95 4R70W rebuild - TCCoA Forums
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post #1 of 1 (permalink) Old 11-08-2015, 11:07 AM Thread Starter
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Arrow 95 4R70W rebuild

Vehicle owner complained about no gear engagement(park to reverse or park to drive) in colder temperatures. Test drove, several times and could never duplicate the problem. The transmission fluid was brown, over filled and had a odd odor (not burned). During the test drive the transmission had a very harsh 1-2 shift, but all other gears engaged normally.

Pulled the transmission pan, in preparation to remove the transmission. the fluid was brown and the consistency of engine oil. the transmission pan had a normal of amount of friction material and pan magnet had been removed. Once the pan was removed, I found a length of rubber hose wedged between the case and valve body, not sure what the purpose is for that. It was removed and discarded.

Removed the transmission and disassembled it. All the rubber seals and o-rings were flat and brittle. The 1-2 accumulator spring was broken and had damaged the accumulator piston and cover. The Intermediate clutch teeth had worn to a sharp point where they mesh with the outer race of the Intermediate one way clutch, the OD band was dark and glazed and the metal clad sealing rings on the front pump stator and out put shaft were worn and polished. Oddly, there was no wear to any of the friction material, you could read the part number on almost all the clutches.

Once I got the valve body apart, I found the issue. This valve body still had the old style reinforcement plate installed. there was a TSB from Ford about this in the mid 90's that talked about installing an updated plate kit that eliminated pressure cross leaks between the reverse and forward clutch circuit. In addition to this issue, I found one of the rubberized checkballs was worn and oblong, as well as the pressure regulator valve being worn and lightly scuffed.
Read about TSB here -> http://ww2.justanswer.com/uploads/bk...trans_slip.pdf

The transmission was rebuilt with a new gaskets, seals, clutches and bands. As part of a normal rebuild, some of the parts were upgraded and I performed the normal lubrication modifications.
The cast aluminum accumulator pistons were updated with the newer, bonded rubber pistons and the smaller OD Servo (with the sleeve) was replaced with the larger, 2.7" piston. The older style 1-2/2-3 shift solenoid was updated with the new style shift solenoid. The valve body was cleaned and rebuilt. The Sonnax pressure regulator valve, boost valve and increased pressure regulator spring were installed along with new, updated reinforcement plate and new rubberized check balls. A very mild version of the Jmod was performed to improve shift quality but with out making shifts harsh.

I rebuild AOD/AODE/4R70W/4R75E transmissions....Check out my Facebook page: https://www.facebook.com/pages/North...48414635312478
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