'85 380 Shuttling upon acceleration...experience this?

[RickM]

Had a few things done by Indy not too long ago.....Passenger side camshaft, rockers etc.
I noticed shortly after that, when I accelerate, that I feel a shuttling / vibration through the pedal...and probably through the seat...not sure. It happens most pronounced under hard accelearation from stop but also happens less so any time I accelerate.

I'm thinkling it may be engine or transmission mounts. Any educated guesses?

[ctaylor738]

If it's a thumping type of vibration, I would bet that the driveshaft center bushing/bearing, or the front flex disc have given up. Maybe both.

[RickM]

Hmmm, not quite a thumping but a vibration in the drivetrain....no noise to speak of...just the shuttle vibration as I accelerate.

Would the flex plate/driveshaft or center bearing be obvioous if worn?

BTW, Thanks for the reply, Chuck.

[ctaylor738]

The rear flex disc is easy to check out.

To get a look at the front disc, you need to remove a serious metal plate that forms the bottom of the transmission tunnel. If you do that, then you can shake the driveshaft and if it moves, you probably need a new center bearing.

Warning - very dirty job.

The front flex disc has a sort of webbing design that helps it act as sort of a shock absorber. On my 280SL with 181K, this webbing was completely broken out. The center bearing was toast.

A good repair "package" is both flex discs, the center bearing, and rear trans mount. You need a special puller and press to r/r the center bearing. I took my driveshaft to Herr Fuchs, and he charged me an hour's labor for the r/r.