The Stovebolt Site Forums The Shop Area Driveline TH400 rebuild kits?

Anybody have recommendations for a good, complete TH400 rebuild kit? This isn't a high performance application. It'll be going back into the truck it came out of behind a 4.3L V6.

This will be my first automatic rebuild, so any recommendations for a decent rebuild manual with clear instructions (and preferably with lots of pictures) would be much appreciated also.

Why TH400 behind a 4.3?

Transtar makes a good rebuild kit. Probably some others out there.

That's the way it came from the factory. 85 Custom Deluxe with a carbureted 4.3, TH400 and 2.73 rear gears. I lost reverse in it the other day and the forward gears aren't shifting very well. I know it's not technically a stovebolt, but I figure since a lot of people are using the TH400 in stovebolt applications there should be plenty of know-how on here.

Make sure that you get a new or reman torque converter when you do the job.
These guys have quality rebuild kits avalable.

http://www.fatsco.com/

400's are a little tricky to rebuild. A couple of the clutch packs have a very tight-tolerance fit between the piston and its bore, so getting the clutch assembled without damaging the outer piston seal is a challenge. One sneaky trick is to leave the piston, with seals installed, in a refrigerator overnight to shrink the seal a little, then install it quickly with LOTS of Vaseline as assembly lube before it warms up. There are also two identical diameter lock rings associated with the center support and intermediate clutch, one with a chamfer, and one square-shouldered one.

DO NOT INSTALL THE TAPERED RING IN THE GROOVE IN THE CASE!

If you do, the transmission will make one 1-2 shift, and the pressure of the clutch discs against the tapered ring will dislodge it. You'll have to tear everything down and swap positions with the lock rings. The square-shouldered ring MUST be installed in the case groove ahead of the intermediate clutch! Don't ask me how I know that!
Jerry

Did you invent any new cuss words when you had to tear it down the second time? :-)

A properly-qualified journeyman mechanic should be able to swear nonstop for at least 10 minutes, preferably in 2 or 3 languages, without repeating himself. It's one of those obscure ASE certifications necessary to attain Master Technician status. (Did I mention I am Master Certified in 4 categories?)

LOL!
Jerry

Rebuilt mine with a kit from tci. I wouldn't use any shop towels around the valve body. Seen lil red fibers cause hell for some people.
Side note: keep a shop towel away from lifters as well.

On a side note- - - -valve body valves (and lifter plungers) are fitted so closely that simply holding one in your hand for a couple of minutes will swell it enough it won't go back into the hole it came out of. When working on either valve bodies or lifters, surgical cleanliness is an absolute must.
Jerry

Jerry, do you have a clean room for rebuilds? I made a lil section in my garage for such instances.

Looks like this project is going to take some prep work before I even consider dropping the transmission. A buddy of mine has offered up his garage as a place to work. I'll make sure we've got a nice clean corner to work in.

As far as kits go, I've got three different recommendations from the comments above. Maybe a better question for me to ask would be, are there any kits it's recommended I steer clear of?

I haven't heard of any kits being junk. When you do get it apart, just be clean and stay organized. They're not too difficult.

The main difference in automatic transmission rebuild kits is in the quality of the clutch disc facings. I'd reccomend choosing a kit somewhere in the mid-price range. The high-dollar racing kits use a very hard clutch facing material that works best with "Type F" fluid and gives a VERY positive shift because of the extra friction enhancers used with that fluid. The clutch facing material is almost black in color, and quite dense in texture. The clutch material used with Dexron type fluid will be medium-brown in color, and gives a smoother shift when used with the proper fluid. Using Type F with soft clutches can result in the clutch material shearing off the plates.
Jerry

Thanks Jerry, that's what I was needing. I just want a good reliable factory spec rebuild.

I checked O'Reilly's and Autozones websites. O'Reilly's carries Powertorque and Pioneer brand kits. Autozone carries Dacco and ATC brands. Looks like the most complete kits and a new torque converter are going to run around $300, give or take. Not too bad. It's less if I get a kit with less stuff in it. It's kind of confusing figuring out which kit has what, as each brand seems to carry 3 or 4 levels of kits. We've got a local family owned parts house in town I'm going to check with too. They tend to carry good stuff and know a lot about the products they stock.

I checked with the two transmission shops in town just out of curiosity. They both quoted $1400 to rebuild. That's probably more than the truck is worth.

Any special tools I need to pick up, or can I do this with just the basics?

DACCO is based in Cookeville Tennessee, and I've been using their products for about 30 years. They're a good, well-established company, supplying rebuild kits and reconditioned torque converters.

You'll need a few special tools to disassemble and reassemble the spring-loaded clutch pack pistons, plus some dedicated design snap ring pliers. Use LOTS of Vaseline to lube the clutch piston seals, and soak the fiber clutch plates in clean ATF before assembling the clutch packs. Follow the service manual specifications EXACTLY where clearance between the clutch discs and pressure plates are concerned. Too-tight clutches will overheat and burn, sloppy clearance will result in delayed shifts and slam-bang engagement.

I started working on GM Dual Range Hydramatic transmissions (the kind in stovebolt Chevy and GMC trucks) in 1958, at age 12!
Jerry

Throw in a new vac modulator while you're down there