forcd ind

iTrader: (7)

I know people are using the 350 pump bearing for converting a 400 to rear thrust bearing-the rear case bushing is pushed forward to allow a lip to hold the bearing-not sure how much of the case bushing can be sticking out-I need a .020 shim under the bearing, and seems if the bearing isn't comp. registered on the bushing, it can slip off and rattle around-you would need almost zero end play to keep it reg.
Somewhere I saw a bearing the same ID as the output shaft, seems that would be ideal, less chance of the bearing flopping around

clinebarger

You can leave the Bushing as far up as you need...Within reason to register the bearing. If the rear end-play is set correct....The bearing can't get between the Bushing & output flange.

Loctite the Bushing in place! TH400's are known for case bushing walk. I use a Sonnax "No Walk" case bushing that has a lip to prevent walk out & the lip is handy for shims & a bearing register. The Bushing is also a lot wider...

I was working on a 4L80E here....Same bushing as a TH400.

forcd ind

iTrader: (7)

Thanks for the reply-I have used the no walk bushing using the 3 tang shims, but the lip is wider than the ID of the 350 bump bearing, so it wouldn't work-I will have to mic the length of the no walk, maybe it could go in from the rear and stick out some on the inside enough to register.
Doing these conversion type things when you are a do it yourselfer is hard as you don't want to do half of a thing and make it a failure point, so I try and reason what the parts are doing, lol

clinebarger

I don't know what I was thinking, Duh...., The TH350 bearing requires the stock bushing OD.
A '91-'96 4L80E pump bushing works & is wider than the stock case bushing, The '97 & up bushing is even wider. Just be sure to Loctite it! The factory staked the case bushings on 4L80E's. Don't recall if TH400's were the same way?

You can measure the overall thickness of the Shim & Bearing, Subtract .015"-.020"....This is how far you can let the bushing protrude out of the Case.

This is a neat mod and all. But is completely unnecessary, How often do you see damage to the Thrust & the 3-Tang selective??? HP gains/ET reduction....Probably not.

forcd ind

iTrader: (7)

Thanks-I will prob go back to the 3-4 tang setup and no walk bushing-someone had tried to convert this one but it wasn't right-I went to the local Trans Star shop but they didn't have the 3 tang spacers, prob have to get them thru the mail
I would prob like as much of the case bushing actually in the case as opposed to sticking out unsupported-the bearing and shim are like .150 so
it would take a lot of bushing exposure to keep it reg.

Dynamic396

I use an early pump bushing, as was stated. You will have as much bushing in the case as the case will allow, plus you will have plenty on the front side to register the bearing and shim on. Just make sure you don't restrict or block any lube passages on the back side (under the seal). It's pretty self explanatory, though...

Is it an absolutely essential mod? No, not in most cases. But it is cheap and easy, and allows you to dial in your gear train end play perfectly with the shims. I do it on every unit.

john kilgore

A little hint, remove 4 of the 30 splines from the input shaft. Oh not all together 12-9-6-3.