Ford Transmission :: 4R75 - Loud Pop Noise And Reverse Stopped Working

I have had 2 transmissions brought to me, both complaining of no reverse. The first belongs to my nieghbor, its an 2005 F-150 4wd. He says last week it made a loud "POP" noise and reverse stopped working. This is a truck he uses for his work and its got 337K on it. A remanufactured transmission was installed at 70K.

The fluid in this transmission was very dark and dirty. I doubt it had been changed since the reman transmission was installed. Once I got the transmission apart, I found the reverse band was worn and broken. This is cast band, so it would make a rather loud "POP" when it breaks.

The sungear bushing was worn and grooved and scored the snout on the direct drum. The Over drive band was burned and pitted.

Since this is a remanfactured transmission the case is painted gray, the paint is blistering from heat. The torque converter has been so hot the paint blistered and the metal was rusting.

The sealing rings on the pump stator had cut mild grooves into the reverse drum and the snap ring that holds the intermediate one way clutch on the reverse drum was bent and about to fail.

The over drive servo snap ring was broken, which seems to be common on these trucks. The aftermarket replacement snap ring is hardened to resist breaking and is black in color

This transmission will be rebuilt with new gaskets, seals, clutches, both bands and reman torque converter. The overdrive band and low/reverse band will be upgraded with new bands that have a high carbon friction material, that will resist burning, installing a spiral snap ring and replacing the direct drum and sun gear.

The second transmission that lost reverse is from a 2006 F150 4wd. The owner of this truck removed the transmission himself and brought it to me. I am told the truck has a lift kit and larger tire. The residual fluid is clean and bright red. The owner has a drain plug installed in the pan, so I can assume the fluid is changed regularly.

Once I got the transmission part, the only damage I found was a broken reverse band. It appears this band has been broken for a while since 2 of the fingers on the band that would still engage were worn to the metal and and the friction material is burned. The band surface on planetary gear was slightly scored. Everything else in the transmission shows very little wear.

This transmission will be rebuilt with new gaskets, seals, clutches, both bands and reman torque converter. The overdrive band and low/reverse band will be upgraded with new bands that have a high carbon friction material, that will resist burning. Also installing a spiral locking ring on the intermediate one way clutch.