I have a recently purchased 2000 f150 4X4 XLT with a 5.4 and a 4R70W (axle code is 19). It has 162,000 miles. The previous owner damaged the tranny pulling another truck out of a snow bank. It has no reverse at all, but works fine in drive until it hits 37mph. Then it freewheels until you slow down to about 21mph. Then it kicks in and drives again until you hit 37mph and so on. I pulled the tranny and tore it down. The sun gear shell is bad (weld is broken and spins freely). Sounds like this would explain the reverse problem, but would it cause the drive issue? Could it be the torque converter? I found a 1997 F150 with a 4.6 and the same tranny code (U). Would this be a clean swap if I decide to go that route or would I run into problems (speed sensor, etc)? Would the one with the 4.6 be as strong as the 5.4? Any help would be greatly appreciated.

 

It can't be the torque converter. The torque converter does the same thing in every gear at every speed. If it were the converter the truck wouldn't move. It's the sun shell.

 

Thanks Mark. Everything else internally looks great, but I would imagine it would be a good idea to replace clutches and seals while I have it apart.

 

agreed, sunshell is the problem.

replace the sunshell with new part and rebuild/upgrade as required. make sure the reverse clutches are good. might be a good idea to upgrade from a 3 clutch to 4 clutch reverse clutch pack.

at a minimum, I would reseal everything and install new clutches while its apart.

 

check out this video..