Started getting this clunk from underneath the car about 2 months ago. It only does it in 1st gear if I suddenly step on the gas like if I need to get into the next off a red light. If I come off 1st gear normal driving no clunk. It doesnt make the clunk on any other gear or if im already rolling. To me it sounds like its right underneath the driver side or transmission area. Would a bad compression rod cause this clunk? I can feel like something hits underneath when the clunk occurs.

Ive jacked the car up and checked the front suspension and didnt notice anything loose or cracked. Motor does not vibrate and looks stable when the car is on or I accelerate so I doubt its the motor mounts. Ive also checked the rear suspension and same everything looks good. Ive replaced the diff bushing with urethane ones a while back. So I thought maybe the transmission bushing. Took it off and it looked in good shape possibly the original one. Anyway I still replaced it with a new one since it was cheap and the clunk still there.

I installed some new TEIN coilovers about 4 years ago. I was thinking maybe they are blown now but im not sure if they would cause a clunking like this.
I inspected the compression rods and the bushing seem intact. I did replace both like 3 years ago.
Front lower control arms bushings were replaced with whitelines 3 years ago. Low ball joints were also replaced about the same time. Sway bar bushings and end links were also replaced. Im hoping its not the motor mounts but normally when ive seen mounts go bad its obvious because the motor will move/flex when parked and reving it. What do you guys think?
The clunk is definitely in the front. I have a feeling its a bad compression rod. I guess the only way to really find out is to take them off and inspect them. Anything else I should be checking.

 

Yes, blown compression rod bushings can make this noise. But so can a worn tie-rod ends, steering rack bushings, motor mounts, upper strut mounts, and other things. Have you tried the wheel tug check? By that I mean, push/pull wheel while gripping at 12 and 6 o'clock position, then do the same at 9 and 3 o'clock (with the front wheels off the ground of course), if something feels loose that helps narrow it down a bit.

What did you replace the compression rod bushings with 3 years ago? More whiteline?
Cheers!
-Icer

 

I have done the wheel tug check and everything checks out. As for the compression rods I replaced the entire arm with stock ones. I was having a click/clack noise coming from the front at that time. I initially just replaced the bushings with the GKtech spherical bearing kit they had but noise was still there. Found out that the ball joints on the oem arms were shot and were causing the noise. Once I replaced the entire arm no more noise. The clunk im experiencing now is much different than that but I have a hunch that the rubber bushing are shot although from visual inspection they look fine. Wouldnt hurt to remove them to get a definite answer.

Im really hoping its not the motor mounts. Seems like pita to replace those mounts.

 

Yeah, those heim joint (spherical bearing) kits can start making a clunk or clicking noise overtime, especially if they don't have a Zerk fitting for greasing them. Which is why I stay away from them. They're really more of a dedicated track or race car modification. A lot of my Z32 buddies that switched to them have creaking/squeaking/clicking noises after a few months of use. One of them is so bad, you can hear the suspension squeaking from two blocks away.

I'm running with Whiteline compression rod bushings, inner FLCA, and strut FLCA. I replaced the front lower ball joints with greaseable aftermarket units (zerk fittings). I replaced the strut hats with fresh OEM units when I installed my Bilstein B6s a few years ago. I also did my sway bar bushings + end links with fresh OEM. Basically, the only original components left up front are my front Upper Control Arms + bushings & ball joints & the tie-rod ends and rack bushings. So far so good (knock on wood).

I also hope it's not your engine mounts, as they are a challenge to replace, but can be done without dropping the subframe. The hardest part is getting that top nut off, I've seen videos of guys using a crowsfoot adapter or stubby wrenches to get it.
Let us know what you discover after more investigation.
Cheers!
-Icer

 

Yea I hope its not the motor mounts. Im going to remove the compression rods this weekend. I feel like its the driver side one as I kind of feel the clunk on the driver side. Any other way of checking the motor mounts besides checking to see if the motor flexes while accelerating while on gear?

 

The only other option I can think of for checking Z33 motor mounts would be to use a large prybar and see if you have excessive movement. Usually it's pretty clear from doing a torque check with foot on brake (parking brake engaged), then putting in gear with a minor torque load, kind of tricky to do on a manual. If the engine starts lifting a significant amount (over 1/2 inch), then the mounts are toast. If you have a factory tower bar in place, the intake manifold would start banging into it if your motor mounts were shot. Checking for some witness/impact marks around the tower bar and intake manifold would also be a good indicator. Also, double check the lower bolt for the mounts, it's pretty easy to access. Make sure it's not loose.

I've never had an engine mount failure in my 16 years of ownership with Z33s. But I have a set of BDE poly mounts ready as backup should the OEM mounts fail (still on the fence with Poly mounts though, I'm concerned about NVH).
Good Luck! I hope you find the root cause!
-Icer

 

Thanks Icer for your input

 

Update. So I confirmed that one or both the motor mounts are shot. Most likely the driver side. When revving the engine on neutral there was not much flex on the motor. I chaulked the wheels and applied the parking brake on. Put it in 1st gear and put some load on the engine and sure enough the motor lifts up and does hit the strut brace. So motor mounts it is.

 

That is more of an issue with cheap spherical joints, SPL typically lasts quite a bit and are relatively silent. I have spherical bushings on 2 of my arms on my DD and so far no abnormal noise.

 

So got around to replacing the motor mounts this weekend. WHAT A PAIN IN THE ***. Getting to the top nuts was a challenge but breaking them loose was the real challenge. I read that the passenger side was the most challenging so that's where I started. Got that nut loose in about 15 minutes tops. I was like man this wont be as bad after all. So now I go over to the driver side. Nut is completely visible so I thought this should be quick.... WRONG I fought and struggled on the driver side. Ended up taking off the heatshield from the exhaust manifold which is only 4 bolts but man was it challenging to get that shield off.

Anyway got the shield off to give me more room to work with. I struggled and battled to get that top nut loose for about 4 hours trying different approaches and different tools. I finally made up my own tool and thankfully it worked. Got the nut loose. Lifted the motor up. Slid the old ones out and new ones went in like nothing. Got the nuts back on on top with no struggle.

Driver side mount was completed torn.
What i strongly suggest is use only a stubby 14mm wrench that's 6 point only. If you dont you WILL strip the nut and then youll have a real big problem or you can make a tool like I did with a 14mm socket 6 point. This only worked for the driver side.

For the passenger side i used a 14mm stubby wrench and used a bar for leverage to break the nut loose. There is no way to get a socket on the passengef side nut. I would also strongly recommend using a 6 point stubby wrench. I know some some people take off the mount bracker unbolting the 4 bolts from the block and then taking the top nut off but I didnt have to do that. You can definitely take the top nut off from the passenger side without removing the bracket. Taking off the oil filter and alternator gives you enough access to get the passenger side top nut.

 

Removing the alternator isn't a fun prospect either. Did you have to completely remove it from the vehicle or just loosen the mount bolts to give better tool access to the nut? Was this required to remove the top nut or for removal of the mount itself? Same question for the oil filter? Is the removal for tool access or to slide the old mount out?

Lastly, with the driver's side mount obviously broken, did the replacements finally fix the clunking issue? (problem solved?)
Edit: Somehow I missed your earlier post about testing/checking/confirming at least one mount was toast. How are the new mounts doing? You went Poly right?

Cheers!
-Icer

 

Removing the alternator and oil filter was to get better access to the passenger side top nut. Ive seen others not remove this but I felt like it would give me more room to work with. You dont need to remove the alternator or oil filter to get the old mounts out and new mounts back on. You can just lift the engine up just enough to slide the mounts out and in. Reinstalling the alternator was a bit of a struggle. Behind the alternator theres a small bracket being held by 2 10mm bolts. Getting them off was no problem but getting the bracket back on and lining up those 2 bolts was a PITA. I have fat hands so im sure that made things more challenging.

I used the Z1 poly mounts. Theres definitely NVH as expected. At idle is when you notice it more. How bad is it? I expected this, so for me its really not a big deal. The car is basically a daily between my son and I. My son is 18 y/o so he definitely doesnt mind the NVH. So for those who their Z is not a daily and only a weekend car its really no big deal in my opinion since the car is not a daily. I actually like how the Z feels with these more solid mounts. The car feels much more stable and solid. Shifting through the gears feels good. We took it for a canyon run Saturday late night and the car felt real solid. Ive read that after a few miles the poly mounts kind of get quieter.... is that true who knows. I'll update and confirm that in about a month or so. Overall im happy with these poly mounts.

 

^^^^ THIS. I ran into the same problem during my alternator rebuild experiences. It's no easy task to accomplish re-installing those bracket screws. I bet most people who replace the alternator simply leave the harness bracket loose, but that's not my style. One small correction though, the two bolts are 8mm, at least that's how they are on my 06. I actually picked up an extra long, offset, Gearwrench set after pulling the alternator out the 1st time because of how much of a PITA this was. I'm glad I did because months later, I was back in there pulling the alternator for a 2nd time.

Good feedback on the poly mounts and as stated, some added NVH at idle is to be expected. Anecdotal, but my Z32 buddy put BDE poly mounts on his TT, and you can for sure hear/feel the difference, but it's not what I would consider terrible, even for a daily driver. I've never had the chance to sit in a Z33 with poly mounts to gauge the difference yet, hence my curiousity.
Cheers!
-Icer