91 Q45 Transmisssion mount?

[timatt]

My 91 Q has 68,000 miles on it. I have purchased and am getting ready to install a new drive-shaft (propeller shaft) to eliminate higer frequency (than tires) speed dependent vibrations. I've heard recommendations of replacing the transmission mount also. My questions are: 1. How can you diagnose a bad transmission mount. Is if visually evident? 2. What is the life expectancy of the OEM transmission mount? 3. What can I expect to pay for a transmission mount?

Thanx in advance

[DAEDALUS]

The rubber in the mount compresses and hardens over time. It doesn't just go bad all of a sudden, it gradually goes bad, even without the engine running. When I did mine, I supported the transmission with a stand and removed the old mount. When I torqued up the new one, it raised the transmission about 1" off the stand, showing exactly how much the old one had compressed. Don't know how you can tell visually, but after 13 years, I would assume it should be done. I'll probably do mine again in 4-5 years if I still have the car.

The mount itself is about $85 from Scottsdale, but I recommend you also replace the exhaust brackets that you have to remove to get to the transmission mount since the labor's free at that point. Those are probably another $70-100.