ls1247

iTrader: (2)

My UMIs aren't playing nice with my carbon fiber shaft and have turned my car into a giant tuning fork.

Considering options....are the factory mounts failing under the weight of the engine or because they are being over extended by the torque of the engine twisting on them?

If they are failing because they are being over extended by the engine moving under torque, I could fix that with a limiting strap.

Any thoughts?

8ty8 LS1

iTrader: (3)

for what it's worth, my father put in some poly motor mounts when he did his longtubes. He didn't like the vibration at all, put new stockers back in and all is well. His only failed from normal wear and tear. Then again, his car has been stock up until the headers.

JD03Cobra

I had my first OEM motor mount fail at 110k. So I had both replaced with the OEM's again because I can't stand the vibration for the Poly's. I'm ready to re-move my trans mount and go back to stock as well.

ls1247

iTrader: (2)

Glad to know I'm not alone here. Autozone has OE lifetimes for 100 or so bucks a piece and maybe with a limiting strap I can get few miles out of them.

ryridesmotox

They are failing because they are a poor design. I removed mine at 90k and they had been destroyed for over a year. A clunk I had in the front end, that I thought was suspension, was the mounts allowing my engine to rotate into my steering shaft. They had been bad for a long time before that. I thought it was the sway bar bushings allowing the sway bar to clunk around. If you do get OEM mounts, hopefully you get a warranty with them.

ls1247

iTrader: (2)

New GM mounts from Lindsay are $110. Not bad

ryridesmotox

Right, but are they going to be bad in 2-3 years? When I bought mine from the dealer as a used car, they had already done brand new mounts. So three ones that replaced the originals only lasted like 20k miles

ls1247

iTrader: (2)

From your perspective what's poor about the design? Their ability to hold the weight or their ability to survive the torque or both?

My guess is torque....

isis

iTrader: (1)

My drivers side factory mount was pulled apart at 40k. The revshift ones I put in didn't increase vibrations that I could notice. I'm not sure they'd outlast new factory ones but we'll see.

Shifter alignment is much improved so I think in addition to the stocker pulling apart, they were probably sagging pretty good once the oil was puking out.

Aaron Thomas

iTrader: (1)

I had my stock MM's (both) replaced at 55K under warranty. When I replaced them again at 75K due to one leaking fluid and completely separated I put in poly when installing headers and have been fine for almost 25K. Not my choice to change motor mounts every 2-3 years and would rather deal with a few minor vibrations.

ls1247

iTrader: (2)

Think you could prevent this by limiting the distance the engine could twist with a strap?

ryridesmotox

I doubt it. The issue isn't necessarily the torque alone. But the issue is compounded by heat, vibration, the material (the rubber on mine seemed unreasonably thin), and then the torque. Yea so the torque is an issue, but putting a limiter strap on the motor would probably cause other issues. How and where would you strap it? Where would that torque now go since you are limiting the twisting motion of the motor?

Basically, to me its either replace stock ones when they break, which wouldn't be a big deal if you have the proper equipment. My 95a mounts haven't really had any ill effects on my car. Sure there is a little more vibration, but that could also be because I have a 12lbs flywheel.

isis

iTrader: (1)

I dont think so. I doubt the stress rip is caused by overextension. I think the upper bolt is mounted to a plate that's embedded in the rubber. As this plate moves up and down, the edges just kinda wear the rubber out. The final 'tore the *** out of it' failure might have been from overextension once the rip started, but I think the initial failure is just from the basic construction of a liquid filled mount on a high torque engine.

Sssnake

Has anyone consider drilling new stock MMs draining the fluid and refilling with window weld?Likely firmer than stock (duh) but I would think they would hold up better as well. I am torn between trying this on my Solstice or going back with similar fluid filled dampers...

ls1247

iTrader: (2)

I'm liking the way you think here. Guess you could buy the el-cheapos from the zone, drill a small hole in them, drain them, clean them out and fill them. That would essentially be a 60A motor mount versus the 80A offered by CS and revshift ? Would the window weld actually cure at that thickness.

Has anyone in the Solstice community tried this and does the Solstice have the same issue?

Fweasel

iTrader: (6)

Honestly can't say my 80A poly mounts under the motor or trans have ever transmitted enough NVH to even tip my radar. I'm pretty sensitive to noises and squeaks, drive's me insane, but not once have I ever regretted the poly mounts and bushings I've installed for vibration annoyances.

ls1247

iTrader: (2)

I believe it. But after putting the one piece driveshaft in and losing the giubo, there's nothing squishy left in the dirveline to let it "wiggle" so now the harmonics are a little more pronounced. I had learned to live with it until last night when I took a German co-worker to dinner and he said something was wrong with my car.....

isis

iTrader: (1)

Same here. I have cradle and diff bushings, trans insert, and 80A motor mounts. All the noise comes from out back. I'm sure with this drivetrain you could do cast iron motor mounts and not notice.

With the driveshaft differences, I have no idea.

mild83

So what is the ultimate benefit of getting the poly mm? I am getting ready to install a blue set from creative steel, as well as the transmission mount.

LS BRAVADA

iTrader: (4)

I like this route and will be checking into it. I should of done this before I got the polys. I think I'd be happier with no vibration even if I had to change them once a year. Now that I know how to change them it takes longer to jack the car up and drop the cats and starter. My grand national and typhoon both have limiter straps with no added vibrations.