Hawkeyes

I replaced the transmission mounts on my '89 S4 Auto last weekend. Both had lost their elasticity and were sagged about an inch (see photo - old on left, new on right). The bolts holding the mount to the crossmember were relatively easy to reach and remove. A 19mm socket and breaker bar loosened them quite easily. The upper bolts holding the mount to trans. were a different story.

Left side was not as hard as right because I could get a socket on it by reaching around the tail pipe. Not much clearance between a body flange/tab and the bolt head, but just enuf to slip a shallow socket on it. Breaker bar had about 3" travel, but it was sufficient although very awkward to do when on my back.

On the right side, I had to remove the tail pipe-to-resonator clamp, then loosen the tail pipe at the CAT & swing the pipe down and away from the trans (pic) in order to get a socket on the mounting bolt. Once that was done however, it was pretty easy.

I cleaned up the bolt head flats with a file & spread a nice layer of anti-sieze on the threads. I did manage to get my shorty torque wrench in position & torqued all four to spec - 61 ft/lb.

Did I notice a difference? You bet!

My driveway has a slight incline & I would slow nearly to a stop when turning into it. When I then applied a little pedal, I could feel a low vibration at the rear until I was nearly level again. Now that vibration is gone. In addition, the driveline feels a lot smoother when pulling away from a stop sign or light.

New mounts were $72 each from 928 International.

Hawkeyes

Jim bailey - 928 International

Good post indicates another rubber bit which seems to need to be replaced to keep the 928 feeling like a Porsche !

BC

Cosmoline, my arch nemesis.

killingmoon65

" Keep the 928 feeling like a Porsche"
I love that saying!
Thanks Jim

Tony

Thanks for the images! thats on my list of to do's also. Of all the mtc we do on these cars i bet this is one item that is for all practical purposes never done. Ive never replaced them on either of my cars.

borland

Great job. Glad you also included a photo of the new part.

You didn't say about supporting the transmission while removing the upper bolts. Did you jack from the differential, or use the pan?

Since the mounts are bolted to the front of the crossover, it looks to me, that wrenching from the front is easier.

Hawkeyes

I used my floor jack under the differential with a wooden 1x6 spacer.

Yes, wrenching from front is the ONLY way you can get the RH upper bolts out. It's easy to fit a socket from the rear, but the axle-to-crossmember space is inadequate to get any leverage.

On the LH upper bolts I actually had better clearance from back than front, but it was so dang awkward I could be wrong. Anyway, hope the pics & thread help point out another rubber/metal part deterioration on our cars.

Hawkeyes

Peter F

I have done this on my -81 manual and also on the GT when replacing the motor mounts this winter.
Not very expensive and relatively easy to replace, well worth the effort.

/Peter

Jim bailey - 928 International

I guess 900 lbs of driveline bouncing around on just 4 bits of rubber plus all the torque is bound to cause some degradation over time.

Bill Ball

I have to get my car up in the air for a look. I don't yet understand these mounts. I thought the AT rested on some shimmed tabs on the crossmember. I have loosened a couple of 19mm vertical bolts and been able to slide the tranny back until the pan hit the crossmember (about 1.5 inches). I noticed nothing holding the tranny up from these two tabs and never noticed the rubber mounts. I have no driveline vibration, etc., so I assume they are there.

EDIT AFTER POST: OK, I saw the mounts are above the 19mm tranny bolts, and I see that the function is analogous to the motor mounts. There is clearance between the crossmember and the diff case. When the mounts collapse, there can be contact of the diff and crossmember and vibration, just like the oil pan hitting the front crossmember.

In my case, there is a gap between the diff and crossmember, so the mounts are not yet collapsed despite 180K miles. I can't quite see the side profile of the mounts to see if that gap in the mount structure is open or closed. It looks almost closed. If I removed the rear exhaust, I think I could get better view of it.

Thanks for alerting me to this. I still have a gap between the diff and crossmember, but I will monitor this and change the mounts at some point.

borland

I just replaced the transmission mounts on my 90' S4 Automatic, well actually last weekend.

Mine were original, but not fully compressed like those shown in the photo above.

I did notice that now the transmission doesn't bottom out over bumps like before. So, I'd say it's a big improvement in the smoothness of the ride.

Bill Ball

Borland:

What clues where there than the tranny was bottoming out over bumps?

borland

Bill,

With an inspection mirror, you can visually inspect loaded mounts for clearance between the upper aluminum bracket and the rubber bridge. The photo above shows a totally collapsed mount along side a new one.

Before installing the new mount, I had assumed that the bottoming out noise over bumps was normal. It wasn't a metal to metal noise, just a thud. Like Jim B says, it's a pretty heavy transmission and drive line.

Shane

I did this job on both a 5sp and auto and it is well worth it, IMHO! I did mine at the same time I was doing the brakes and suspension on the rear.

Nicole

Very interesting... Wonder, if that's one of the secrets of why Schocki's GTS is soo smooth!