Hello, I have an S4 Tii, and I have a diff clunk, from what I read, its mainly the mounts and bushings. Ive done the snubber mod, new bushings, and beefed up the front diff mount. But I still have a clunk when I get on or off the gas. It is a lot like this GeenIdee's post on this forum clunk noise coming from rear - RX7Club.com - Mazda RX7 Forum

Please let me know your thoughts, Its driving me crazy.

 

Have you checked your transmission mounts? The center one can cause a clunk sound from that direction.
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If you've already replaced all the bushings (I'd check the rear trans mount as well), It could be a driveshaft U-joint or potentially there is excessive backlash in the diff itself. I suppose it could be a worn CV joint in an axle as well.

 

You know what, I never checked or replaced the trans mounts. The cv joints are good. I’m an hoping it’s not the diff, what would I do about excessive lash?

 

if you have a camber link and really crank down on it, the diff ends up really close to the floor and it can still hit the floor.

if you haven't done the trans mounts yet, those are bad for sure

 

Nvm I’m looking at my parts list, I did replace the trans mounts. So I guess those are good. Now the list seems to be driveshaft, diff internals, or diff still moving?

 

So, I had the kaklunkety-klunks too. S4 TII diff, the LSD. In my case, it was worn internals. The ring and pinion are fine. However, the friction discs were well beyond worn out, and so were the thrust washers that center the spider gear assembly. The kaklunkety-klunks were coming from the spider gears being loose and having extra backlash to slap each time the differential changed load. The spider gears were loose because they were not being held axially. The tightness of the spider gears is completely dependent on the two thrust washers internal to the differential rotating assembly. If they are loose (mine were 0.045" too loose), they slap around. The clutches themselves don't take up any of the axial load from the spider gears, so if they're worn out, they just slip.

My $0.02 since I just measured the thing a couple weeks ago and still have to put the rear end back in the car once it's all painted.

 

thanks for that input, did it damage anything that is hard to find?

 

Those thrust washers are a wearing part. There are a couple different sizes to used depending on the overall amount of wear in the spider assembly. You have to pull it apart and measure to see which ones you need to meet the correct tolerance. The FSM has the procedures on doing that. There are also minimum tolerances for the friction disks, friction plates, and springs. The FSM has the entire process start to finish.