This has been an ongoing problem ever since I've owned this vehicle ('90 240SX). Let me start by saying that I bought the car 100% stock. It has redtop with bolt-ons, has been through 2 differentials, 2 transmissions, and has subframe spacers (collars) installed. Now the problem I have has been progressivly getting worse as the years roll. Now to the problem. Between shifts, on and off the throttle, there is a clunk or thump from the rear end that is associated with movement or play in the subframe. This happens when on and off the throttle at any speed and gear as i can feel slack somewhere in the subframe "lock" when on the throttle and vis versa. Also when the car is at a complete stop (car is running), every once and a while when I put the stickshift into first it will jutter the whole tranny and subframe. These problems have not seem to effect and have broken anything on the car yet, but they are becoming annoying and questionable (to the point where i think something might break). I don't even think that bushings would cause this much play, but I don't know. Everything looks tight and solid. I have searched hours and 4 forums and I come up with no solution to my problem. I understand that alot of people have problems similar to this. If you have had any experience with this these 2 problems and have remedied the culprit, fill me in on what it was and how to fix it.

 

I had the same problem and it was pretty bad.
My diff went to shit.
Replaced it.
No more clunking and thumping.

Other than that, maybe everything isn't completely tightened down and the bushings are not compressed properly.

But I'm just some girl. What do I know.

 

My first VLSD clunked then I swapped another one in and now for the most part the clunking is gone.