Th400 2nd Gear Problems

[Andy Durrett]

Hey guys. I have recently gotten my truck running with the new 496. I have since installed a truetrac, and Mickey Thompson’s. I have been running for at least a month with no trouble or hiccups. The trans is roughly a circa 1990 TCI street fighter th400. I went out testing the other night with my new drag radials. The truck launches like a beast, but when I shifted into 2nd, it hit the rev limiter. I immediately lifted and floored it again, and 2nd was there and not slipping. This only happens at WOT, as the trans runs like normal during normal use. I have called Jakes, TCI, and ATI, and they all pointed me to the intermediate (2nd) sprag. Do you guys agree, or do you think it’s someth else? Thanks

 

[Grumpy]

Im sure there will be more experienced people answer,
but if it functions normally in daily use yet full power higher rpm shifts,
don,t fully en-gauge under full power...
the internal clutchs or sprag are suspect

http://garage.grumpysperformance.com/index.php?threads/rebuild-a-th400-info.15291/#post-89090

http://garage.grumpysperformance.com/index.php?threads/th400-rebuild-turbo400.508/

 

[Indycars]

I'm no expert at trouble shooting an automatic, but if 3 different companies pointed me to the
sprag I would tend to believe it. Either way sounds like it's time to drop the trans and see what's
broken. Don't think I would be driving it unless you have pulled the pan and checked for metal
shavings first. If it was built in 1990 and used in a performance application, now would be good
time to replace all the consumables while you are in there.