So I'm reading the other thread with @vorteciroc schooling us up on how front and rear end play work together and It struck me that I really only have two current ways to adjust front endplay. Either I use a .078 or .094 thrust washer at the (stock .063) forward clutch hub to direct or I keep an array of front selectives on hand. Both usually get me right where I want.

But today I was looking at the torrington bearing in the face of the forward drum that the overrun sits against and I just happened to have some th350 rear shims on the bench and it hit me...what if I slip a .015 in under the torrington bearing? seems like it works really well.

Input is appreciated

 

Yes a shim at the bearing location at the over-drive ring-gear to over-drive planet, would adjust the end-play...
As does the selective plastic thrust washer at the back of the pump.
There is really no need for a shim on the over-drive ring-gear though... and excessive shims here can cause sealing-ring issues.

I like to reference the THM400/ 3L80 for part of the end-play explanation here.
For the THM400 front end-play stack-up:
-Build up through the intermediate clutch pack, retained by its snap-ring in the case.
-Leave out the direct clutch drum.
-Install the forward clutch hub onto the intermediate shaft.
-Install the thrust washer on the back of the forward hub.
-Install an empty forward drum.
-Install the pump to case paper gasket.
-Install the selective plastic thrust washer and pump assembly.

This is what is needed to measure the end-play.
The direct drum is not a factor... essentially there should be float here on a stock assembly.
The thrust washer between the direct drum and forward hub also should not be a factor (unless too thick, lifting the hub off the intermediate shaft).

The 4L80E stack up would be the same, but also include the over-drive planet assembly with the input-shaft.

 

alternatively, you can stack it with the direct drum and put a bearing (not washer) on the fwd hub.
The bearing will lift the fwd hub up off the mainshaft and now the thrust path will not travel through the mainshaft but rather through the direct drum.
Using this method on a th400 the fwd drum will be moved closer to the pump and I like that for sealing ring depth.

I do this on an 80e also

Can only do this with a bearing, don't do it with a washer

 

This is my preferred method, when I machine the center-support for a torrington bearing to support the direct drum.
This will direct thrust loads to the center-support instead of down further through the gear-train.

 

i was under the impression that the dogbone sprag sat against that face....but now that I think about it yeah they cant carry thrust loads.

I would love to hear more...bearing part number and cut specs if you dont mind sharing

 

The torrington bearing is the same THM350 Pump bearing that is used to rollerize the THM400 output-shaft, and reaction carrier.

The direct-dum should more or less "float", in a sense like the reaction carrier.
The direct-drum is not very well supported in the stock arrangement... and is one of the many reasons why the intermediate sprag is relatively delicate.
Some builders will machine the center support for a bushing or bearing that supports the direct drum from the sealing-ring bore.
You can see a bronze bushing bellow the sealing rings that help reduce drum wobble, in the image bellow:





I personally prefer machining a pocked in the face of the center-support for a bearing as it supports the direct-drum and changes the thrust path for multiple improvements.
In addition, I usually also use a Billet sun-gear shaft that has a very tight press-fit into the direct drum; to provide even more control/ support of the direct drum.
The pocket that gets machined into the center support can be done so, as in the article bellow:
Article

 

thank you for that. that whole series of articles is amazing. I'm gonna gather up the needed goodies and fully rollerize my transbrake transmission this winter.

 

Obviously most of the thrust washers can be replaced with torrington bearings... But there are still locations where no bearing is available (and also not really needed).

The 4L60E on the other hand can be fully rollerized very easily.