I'm going to look at an s4 TII at the end of the week and the only concerning problem is the owner is claiming the clutch clunks when let out quickly in 1st. I'm wonder if anyone has any ideas? The vehicle had an engine/tranny rebuild about 10k miles ago. Could this be something simple like a bad tranny mount, or could it be something serious like the diff or transmission? Any insight is greatly appreciated. I don't want to make a mistake I'll regret.

 

Also to add, the noise is described to be located "in the middle", so I would assume that would be somewhere between the tranny and rear end.

 

Front differential mount is sheared and needs replacing

 

^ I'll second that. The front diff mount is the most likely culprit. A sheared mount will also clunk between hard gear shifts (especially 1-2 and 2-3).

https://www.rx7club.com/2nd-generati...rtible-876959/

The stiffer competition mount goes for $100: Differential Mounts, Diff Stub Shafts, LSD Additive & Gear Oil

 

Thank you both very much for the quick response, seems like this might be a common issue


Any idea why the arguably "better" mount is nearly half the price?!

 

No idea why it's cheaper. Maybe it is/was made in a different factory.

 

I have an update: I got the car on a lift tonight and inspected the diff mounts. Obviously they're very old, but none had any visible or concerning damaged. The transmission "bridge" mount however seems to have completely deteriorated. The bushing between the bridge and tranny is basically non-existent. Is it possible this could be the source of my clunk, or is my front diff mount bad and I can't see it?

 

If the bushing in the transmission crossmember is gone, the rubber y-block mounts that go between it and the transmission have probably sheared. That would cause a clunk similar to a broken front diff mount.

If you didn't already try, a prybar under the nose of the diff can tell you if the front mount is sheared off. When mine let go, it "looked" fine from under the car. It wasn't until moving the diff that it became clear it was no longer connected.

 

I ordered both competion y mounts and the saddle mount for the transmission. I forgot to use a prybar on the diff, but will certainly check that as well. Thank you very much for the help in diagnosing the issue.

 

I meant to come back and edit the post, but the y-blocks may actually be ok (of course replacing them won't hurt). The y-bracket they attach to would end up banging against the crossmember, which could cause the clunk noise. Replacing the crossmember would be the main goal, but that may be what you mean by "saddle mount".

 

This is what I've seen referred to as a saddle mount, is this the same thing you're speaking of? I ordered a new one today as this is what had the deteriorated bushing.

 

Yep

 

I looked at the mounts on the transmission and the diff and my step dad and I shook it and it looked and felt very solid and we did this with out using a crowbar.

 

Replace the cubes or you will ruin the new saddle bushing. If it doesn't clunk anymore your done. The front differential mount is hard to see until it is removed though

 

I'll try the cubes and saddle first since they're in the mail, if they don't solve the problem then I'll move on to the front diff mount.