Hello, I am rebuilding my transmission and I am really confused about if I got the right reverse
drum. I ordered a AC Delco 24245624 drum and when I look at fluid passage hole where the Teflon seals ride the hole is a much larger square hole. My old one has a much smaller round hole. I would greatly appreciate some help, I can’t seem to find any info in the atsg manual, before I bought the new drum it said it fit my car

 

Ok I guess it’s my fault for not carefully going thru the atsg manual here is pics of the manual. I’m still a little confused do I have to add a checkball to the valvebody

 

Assuming the following:

1. I'm not a transmission expert, but I've done a few successfully.
2. Your trans is a 1988 model.
3. You purchased a housing for a 1993 model gear box (probably the only one still available).

Compare both "requirement" lists in the manual for the 1987 - 1992 and 1993 only housings. The only differences should be the check ball quantity (you came to the same conclusion, yes?).

Put three check ***** on the VB side of the separator plate, five check ***** on the case side of the separator plate as described in your image.

However, are you also using the ATSG 700R4 - 4L60 update manual along with the one you have? I'd follow what ever the updated manual instructs. There may be other things that might need to be taken into consideration (https://www.atsg.us/atsg/catalog/pro...date-handbook/)

Before installing the VB, check the separator plate for "peening" at the check ball locations. Replace the separator plate with the identical alpha-coded one. You might consider replacing the metal check ***** with Torlon. Torlon won't peen the plate like the metal ***** will.

Are you also installing a shift kit or making other modifications?

These things are fun, aren't they?

 

Just replace the drum, with no other changes. Square hole vs. round hole mean nothing. I have used hundreds of these later model reverse/input drums without any problems. Do not change or modify the feed hole in the aluminum piston, leave it alone. Use the waved steel, instead of the bellville steel along with 4 turbulator steels and 4 clutches here to get the best results. The bellville steel eats into the drum, the waved steel does not. Clutch clearance 040" - .070" is what you are looking to get. The pressure plate comes in several thicknesses. Make sure you use the early 1982 - 1986 type of clutches here. They are .080" thick and the later ones are .070" thick. This will make it easier to get the right clutch clearance, without changing the pressure plate.