tin can banging on the underside of the trunk... had the exhaust guys beat on the (stock) exhaust - nothing. With the car in the air I can't find a rub point or anything loose.

This started after installing most every Cusco suspension part offered, JIC coilovers, ST sways front and back, Kazama subframe collars...

Noise is worse when a passenger is in the car with me, worse on turns, seems to follow tire RPM not eng or driveshaft.

I was leaning towards motor/transmission mounts but after driving to work without the hood today, noise does not quite correspond to engine movement. My thought is rearend too now...

If this sounds like it's not related, Ramius, let me know and I'll edit it out - Don't wanna jack your post!

Thanks in advance,Mike

[Ramius83]

That sounds about the same to me. It is a constant cluncking noise. I thought I may have improperly shimmed the diff. back into the pumpkin casing. So I got another S14 diff, switched my LSD diff into the other casing using the other casings shims. Still have the same problem.

I am gonna be getting another S14 Open diff (stock) and drop it in and see if it goes away. If it does, I know that it is the diff. If not, then I can lean towards axles, etc etc.

[MdaddyS]

I now have a friend betting me it's wheel bearings... which I can see the argument for but it all doesn't add up.

I'm going to check slop in the driveshaft - 3 universals and a bearing give plenty of room for failure after 8 years in my case.

Let me know what YOU find,Mike

[Hijacker]

impropper shimming can lead to the ring and pinion gears slapping each other. Did you just pull the old open diff out and reinstall it with the same shims? If so, it's most likely the diff itself. When rebuilding a diff, you have to be careful about the shimming it. I spent a good amount of time shimming mine up properly when i installed the VLSD and have never had a clunking issue, nor any clattering or chattering.

[Ramius83]

impropper shimming can lead to the ring and pinion gears slapping each other. Did you just pull the old open diff out and reinstall it with the same shims? If so, it's most likely the diff itself. When rebuilding a diff, you have to be careful about the shimming it. I spent a good amount of time shimming mine up properly when i installed the VLSD and have never had a clunking issue, nor any clattering or chattering.

I did just slap it into the pumpkin with the existing shims because that is what the majority of other people do out there. It is just funny that "I" have the problems with doing this.

What is the proper procedure to shimming this sucker? I do have a FSM, so I will review that later tonight when I get home. Thanks.

[95lstegman]

just because you have subframe spacers doesn't mean you're out of the woods. if your subframe bushings were busted to begin with, spacers will only slightly improve the situation. go all out and spend the $130 on SPL Aluminum Subframe Bushings. no more clunking. i need to do mine because it's really pissing me off!

other than that, your LSD may just be tight. i know a lot of clutch-types clunk at low speeds while turning, like in parking lot situations. perhaps it's when you stop hearing this noise that you should worry . . .