Bertrand Daoust

Hello.
I replaced my MM (and OPG) last week. The motor rocks and is smooth as silk at every RPM... On park and neutral!!!

The problem is that it has an annoying vibration at about 3000 RPMs while in gear (2, 3 and 4) under load. No problem at all when cruising or on lighter load
in 2 and 3 but it looks that it stays on way over 3000 in fourth gear (but that could be another problem!).

I hope somebody will help me with that. All that work and still got a problem

Mrmerlin

the symptoms you descrbe sound like a Torque tube bearing that has moved out of position or the TT damper is either loose in the tube or was not reinstalled when your TT was rebuilt, can you provide any more info?? This is something else to check the front flex plate for a crack where it bolts to the flywheel, also check the driveshaft clamping bolts and the CV joint bolts, and the trans mounts, also the heat shields you might have bent one look near the front shields where the Ex manifolds pass by the front crossmember side supports, and the canter heat shield as it runs along the top of the exhaust

the flyin' scotsman

If the TT brg has moved does the problem cause further issues other than the annoying vibes?

SeanR

Eventual failure.

Bertrand Daoust

Mrmerlin: The PO change the TT back in 2000 I think. I bought it sept. 2005 and had some vibration since then. Last year I installed a Jager Speed Mount. It was better but still add vibration in the 2800-3000 RPM range in every driving condition (in park, neutral, cruising or under load). Now it's a bigger vibration than it was but only on load like I wrote. Is it possible that when I replaced my MM, it amplified another problem?

Mrmerlin

Bertrand its possible that the TT damper was left out upon reassembly somtimes these dampers ends will soften and let the damper move in the TT you might notice if when you stop you might feel a small thud from the drivelin more noticable when stopping , but as i stated before either a bearing has moved or the damper is gone or not secured in the TT, you can get some kind of an idea whats going by removing the exhaust system and the center heat shield then going to the rear inspection/bolt removal hole on the bottom of the TT and with a ben piece of wire see if you can feel either the bearing or the Damper the damper should be in the TT about 20 inches from the rear of the TT and then the rear bearing, somtimes the rear bearing will walk out of the tube and sometimes the front bearing will walk to the flywheel so check the front connection as well, by removing the bell housing cover

Bertrand Daoust

Thank Mrmerlin for the info. I will try to find some time to check that (or have my mecanic check that$$$).

Also, can it be related to the torque tube if it happens only on load and not in Park or neutral?

Thanks again.

Fogey1

Transmission mounts? Now that you've changed the angle of the TT back to the trans by installing new mounts.

dr bob

TT bearings are not load-sensitive, only engine RPM sensitive. If you have a vibration that only shows up under load in a specific higher gear, start with basic engine stuff that might cause it to miss under that load condition. Driveline parts tend to vibrate based only on --their-- RPM's, so driveshafts and CV joints and tires/wheels will be related to road speed.

Mrmerlin

DrBob, interesting thoughts about the engine possibly misfiring,although Bertrand says the motor is running smooth as silk, I wonder if a coil wire, ignition wire or spark plug might be bad and with the engine under load it causes a misfire.......... I know that the TT damper not installed in the TT will create a vibration in the rev range that Bertrand is talking about , but it seems unlikley that it was left out on the TT rebuild, however, I have seen a few dampers pound out the rear bearing and move the center one forward, this can be noticed be feeling a thud in the driveline when stopping fast, anyway I hope Bertrand figures out what the problem is

dr bob

Stan--

I'm with you on the damper moving around, except that the vibration from that will happen in neutral or park with the car sitting still, engine at the sensitive RPM range. That range would depend on where the bearing have migrated as well as where the damper has migrated, or whether the damper was left out at some point. Keep in mind also that the TT & damper issues would not change with a MM swap. Nothing in the MM process tweaks the TT unless the engine was supported at the bellhousing during the mount and pan gasket change. Then the overturning moment of the engine would risk bending the whole tube. Again though, that vibration would not be load-sensitive. That's pretty much my reasoning for looking for something that is load-sensitive, like engine under varying loads.

dr bob

If the MM hadn't been in play, I'd be looking at CV joint wear as a possible cause.

Bertrand Daoust

Hello everybody.

I used some 4x4's as a "hoist" to lift the motor (thanks to Andrew Olson for that method) and everything went perfect. Honestly I can't see how I would have damaged the TT. But I'm not 100% sure... And like I said it's realy realy smooth in Park at all RPMs It's only under loads that there is a problem.

First I will revise the full procedure I used
http://members.rennlist.com/pirtle/svc_mm.html
A very good one by the way and make sure everything is OK there. And then will see.

Thank you everybody for your help.

Bertrand Daoust

I might have found something.

I can see from under the car that the lower bolt of the left MM is very close (might be touching) the steering rack oil line. The right one is fine. I remember that bolt was longer than the one on the original MM (see pic). That's sure it is not right and might be why I have so mutch vibration mostly in the steering and a little bit less in the rest of the car. And 3000 RPMs = maximum torque...

What do you guys think about that?

I think I will have to lower the steering rack and grind that bolt... I will do that later this week (I'm working night shift for few days).

I hope this is the problem. I'll keep my fingers crossed.

Thanks again.

Bill Ball

That does look like a good suspect.