In the process of building a th400 with a 4L80E direct drum. I noticed the 4L80 drum has only one direct oil hole and one reverse oil hole as compared to every other th400 drum I have. The older th400 drums have two feed holes for each chamber. Which drum should I use? Seems the more oil holes the better.
I have four older drums but the pressure plate snap ring groove is too low to use six frictions, even with thin pistons and steels.
And to make matters worse the old drums have no check *****. My thinnest pistons have no check ***** either. Can the ***** be added to the drum or the piston? (if that becomes necessary).

 

If you use the Trans-Go setup the late drum will be fine. If you are going to go over 6500 rpm then drill a .040 hole at the outside edge below the piston to vent oil. When using the Trans-Go setup, it should supply you with the SHD springs to replace the stock ones in the direct drum, with both of these modifications (oil hole & SHD springs) the drum could see over 8,000 rpm without any problems. The TH400 when setup right can take an easy 800-900 horsepower & live for awhile.

 

Do you know the reason why the 4L80E drum uses one hole that goes from the center support to feed the direct side of the piston? It also has one hole to feed the reverse side of the piston. All older drums I have use two holes that go from the center support to the chamber behind the piston, two for reverse and two for direct. Will this effect performance or should I use an older drum with two feed holes for each chamber?
I am going to use a full manual reverse pattern valve body and a set of the transgo direct springs (and a few other things).
Thanks for your help.

 

It was cheaper to make the drum with one hole. I have not seen any negative effects from the one hole drum so far.

 

Thanks for the help.