Is there any reason someone should not run a poly motor mount on one side & rubber on the other? There is still limited supply of GM mounts available for the passenger side on these cars, but driver's side mounts are all aftermarket. Based upon what little info I've been able to find, which isn't really LT1 specific, consensus seems to be that aftermarket rubber mounts are junk. I've already picked up a GM mount for the passenger side and just wondered if running poly on the driver side might be a better option and also wondered if doing so would be a bad idea. I want to say the only concerns I've seen expressed were in regards to running rubber motor mounts and a poly trans mount. All thoughts are welcomed.

Please move if necessary. I figured this forum might present a better opportunity for views.

 

No reason at all not to do that. In fact, on some platforms it’s a popular choice among people who want to increase mounting stiffness but don’t wish to go full poly.

 

Not sure about the supposed problem of running rubber engine/poly trans mounts. I've never experienced any problems while running (the original) rubber motor mounts, with an ES poly trans mount. I've seen stories about damaged transmissions, etc., but I've used the same poly mount under three different trans setups - T56, TH400, TH400+Gear Vendors O/D - and nothing has broken or worn out prematurely.

Listen to JakeRobb.

 

Don't think anything would be a problem using one poly and one rubber, other than the rubber one likely wearing out first....but I would replace both with ES black poly and use a stock rubber trans mount

 

I very much appreciate the input and I'm glad to see all of you are still around and active on the forum. Time moves on. Your elders tell you that when you're growing up, but it's difficult to relate until you've lived it. For the dwindling numbers of us that are still looking for info, your input is valued. For anyone that may be thinking about bailing, I hope you keep that in mind.

This is about get to get off topic for a bit, if it hasn't already, and I apologize. I remember hauling my car from Atlanta to KY and parking it in my dad's garage around October of 2000, with no prep and no plans of leaving it there very long. It ended up sitting in his garage until 2006-2007, at which point my brother and I pulled it out and started working on getting it running again. It seemed like it needed new everything and this forum was invaluable. I used to joke with him about getting it drivable and bringing it to Michigan, which is where I live now, before I turned 60. 60 is now right around the corner and it doesn't seem like such a joke anymore. It's starting to feel like more of a challenge, or a goal.

With regards to the concerns of running rubber engine mounts with a poly trans mount, there is a good chance there was no validity to it. That's also assuming I remember what I read correctly, and that's assuming that I read anything at all. I want to say it was nothing more than a couple of posts on some forums, and quite possibly this forum. It's been virtually impossible to find anything at all regarding running mixed poly & rubber engine mounts. I am planning to order a new "GM" transmission mount.

Does anyone think there is a dime's worth of difference between the ES and Prothane poly mounts, or any reason to favor one over the other? ES seems much easier to source compared to Prothane, but I do believe I have read posts where some people seemed to strongly prefer Prothane, probably due to purchasing Prothane.

JakeRobb, I just noticed you're in Okemos. I live out towards Grand Ledge. This is a bit of a small world moment.

 

I use poly mounts on motor and trans on my t56. Have had 0 problems also noticed when i went to these extreme energy mounts car handled much better around corners.

 

I must have been feeling a bit nostalgic during my last post. That's not entirely out of character, but I don't think I had even finished a single beer.

I picked up some Energy Suspension poly mounts from Rock Auto. If I ever get around to installing any combination of the mounts I now have in my possession, I will follow up. I have to say, I'm not really looking forward to it based upon some of the things I've read. I'm thinking about picking up a Happy Hooker from TPIS in case that might be of any benefit.

 

i would say to put the poly on the side that pulls up & rubber on the side that pushes down.

i did try poly on the trans and couldn't swap it back fast enough because of too much road noise -vibration.

 

I have an OEM passenger side mount, so assuming the motor torques to the right I guess the set up would mirror what you have described. I also picked up an OEM trans mount.

 

when my tranny one broke, i went looking at different parts stores and bought the beefiest one i could find. they are suppose to be heavy-duty because that same part number is used on trucks too!
i've had mine in now for about 10 years, and still get 1st, 2nd & 3rd gear scratch, without it breaking.

 

That transmission mount seems to have a very broad use case. I don't think any of my mounts are broken, but they're all factory originals and likely quite worn. I wish I would have changed my motor mounts when I was installing headers, which was around 2006-2007, but I wasn't really aware that was the best time to do it. GM mounts might have also still been available for both the driver & passenger sides.

 

I've got ES motor mounts on both sides. No complaints. Heck, don't think I even noticed a difference after the install. Now I did notice a slight increase in vibration after the Kooks headers went on. I think that's because there are no flex couplings on the exhaust anymore to dampen some engine vibration.

 

i know this is an old thread, but I haven’t had much luck getting the info I’m looking for. I’ve got the trans/clutch/ flywheel out of my car right now and I’m replacing the AC condenser while I’ve got her up in the air. Since I’ve currently got more access than normal with numerous things out of the way, I’m considering replacing the motor mounts too. It’s a 96 SS with 84k miles.

anyway, any advice on how to lift the motor up to pull the mounts? I don’t want to dent the oil pan any more that it already is. I replaced the mounts in my 05 CTS-V. It was a PAIN, but at least it had the solid aluminum oil pan that I had more faith putting a jack and block of wood under to lift the motor a little.

any advice is GREATLY appreciated!

 

One possibility, an engine support bar. See if this link works (post #492):

The Resurrection: 94 Firebird Formula - Page 50

If you read further posts, the bar actually shifted when he started working on the mounts and he had to assist by lifting under the damper. The suitability of that is discussed in the thread.

 

Pittsburgh engine support bar:

https://www.harborfreight.com/1000-l...kaArGtEALw_wcB