RPOL98

i'm confused. white hard plastic? brown rubber?
i have 2 versions. the ATSG 87-93 700R4 book (fig. 100) says that for the output shaft that has the lube hole on the slanted bevel taper, to use 8677268 which i believe is the brown rubber seal. for the output shaft with the lube hole on the flat part cylindrical part of the shaft nose, to use the white hard plastic, 8642178.

and then, during the assembly instructions, in the "install overrun clutch plates" section (p. 72), it points out there are 2 different seals, "but the hard plastic will work either way". what the heck?

for the trans-at-hand, the output shaft lube hole is on the slanted taper bevel. i went with the white hard plastic, because when it was going together, i couldn't find the brown rubber version. but now...

i have both types of the seals, the white hard plastic, which AC Delco says to use for 82-91 model years (early style shaft, lube hole on straight), and i have a brown rubber seal, which AC Delco says is for 1992-current.

i went with the white hard plastic since the manual says it'll work either way. just looking for confirmation. i've got the 2004 edition of the ATSG 700R4 book.

daferris

iTrader: (8)

Per Dana at Probuilt use the soft brown one others work but the soft one seals better and lasts longer.

RPOL98

thanks, i'll dive back into it and disassemble and swap it out.

Pro Built Automatics

The late Viton (brown) seal was introduced around late 1991 to eliminate the loss of oil to the rear planetary and other areas. The plastic wore badly and as time went on the rear area was getting less oil as the seal lost its sealing capability and the rear planetary would burn up. The late seal is pressure sensitive, takes a lot of heat (625F) and rear planetary can last for 2 or 3 hundred thousand miles. TransGo solved this partly by grinding off the one land of the pressure regulator valve to get more oil to the rear area.

RPOL98

thanks for the explanation, that makes a lot more sense.

the ATSG book also says to grind a couple flats on the pressure regulator valve, p.94, step 23, figure 174. but it doesn't mention that this is related to oil supply to the rear planetary.

thanks again.

Pro Built Automatics

In 1993 the engineers at GM introduced the pressure regulator valve with all the fixes. It has a "3 ring" ID at the top of valve, earlier 700R4 valves have the "2 ring" ID at the top of valve. The "3 ring" valve has the two flats and smaller balance hole just like the 4L60E PR valve. If you have this valve "do not modify it", install it "as is". I put this 1993 valve in all of my modified Shift kits and rebuild kits.