Horrible grinding/rumbling and vibration under acceleration
This is a solution thread (happily) that I hope might help someone in the future with similar symptoms.
I recently replaced the gearbox on my 2.0TS and at the same time changed the old gearbox mount for a brand new one.
Once all put back together again there was a horrible grinding noise during acceleration, accompanied by a strong vibration. The harder I accelerated, the louder the noises.
At this point I started having dark thoughts with respect to the 'new' 2nd hand box and whether it was any good.
However it struck me (and the garage who did the work) that having replaced the g'box mount we might have drastically altered the engines geometry in the car if the other mounts were knackered.....
After a bit of investigation it turns out the top mount arm (and the separate rubber mount on the engine block) are absolutely knackered and essentially not doing their job at all.
The combi of new and old mounts had made a critical situation that allowed the engine to move so much that the metal band on the inner CV joint on the passenger side driveshaft was rubbing against the subframe/chassis.
So new mounts all round ordered and hopefully all good from now on.
The symptoms felt a lot to me like a dodgy CV joint, as it was also knocking when turning corners, but again this just must be down to a funky engine geometry because of the mounts.
Hope this helps someone at this point.
-1998 916 Spider 2.0TS Lusso-
H&S Corse stage 1.
CATCAMs stage 1 cams with Savali custom ECU remap.
305mm discs with 166 4-pot callipers.
Ragazzon exhaust mid section.
Biscione Racing 2x70mm rear section.
17" Zender Siena wheels with 3mm rear spacers.
etc etc etc!