Porsche Repair: porsche 944, central tube, porsche 944

Question
I recently bought a 944 1988 im going to keep it a long time it only has 36000 miles on it it has been garage kept I notice when I first start it there is vibration so I was told to replace the motor and transmission mounts will this do away with the vibration when you put it in gear it stops what do you thin.thank you

Answer
Hi Alex,

Sorry I've taken awhile to respond to you.  I've been looking in my previous answers because I know what you are looking for is there.  Turns out my record keeping is crummy.

Anyway, the answer is that it always 'could be' the motor/transmission mounts, but I suspect the problem is a bit deeper than this.  What bothers me is that with only 36,000 miles you shouldn't have either mount trouble OR the problem I'm about to tell you about.  I don't understand having this vibation issue so early in the car's life.

The culprit is in the "central tube".  This design is fairly unique to the 944.  Essentially, the driveshaft is enclosed in the central tube extending from the engine/flywheel area all the way back to the rear axle which is where you'll find the transmission.  So, in effect, the engine and the transmission, instead of being bolted together are held together by this tube.  Inside the tube is the driveshaft.  To keep the driveshaft happy and in its place are bearings that ride inside the tube and hold the drtiveshaft in the middle of the tube.  When the bearings fail, the driveshaft is allowed to flop around like a fish on the deck of a boat.  Putting it in gear tends to re-affix the transmission to the engine, controlling the fish-flopping so it is not so noticeable...I hope you're getting all this.

Here's what I'd suggest.  1.  Write back to me if you'd like me to dig deeper into this for you.  I seem to remember that the answer is to leave the vibration alone until its time to do major work on the car because taking the central tube apart is major work $$$ itself.  I'd like to do a bit more research to confirm this "let it go and live with it approach"...if you'd like me to.  Or...  2.  Get a second and third opinion before you spend any $$$ on repairs.  

Let me know what you think.

Dave