I've heard solid motor mounts will crack my rear iron.
 

I've installed solid aluminum motor mounts. Will the stiffness cause my rear iron to crack? Anyone have experience with this?

well if the crack is caused by something bending, and not detonation/ignition cross fire, then i think we'd rather bend the engine mount instead of trying to bend the engine

if solid mounts could crack irons you would see non turbos with cracked irons, i have yet to see that happen.

So you think I'm good leaving these aluminum oneS on?

Motor mounts are ment to dampen the chassis (and there for you) from the engine, not the other way around. Solid mounts are widely used in racing applications.

Ight. Thanks for the input guys.

Maybe the guy who told me about that keeps detonating, and blaming the cracked irons on his mount.

maybe drag racing. in road racing it vibrates things loose, and weird parts fall off the car, plus the driver sees double, so its just doesn't work

aren't the mounts attached to the Center iron?.

^^

Yes, I have always cracked/bent my center iron on the passenger side where the motor mounts bolt on.

So it is possible for the solid mounts to crack the center iron?

Probably and definitely with contributing factors (see below).

Mine was not solid engine mounts, but the Mazda competition rubber mounts.

I think the contributing factor on my center plates cracking is I put an engine torque brace from the alternator mount to the chassis. I think this changed the engine torque pitching to where it was redirecting force to the outside passenger engine mount bolts.

On my last build I left off the torque brace, but I did re-use the cracked center iron so I won't know if it worked or not. Also, that engine cracked the front plate at the upper dowel.

And to add this tired old refrain, solid mounts are typically not suitable for street use and sometimes not suitable for race use as pointed out above.

They will transmit every little vibration to the chassis. Now the engine doesn't vibrate very much, but the entire drivetrain certainly does see shock loads, banging, vibration, changes in direction, etc. that will transmit up through the engine to the car.

On the street this is...highly unpleasant. It will vibrate the whole car, resonating the chassis and drill into your brain.

If you want a set of stiffer mounts that still have some isolation, AWR Racing makes a very nice set of FC mounts based on poly bushings. Yep, expensive, but you get what you pay for.

Not good
 

I had solid engine/trans mounts on my fc and my ride was horrible.All the noise/vibration from the drivetrain was disgusting.I could hear my flywheel/clutch/pressure plate moving along with all this noise from everthing else..........not a very friendly ride at all plus bolts and nuts coming loose all the time.I put semi solid competition engine mounts and red delrin trans mounts and is all good now.

i wouldn't assume solid mounts could ever crack a rear plate, perhaps as Blue mentioned they could cause damage where they physically bolt to the engine though.