Motor mounts... rubber, poly, or solid?

Just curious as to y'all's opinion as to motor mount material of choice.

Vehicle in question is my 5.0 'vert (lots and lots of Maximum Motorsports parts, stock drivetrain).

Mostly the car is an autocross and track day toy at this point. I do drive the car to work a few days a week, but that's only about 3 miles up the road.

Rubber is cheap, and I know it'll be the best in terms of NVH. But that's boring.

Solid is the next one up in price, but it honestly scares me. Just seems like it'd shake the car apart. But it's race car, and that makes it cool. Maybe it's not scary once it's actually in there?

Poly is by far the most expensive (double what solid bushings are), but supposedly gives a best of both worlds.

Of course, I honestly don't know what the actual benefit is. I mean, I'm aware of the claimed benefit, less torque lost in twisting the motor relative to the chassis means more torque getting to the tires, but how much is really lost there? And how overhyped is the shaking?

Poly will depend on it's hardness. Rubber usually has voids that Poly does not.
How smoothly does your motor run? If it runs even remotely rough you will feel it with solid or stiff poly mounts.

unless the car is a full on track rat.. I do not see a reason to use anything but soft poly or rubber.

On my old 89 GT, I ran Moroso solids with a poly trans mount. Sure the harmonics at times would get to me with the solids, but overall it was livable. Would I do the same combo again? That is a stupid question to ask as I would within minutes of owning it.

Forgive my commentary (since i am a fox body fan), but using stiffer mounts on a fox 'vert is like supergluing a frog to jello.

As far as torque is concerned, the amount of torque that gets transferred is exactly the same. If you mount the engine with solid mounts, the torque is transferred quickly (based on the torsional flex of the chassis.) If you mount the engine with rubber mounts, the same torque is applied to the chassis, but its delayed by the extra 0.00000001 seconds it takes to deflect the durometer of the rubber.

curtis73 wrote: Forgive my commentary (since i am a fox body fan), but using stiffer mounts on a fox 'vert is like supergluing a frog to jello.

HAHA, I Lollerskated out of my seat on that one...

soild mounts do nothing but stress other chasis parts and snap tailshafts in tranys.

I'm wrestling with this decision myself pertaining to my AW11 (stock mounts are shot). However, in my case the oem mounts are about 3 times as expensive as poly inserts. It's my daily driver though, so I'm not sure I want to put up with the vibration at idle. The engine is fairly smooth once warmed up though.

If you were experiencing chronic problems tearing motor mounts a solid might be a good choice. Problems with leaking fluids eating away at the rubber mounts then poly.

The old school way to handle tearing mounts is use a chain or cable with one end attached to the motor and the other to the chassis. Leave enough slack to allow the motor to move some, but have it short enough to keep the motor from tearing the mount.

Matt B wrote: I'm wrestling with this decision myself pertaining to my AW11 (stock mounts are shot). However, in my case the oem mounts are about 3 times as expensive as poly inserts. It's my daily driver though, so I'm not sure I want to put up with the vibration at idle. The engine is fairly smooth once warmed up though.

This is a good example where to use poly mounts.

curtis73 wrote: Forgive my commentary (since i am a fox body fan), but using stiffer mounts on a fox 'vert is like supergluing a frog to jello.

I fully expect to see this quote in GRM mag. Another vote for poly, just do it.

i was quite surprised to see how much more vibration was transmitted to the cabin of my e30 M3 just going to stiffer rubber mounts. of course an s14 naturally vibrates itself to death.

stiffer mounts in our challenge e30 didnt viberate much more and we were tearing stock stuff anyway, but of course i6's are naturally balanced.

i'd probably go poly rather than going full solid mounts in your case.

Cheap and effective grassroots solution (assuming the OE mounts have some voids in them) is to get a tube of 3M Window Weld and squirt it into the rubber bushings--it is almost like poly and much less expensive.

http://importnut.net/motormount.htm

Hockey puck: Cut to fit mount, drill 3-4 3/8" holes equally spaced from the bolt hole. Use big flat washers cheap and long lasting, but very hard ...you will hear every cylinder fire. If its only an occasional DD car, then youre probably fine, but you wouldn't want it for everyday use.