TH400 Rebuild or replace?

[Kelly C]

I was driving my 86 K30 with a TH400 3 speed auto trans today and it sounded like it slammed down a gear and then the RPMs went flying. I still have reverse and it tries real hard to move forward but makes a lot of grinding sounds. My question is do I rebuild or replace? If I rebuild what kit do you recommend and if I replace what is your recommendation?

 

[NickTransmissions]

I was driving my 86 K30 with a TH400 3 speed auto trans today and it sounded like it slammed down a gear and then the RPMs went flying. I still have reverse and it tries real hard to move forward but makes a lot of grinding sounds. My question is do I rebuild or replace? If I rebuild what kit do you recommend and if I replace what is your recommendation?

Sounds like it needs an overhaul or possible replacement if you completely grenaded the gear train.

Check out my TH400 Information Thread if you're considering rebuilding it yourself...Tons of resources, guidance, parts lists, mods and more...

If you don't plan on taking on the rebuild yourself, depending on where you are in California, I may be able to help...I'm in Las Vegas and regularly rebuild these transmissions.