4L80E vibration

[45467]

Hi,I have just completed a turbo 400 for 4L80E trans swap in my 67 Chevelle. I have a vibration when sitting in park that starts at 1800 rpm & gets progressively worst at the rpm climb. This vibration is felt on the road as well as the rpm gets to 1800 & beyond.This never occured before with the 400 combo. The engine is a 454 which I have been running for the last 4 years.Would anyone have an idea as to what is going on?? G.L.

[Fast01]

What tranny mount do you have? I've found that the poly mounts tend to vibrate hell. My '01 Z-28 has a 4L80E and I switched back to a stock rubber mount because of vibration.

[Jake's Performance]

The first thing I would check is the converter.
Look and be SURE the converter snout is going into the crank pilot hole. If it doesn't index in the crank it will never be running on centerline and it will vibrate.

What are you using for converter? Stock, aftermarket, brand?

If all appeara well, re-index the converter to a different set of holes. Move it 120* rotation on the flexplate, re-attach and snug up bolts evenly.

How well did the 4L80E fit in your '67. I have a customer putting one in a 66 and having clearance issues that seem to be mostly related to the aftermarket engine mounts but it does appear tight in any case.

[45467]

The converter was properly engaged in the pump snout I double checked this . The converter was supplied by the trans builder. I am not sure of its origins but the transmission builder tells me it is a stock style 4.3 ltr converter with a 2200 stall. We will uncouple the converter from the flexplate today to try & isolate the problem.

As far as fitting the transmission in the car we had to hammer in the tunnel in a few places. Clearance for the oil lines, for the rear speed sensor, a bit on top where the tailhousing meets the the tranmission case and another spot on top where it hit a bit. I was actually suprised at how well it fit .

[Jake's Performance]

I think you misunderstood me.
Not the converter hub into the pump, the converter snout into the engine crankshaft.
It indexes into the crank and in some cases (engine mid mount, engine conversion, etc) the snout can be too short.

[45467]

I did misunderstand you, at any rate I checked everything out today & found a couple of things wrong. The transmission was still hitting the tunnel in one spot so I got the ball peen out for some adjustment. Then I found the passenger side header hitting the frame hard in one spot. I also moved the converter to a different set of holes on the flexplate. So my initial problem is solved as the vibration is now gone. Thanks for your help. G.L.

[Jake's Performance]

Good deal.
Easy fix for you.