Quote:
Originally Posted by WeekendWarriorz
I installed Revshift 80a poly trans mounts two weeks ago and returned them in under 12 hours. The vibration was unbearable. And no I didn't tighten them too tight I went back and adjusted it multiple times even to the point of just finger tight. I was pretty surprised that even the softest poly would be like that, so I ordered new OEM ones with lifetime warranty for $5.95 each! I just had my 80a diff bushings in and they feel great! No added NVH at all. Finnegan what would you gauge the NVH to be like with poly engine mounts?
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I think you should always consider the the stiffness difference with the original mounts and not only the actual shore value.
The original transmission mounts are very very soft/squishy. I haven't measured them (hard to do) but I guesstimate them on maybe shore40A
So going to shore80A is a giant leap, where considering the diff mounts (probably stock around shore70A) the difference is much smaller with shore80A
And then there are also other things like how the mount is internally constructed; how much rubber is inbetween the one and other side.
I used generic vibration dampeners with a stiffness of shore55A (cost about $2/piece....), which are considerably stiffer than the OEM hourglass shaped mounts but don't add extra NVH.
You can also look at it from a load pov. I don't know if you've ever (personally) removed the gearbox, but the whole engine/gearbox assembly pretty much rests and pivots around the engine mounts. They take most of the weight and twisting forces. The load on the transmission mounts is very little (you can easily hold up the gearbox with one hand if the transmission mounts are removed); I guess the weight on that point is no more than 30lbs or so, so half that per mount. That kind of weight doesn't need a very stiff mount/dampener to control vibrations.