I recently rebuilt my 4r100 transmission myself. It had a number of issues and I ended up doing all new clutches, solenoid pack, overdrive planetary housing, bushings, seals, etc. I’ve put about 1,000 miles on it towing the trailer. Took it for a long drive last week for the first time went about 50 highway miles so it was in overdrive the whole time. Pulled in to a gas station and when I went to leave could reverse but only if I throttled up and it was really jerky. Fluid was a little low so I topped it off and went to get back on the freeway because I still had all my forward gears but no reverse and it lurched a few times then high pitched whine. Long story short got it back to my house and pulled the tranny out and the overdrive clutches were completely burnt and the over drive planetary gears were shredded. A piece of a Torrington bearing or the over drive clutch frictions went through the planetary but I don’t understand why they burnt up in the first place. I’m pretty sure those burning up caused the gear catastrophe due to shrapnel in there. All the other clutches and drums look good. Feed bolts torqued and not broken. It had a new machined center support with snap ring. Any thoughts would be appreciated. Why did overdrive burn up?

 

I know this is of no help, but this is the very reason that I did not attempt my own rebuild and just called the “man “! Costly? Yes. But hopefully I’ll never remove the transmission again and definitely a big step up over a stock 4R100.

 

As already noted, I for sure am not a transmission guy, but I think you might want to inform the guys that are worth more info. Why did you rebuild it in the first place? Also, did you install a new cooler after your rebuild?