New vibration @ 1800 rpm? Help!

[Jack 34pu]

Had engine and trans out and back in a few times to fix a trans problem. Marked flywheel and pressure plate to reinstall as they were originally. Same clutch plate. As I go up thru the gears and pass 1800 rpm, I get a shudder/vibration and a jangling sound underneath. It passes very quickly. It also happens as I slow down or change gears - but always at approx 1800 rpm. How could something be suddenly out of balance?

 

[CWPASADENA]

BUMMER;

It may be something in the clutch is coming un-done. I do not know what else it may be if you only messed with the trans and clutch. Apx. 1800 RPM is one of the natural harmonics of a V-8 Engine and if there is something out of balance in the rotating assembly, it is usually more pronounced around this RPM.

How about the Pilot Bearing worn or bad or the end of the main drive gear where it fits into the Pilot Bearing? This would allow the clutch disc to be slightly off center whould cause a vibration.

I do not think it is in the drive shaft or U Jount area because this is more "Road Speed" sensitive.

Let us know what you find out.

Chris

 

[Straightpipes]

I've had it happen with the flywheel not seated properly against the flange. Since then I always check the flywheel runout with a dail indicator. Should be no more than .005".

 

[Jack 34pu]

The input shaft was replaced during the trans repair, and since it was in such good shape, I never thought to measure the pilot end for wear. It makes sense that some wobble would occur if there was too much clearance between pilot bearing and shaft allowing the clutch to be slightly off center. It is such a narrow rpm band that the vibration/shudder happens.