Engine Vibration

D

dderensis

Junior Member
I have a 40 business coupe with a vibration that I can't find. It has a recently rebuilt engine with less than 50 miles on it. A machine shop did the rebuild. I've eliminated the fan, motor mounts,generator etc. It's a low level vibration. Has anyone had any experience with flywheel/ clucth vibrations.

Dan
 
Not sure if this helps but I was told that many "vibrations" are due to lack of anti chatter bars. Do you have pics of the back of your motor/transmission? Need a top view but they attach to your frame. Here is a picture someone sent me of a 8ba style anti chatter bar bracket, but has the same idea.
 

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have you presented the problem to the machine shop? did you have them balance the assembly? seems like that would be a good place to start. hope you/they get it figured out.
 
Do a compression check to make sure the engine it's self is running properly. A dead cylinder will cause a vibration.
 
I found a Mercury with a vibration that the timing gears were off 1 tooth. Moved the gears so the marks lined up and the vibration was gone. G.M.
 
I had a similar problem once, turned out to be in the
pressure plate and flywheel, out of balance, took them to a machine
shop and had balanced together, solved the problem
 
makemc said:
I had a similar problem once, turned out to be in the
pressure plate and flywheel, out of balance, took them to a machine
shop and had balanced together, solved the problem
Click to expand...


I agree. The plate and flywheel should also be marked when balanced.
Check the chatter rods frist. That's an easy fix.
 
Too much oil can cause a vibration ---if the oil level is high enough that the crankshaft is splashing in the oil there will be a vibration.

Crankshaft ground off center ---if the crankshaft was set up using worn bearing surface for centering it would put the flywheel off center, I know .003 is enough to have a vibration in model A, the last crank I sent out to be ground came back .008 out, when I questioned it I was told --it's just an old car, it won't matter.

You could take the pressure plate bolts out, rotate it 1/3 and rebolt without taking it out--unhook the clutch adjuster first.

Also the special bolts with shoulder could have been lost and regular bolts used for PP, the shoulder is for centering the PP
 
I talked to the Machine shop and the only thing they can think of is that the flywheel pilot bushing was not put in. I would have thought that this would have caused a much more violent vibration than I have.
 
Kurt in NJ said:
The last crank I sent out to be ground came back .008 out, when I questioned it I was told --it's just an old car, it won't matter.
Click to expand...


If my Machinist said that and did that too me
He would be finding me a new crankshaft.
And I would be finding me a new machinist!

I would also bad mouthing that shop FOREVER!
Bad attitude! & poor quality work
Poor quality in the care of there Equipment
Bad combination

Over the years I have found it harder and harder to find good Hi quality Machine work I cant tell you how many times I have had too send work back to be done over again, ALWAYS double check a machine shops work.

The turn over is Very hi any more in these shops the guys that were good are retired and the kids there teaching think there good but it takes more than rebuilding a small block mouse motor to be good in my opinion.
 
I agree on the clutch replies by far ,You could remove the inspection cover on the tranz and put lead stick on wheel weight s on ,at various spots to try and locate the problem ,
 
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