By Saabnet.comt Member Bill Nesse - '80 900 GLE - '87 900T - '88 900T
Consult the Bentley manual for details on some procedures.
Clean the engine.
Drain engine and transmission oil.
Install the blocks needed where the A-frame comes through the side to take pressure off the ball joints and loosen lug nuts.
Raise the car up on jack stands (I just raised the front) high enough to slide the transmission out the front. I put the jack stands on the longitudinal frame members aft of the wheels where they would be out of the way.
Remove the hood.
Remove the plumbing at the front of the car and remove the clutch.
Disconnect exhaust pipe from the turbo and the catalytic converter and remove the pipe.
Remove the turbo support bracket
Disconnect the shift rod at the back of the transmission
Remove the wheels and disconnect the axles from the transmission. I pulled the entire wheel assembly off the car by removing the caliper, undoing both upper and lower ball joint and the tie rod end and loosening the clamp holding the inner driver rubber boot. It looks like you can get enough room by just undoing the upper ball joint and pulling the axle out, but haven't tried it. Be careful about getting dirt in the inner driver. Note that you don't have to undo the axle nuts. Cover the exposed ends with plastic grocery bags to keep them clean.
Remove the engine oil filler tube and transmission oil filler tube. To remove the engine oil filler tube, disconnect it at the top and unscrew from the bottom. Stick a wood dowel in the tube to straighten it to ease the job. I had to drop the transmission partially out to get to the bottom, but it looks like a 1 1/8" crows foot wrench for a socket set with a long extension would do the job.
Unbolt the front motor mount and raise the front of the engine enough to remove the mount. I ran a pair of 2x4s between work tables on either side of the car and connected an eye bolt through the 2x4s to the front hoist point. An engine hoist would obviously work too. If the car is 88 or newer undo the cooling tube to the turbo at the turbo and from the bolts on the transmission so it won't be in the way. This will require partially draining the coolant.
Remove the cross-member and skid pan beneath the engine.
Fabricate a platform on a floor jack that will support the transmission. I cut out a piece of plywood (~9x16") and ran a bolt through the plywood and the hole in the center of the floor jack cup. I then screwed another piece of wood to the front edge of the plywood so that it would support the transmission at the right angle. It will take a bit of fiddling to get the support at the right angle. If I do it again, I'll consider putting some extra wood blocks on the support to block the transmission in place. I haven't tried it yet and don't know if it will work, however.
Begin by removing the @#$% nut that goes on the stud at the rear of the transmission. It screws on from the top. It's easiest if you bend a 13mm wrench at nearly right angles so that the box end goes over the nut. To bend the wrench, clamp it in a vice, then heat it at the bend point (~1.5" from the box end) with a propane torch. Grip the free end with a vise grip and bend it as it gets hot. To provide leverage to turn the nut, clamp a vise grip on the wrench.
Next, remove the bolts on the right-rear side of the transmission that are difficult to get to and crack the rest of the bolts loose. You can remove some of them, but leave enough in so that the transmission remains in place.
Now, roll the floor jack in under the transmission and raise it enough to support the weight of the transmission.
Remove the rest of the bolts. Counting the stud at the rear, there are a total of 16. Be sure you get them all.
Carefully and very slowly lower the floor jack to allow the transmission to separate from the engine. Don't let the transmission get cocked relative to the engine. That's why it's important to get the support platform on the jack at the right angle. You don't want the alignment pieces on the right side of the transmission or the stud at the rear to be jammed or bent or break the castings. You'll need a helper. One person works the jack, the other guides the transmission. As you lower the transmission, be careful to avoid getting hung up on the clutch shaft and be careful of the oil pickup tube inside the oil sump. If you weren’t able to remove the oil filler tube before, lower the transmission enough so that you can get a wrench on it now, just be sure that the filler tube doesn’t get hung up as the transmission is lowered.
Once the transmission is lowered, slide it off the jack onto a piece of cardboard and pull it out the front of the car.
Reinstallation is the reverse of removal. Just be careful to get things cleaned up so grit and crud won't get on the gasket as the transmission is raised. Sliding the transmission back up on the floor jack under the car can be a pain.
I think this covers the main points, though I may have forgotten some details. The first time I did it, it took maybe 15+ hours to take out, and 5 hours to replace, with lots of time figuring out how to do things. The second time (there was a problem with the tranny) it took about 5 hours to remove and 4 hours to replace, but I already had all the tools, etc. organized. This is in my garage, not an auto shop. I had my sons help me with the lowering/raising parts.