To update everyone. After a Yank 4L80e C5 transmission conversion I had horrific vibration....in park....and when driving!

So.....I pulled the setup. Sent the Drive Shaft Shop drive shaft back to check for balance....it was fine.

Sent the rear bellhousing, Rear torque tube bearing carrier, rear flex plate, converter, transmission bellhousing and transmission pump back to Precision Industries (Terri made all the parts for the conversion). Everything checked out as far as alignment of the components and the torque converter balance was fine.

I also eliminated the "two piece" Yank torque tube.(it was .150 out of round) I shortened a new torque tube and mounted the complete setup as GM designed it.

I also replaced both rubber drive shaft couplers with new GM units. All bearings were changed, I also checked for straightness of the torgue tube input splined shaft....all checked good...

Quess what.........I still have horiffic vibration....

I have replaced and checked all the parts that I can...all components have been checked..........

I am at a loss.......I dont know what to do....I am ready to hang up this whole project after a year and 12,000 dollars later...

I am running poly engine mounts... evrything else....(engine and engine flexplate are the same as when I ran the 4L60e and didnt have a problem.

Any ideas?

tom

 

If everything checks out on the back side what about the balance of the crank shaft. I am unsure but aren't the corvettes externally balanced? If so was thier any weight added on to the flexplate?

 

No, all the parts are internally balanced.

Keith

 

After checking everything you have, the only thing that is really left if the 4L80E. How has Yank stood behind their product. I would be pretty upset too after spending $12K.

Keith

 

I know the truck guys who did the 4L60 to 4L80 swap had to use the 6.0 flexplate with crank spacer. Are you still using the 4l60 flexplate?

 

did you swap the flywheel? What else - just the convertor?

..the vibration is likely a result of what you recently changed. Put the old converter back in and see if it vibrates.

 

He can't. The 4L60 and 4L80 converters are different.

 

vibration was the billet engine mounts......replaced them with stock units....vibration gone!
Tom

 

I am sorry but I had to chime in... You went through all that and it was engine mounts... I would have been sooo pissed.