startupboy

Hi.
My new 98 cl600 with 110k mile,makes a thumping noise when accelerating.
Worst in 1st, and 2nd.
Like the transmission is hitting something.
I can feel it coming from underneath the center arm rest

Under very light acceleration, and maintaining speed ,it is smooth.
The transmission shifts normally


I thought it was the transmission mount, but it looked good. Not very old. I have a new one, but did not replace it
No cracks on the flex disc. They look good.
All the fluids have been changed..
Is it possible that it could be differential shudder?

Plutoe

The only way to eliminate the guess work is to put the car on a lift and inspect while going through the gears---whats out of round??

startupboy

I finally got around to change all mounts, and my thump, thump , that I can feel through the center console, hitting is still there. I did a full throttle acceleration, and now its worse.
All the old mounts were still good.
Next will be the front flex disc, however it looks ok.
There are no vibrations at freeway speeds.
Is it possible the exhaust is hitting, rather then the flex disc?

burgca

As Plutoe suggested get the car up on a lift and check everything, is it the correct transmission mount, is the exhaust tight, flex disc, rear suspension, etc. process of elimination to discover root cause, or take to dealer or indie have them diagnose then decide what to fix.