Vibration

[Macs95lt1]

Put in new poly motor mounts and trans mount. Car now vibrates a lot when taking off gently or WOT. Smooths out at cruising speeds. The alignment of the torque arm is good. Car has original drive shaft [steel ]and u-joints. Is this normal with poly upgrades or do I need an aluminum DS or something else? Sould I try replacing the u-joints, they are 11 years old? Vibration seems to come fron under center console and maybe the right front too.

[93yellowfbody]

with the poly bushings in some instances they are shorted than the stock ones and will make the u-joints viberate...........but did you remove the driveshaft?did you mark it before removing it?

[Midnight T/A]

Where do you mainly feel the vibration? Through the seat or through the steering wheel?

I will say this, when I put on my poly tranny mount I felt alot more vibration then I did with the stock one. It's just something that alot of people feel with the poly ones and something that most people get used to since there's nothing that can really be done about it.

[Fire67]

When you do the poly trans mount, its about 1/8" taller than the factory one (assuming you installed it correctly with the backer plate). So that will mess with the driveshaft angles and cause a vibration from the u-joints. My remedy for this is to simply install some washers the same thickness as the backer plate between the crossmember and the floor board.
Others have simply left the backer plate out, which according to the manufacturer will cause a shortened mount life but also eliminates the vibration due to misalignment.
You should still notice a little more vibrations than you are used to because the poly mounts are harder... But a bad vibration is more than likely the u-joints.
Oh, Ive had my driveshaft out so many times I couldnt even try to count, and Ive NEVER even worried about putting it in the same way it came out... That just doesnt matter. Do you honestly think GM balanced the driveshaft in the car? Or even with the pinion mount attaced? All the rotating pieces are balanced seperately from each other to a zero balance, so rotating your driveshaft 180* in relation to the pinion shouldnt cause a vibration.

[93yellowfbody]

it does cause i vibration especially if you happen to change the u-joints and i 'm not talking about a really bad vib just a annoying small vibration

[93yellowfbody]

oh and you could check the angle of the driveshaft from the caps and as long as it's not over 2-3degrees you should be fine.

[Macs95lt1]

I didn't take the DS out. I had poly mm and tm installed. The vibration appears to be coming from under the center console and towards the right front. Steering wheel shakes a little too. I did notice my front tires are cupped some what. I'm gonna try rotating them and see if it helps. I have new bilstins for the front as well, it still has oems on her. The line of the drive train/pitch looks good.

[lt1firebirdslp]

you mentioned that you still had the stock steel driveshaft. these have a bad reputation for getting horrible vibrations. my stock steel steel driveshaft would make the whole car shake at 75-85+. also you mentioned when you were starting out or accellerating at WOT, possible clutch chatter? a loose or broken tranny mount will produce a vibration or shaking when starting out or at WOT. make sure the bolts for the TM are all tight under there. good luck

[94m6hardtopz]

my poly trans and torque arm mounts vibrate a little even with an adjustable torque arm and the pinion angle set. its just a stiffer mount.