w124 300TE Shift shock
 

On my 88 300TE 147,000Km, everytime I shift gear say P->R or P->D, or R->D, D->R there is a jolt when the transmission engages

I have changed the Flex discs, transmission oil and differential oil about 7000km ago but nothing has really changed.

I've also tried adjusting the the vacuum modulator about 1.5 turns. The shifting shock during driving has softened but still have jolt when changing gears while parking (R->D, D->R).

Any thoughts on what's wrong? Any remedy to this problem? Perhaps I need to adjust the modulator more?

Thanks in Advance.

Sounds like your idle is too high?

I read somewhere that idle wasn't adjustable... or is it?

Not exactly adjustable, but fixable if wrong.

You mean clean the ICV and check the tubes?

Idle should be 650 warm out of gear and 500 in gear, cold will be as high a 1500 on start, dropping as it warms up (quickly!).

I would also check the vacuum line to the modulator, unless replaced the rubber is completely dead by now. I replaced all the small connectors on the TE when I got it four years ago and cured a number of similar ills.

You should also check the engine and transmission mounts -- all are likely dead by now, and will cause both rough idle and thumps when engaging the tranny. The engine is sitting on two springs with no damping when the glycol leaks out of the engine mounts!

You can check them by just looking -- if you cannot see the trapezoidal steel insert on the bottom, or the "rim" in the center of the mount is less than 1" away from the frame, the mounts are shot, replace them. Makes a huge difference. If the tranny mount is soft, replace it too.

Peter