Author Topic: Engine/car vibration  (Read 761 times)

Gary 30U

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Engine/car vibration
« on: August 22, 2010, 09:52:05 PM »
Since I have started driving the car I find that I have a serious vibration that is RPM sensitive. I have taken the fan belt off the water pump and generator and that didn't affect the problem. I did find that I needed a new bushing in the generator.

I talked to another member of the club and he thought I had something solid attached between the engine and the frame that would have picked up the sympathectic vibration.  I checked this out and found an exhaust pipe hanger attached directly to the bell housing - not directly to the frame.  I also found the exhaust pipe touching the gravel guard where it went down through it. I fixed both those problems without reducing the problem.

I next checked the front motor mount and found a big problem. The rubber donut had apparently disintigrated many years before. When the previous owner rebuild the engine in 1980 they had not installed the mount correctly. They had run bolts up through the frame, through the top and bottom plates of the motor mount and directly into the front timing cover. This obviously created a direct contact between the engine and the frame.

I took out the motor mount and sent it to Andy Bernbaum and had it revulcanized. It took some time, but only cost $49.00 plus postage.

Well what I was getting at was that this greatly reduced the vibration, but didn't eliminate it.

NOW anyone have any other ideas as to what my problem might be. I have thought maybe the engine, flywheel or cluthch might be out of balance. Anyone have any experience with this or any ideas?

Thanks, Gary

Rusty

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Re: Engine/car vibration
« Reply #1 on: August 23, 2010, 08:09:54 AM »
You said that it is RPM dependent.  So it happens with the trans in nuetral and now driving.  I would check the clutch first.  Did a bolt fall out, etx.  Pull the lower part of the bell housing off and take a good look at the clutch.   Could a piston break???  A piston that is missing half it's skirt could do it.   There are a rubber motor mounts that bolt between the frame and the bellhousing, one per side.  Are these missing/dry rot?   At what rpm does stuff start to happen???
rusty

Gary 30U

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Re: Engine/car vibration
« Reply #2 on: October 01, 2010, 11:42:57 PM »
Rusty, Sorry I haven't updated on this issue. Thanks for your suggestions.

When I put the new front motor mount in I was looking at the gravel/dust shields. It makes no sense to me the way they are istalled in the car. Starting at the front they are mounted below the motor mount, this mounts them directly to the frame. Then they are attached to the frame rails down either side. But then the rear portion has holes in them that match up to threaded sockets in either side of the bell housing. If you but these bolts in to stabilize the dust pans you make a direct connection from the frame to the engine.

I don't know what the effect of this connection is because I have tried it both ways, with the bolts in and with the bolts out, and it doesn't change the vibration.

I took the bell housing clutch cover off and don't see anything wrong there.

My next project is to take the engine out and have the clutch and flywheel checked for balance. At the same time I can also mount the engine in a stand and run it to check for vibration independent of the car. By having it out I can also check the rubber portion of the bell housing mounts.

If all that fails I guess it is pull the engine down and do a balance job on the complete engine.

See my other post about radiator belch.

Thanks for your suggestions and Happy Motoring.

Gary