I have a 4L80E from a 2003 Express van. The extension housing (tail housing) bushing does not fit tight around the slip yoke. With both pieces removed (tailhousing and slip yoke) the slip yoke can slightly rock inside the extension housing bushing. I have tested this with two different TH400/4L80E slip yokes, my old tailhousing bushing, and a new bushing in the rebuild kit, all with the same result.

Is this normal? Is there some sort of upgraded bushing that will support the slip yoke?

 

I think it's normal, mine is the same.

 

VinceB would know best, but I do believe the bushing was changed in the early 2000s. On both of my 80s, my slip yoke has been nice and tight, very minimal movement.

 

How much play around the yoke are we talking about here? It will not be a completely snug fit if you are just test fitting the bushing. When the bushing goes into the tailhousing, it will compress the bushing slightly and make the fit a bit tighter. Your best bet is to press it into the tail housing and test it that way. If, by chance, it is still too loose, which is very uncommon, and usually due to the tail housing bushing bore being too large, then you may as well drive it back out and then find a new bushing.

 

Thanks for the info guys. I didn't measure the play or anything, I just noticed that it wasn't a tight or close fit. The best way to describe it is like this: The trans was taken apart and rebuilt because the rear case bushing was badly worn, allowing the output shaft to rock back and forth. Even with all that wear and movement, only a very small part of the extension housing bushing was worn.

 

Hmmm the bushing wasn't even close around the yoke? As in no contact whatsoever, the yoke can go clear through it without touching any part of the bushing?

 

I installed the trans and driveshaft yesterday and it feels pretty good. I cannot tell for sure if the yoke is engaging the tailshaft bushing, but I think it is. If you grab the engine-side of the driveshaft, you can shake it and feel a little bit of rocking in the tailshaft. This seems consistent with a couple of TH400's we have sitting around. However, there was also a G8 on the rack with a 6L80E (I think?) and it had absolutely no play in the driveshaft...

Also, I took the car out today and it seemed smooth. I am taking it easy on the trans for a while because it was just rebuilt and I want it to break in. On the old setup, I first started noticing the driveline vibration under heavy throttle of hard 1-2 shifts. I might try to run it a little harder tomorrow and see if it vibrates.

 

How about this. How far do your splines run inside the yoke. If they are short it will vibrate badly when u lift off throttle or make a wot run. I know from experience. And i would think it would make it seem loose bc of the shorter spline length not engaging fully. Alot of th400 yokes are like this.

 

I'll have to measure next time it's up in the air. I can see about 3/4" between the seal and the shoulder of the yoke. The output shaft itself sticks out a little past the seal.

I don't know much about the TH400's in the cars, but I do know that the two sitting on the ground in the shop both have a little bit of play in the output shaft. One is an older stock unit and the other is a super built unit I think from CK Transmissions.