Replacing the OD band

December 05, 2009, 05:51:48 PM

My OD is slipping on my SC. The car was driven with the TV cable off and I think thats what damaged it (the plastic bushing broke and my dad drove it for a short distance). The OD still engages, if I apply torque it starts to slip. Of course this happens while I am trying to sell the car.

Everything else about the trans still runs great.

I plan on replacing just the OD band. I figure I need the following parts:

1. New OD band.
2. Upper/Lower Valve body gasket.
3. Front Pump gasket.
4. Filter/Pan gasket.
5. Front (TC) Seal

Am I missing anything? Is this totally crazy?

Replacing the OD band

Reply #1 – March 22, 2010, 11:26:22 AM

Since no-one responded I thought I would Give an update.

Yes, this worked great.
I also replaced the seals on the OD accumulator piston and the 1-2 shift piston as these were old and hard as rocks. The procedure was actually pretty easy. Just remember, this will only fix the slipping OD gear. Like I said, my 1-2, 2-3 and even the 3-4 shifts were crisp, but the OD Band wouldn't keep stay engaged. I parked the car immediately. If you keep driving it, the excess heat created will eventually fry all your remaining seals and kill the trans.

It looks long, but its not all that hard. Just make sure you work in a CLEAN envoronment and lube all new seals with plenty of fresh Mercron. My total outlay was around $100. Rebuild kit was around $45, the OD band about $12, $10 for a new filter, and about $40 in Mercron. Not bad for a fully functioning trans.

How long will it last? No idea. Like I said, other than the OD band, it worked great, so hopefully a long time. If you ask me, $100 to get you going again for even just another year is probably worth it (I'm super cheap), especially if you don't have the coin to drop on a full rebuild.

Materials:
Basic Rebuild kit (gets you all the gaskets you need and then some) Bought mine from here: http://bulkpart.com/ Their prices are great and they ship lightning fast.
OD Band, 1.5" for 1992 and earlier, 2.0" for 1993 and later.
8 qts of Mercron
Huge drip pan.
3 bolts that fit the front pump.
Set of snap-ring pliers (or two small flat blade screwdrivers)

1. Remove the Trans from the car, drain and store the Torque Converter.
2. Get a huge drip pan from wallmart and flip the trans on its back on the pan.
3. Remove the front pump bolts.
4. Go to the parts store and get 3 bolts that thread into the front pump (not the case, they are larger than the case bolts. They are also metric).
5. Rent a slide hammer and 3 jaw puller. I used the one with the retaining ring to make life easier.
6. Remove the pump by threading the 3 bolts into the pump housing. Attach the slide hammer to the 3 bolts (one at time) and slowly tap the pump free with the slide hammer working in a circle.
7. Carefully remove the pump and set aside. KEEP EVERYTHING IN ORDER.
8. Carefully remove the intermediate clutches and steels. KEEP IN ORDER.
9. I Was then able to reach inside and unhook the OD Band and remove it since it was really loose. Should end up looking something like this: (Borrowed from http://www.explorerforum.com/forums/showthread.php?t=160569 an Excellent Reference).

10. Remove the trans pan, and unbolt the valve body and gear selector detent. Put the valve body aside.
11. The big servo in the middle is the reverse. Closer to the front of the trans is the OD piston. Remove the snap ring on the OD Piston and carefully work it out of the bore. Its easier to push it up from inside the trans where the OD band was attached.
12. Clean the OD Piston and bore with brakeclean. I used a scotchbrite to clean bore and give it a dull sheen. Replace the gaskets on the OD piston and bore with ones from your kit.
13. Soak the new OD band in ATF for a couple hours. Then work it into place inside the trans.
14. Push the OD Piston assembly back into the bore and make sure the OD Band is hooked on the guide pins.
15. Re-Install the snapring. This took considerable effort and I had to have a friend help push it down while I installed the snapring.
16. (OPTIONAL) replace the 1-2 piston seals. These come out the same way as the OD piston. But, you must use a thin piece of paper to keep the seals compressed as you re-install the piston.
17. Clean the paper gasket off the front pump, careful not to get any into the pump ports. Replace the big rubber o-ring on the pump.
18. (OPTIONAL) I replaced the torque converter seal at this time because it was easy, and came with the kit.
19. Inspect and re-install the intermediate clutches and steels. Should now look like this: (Again borrowed from http://www.explorerforum.com/forums/showthread.php?t=160569 )

20. Align the pump and carefully slip it into place making sure not to scratch up the seals on the pump. Align it carefully and torque it into place using the pump bolts.
21. Make sure no crud made it into the valvebody. Then Locate the lower valvebody gasket and install it into the trans.
22. Install the valvebody and torque per the attached PDF.
23. Install the Shifter Detent.
24. Install a new O-ring on the fill tube.
25. Check filter screen for debris, clean if necessary. Install fresh filter and gaskets. Re-install pan bolts and torque per attached PDF.
25. (Optional) Flip trans back over and replace the tailshaft seal.
26. Re-install transmission. Fill and check level. Set TV Cable. Test drive. and enjoy having OD again.

Valve Body Bolt length and Torque Pattern:

Big thanks to the the Explorer forum for the 4R70w Rebuild diary. This is a great read as the AOD is very similar.
http://www.explorerforum.com/forums/showthread.php?t=128800