weird vibration after installing new guibo, tranny mounts and driveshaft bushing

[rootuddha]

i just got done installing my new guibo, uuc red (street/track) transmission mounts w/ enforces and a new driveshaft bushing and im getting a really strange vibration...

its a "fairly" mild vibration and its a lot more noticeable under acceleration...its noticeable when im not under acceleration and the really strange thing which i cant figure out is that even when the car is at a dead stop and i rev it up it vibrates...what the hell do you think that could be?

[Stück]

Did you over tq the tranny mounts? Did you seperate the driveshalf halves to install a new center support bearing? If so did you put it back together in the same alignment? It is balanced as an assembly...

[rootuddha]

i didnt install a new center bearing and never seperated the halves but i did have the driveshaft hanging from the diff overnight....however i dont see how that could matter.

i dont think i over torqued them but i may have..i couldnt get a torque wrench on them. even if they are over torqued would that still cause it to vibrate even when the car isnt moving? thats what i dont understand...

[FredK]

Yes. The UUC transmission mounts are very sensitive to vibration transmission if you overtorque the mounting nuts. The spec is 16 lbs-ft, which is barely snug with a normal 3/8" ratchet.

[rootuddha]

awesome i'll re-tighten them tommorrow and see if that helps. thanks a lot guys

[e30s50bizzle]

its a "fairly" mild vibration and its a lot more noticeable under acceleration...its noticeable when im not under acceleration and the really strange thing which i cant figure out is that even when the car is at a dead stop and i rev it up it vibrates

Vibrate more under load? Vibrating in neutral when lightly reved Your also describing a situation that happens when ones motor mount is shot. If your noticing a vibration in neutral on a free rev than all or some of that vibration has nothing to do with anything from your transmission back

[rootuddha]

you see thats what i figured. ive tried adjusting the torque on the mounts 3 times now. each time i still get vibration....but i cant get a torque wrench on it so im only estimating. i dont know how anyone can get a torque wrench on those things....

the other problem i noticed is my actual transmission mount is off balance. by that i mean more pressure is being put on the passenger side mount than the driver side. i can actually spin the entire driver side transmission mount while the passenger side wont budge - both are just past finger tight.

further, upon inspecting my old transmission mounts i do notice that one is slightly less "compressed" than the other. what on gods green earth could be causing that? im pretty sure this is the source of my vibration problems...ive got an autox tommorrow but with this vibration im afraid to track it. :( somebody please help and shed some insightful input on this!

[turbosporttsi]

pass side motor mount sounds like its going....

[erobinson]

pass side motor mount sounds like its going....
Agreed. The only other thing I can think of is if you didn't remount the center-bearing in the same position, I know from your other thread you didn't mark it's position. However if it does this in neutral, that wouldn't make sense. If it's happening in neutral it must be something transmission or forward. You didn't drop the exhaust, right? The thing to me is that before you started this project, you didn't experience vibration I assume. Well, since then you've changed only one dampener, your TMs. Try putting your old stock ones back in and see if the vibration goes away.

Also, remember that the UUC Red + enforcers has been reported to cause vibration. I have the blacks + enforcers on my car, and there was no additional vibration.

[e30s50bizzle]

This info only puts more clues leading towards a engine mount based on the info given ,like one other member had mentioned probably passenger side.

Get in there and inspect, you got an auto-x 2morrow. I have one in Fl 2morrow too im checking everything before i go aswell.

[rootuddha]

it probably is the motor mounts. i'll give them a good check over and i'm also going to go ahead and put the old transmission mounts back on for now and i'll report back. i did drop the exhaust...but i put it all back up just the way it was and the hangers and everything are in decent shape. and youre correct i had zero vibration before starting the project. im pretty sure the lopsided tranny mount is the culprit here...and the only thing i can think that would cause that is an engine mount. i guess theres only one way to find out!

[rootuddha]

old mounts replaced - vibration COMPLETELY ELIMINATED! thanks for all the input everyone looks like i'll be dodging cones tommorrow (read: smashing into them) - old mounts are still in pretty good shape - i checked out my motor mounts and while i didnt see any physical damage or abnormalities they do look old as shit. i guess i'll get some urethane motor mounts then reinstall my urethane transmission bushings.

[erobinson]

old mounts replaced - vibration COMPLETELY ELIMINATED! thanks for all the input everyone looks like i'll be dodging cones tommorrow (read: smashing into them) - old mounts are still in pretty good shape - i checked out my motor mounts and while i didnt see any physical damage or abnormalities they do look old as shit. i guess i'll get some urethane motor mounts then reinstall my urethane transmission bushings.
Sounds like maybe the red mounts aren't for you, or you should just leave them in for auto-x and swap with new OEM TMs for the street. That, or maybe you need to experiment with torquing them. Also, when you are snugging the mounts do you have the transmission preloaded with a jack underneath it so that there is no weight on the TM while torquing?

[rootuddha]

no trust me there was a gap on the driver side bushing. it was visible...and i could spin the actual bushing with my fingers. the passenger side bushing however wasnt budging. im almost positive the old motor mounts are to blame....i cant think of anything else that could cause something like that.

the vibration was extremely excessive due to more load being on the passenger side tranny bushing. i tried retorquing them about 4 different times each test drive produced the same results.

in regards to preloading...i tighted the bottom nuts to the tranny brace, installed the brace (with the tranny jacked up) and bolted it down. i then let the tranny down off the jack and then tightened the top nuts. this is the correct procedure is it not? regardless...i need to get rid of that gap before i can put them back on. like i said..even on the original bushings i took out there was a noticable difference in height. it was a couple of mm.

[turbosporttsi]

well, sounds like you got it figured out!

however, IIRC.....the correct procedure for installing the TMs is to bolt them to the brace, then the tranny, then start the brace bolts, drop the jack, and then tighten te brace bolts. its been a while, but i think thats the sequence.

[rootuddha]

hmm that makes a little more sense...thats one sure fire way of making sure your brace is lined up correctly. ah well