85 300zx na clunk noise! please help!
 

Hey I have an 85 300zx na auto. And when I put my car in reverse it clunks in the back of the car. When I am driving the car will clunk really hard in the front on downshifts. Any advice? I had heard maybe it could be the U-joints?

most likely cause of a clunk is the diffy mount is shot or loose. Get under the car. have someone turn a wheel and observe the drive shaft U's. Check on the half shafts also. you might also check your suspension if you hear the clunk in the rear and then in the front maybe some shocks are loose or broken.

Most common causes of the dreaded clunk.
1. differential mount
2. rear cross member bushings
3. u-joints
4. upper rear shock mounts
5. CV joints in the rear axles

Thank you for the advice guys! Sometime today or tomorrow I will get under there and check everything! Just got done fixing my brake light switches, that was annoying!

Bad diff mounts easy to spot. I betcha $20 that's the clunk. Replaced them twice so far on my 86na (260K miles and still going) and once in my turbo. I wonder if Nissan's hard rubber/center bolt solution was the best design they could come up with in the 80s. Of course, they probably didn't contemplate 260K miles - but wouldn't a very stiff steel spring-plus-damping gadget do the same job and last longer? Anyway, the OEM replacements are about $40 each, I think. (I'm not an automotive engineer - but I did spend last night at a Holiday Inn)

INSULATOR-DIFFERENTIAL MOUNTING
Product SKU: 55476-Z31002
Your Price: $149.52
Online NISSAN dealership
Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

Wow. I paid only $40-$45 each in July 2013. for my 86Turbo. Must have been aftermarket. That means NAPA or Advance Auto Parts. I could have sworn I bought through a Nissan dealer and he handed them to me in a plastic sack when they arrived. Nissan calls them "insulators." Price sure went up in 6 months! Check aftermarket.