Help with vibration

[Lee Mitch]

I need some suggestions FB's. I had to remove, stitch and reinstall my low miles engine recently. A new problem that developed after my install is a vibration that occurs from about 37-43 mph. That was my former "sweet spot". Please help me trouble-shoot what I might have done wrong.



While the engine was out I checked bearing clearances and set the valves. I removed the flywheel but I am certain it is aligned with crank as I made proper location marks. It is a balanced crank/flywheel.



I changed the pressure plate and disc because the plate was faulty and had been causing chatter. The replacements are new units (Bratton's and Snyder's), and I adjusted the fingers properly. It performs very nicely now. No chatter, and engages where it should.



I have new float-a-motor rubbers, but all same dimensions as previously.


The vibration exists whether the car is moving or still. (driveline related)



At one point I did have some pressure on the transmission output (drive shaft) while I was doing the reinstall. It was not perfectly lined up and the driveshaft hung up on the clutch plate. Do you think that could be it?



Suggestions?


Thanks!

[Step-down]

I chasted a vibration until I bougth a NOS U joint and installed . Smooth sailing now.

[Kurt in NJ]

was the new pressure plate balanced

[Lee Mitch]

I did not have it balanced. I have been told that they are balanced when coming from suppliers.? Also, not sure how useful since it can’t be balanced with crank/flywheel (Unless of course I remove crank/flywheel from block). I was wondering about this as a possibility....

[jetmek]

the engine rotating assy, flywheel and pressure plate are balanced separately I would take the word of the pressure plate vendor as to balance skeptically

[deuce5wndw]

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If I'm reading correctly it was smooth before and the only thing you changed was the clutch and pressure plate so that is where I would start.

[ryanheacox]

Float A Motors too tight?

[Lee Mitch]

I have readjusted float-a-motors, so I don't think that is it. thx

[J and M Machine]

Originally Posted by Lee Mitch

I did not have it balanced. I have been told that they are balanced when coming from suppliers.? Also, not sure how useful since it can’t be balanced with crank/flywheel (Unless of course I remove crank/flywheel from block). I was wondering about this as a possibility....

Ha! I have never seen this even with the expensive pressure plates.
You'll have to take the flywheel off and balance it with pressure plate as an assembly.

[Lee Mitch]

Not with the crank J and M? Could pilot bearing damage or drive gear bearing damage (assuming that I could do that) cause this?

[J and M Machine]

Originally Posted by Lee Mitch

Not with the crank J and M? Could pilot bearing damage or drive gear bearing damage (assuming that I could do that) cause this?

No:
You don't balance flywheel with crank and there is no 180 degrees this way or 360 that way.
If the crank is balanced it doesn't need the flywheel to keep it's balance. Same goes for the flywheel and pressure plate.
They should be balanced as I have shown. You have taken a balanced assembly and changed it, by adding a foreign part the new pressure plate you've thrown your balance to the wind.
Make sure the machine shop has a good machine, digital not analog that can balance it for you.
http://www.jandm-machine.com/balancing.html

[Lee Mitch]

Thank you very much!