a73camaro

The rear planetary gear set from a truck 700R4 is showing evidences of overheating. On the planetary pinions, there is a thin layer of "coked" on oil, but wipes off with a rag. There is no unusual wear on the gears.

I have not towed in overdrive, and I only use overdrive on the highway.

Is there anyway to provide additional cooling for the rear planetary gear set? The bearing of the pinions ride fine.

Thanks

4L60bliss

Look at the bottom of the planetary for the oil slinger. It looks like a big metal washer on the bottom. If you can see the pinion shafts, you don't have one. If you don't have one, you should get a planetary that has one (I don't think you can get them without anymore). Also, if you don't have the slinger, you may have to update the Reaction carrier internal gear support, since the new ones are chamfered on the inside to accomodate for the slinger. Also take a took at the seal thats up inside the input housing (if the housing is still together, then you will see it through the hole in the foward sprag. If that seal is cracked or broken (non viton seals get brittle and break) then that planetary lost alot of lube oil. Do you have a tranny cooler?

Pro Built Automatics

If the planetary looks & feels ok?, then make sure you add the "viton" input to output shaft seal in the transmission (it sits in the input drum) and modify the pressure regulator valve (as per Trans-Go specs), this will guarantee the rear planet oil. If you do this then the planet with the oil slinger is not necessary.

4L60bliss

GM says the viton seal should not be used on output shafts built prior to '91. Shafts built prior to '91 have the lube hole on the shank, while the '91 and later lube hole is on the chamfer. Is this BS or is it OK to use the viton on the older shafts?

As for the planetary, I don't even think they make them without the slinger anymore.

Pro Built Automatics

It's BS. GM back in 1996 faxed me information that said if I use the viton seal it would cover a hole & would burn up the rear planet, if that were true then the rear planet would get more oil according to the information I was given. (1) It seals against the same area as the plastic version. (2) I have seen this seal on 250K+ mile units with the rear planet worn out (not burned up) so the seal must be working. I have told over several hundred shops about this "viton" seal and the feedback is that they have had no problems at all. A few months later GM said it would not hurt anything, (I suspect it would hurt their rear planet replacement business though).

a73camaro

Thanks for the replys!

4L60bliss

Sweet. I'm going to throw all those hard plastic seals out...

As for the non-slingered planetary, I answered my own question today. I tore down a 2002 4L60-E and the reaction planetary did not have the slinger. Its been so long since I saw one without, I assumed they stop making them.