we checked and there was no signs of anything hitting..

seems we have the same problem.. what brand rear diff bushings are u using.. and did it make the sound before it was installed? update me if u find out anything please

i already had transmission mount installed before any of these and it never made the sound. yea ill probably bring it to a speed shop soon when i have time

still on stock oem suspensions and its tight

I had swapped my rear dif. bushing to Whilelines one. I added my DIY vids. install tot he DIY that was already posted. I never really noticed the minor clunk until after my turbo install. I think It might of always been there but I never noticed it. The other thing is that my clutch/flywheel might play a roll in the clunk too. It has a more on/off engagement than the OEM one. I suspect that this quick loading and unloading of the drive train made the cluck more prominent and noticeable.

Anyhoo, I was just under the car inspecting and trying to figure the cluck out.

It turns out to be a 2mm or 3mm free play of rotation in the drive shaft and rear differential. I held the rear tires still and I manually turned the drive shaft by hand. The drive shaft is able to turn about 2mm or 3mm before it locks in the other direction.

Basically, as you load then unload the drive train, the car will drag (you are off the pedal and friction and the weight of the car will slow) and will make a cluck as the 2mm of free play is used up and the car loads the opposite end of the rear diff. This is like a 1 ton hammer with only 2mm swing tapping the back or front of your car every time you get on and off the gas really fast.

I have the OEM tranny mounts but it's on my to buy and install list.

YzGyz

yes.. i also notice the free play on the drive shaft few days ago when my car was on the lift. but i never heard of it clunk before i had all my bushings and mounts installed..
so is the play and clunk normal? because if it is.. wont everyone will have this sound on their z?
also when my car was on the lift.. the sound came from the where the trans meet the driveshaft area... but when driving it sounds like from the rear..

It appears to be normal to me. It's actually free play in the rear diff itself. I can't do anything about it so I'm leaving it alone.

YzGyz

I have the same issue. I installed the Z1 tranny mount and now hear this clunk and weird noises that sound like it's coming from the diff. Put the car on the lift and there is some play in the diff. I also have a PST CF Driveshaft. So is this play normal in the diff? I also had a shop install some 4.08 gears about 4 years ago. So any info would be great. It's just weird I did not hear it until the tranny mount but the sound is annoying.

My theory is that this clunking was not notice or present until the drive train was stiffened. The 3mm rotational free play was absorbed and dampened by all the OEM rubber. The clucking is more noticeable now that everything is more rigid, transferring the energy and sound to the diver more, hence we now notice it.

YzGyz

the clunk is alot louder and clunks rapidly during wheel hop.. does yours do the same thing too? YzGyz? and usually clunks at lower rpm shifting (under 3500 rpm)?

Im not sure if I missed it, but does it clunk more/louder over bumps? Or only under accel and decel?

doesnt clunk on bumps such as bumpy roads or speed bumps... but it does clunk louder and rapidly during wheel hops.. and clunks when clutch is engaged and released in 1st and 2nd gear on lower rpm and sometimes 3rd gear.. or when pressing throttle and letting go causing that jerking motion..

It's there during wheel hop, and of and on throttle in first gear, and some in second. Again my theory =hop loads and unloads the drive train as tires grip and let go causing clunking.

YzGyz

i wonder does all z has that much play on their driveshaft or we r just the very few that has it..

There is always going to be some play in gears by design or they would not mesh right. But Like everything there is a certain tolerance that I do not know off hand. I'm sure the service man has it. But from what I have noticed it's a lateral clunk and not a rotational clunk. I've also noticed when I let off the gas only in high gears my shifter moves back and forth. Since I have been looking into this more I notice more things as the days pass and my OCD on noises have kicked into high gear. I am a sound analyst so when stuff bothers me I wig out. Hopefully we can solve this together.

Only on load and unload. Bumps and such don't make any abnormal sounds

YzGyz

update! so as for the shifting clunk.. it is not as loud anymore and seems to b normal to make sound when releasing the clutch or pressing the clutch too fast..

the rear sub frame is confirmed by spl that even tho the instruction said 2 shims on the front and 0 shim in the rear for oem spec... 2 shims front and 1 shim rear is ok too and there would not b a problem..

now i have a new problem... front driver side lower rear impact bushing is creaking/squeaking when turning slow or driving slow or coming to stops.. basically when there is load to the front... im sure its the bushing and not the endlinks or sway bar bushings and all the bolts is tight... did anyone grease any of the spl bushings? it started making the sounds after a month of install and its getting louder and louder.. very noticeable..

Does it look like there is movement in the bearing? Like are the surfaces smooth or rough? Could be binding due to a weird angle of force?

I have put some white Lithium on mine in the past, not sure if that is correct or not though.


-Daelen