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Earlier this year I posted an inquiry about a vibration after replacing my torque tube with a rebuilt unit. Some vigorous discussion ensued over details of bearings and dampening, so I'll start a new thread for this update.
The vibration was linked to engine speed and occurred at about 2100 rpm. It seemed to fade as I drove the car over the next week or two, almost to the point where I didn't notice it. The car has been sitting for about three weeks since then due to weather and other unfortunate events.
I took it out today and didn't notice much vibration ... until I encountered an uphill left turn at about 2100 rpm. I could repeat this on other left turns, but there was no vibration at all in right turns.
I'm afraid this symptom may confirm something Dave C. was talking about in the previous thread. Something I didn't want to hear. Was one of my motor mounts (Volvo) damaged when I left the engine free to rock on its mounts?
Curt i had a similar issue on my first Volvo MM install.
put the car on a lift and get an inspection mirror and flashlight and inspect the fingers of the MM hooks.
NOTE If you didnt put the finger plates into the vice and hit them to bend the fingers slightly,
then one of them is most probably hitting .
NOTE you can twist the finger plate with a long prybar and hammer OR
if the finger is aligned and just hitting, lower the car get a floor jack,
and a 10 inch 1/2 inch extension and 17 mm socket.
Carefully position the jack under the offending MM then put the 17 mm socket on the 17mm bolt thats closest to the finger,
then carefully jack the socket and extension onto the bolt head,
once the jack is putting force on the bolt,
jack it up a very small amount,
this will in effect lift the finger upwards.
Lower the jack and inspect your work,
NOTE it doesnt take much to move the finger.
once you can see a few mms in the finger slot,
then take the car for a drive.
If you replace the motor mounts can't you just eliminate the safety brackets/hooks(unless they're integral) ? I would think if you got into a bad enough accident that these hooks are needed you're not going to make it anyway.
Curt i had a similar issue on my first Volvo MM install.
put the car on a lift and get an inspection mirror and flashlight and inspect the fingers of the MM hooks.
NOTE If you didnt put the finger plates into the vice and hit them to bend the fingers slightly,
then one of them is most probably hitting .
NOTE you can twist the finger plate with a long prybar and hammer OR
if the finger is aligned and just hitting, lower the car get a floor jack,
and a 10 inch 1/2 inch extension and 17 mm socket.
Carefully position the jack under the offending MM then put the 17 mm socket on the 17mm bolt thats closest to the finger,
then carefully jack the socket and extension onto the bolt head,
once the jack is putting force on the bolt,
jack it up a very small amount,
this will in effect lift the finger upwards.
Lower the jack and inspect your work,
NOTE it doesnt take much to move the finger.
once you can see a few mms in the finger slot,
then take the car for a drive.
Another casual inspection doesn't show anything amiss, except that the left-side finger is slightly out of the correct rotation. There is plenty of up-and-down clearance - they're right in the middle. But the clearances to the sides are small. I'll get out the endoscope later.
Originally Posted by worf928
Also, review my post in TOT about an ‘emergency motor mount’ as a means of data gathering.
A worthy experiment. Will do. The only old tire I have lying around is for the Unimog, so I'll have to scrounge through other piles of junk.
In a left turn, the engine will unweight the left mount. Torque will also unweight the left mount. I was thinking the right mount would be the more likely suspect, but not necessarily. Which was the case for Brian's car?
Recall I jammed a stick in a wide vertical gap of one of the transmission mount attachment areas, an experiment that appeared to do something. It's fallen out ...
Originally Posted by gomez123
If you replace the motor mounts can't you just eliminate the safety brackets/hooks(unless they're integral) ? I would think if you got into a bad enough accident that these hooks are needed you're not going to make it anyway.
I read many years ago that busted motor mounts could mess up the accelerator linkage in a dangerous way. Never thought about keeping the engine out of the passenger cabin in an accident. When I'm asked by someone wanting to do something like this, I usually reply "I can't give you permission", even though I might do it myself.
These darn fingers are certainly troublesome.
Curt - check to make sure your exhaust isn't coming into contact with a heat shield. When the car turns it twists and things move into close proximity that look like they have plenty of space while at rest. An exhaust clamp was rubbing on the shield just forward of the transmission on mine. I found it by spraying some black paint on the heat shield and looking for shiny aluminum where it was rubbed off after a twisty drive. It worked!
I cut a bunch of strips from a parted-out treadmill tread*, raised the engine with a lift safety stand, and shoved them in. Raised something like an 1/8 or 3/16". I also shoved some of the same strips into the gap of the right-side transaxle mount, like I'd done before with shim stock (that fall out).
No difference in the vibration.
The vibration is something I can feel as well as hear - a high frequency thudding sensation (definitely not from sheet metal). It comes and goes very gradually - not what I would expect if the mount fingers were making/breaking contact with something. I have not yet put the endoscope to use on it - I'll be doing that later today or tomorrow when I remove the strips.
I was giving it hell yesterday, and noticed it also vibrated upon deceleration in third gear as the engine passed through 3500 rpm. While I get a vibration at around 2100 rpm in both 3rd and 4th, perhaps we should be open to the possibility that this is a coincidence: 3500 is not an even multiple of 2100. Not 3:2, either.
I'll have to keep exploring various speeds and RPM, where law enforcement allows. But maybe a wheel weight fell off...
=====
* Why would I have a treadmill tread lying around? Well, the treadmill had failed years ago. I finally put it in the "free stuff" section of Craigslist last year. The guy that came for it looked real scruffy, as this category can attract. It looked like he lived in his van. But it turns out he had a thing for building off-grid cabins, and the motor from this particular treadmill (which fail often) is a favorite for home-brew wind turbines. He was also a member of the Oneida Nation, and had lacrosse and feathered items in the van. We had a good time taking the whole thing apart, and I kept a few items to satisfy my own packrat instincts. The tread has been serving as a door runner "carpet" for my workroom.
How does it behave revving in your garage? Could it be the harmonic balancer? Sean R described an annoying vibration that was fixed with one of Greg's replacements.
Jon: This is the sort of thing where my tendency to over-think rules out all potential causes. Not helpful. Regarding the harmonic balancer, for example, I cannot see how it would be affected by turning left or right. Perhaps it is supplying the excitation, though, and something else is not damping it. Could be a new/old, old/new, or new/new circumstance, if you know what I mean.
Bob V. is probably thinking I've picked up a heavy bolt in one of my tires.
... until I encountered an uphill left turn at about 2100 rpm. I could repeat this on other left turns, but there was no vibration at all in right turns.
I'm looking at this, now, with fresh eyes and zeroing-in on the above which I missed until you repeated, just above, that the vibration is 'turn dependent.'. A vibration that strengthens when you turn is usually a symptom of front wheel bearing issues. In particular the right front wheel bearing since in a left turn weight shifts to the right side and weight shifts off of the right side in right turns.
When was the last time you checked your front wheel bearings?
... When was the last time you checked your front wheel bearings?
Yesterday, after removing the "emergency motor mount" material and probing with the endoscope.
I had a short-lived "aha!" moment when indeed, the right wheel could wobble left and right in my hands - freely, about 1mm at the diameter of the tire. But not in the vertical. I removed the wheel and still couldn't get movement of the rotor when grabbing it top and bottom, just left and right. Then I noticed the slack was in the tie rod's connection to the the rack. No such looseness on the left side. I see some complicated business about updated "stops" in the WSM.
But: I have not noted any particular vibration in the steering wheel. Surely, I'd feel it very strongly if the wheel were wobbling. I'll take another test run. Requires attention in any case.
Meanwhile, I also found that wheel weights had moved and/or gone missing on the left rear. The rubber "shims" I'd shoved into the transaxle mount vertical gap (right side) had fallen out. What else? Oh, I found no recent contact of mount fingers across their gaps, but the gaps are kinda small (0.100 inch for one finger on the right), and there are rusted-over areas where contact has occurred in the past. Are there just two locations to check? Aft on the right side, forward on the left? What exactly is the damage to Volvo mounts when leaving an engine free to rock on them?
Mustn't forget the obvious. The sequence here was: No vibration - TT bearing replacement job over the winter - vibration. But there's nothing worse than multiple sources to confound the investigator.
(You may be confused by these photos. Me, too, and I'm overdue for a colonoscopy as well.)
One of my inner tie rods went and I never noticed it - ironic as I had replaced the outer tie rods year before. Complete assembly [inner plus outer] was no more expensive than the outer alone as I seem to remember. Just give Roger [or your favourite parts supplier] a tinkle and replace both sides.
I found my issue as I was doing a routine yearly inspection- was gob smacked as to how one never noticed this during driving- never felt a thing to be suspect about!
04-28-2018, 04:40 PM
Vibration after torque tube bearing job - update
