Mike Geary

Car was put together last year and has always had a vibration that seems to be coming from the bellhousing area. Can feel it in the gearshift lever, and really feel it by touching the clutch fork.

Vibration is most noticeable at 2400-2600 rpm. Does it while car is standing still and with the clutch engaged or disengaged. Removing the belts had no effect. Different harmonic damper also made no change.

So I pulled the 4-speed to see if the input shaft was really loose, like a shot input bearing. It seems tight.

I've got the pressure plate and flywheel out for a balance check at the machine shop.

The pilot bearing is a roller type, and appears fine. But,I am going to replace it with a GM oilite solid bearing when it goes back together.

What else should I check at this point in the hunt? Crank to bellhousing alignment?

Thanks in advance. Mike

Procrastination Racing

I had a vibration like that once in the 3000 rpm range for a couple hundred rpm. It was the flywheel and pressure plate balance. As such, I never install an unknown one (including new ones) without having them balanced first. I've had new ones be several grams out and you can feel it.

The other issue can be a bearing in the transmission, although they tend to be vibrating all the time and increase as the speed gets higher.

Mike Geary

Appreciate the input Procrastination. I should find out Friday if the flywheel & PP check out. I marked their relative position so my machinist could bolt them up like they were on the engine.

Dan Hampton

Typically, if you have a bad tranmission input bearing (one that could cause vibration), you will have trouble engaging 4th gear. If you can engage 4th. with no problem, drop that from consideration in locating the vibration.

Mike Geary

Thanks Dan. I'll cross that off because the Muncie has never misbehaved in any way.

67*427

If it does it with the clutch DISengaged, it's not the transmission because disengaging the clutch stops the input shaft. That is assuming the the clutch is completely releasing. To be sure, disengage the clutch and put the transmission in gear. If it STILL does it, it's definitely NOT the transmission.

From what you've stated, it's most likely in the flywheel/clutch assembly.

GeoffM

I hope yours is In the clutch or flywheel , chased mine through all what you have done, turned out to be the crank good luck