I pulled the motor mounts out of my '87 and compared them to the new mounts and the old ones are only about 3/8" compressed. Since the car has Gemballa mods and a mechanic owned the car in '96 these may have been replaced. I haven't checked the manuals, but does anyone know what is acceptable?
'87 Red/Black 5sp Gemballa
My mounts were original, as far as I can tell, with 95K miles and 19 years on them. The MM's I took out of my car measure 67 mm from flat-to-flat, while the new ones measure 81 mm. About a 1/2" difference. All measurements are with the mounts removed from the car.
When the engine and mounts are in the car, supposedly with good mounts you see the engine rock if you blip the throttle (obviously while stopped and with the hood open!!). My engine certainly never rocked before, but I don't have it back in with the new mounts yet.
83S 5Spd. Red
That bloody speed hump is still to high! Not sure about the earlier cars, but
with the S4 if the engine mounts are OK then the sump will be above the
cross-member and there's far less than an inch between the cross brace and the
oil filler neck. This will cause a strong vibration at 1500-2500 rpm and will
increase when the fluid-filled motor mounts seize. An easy check is revving the
engine and watch the engine play against the mounts. The mounts act as shock
absorbers allowing the engine to twist when you rev it. A very stable looking
engine that lies a bit low is a good indicator of bad mounts.