For a road race car... I was going to put solid body/subframe mounts but someone told me poly would be better. Also... I was going to use solid motor mounts but I heard you should use poly or rubber for the tranny instead of solid. Anybody know why besides the shake-my-body-to-pieces effect? What about the rear spring rubber. Poly, rubber or solid?

If its a RACE ONLY then solids would be OK, except for the trans. They tend to break rather easily with solids, so I'd suggest poly on that one.

As for which is better...the soilds are harder than poly....and don't 'melt'....so I'd suggest them for a race car, which can push a car to extremes....

<font face="Arial,Verdana" size="2">Originally posted by rscamaro73:
If its a RACE ONLY then solids would be OK, except for the trans. They tend to break rather easily with solids, so I'd suggest poly on that one.

As for which is better...the soilds are harder than poly....and don't 'melt'....so I'd suggest them for a race car, which can push a car to extremes....</font>

if your car has subframe connectors I would recommend solid body mounts as well to prevent stress cracks

DO NOT use a solid trans mount.

You WILL break the case.

Next,
solid motor mounts WILL cause bore distortion under high load, scoring the cylinder walls, and potentially cracking the case of the block.

Solid body mounts are fine on a race car, I would use poly or rubber for everytintg else. Nothing wrong with rubber, everyone has to try to reinvent everything that GM spent countless hours getting right...

Ok... Went with the solid Moroso mounts. Getting ready to install them as well as CE bolt-on subframe connectors. The solid kit only has 1 bushing for each mounting point (between the subframe and the floor) but the stock setup had 2 per point. Do I just use a shorter bolt and a big washer and tighten it all up or do I use the old (but good condition) bottom spacer? Also.. the SFC's are supposed to be mounted between the bottom busing and the inside of the subframe. Will it work if I just use a short bolt and big washer? thanks again.

About the engine mounts.
My SS has solid mounts in it.

The original owner had them installed either at the factory or at the dealership.
From what he has told me, back then they believed that solid mounts were better for a drag car. That is exactly what he did with the car right from the dealership.

Should I replace them with poly mounts, or leave them the way they are? My engine is pushing out 426hp and 459ftlb.

If the solid mounts do what you say they do, then my engine would probably break the suckers off, wouldn't it.

<font face="Arial,Verdana" size="2">Originally posted by jakeshoe:
DO NOT use a solid trans mount.

You WILL break the case.

Next,
solid motor mounts WILL cause bore distortion under high load, scoring the cylinder walls, and potentially cracking the case of the block.

Solid body mounts are fine on a race car, I would use poly or rubber for everytintg else. Nothing wrong with rubber, everyone has to try to reinvent everything that GM spent countless hours getting right...

</font>


I agree totally Jake. Poly mounts are more than enough. I don't like solids one bit, especially the amount of vibration they transmit through the car!

Since the car will just be used as a road course car and never on the street, I went with the solid bushings. Do you just put a big washer and shorter bolt to hold it all together since there is only one piece per mounting point?

You gotta consider the strength of the chassis you tieing the motor to. Solid engine mounts, solid trans mount and a flexing chassis is a shortcut to a broken trans case. If you don't have a full cage and supports running through the firewall to help support the front subframe,,, the chassis IS going to flex and twist at the unibody. With the rear of the trans tied to the unibody via the cross member, and the motor tied to the front subframe,, get ready to be looking for a new trans case. Watch for cracks to start at the 3rd bolt above the starter.

Years ago, Hurst performance used to produce what they called a "muscle mount". I have a set on my 70 BB. I have no idea if any are around today........

Classic,

Take alook in your CE instructions. They say to flip the under GM mount and use it on the outside. They also give a part number for replacements if yours aren't in the greatest shape. I wasn't real crazy about using the half and half route(1/2 solid, 1/2 rubber) but thats what they say to use.

If you don't have the instructions you can look them up at http://www.competitionengineering.com/default.asp

Good luck

..and then enters the advocate of solid body mounts all the way....
I for one see no reason what so ever to use the poly ones.I just dont´t.
Have used both over the yrs,and that the solids would transmit all that much noise is pure BS IMO.
Cracks forming is another load a BS as far as i´m concerned.
I do however agree with Marv on a total race car,cause a F will crack when enough torq and grip is transmited through it.
Another point of interest is the common cracks after the roof line at the B pillar.

On my "slightly" over engined 71 i even had transversal cracks in both parts of the floorpan with the old cage installed.

Run solid engine mounts,and as stated flex trans mounts,on both-and have been for thousand of miles and yrs-on both.
No ill effects what so ever.

The only thing I regret with my solid motor mounts is that I didn't install them sooner. My car doesn't shake one bit more with the solid mounts. And I don't have problems with leaking header gaskets anymore.
My .02

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//Fred
11.58@116 N/A SBC