HELP!!!! transmission mount replaced today and now the car vibrates under acceler!!!

[Peterofdevon]

Help,

My techs replaced the tanny mount in the black 96 today (it was running perfect excpet for a little vibration at idle). I suspected transmission mount.

Got one off Joe and had it installed today...the car is now smooth as glass at idle BUT vribrates under acceleraltion.

What could have gotton screwed up? All they did was raise the back of the transmission to put the new mount in? I've had this done on other Qs by this shop and had no problem.

What could have happened!!!! HELP.

They are keeping the car over night and the sr. tech is going to work on it tomorrow---where should he start????

Help!!!

Thanks, Peter

[superuber]

You didn't have RyanH work on it did you? (low shot!)

Anyway, what did that mount cost from Joe?Did the guy drop the drive shaft?

[elwesso]

Shouldnt have had to drop the driveshaft to do the mount. Maybe it will take a few days to settle?

[maxnix]

Something is foul in Denmark!

[Q45tech]

And how are the front motor mounts................fixing one end ONLY often translates to other problem...................same with a 11-12 year old driveshaft..................have you indexed it lately as you changed the angle with a new transmission mount.

To get a used car to behave like brand new you have to change all the used parts..............that are appropriate to what you are trying to fix.

[Peterofdevon]

I had them put the old mount back in and the "under accerlation" groan/vibration is still there plus the slight original vib at idle is back---so the mount needed to be replaced.

The last Q I had a transmission mount done on had 130K and I only did the one mount and nothing like this happened.

Q45tech, where should I point my tech tommorow.

Thanks,

peter

[RyanH]

You didn't have RyanH work on it did you? (low shot!)

Thanks. So now every time something breaks, its me is it? I ask merely for information. It could be my 'thing' here!

[Q45tech]

Stress relieve the drive shaft ujoint then measure the shaft runout per fsm and decide on the proper washer count under the center bearing.

Put on a lift wheels off ground and simulate acceleration see if you can feel vibrations on various drive line components.

[superuber]

Something is foul in Denmark!

Well Brian I gotta say your right here!

OK here is how the drama unfolds:Tech 1: I got the mount in, wanna "road test" it?Tech 2: Suuuure. I have been wanting to see what one of these infiniti's will do.Tech 1: Hey, take it easy out there. It's still slippery from the last snow storm.Tech 2: Right (wink) On the road the Q handles like it's on rails. Tech 2 gets confident and pushes Raw seex into a corner.......uh oh....Curb....WATCH OUT..........OH NO....right rear rim bent. Aw, no one will know! It's Philly, everybody has bent rims!

This of course is just one opinion of what could have happened!Please don't think all shops do this!

[DrewQ45]

Did the guy drop the drive shaft?

Excellent question. I'd crawl under the car and inspect to nuts and bolts on the rubber donut (guibos) to see if they were pulled. You might also want to check if the rubber surround on the centerline bearing was ripped.

Does the vibe happen only under acceleration or does it increase or decrease at certain speeds? Run the car up to 50 mph, drop it in neutral and let me know if you still feel the vibe.
Modified by DrewQ45 at 6:18 AM 3/23/2007

[qsiguy]

Did they also do the exhaust hangars? I did those on mine when I did the transmission mount. They can cause some vibration as well.

I'd also check the motor mounts. Seems more likely to me that they are bad then the driveshaft is off. If it's only under accelleration and not when cruising at speed. If it was the driveshaft I think it would more likely do it all the time the vehicle is moving. The motor flexes with torque.

My $.02

[DrewQ45]

If it was the driveshaft I think it would more likely do it all the time the vehicle is moving.

Driveshaft vibration is not constant. At very slow speeds you'd never know. When mine went bad, it vibed in the 35-55 mph range, then again and roughly 80-90 mph. This is commonly seen.

[Q45tech]

The transmission mount sets the input section of drive shaft angle. The center bearing sets the output of the input section angle AND the input of the Second section just as the diff mounts set the output of the second section.

Don't confuse the vibration of the center bearing slop or sag or lift with that of just plain bent output [second] shaft or notched/locked up universal joints.

[DrewQ45]

My driveshaft vibe started when I had the transmission replaced. The mechanic incorrectly removed the drive-shaft by pulling the rubber guibos apart. I upgraded to a 94' shaft and things have been much better since.

[qship96]

check the rubber exhaust hangers that are bolted to transmission mount,sometimes the twisting while removing them to get the mount out further tears the old rubber isolators-I bet you find bad hangers contributing to the vibrations

[Peterofdevon]

Well, well see but it looks like its solved. I picked the car up and my tech had already left for the weekend--the guys at the shop said he said he got it. It ran perfect home---I'll take it out when the weather clears to make sure. They said bring it back Monday for a look over.

Thanks Q45tech, and everyone who offered advice. Rax Sex is back on the prowl.

Peter

[xerexabante]

I would like to know if they dropped the drive shaft. If they did make sure they used the same bolts that cam off you drive shaft.

One other thing is if they ooulled your drive shaft of and had the yolk and the main drive shaft miss aligned. It need to be marked before disassembly.

[elwesso]

didyou do anything to it?