Clunk noise over bumps - driveshaft or?

[dma05]

I went to go dyno my car again after redoing the whole front and rear suspension, minus the rear axles, and while on the dyno they had to stop. It was vibrating uncontrollably while in 4th gear at 5k RPM.

The tech told me I needed to fix that vibration before they can continue. He said he can feel it in the rear and that it’s possibly the driveshaft or the axles. Ive had the driveshaft length fix and rebalanced before the dyno as well.

I got the car on the lift and saw a few places were the driveshaft was rubbing on the heat shield for the gas tank. So I modified the heat shield by cutting windows out so it would grind on it any longer. This seems to have made some improvement, but now while going over small bumps in the road or driveway lips I hear something “clunking” or moving around that shouldn’t be. It sounds like the driveshaft moving up and down. I don’t know what it could be!

Any thoughts or ideas on where to start looking?
Driveshaft or axles?
Pinion?
Tranny rear output?

Thanks for any and all help!

[dma05]

More info:
I do notice the sound coming from the rear, probably not the driveshaft. If I turn right into a driveway, right when the back tires hit the driveway lip, I hear and feel the clunking (almost like a rattling or grinding sound). It only happens when the rear tires hit a lip or hole in the street at slower speeds (I usually here it while in neutral).

I have a 6 speed manual transmission.

[fz4k98]

The original inf you mentioned stated the driveshaft was hitting the shield and you removed some material to stop the rubbing. This is where you may want to start. The driveshaft should not be moving up and down that much. If it was rubbing or touching when you are underneath and looking at it that is one thing (alignment of parts).

If it is moving while under load it is another. Differential rotating under load which could be from suspension bushing wear either on the differential or the rear frame.

It is imporant to understand why the need to remove the shield material as it is a signal that something is wrong.

[camguynj]

If you added any rear suspension parts check their connections.

[The SS Godfather]

Originally Posted by dma05

More info:
I do notice the sound coming from the rear, probably not the driveshaft. If I turn right into a driveway, right when the back tires hit the driveway lip, I hear and feel the clunking (almost like a rattling or grinding sound). It only happens when the rear tires hit a lip or hole in the street at slower speeds (I usually here it while in neutral).

I have a 6 speed manual transmission.

I had a noise going over bumps at speed, Was main aftermarket pipe running Right rear , could not get it to move when stationery, but got sorted last service!! worth a good look ??

[dma05]

All bushings are new. The differential bushing were replaced with Hendrix off-set bushings due to the new lowered suspension. I checked torque on all bolts and bushings and everything checks out. Here is a video of the noise. I’m now sure there is a differential issue.

This noise isn’t normal right? What would cause it and what is the fix?

Also, is the play in the axles normal?

Here is my video of the issue:

https://youtu.be/-jMmZG9IDdo

[1JEWLDSSRS]

Video says it is private, can't view it..

[dma05]

Sorry about that. Try this link now:

https://youtu.be/-jMmZG9IDdo

Thanks

[fz4k98]

The issue of vibration and the issue of noise at low speed may not be related. The high speed vibration can be caused by driveshaft, driveshaft angle, wheel and tire balance, tire runout etc.

My car with the one piece driveshaft has the same play and noise when i rotate it.