Hi everyone,
I have a '87 745 GLE with m46 trans. When I come to a stop headed uphill, when I start to go again, I get a really back knocking sound from middle to rear of the car. This happens more so on steeper hills, right when I release the clutch. It seems to be getting worse. Almost sounds like the drive shaft is hitting the under-carriage.

Any idea what this could be? Maybe time to replace the flex disc? I haven't been able to go under the car to do a visual inspection.

Any advice helps. Thanks.

 

I'd go with the flex disc.

 

Flex disc, transmission mount ( I favour this one) or centre bearing rubbers gone.
You'll likely find all three of these need replacing on your car, they die with age.

Regards, Andrew.

 

Might also be a good idea to take the cover off the rear end differential and check those bearings and bearing caps.

 

Got the car on a lift today. Inspection showed what was up. Cracked flex disc (4 years old)... not the total culprit, cracking was pretty minor, will change it as a preventative step. Tranny mount (4 years old as well) was loose (result of bad vibration)... tightened it, but will probably replace it too.

Main problem: Center Driveshaft support failure. About to get the kit and do it, along with those other issues.

Differential looked ok.

Thanks for your help.

 

my car does the same thing but does it from any stop and rumble until about 5mph and stops what could it be and where is tranny mount to try and tighten that