Oh my gosh! I think I've totally destroyed my car now. :-(

I just finished replacing a thoroughly worn transmission mount. Getting the old one out was bad enough,, but when I tried to reattach the crossmember, the only way I could align it was to push with all my might about an inch toward the passenger side.

Now everything's secure, but I get a really bad vibration at maybe 2500-3000 rpm. I don't have a tach, so this is a guess.

What did I do wrong? Did I jack the transmission up to high? Did I destroy the motor mounts? Is the drivetrain misaligned? And I thought this would be an easy job!!

Check the post labled "Jacking stress points" from 09 SEP. HAd the same problem after muffler and tranny mount changes. This cured everything.

Well that's really interesting. The crossmember and the bottom of the unibody look fine, but I do have an exhaust leak around the header pipe that I didn't have yetserday. I'm gonna take the crossmember out and run the engine with a jack supporting the transmission. I'll move the jack up and down in short increments and see if that gets rid of the vibration. Thanks for the info!

Not sure if it can cause such a severe issue, but they say to 'mark' the position of the driveshaft with tranny tailshaft to reinstall in the same position - for balance... anyway.
Did you undo the tailshaft? Check to make sure you did not do anything to undo alignment of the center support bearing.
Something obviously is not back into original position.
Maybe you have a worn out tailshaft bushing that got severly louder now that the tranny is better aligned? Use your hand and shake your shaft (that's the tailshaft of the tranny wer're talking about here). See if it has play.

Greg Mustang
Montreal - Ottawa
Canada

Hey, thanks so much for the suggestion Greg. I'll give it a shake!

Did you remove the driveshaft for any reason?

I know another Roger Williams -- a true descendant of *the* Roger Williams (for which the university is named...)

Any relation to you?
--
Don Foster (near Cape Cod, MA)

Hi Don,

I'm sorry for the delayed response. Sometimes i get tired and I fall asleep.

No, I did not disconnect any of the drivetrain.

I dunno if I'm related to that more famous Roger Williams. My dad's parents lived in Milford, New Jersey.

Check to see if there's still plenty of clearance between the oil pan and engine crossmember; perhaps the engine mounts sagged/degraded in a sympathetic manner.

It could also be stress on the exhaust system; if it's stretched/bent or modified/installed with the bad mount, it may be the cause of your misalignment with the new mount.

But first check and be sure that it's in right:-) as someguyfromMD says.

Gotta replace my own trans mount.. and wiper blades.. and headlight.. and wiring harness.. and suspension bushings.. and heater control valve.. and....

Kyle
--
1980 242GT 197K, 1990 744Ti 113K

I'll take a close look at the exhaust. I don't know if it's hitting anything, but I'll bet I put some stress on it. I may have even cracked it a bit. Thanks for your suggestions.

I've got to do my heater control valve soon. I get either hot or cold air, but nothing in between.

You might not believe it could happen, but you may have the tranny mount installed upside down. Please don't ask me how I know this could give you the symptoms you are experiencing, just trust me and try flipping the mount over and reinstalling.

someguyfromMaryland

Hey someguy,

Thanks for the suggestion, but these mounts are foolproof (just my speed!). They have two tabs on the bottom of one end that line up with the bottom edge of the bracket that's attached to the back of the transmission.

So I coundn't have installed it wrong, even if i tried.

Thanks again,
Roger