Years ago, I bought a new polyurethane tranny mount from PST. I never installed it. I recently got a new stock replacement (rubber) mount that I will be using instead. My question is: Are there any other cars besides thirdgen F-bodies that use this same mount? I'm not gonna use this new polyurethane mount, and really don't wanna throw it away. I would give it away for free, but the recipient would have to cover shipping charges if not here to pick it up locally...

 

Most of the poly trans mounts for GM apps have three bolt holes so they are relatively universal.

Trouble with stock replacement rubber is that they tear apart. Poly can vibrate, but usually it's not an issue.

 

There were issues with the original poly mounts. With the preload bracket users noticed vibration, mainly because driveline angle was changed by raising the transmission. Later ones were revised. Es actually makes another one that is even shorter. Either or if your car is stock or close to stock the rubber one will be fine. When my car was just bolt ons with drag radials I did break a few of the rubber ones at the track when it hooked good.

 

This is an older mount (but never installed in a car) that has a metal plate that goes on the top.
This car just has a 250hp 350, so nothing radical..

 

Plenty of V6 cars and LG4/L03 cars have broken mounts. My buddy's 83 Monte Carlo with a whopping 140hp, 250c three speed, and 2.56 gears broke the stock mount. Honestly I can only think of one thirdgen I've ever torn apart that still had a good mount. The ES poly mounts actually have the top and bottom halves of the mount keyed together, so they can't rip apart. In thirdgens, it's important because of the torque arm being bolted to the tail shaft of the trans. The suspension bears on the trans, and therefore stresses the mount more than other applications. That doesn't stop people from using the stock replacement rubber mounts, or trying to bandaid them by strapping large hose clamps around them, or other workarounds.
Your mileage may vary, but there's a reason they're popular.

 

So with all the past discussion of throwing off pinion angle and causing problems, are the new PE mounts now short enough to avoid this?...

 

Earlier this year, I replaced a broken mount with Energy Suspension's 3.1142G. The installation instructions say specifically to use the preload plate, but it looked to me like it would throw the driveline geometry out of whack. I installed the mount without the preload plate, and the geometry looked to be exactly the same as it was with the stock mount.

It worked out well - no more clunk on hard launches, no vibration, nada. I was very happy with the poly mount.

YMMV.

 

I have the ES mount on my 86, and for my recent 91 Formula I got the Prothane mount. Both are super-duper CHEEEEEP. And no vibration issues that I have seen. The 91's rubber "mount" was so floppy it would bounce the trans out of gear sometimes.

I would use it if you already have it. The urethane mounts are like..... I think it was $17 or something from Summit's wholesale (A-Tech).

GD

 

You are hinting at something. Spill the beans.

 

A-Tech Motorsports? It's Summit's wholesale division. The pricing is marginally better than the retail site. Not by much - more on some brands than others. I have much better wholesale accounts but A-Tech has extremely fast shipping. Often next day from Reno. And some brands my other accounts don't carry.

GD

 

Since it was brought up, I also have 2 ES Poly parts that maybe someone else can use:
ES 3.1109G Black Secondary Transmission Crossmember Mounts (donuts for the 2-piece transmission mount)
ES 3.6108R Red Upper GM leaf Spring Pads (Chevelle)

 

What are those round rubber donut things on the transmission crossmember called? Where can I get new ones?...

 

Exactly what I listed in post #11 - ES 3.1109G Black Secondary Transmission Crossmember Mounts (donuts for the 2-piece crossmember)

 

Sorry, I overlooked that. Thanks!

 

how long are all of these transmission mounts/bushings designed to last under normal operating conditions and years of sitting in the elements? Is pretty much every car that ever came out of the factory at this point in time due for new ones regardless of mileage? Or are the designed to last for the life of the car under normal conditions? I look at mine, looks fine, but never pulled it out to find out. my front sway bar bushing were essentially shot after 64K miles (probably less) probably 30K. Is that the same with these?

 

What breaks these in a hurry is traction. I never had an issue. Car had 50,000 when I bought mine. First time to the track in 96. I got it to go 14.2 with a 1.7 short time on drag radials. 3 passes and it separated. You will know. It bangs the trans around in the tunnel. Traction will snap it in a hurry. If your stock with street tires it will live a long life.

 

Just like batteries, rubber and plastic do have a life span, whether you use them or not. Obviously they wear out faster if used.