Rubber or solid motor mounts?

jayem · #1 (**permalink**) 12-02-2003, 06:46 AM

Would you use rubber or solid motor mounts for a 500hp 351W?

trularin · #2 (**permalink**) 12-02-2003, 11:09 AM

How much vibration do you want to live with?

Rubber works.

Cobra20646 · #3 (**permalink**) 12-02-2003, 11:53 AM

I have solid mounts holding my 302 in the car and don't notice any appreciatable vibrations...... can ride over a dime and feel the bump more than the engine running

vettestr · #4 (**permalink**) 12-02-2003, 11:54 AM

There is a happy medium. Use the rubber mounts so it does not rattle and shake but limit movement with a snubber chain. On the torque side or side that rises when you blurp the throttle, use a chain or about 3/16 cable. Mount one end of cable/chain under a bolt in the front of the head or lower on block and the other end to frame or the upper A-frame mount.
Mount with just a little slack so vibration is not xfered but does not allow motor to rock on mounts very far. Repeat on rear of block, under a bolt on scatter shield to frame if needed. You only need to do this on torque side of engine. It does transfer some vibration when taught but much less than solid mounts. I do not think you will like solid mounts but if it tears mounts you may not have a choice.

flipper35 · #5 (**permalink**) 12-02-2003, 12:26 PM

I agree with putting a strap on both ends of the block. My tranny mount was twisting with just the front chained with rubber mounts. The chain did stretch quite a bit so I had a buddy fab up 3 straps with heim joints. On on the drivers side front of the block and one each side of the rear of the block which then becomes a structural member (the rods). You will notice a difference in the chassis because with a solid strap it transfers the torque to the chassis. If your engine is balanced the difference in vibration should be minimal.

DonC · #6 (**permalink**) 12-02-2003, 04:05 PM

Jayem:
There was a discussion on the ERA forum about modifying the rubber motor mounts with a through bolt to limit engine torque roll effect and still retain the vibration minimizing elements of the rubber mount.
You may want to take a look at it.
DonC

foothills gary · #7 (**permalink**) 12-02-2003, 06:10 PM

I saw that,DonC.There was also a great picture of the mount with the bolt in place.I believe it was in reference to sidepipe brackets braking and headers rubbing the body as a result of flex in the mounts.It would seem that you could have the best of rubber and solid with this setup.

cobrashoch · #8 (**permalink**) 12-04-2003, 08:02 AM

I went soild plates (elephant ears) front with a rear midplate after fooling with ALL kinds of mounts. Vibrations in my car were actually less with plates that with mounts in all cases. I also put thin rubber strips between the plates and the midplate and that actualy made things worse too, so out the strips went.
I've seen cars where the opposite happens. I think it has more to do with harmonics and the chassis design than anything else.
My advice on this one is to quiz owners of the same make of your car with similar setups, and the original manufactures too. And place a lower priority on the rest, such as with my own experience. All Cobras are not created equal, but don't be afraid of plates too.
cobrashock