Just replaced my broken stock mount with an Energy Suspensions poly unit. Now I'm getting a vibration from about 2000~4000 rpm that I don't know the source of. The car is an 89 Formula with a T-5.

Has anyone else experienced this when going from a stock mount to a poly mount?

I'm wondering if the new unbroken and stiffer mount is driving engine/clutch/trans vibrations into the body. The vibration may have been there all along but I didn't realize it with the broken mount.

 

im getting vibrations too after replacing the tranny mount
From what ive read its because my driveshaft is unbalanced

 

Did you use the pre-load bracket? When I went to the poly mount I put the pre-load mount on it and I had serious vibrations. When I removed the metal bar it went away. So I would recommend removing it. BTW, I also have a 5-speed, so maybe that will work for you.

Thanks,

Jason

 

I'm also having the same problems and I installed the pre-load bar. I think my problem is something else though...like my clogged cat converter. I still get more vibrations but it's strange. What good is the pre-load bar anyways?

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, Jon (350 TBI!)
91 Red My website

 

What kind of condition are your motor mounst in? If they're pretty bad, the vibration could be because the tranny mount isn't giving as much and the engine motor mounts are moving more. Worth a look at least.

 

Never heard of a "pre-load bar" but I'm sure they are refering to the shim. Throw that shim in the trash. It increases the driveline angle to a point that the U-joints can't cancel each other out, thus inducing a vibration.

Its tried, tested, and true. Throw it out.

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If you live in Southeastern US, check us out!
South East Thirdgen

1987 Trans Am 305
14.88 @ 92.81

 

it is because of the mount. the poly bushing is much stiffer than stock. it is transmitting the vibrations from the drivetrain to the car now. when mine broke in my '94z28 i put a poly in the car and it shook real bad. i took it out and put a stock one in and it went away.

 

Why would they say you MUST use it if it isn't important? What the heck does the bar/shim do other than raise the tranny a little bit. BTW, I have poly motor mounts and they're looking brand new still (after 5000miles ).

 

Why do they tell you you MUST? NO clue.

But everybody I know who installed a poly mount w/ the shim, had a vibration. Taking the shim out restores proper driveline angle.

------------------
If you live in Southeastern US, check us out!
South East Thirdgen

1987 Trans Am 305
14.88 @ 92.81

 

Solid Mounts, Solid Mounts, Solid Mounts.
I like Solid Mounts.Never picked up much vibration,and geometry is still correct.
They're cheaper than polyurethane and last forever.
Just my 2 cents.
-Rich-

 

Thanks for the tip on the shim. I'll make it go away and see what happens. Even if removing it reduces the life of the mount, it will probably still live longer than a stock rubber one. The vibration is speed related and does not go away when I push the clutch. Almost feels like tires but could be the driveshaft I guess.

 

My driveshaft used to have a terrible wobble at some speeds. Hasn't been a problem since I had it balanced.
I've heard for years that the factory balance on these is questionable.
When you're ready for U-joints, take it to a driveline shop and have it balanced.In my case, it was well worth the expense.
-Rich-

 

Ultimately I would like to go with the 1LE aluminum shaft. I think I will have whatever shaft goes into it balanced when the time comes. Thanks.

 

Am I the only one who installed the mount with the shim and hasn't had any problems? I feel so special.

I still have the clunk in the rear after tightening my shocks up... but thats totally unrelated.

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1985 Camaro SC - 2.8L, auto.

C'mon, spin 'em for papa...
http://www.xenodrgn.f2s.com/Frontright.jpg

 

My IROC vibrates like a ***** after my 700R4 to T5 swap. It vibrates so bad that I'm wondering if I've got engine problems. I guess I'll spend tonight taking that shim out to see if it helps.

 

Rubber by its very nature is quite absorbant to vibrations whereas the poly isn't. From what I've heard it is a trade off you have to pay for the change and longevity.

Does taking the shim of reduce the life span of the poly tranny mount then?

But in answer to the original post, I reckon it's the driveshaft that needs balancing as I have exactly the same problem.. Got to go aluminium or get it balanced.

 

Just to update...

I did not remove the shim. However, I did find a vacuum leak that I now believe was causing most of my problem. Just a coincidence that it started right after the installation of the new mount. My apologies to Energy Suspension and to my car for the unkind thoughts that I had been thinking!

There still is a slight vibration that may just be inherent to the stiffer poly mount, an unbalanced driveshaft, or a combination of both. It is much less objectionable than the vibration that my old tires had been causing.

I have also taken delivery of a new 1LE aluminum driveshaft that will be going in the next time I can get on the lift after work.

 

Since there is no give to the poly trans mount (the transmission sits higher, to much driveshaft angle), I can see why you would take out the shim to eliminate vibration. Never use solid mounts in all three locations, you will break the trans at the bell housing. I have seen it happen several times, and it does it on the 2-3 shift at WOT.

 

i just installed the mount today and dont see any difference in vibrations. same smoothness. also i had the shim in it. is it bad to use, i hear u guys talking about too much angle. why would they sell something that would change the angle too much.