There's a description on Tony's website, don't know if you're aware of this. Here is a link:
It seems to be possible to do the job with only lowering the cross section,
but its tight. I will be doing this in a short while, trying out the Anchor
mounts as John Pirtle also did:
The Porsche mount is 79mm tall unloaded (thanks to Greg Nichols for
measuring one for me)
Measure the height between the mounting surfaces. My Anchor 2698 mounts were 78mm. I added a 1mm thick flat washer, also to adapt the slightly different bottom side. The "splined" stud that protrudes the bottom side of the OEM mount has a larger diameter that the Porsche one. The hole in the mounting bracket needs to increase from diameter 13mm to 14.3 mm or you will have to add a shim to compensate. I added a 1mm shim. The studs are maybe 5mm longer too. That's still fine.
My mount studs were standard M12x1.75 ( vs M12x1.5 OEM) .... some report the
#2698 to have SAE threads. I used locking new M12 nuts and shims to mount them
The collapsed OEM mount was sitting at approx 65mm, so 79mm was a huge improvement !
1988 928s4 cherry red
From: Ken Postma [firstname.lastname@example.org]
Sent: Wednesday, August 09, 2000 10:27 PM
Subject:  Re: What a "!"great week - Motor mount replacement
Saturday, I'm ready to tackle the motor mounts, I get a authorized leave of
absence from my wife to go in the garage for awhile ;o)
I've done my research, Ed's post (old) says it's a 6 hour job. Looks more like a 4 hour job to me.
So up goes the car, me on the creeper.
These were the steps I took, maybe right, maybe not. But It worked ;-)
1. Front end high on jack stands.
2. Drop the steering rack cover plate.
2a. Don't know if you need to. I loosened the stabilizer bar and pivoted it out of the way.
3. Remove the 10mm bolt holding the starter wiring.
4. Loosen and lower the steering rack, drivers side won't drop much due to hoses.
5. Support the engine with a bottle jack, large pieces of wood on the oil pan.
6. Loosen the lower motor mount nuts.
7. Loosen the cross member side bolts.
8. Uh Oh, the cross member is between the lower control arms and the frame.
9. Up the time estimate from 4 hours to the 6 hour figure.
10. Remove the 2 big bolts at the rear of the control arms.
11. Remove the 2 big bolts at the front of the control arms.
12. There's a tow eye looking thing in the way, remove the rear bolt, loosen the front bolt, pivot out of the way.
13. Wiggle the lower control arms loose and forward of the cross member.
14. Cross member won't come down enough, Now What??
15. I wondered at step 4? Remove the PS lines from the rack, Don't forget a drain pan. I didn't.
16. Remove lower bolts on the steering U joint. I marked the rack end with a magic marker for alignment.
17. Now the rack comes down enough.
18. Remove the 4 bolts that hold the motor mounts to the block, each side.
18a. Raise the engine a little to gain more clearance.
19. Wiggle the mounts out of the car.
20. Time estimate goes above 6 hours.
21. Put the new mounts in the brackets. The old mounts were squashed 3/4 of an inch!!
22. Reverse the above to assemble.
Notes: Watch the exhaust shields and the mounts when pushing the cross member back up.
Refill the PS reservoir.
Time was closer to 10 hours. Authorized leave more than over!@!@!
My oil pan is now even with the cross member, not hanging below it!!!!
Top it off with a new alignment this Tuesday, Whew.
Ken Postma '86.5 928S Auto (refreshed motor mounts and other new stuff.)