[chrismorse]

Hi nick,
To keep vibration and noise to an acceptible level in our cars, we have to support the conssiderable mass of the engine and transaxle on rubber - no rigid mounting, or you loose your fillings.
So, with the lump quietly moving about behind us, we also need to be able to quickly, accurately and smoothly work through the shift linkage to get the right gear.
Relative movement between the body(which contains the linkage) and the lump make gear selection increasingly difficult.
Cruising is no problemo - however, when you are really cornering, braking or accelerating hard, there ican be significant relative movement which can make getting the right gear difficult.
If the rubber mounts are worn or loose, this can be a significant shifting problem.l

At thunder hill, I was blasting my old Ferrari 308 around turn three up to the top of the hill, turn four, max braking, a fair amount of right oversteer. The lump was tweaked hard right and forward and despite many kind, forcefull, desperate attempted downshifts, I could not find, or engage second.

After consideration of the center of gravity of the lump and the relatively short fore/ aft spacing of the rubber mounts I installed some less compliant custom polyurethane mounts - problem solved, lump secure, reliable shifting under load.

The trade off, (there are always costs), vibration at idle, particularly in the seat, (which is vastly better than the sphincter puckering when you cannot find a gear you desperately need to catch the oversteer).

Not only would I do the poly again, I bought poly engine/trans mounts for Dads 74 coupe.
Chris