Help me diagnose weird "clunk" sounds from my car!

[marshallpre1]

Car: 1990 240SX
Mods (that I think contributes to it):
RB25DET
NA 300ZX LSD
Eibach springs on AGX shocks
Custom driveshaft
Megan Strut bar

Symptoms:
Noise #1:
Whenever I go over a bump, there's a loud clunk. I thought it was my rear seats since it sounded like something is getting lifted off and then dropped down. I checked and they were secure. Checked the hatch and there is nothing loose. Any ideas?

Noise #2
When I take off a little slow there's a clunk sound too. Maybe it's the diff? Not sure, but the car is pretty much quiet after that split second. I'll try changing the fluids, but the fluids are fresh (<5K miles). It's been there since I've owned the car.

Thanks,
Jeremy

[krash]

I have clunk #1. No idea what it is, hopefully I can get some help too

[Lobo240sx]

Is it coming from the front?? I am going to take a shot in the dark and say front radiator core support welds coming off. Very common problem. Many people weld it back on. I over killed mine. Ended up putting bolts in and welded it back. Check your front end buddy.

[Lobo240sx]

Noise #2 I would check the diff/ drive shaft bolts and make sure they are tight.

[breadbox]

If exhaust is a bit loose it can hit the rear subframe around the 90 bend.

[EnjoiNismo]

Noise #2 I would check the diff/ drive shaft bolts and make sure they are tight.

I had this happen to a friend.
I'd jack up the car and check all your parts and make sure they are tightened.

[krash]

If its the same clunk that I'm talking about then its from the rear. And it sounds like a bunch of stuff in the trunk would sound after going over a bump

[S14Kouki10]

change the subframe bushings.

[Raz007]

Is your spare in the trunk? And is it bolted down? Check for loose crap in the trunk. Hopefully its that easy of a fix.

[marshallpre1]

Yes, it's the clunk that sounds like it's coming from the hatch area.

Checked the tire, it's secure.

I'll get under the car this weekend.

Thanks

[barefoot mat]

nosie 1 sounds like my friends car. his car would do it when he made a turn. turns out the front sway bar was missing a bushing, and was hitting the frame where it mounts to.

[DanThaMan]

do you have pillow ball mounts in the back? Its doubtful but it could be them, usually only the fronts go bad though. +1 on the sub frame bushings
-Danny

[minkl81]

mine started to clunk too (usually passenger rear) after raising up the coils few months ago. it clunks every time when the weigh shifts (stop and go most of the time).

after the the clunking started, i got new rear upper control arm, traction rod, rear lower toe arms, and poly subframe inserts. but it didn't cure the clunking issue.

but mine seems like its the rear height issue. it never clunked when i was riding lower but after raising up front quarter inch and rear by half inch, all of sudden it started to clunk. and once a while when trunk is stuffed and rear height goes down, clunking is minimized.

[marshallpre1]

It sucks that a lot of people have the same clunk as me, yet we haven't found a solution yet. I was listening to it more closely and I think it's only coming from the driver's side, possibly the wheel well. What about the bump stops? Do you think blown shocks would do this (I used to hear my shocks compress when I went over bumps, but now, I barely hear it)?


Jeremy

[marshallpre1]

Update. Took the driver's wheel off yesterday to inspect, and nothing was out of place, nothing was loose, etc. I looked under the car and noticed that one of my exhaust hangers was off the rubber hanger. The exhaust wasn't shaky at all before, but I hooked it up anyways. My rubber hangers look like they're almost completed ripped, so I'll be ordering new ones ASAP. Took the car out today to go to work... and magically, no noise! No clunk, nothing! Looks like the hanger that I thought wasn't doing anything did indeed hold off any weird vibrations. Will update if things change, but going to be picking up exhaust hangers first and see if things stay the same.

Jeremy