4l80e bogs in forward, fine in reverse after rebuild

[CR506]

I have a 98 K3500 that lost the snap ring & tore up the transmission lugs which resulted in no reverse. I replaced it with a 2000 model 4l80e only changing the frictions, a few bushings and rear shaft since the 2000 came out of a 2wd.

Now that I put it back in the truck reverse works perfectly but all forward gears bog down like the transbrake is holding it back. Feels like when you hold down the brake and try to take off. Revs up very high but barely moves. Acts the same in all forward gears. Torque converter is new. All solenoids and the wiring harness in the valve body are new. I also installed the HD2 kit.

Any ideas?

 

[CR506]

I have a 98 K3500 that lost the snap ring & tore up the transmission lugs which resulted in no reverse. I replaced it with a 2000 model 4l80e only changing the frictions, a few bushings and rear shaft since the 2000 came out of a 2wd.

Now that I put it back in the truck reverse works perfectly but all forward gears bog down like the transbrake is holding it back. Feels like when you hold down the brake and try to take off. Revs up very high but barely moves. Acts the same in all forward gears. Torque converter is new. All solenoids and the wiring harness in the valve body are new. I also installed the HD2 kit.

Any ideas?

EDIT: I did not disassemble the sprag so I know it is not in backwards.

 

[Supercharged111]

I can ask my neighbor, he owns a trans shop. Chances are you have more than 1 gear engaged at the same time though and they're fighting each other. Usually caused by a fluid leak engaging something that shouldn't be.

 

[CR506]

Please ask your neighbor. I also think two gears are engaging at the same time but I'm not sure where to look to solve the problem.

 

[Supercharged111]

He said likely a sealing ring on the center support, which was my first thought as well I just couldn't remember what it was called. It's that big iron piece with a bunch of sealing rings that are a pain in the ass to shrink down to size.

 

[CR506]

thanks. i'll check that out.