Transmisson mounts: pros and cons?

[FTA1995]

Hey guys, it's about that time that all my new components are broken in properly and ready to take a whomping, but I have a quick question about transmission mounts on the 4th gens, I understand there is a substantial amount of vibration feedback you get through just about everything in the car under load with a poly mount, as I currently have. I'd like to switch back to a stock style mount but I'm worried about snapping it into pieces. For the record I didn't actually completely break the old stock o e, it looked like mostly dry rot damage and just normal wear, at least until a tear started opening up on the passenger side of the mount.

To the point; is it reall worth having a solid or polyurethane mount over the stock when drivability is a concern?
Thanks again to my favorite f body forum

[Nightrage]

I swapped to poly mounts in my motor and tranny when my engine was installed and I can definitely feel vibrations more. It was unbearable at first, but since they've broken in, it's really not much worse than stock. I had my engine installed in the heart of winter also, so everything was cold and rigid to begin with.

[FTA1995]

I see.... My mount is definitely broken in... maybe it has something to do with the fact that the motor mounts are soft rubber still :x

[Injuneer]

I've had the same ES poly trans mount under three different tranny setups over the years - T56, TH400, TH400+GV - and I've never experienced a severe vibration problem. Minor buzz in the shift lever on the T56 was as bad as I ever noticed. And it was installed completely per instructions, including the pre-load plate and without grinding down the "nubs".

[FTA1995]

Yea I did everything as instructed with the mount, used the preload plate as directed, my problem is probably either from some kind of alignment(driveline, not wheels) issue, or not having matching motor mounts then? I really dont think it's combination vibrations from the lca's or anything else, I had the vibe before the new trans, clutch, etc and I have taken basically everything apart underneath and put everything back to torque spec, same vibe, different parts...

Along the lines of new motor mounts, I don't want to get solid mounts since I'd probably break them with nothing to absorb the load shock (a few buddies of mine had issues with them), this might be more of a question of personal preference, but should I stick to new stock mounts or go poly with them? I know the stock mounts have a good amount of give to keep the ride a little smoother, which I wouldn't mind so long as I can get the vibrations to dampen down a little.
Thanks again

[FTA1995]

Another thought to add... I have never personally experienced a failed driveshaft U-joint...

[Injuneer]

My engine is sitting on the original, stock motor mounts.

[Z Ya Later]

Mine's sitting on ES mounts for the motor and tranny and I don't notice any extra vibration. Heck, the g/f doesn't even notice any bad or excessive vibration. I'm also not using the plate that ES recommends, as it makes the mount sit higher than stock (per a post a while ago on here).

I've also got poly mounts on the GN and only notice a slight increase in vibration. Then again, she has HR Parts n Stuff poly mounts, which are probably a bit different than the ES mounts.

HTH.

[FTA1995]

Its going to be quite a job chasing this one down, that's if I dont find anything I missed on my last inspection. Got the new brake system on today which has already eliminated a good amount of moving noise and squeeking, now I just need to get my exhaust quieted down enough to see if I recognize the sound. At first I thought I had a heavy attack of detonation from bad fuel or something, it almost sounds like a ball bearing wheel caster from being spun really fast, and it tracks rpms in high load, it's not a spun bearing I know that.

[Joe K. 99 Zeee!!]

It's been about four years, but I had a poly trans mount on my 6-speed before I sold it. Here's what I remember...

There were a couple brands and I had the one that was considered slightly softer. Anyway, I didn't use the pre-load plat. In fact, there was a small tab on the top of the mount that I ground off before installing it. If you compare a stock mount to the poly mount, you'll notice that the poly mount is taller. When I installed mine there was a vibration increase, but it was relatively small and shifts were much easier and smoother.

There was no way I'd go back to the stock rubber mount after installing the modified poly mount.

A 1LE mount is a good compromise for performance vs. vibrarion, but good luck finding one.

[Joe K. 99 Zeee!!]

Here's a pic showing the difference in heights...

http://shbox.com/1/trans_mount.jpg

And a thread with some more explanation...

http://www.camaroz28.com/forums/show....php?p=6369728

[Craig 94 TA GT]

My $0.02...
I have an ES poly mount for the trans, and Prothane poly engine mounts. I did notice some extra vibration from the transition, but I can't even tell now.

The stock trans mount is worthless for a modded car IMHO. I even broke 2 when I was bone stock. The poly mount has had no issues, and just like others, I did not use the preload plate. You might want to try removing the preload plate, just to see if it's the problem.

Also, it might be worth just see check your engine mounts. Although others haven't had a problem with it, mine were so worn and deformed, that the header was about 1/16" from the oil pan. I don't recall if this caused a vibration, but I believe it either rubbed, or came too close that I couldn't install it without new engine mounts.

[FTA1995]

Joe, the comparison picture makes me wonder about pinion angle a little bit more, not to mention I remember dropping the trans, the height of the shifter deck was a little bit higher up than the last time I had that apart (with the old mount on), I wonder if the pinion angle is too steep when the rear suspension isnt quite as compressed. Craig, I am going to look into new mounts for the motor, I *think* It might be sagging a little, or maybe the torque of the motor is turning the trans/motor at a funny angle with full load since the stock type mounts are up front, are pretty beat up, plus the hard poly mount that is a little taller than a stock mount according to shoebox's info.
Going to rack my brain for a little while to try and figure it out, might pull the preload plate off the mount see how that helps...


Anyone know the effects of running without that preload plate? I've heard a few different things from some people about it, completely conflicting opinions...

Thanks again guys,