toke_

I ordered the 1 lbs of Shore 60A from McMaster-Carr and it got here a couple days ago and i noticed the box was really light so i opened it up and the quart can was only like 2 fingers deep with urethane and the activator bottle was like half empty too. Is that normal? and is that enough to fill both mounts?

Wind Dance

iTrader: (7)

Yes

toke_

ok thank you

TeamRX8

iTrader: (25)

60A is too soft, the minimum should be 80A, I am using 94D for racing

bse50

72A is fine too, for road racing (edit: A lot depends on the manufacturer. I use a fast hardening compound that, despite its 72a shore isn't really elastic and "soft".)
The important thing is to modify the mount so that the soft "hat" doesn't take all of the load since there's no oil\resonator to absorb the load.
Drill press, 2 bolts and a couple of washers.

TeamRX8

iTrader: (25)

You keep saying this but I strongly disagree, once you put urethane in them there is no reason to do that because they can't move enough to tear open. The RH OE mount tears because the combined movement of both the flimsy OE mounts along with the soft diff mounts allows the drivetrain to move excessively (LH collapses and RH lifts). Neither side can move nearly as much (especially if you also go to stiffer rear diff bushings) so this no longer happens*if* you clean the interior out properly and get a good bond with the urethane.

bse50

I agree that it won't happen to most but it still "could" happen especially if you throw the car around a lot. The way I see it it's a mod that takes 10 minutes for both sides and has only benefits (either potential or manifest) and no side effects.
You should definitely try it if you haven't already. If you didn't live that far away from me i'd even send you a set i have.

With or without longer bolts and further thread to anchor to this way of filling motor mounts is much better than any readily available commercial mount.

toke_

well my rx8 is automatic so its not the best for racing. and when i took the mounts out they were in perfect condition so i never used the urethane. I think its the transmission mounts that are causing the vibration in the cabin but i asked and no one replied. I dont know how to change the transmission mounts on this car

Nathan Atkins

The transmission doesn't have mounts per se, the transmission is joined to the rear differential via a "power plant frame" which is essentially a girder that parallels the drive shaft. So basically the motor mounts are all that secure the front of the drive train.