Thud noise coming from transmission

[malice9005]

Hey guys im new and was wondering what the thud or clunk noise could be i heard it when i step on the gas to take off and when i brake and idle

i have a 91 300zx 2+2 all stock

[nissanfreak12]

Could be many things, the main ones are:

Trans mount
U-joint
Carrier Bearing
rear sub frame bushings

Do you have an auto or 5 speed? Best thing to do is go underneath look at the driveshaft, grab it and try and move it up and down. You should have pretty much no movement.

[es.biggs]

Differential bushings are almost always bad too, I had a nasty clunk every time I would get on or off the gas, or on or off the clutch. Those bushings helped a lot.

Definitely check the center/carrier bearing on the driveshaft, there is rubber around it that wears out and it can cause a lot of noises and clunks.

[malice9005]

Its an auto I'll go underneath see what I can find. Is Everything easily visable by going under the car?

[nissanfreak12]

Mostly, you should be able to grab the drive shaft with out taking anything off.


es.biggs, the differential is what I meant, just had a total brain fart moment.

[es.biggs]

Haha gotcha man

Diff bushings are hard to diagnose visually...they can look ok but still not be doing the job. Odds are the bushings (if stock) are just old and worn and could use a replacement. You can take a pry bar and pry on the top of the diff and see how much it moves...someone suggested that to me, and I did it. It moved, but I couldn't tell if it was moving too much or not so it didn't help much...when I put the new bushings in it made a night and day difference though. I'd start with cheap and easy parts first if you find anything else that might be bad, because diff bushings are one of the more involved repairs, it can take a long time and it's not a walk in the park.

You can grab the driveshaft from underneath, and if the bushing around the center bearing is bad you will be able to move the DS up and down in the midde. It will have vertical play.