Gunfreak25

I am pretty good with my hands, I did my first Qjet 6 months ago and it was super easy. I am currently doing my first ever motor rebuild and it too is very, very easy. I cannot think of a single thing i've ever taken apart that i'd ever had a hard time reassembling. I am a part time gunsmith and have played with all sorts of neat toys over the years, so in a nutshell I am pretty good with my hands and anything mechanical. I'm told the Th400 is quite simple for an auto tranny, my step father rebuilt his Th350 and he said aside from keeping everything 100% clean enough to serve dinner on it was pretty simple. Anytime I take something apart I've never worked on before I TAKE MY TIME and never force anything. Probably the reason behind my success with past projects.

I am already rebuilding the motor and I figure while the Th400 is off now would be the best time to do any major work on it. I figure if it works fine for now it will likely give me issues in a year or two just because the thing has never been rebuilt since it was made in 1971. Plus it will be powering a 13,500lb truck with 6.17 gears.

Can I do it? What are the hardest parts? Special tools? Tips? Is it 2 or 3 week job?

Aceshigh

I think you can do it if you get the proper training materials for it.
Armed with an ATSG manual and DVD and you should be good.

Just get a pair of Lock ring pliers from Sears for $15
Dual feed the clutches and you should have no issues.

Here's some tips from Jake who runs a performance trans shop out of Texas.
http://www.jakesperformance.com/TH400_Rebuild_Tech.html

The hardest part truthfully is making sure you have 100% of your parts on hand
before you start the project. I had to wait for weeks at a time for parts

Bulk parts website has a free PDF exploded view of every trans there is.
Here's the 400's. http://www.bulkpart.com/Merchant2/gr...f/3L80-400.pdf

TripDeuces

I rebuilt one years ago. I wouldn't call it hard but it was challenging and like Aceshigh said certain tools make it much easier. Definitely have a book or DVD with good pictures unless you have a photographic memory. There is a whole lot of stuff in there. Also have a large clean work area that has a lip on the working surface so things don't roll around or fall off.

George

matt69olds

They aren't hard to build, if you can build an engine a TH400 should be simple. There are lots of roller bearing that have to go in a certain order. Get a book, study it, take it apart, label the parts, take lots of notes.

joe_padavano

I've built a TH400 with no problems. The clutch packs and gear sets come out as modules, then you work on each one individually. As noted, you need a clean workplace and attention to detail to get everything back together the right way. The two tricks I remember are the need to use a slide hammer to get the front pump out and the use of C-clamps to compress the clutch packs and remove the snap rings. Unlike newer automatics, the TH400 uses cast iron seal rings that are split, so you don't need any special sizing tools for teflon seal rings. You do need bushing drivers if you want to replace the bushings. The Kent Moore kits show up on ebay regularly for reasonable prices. Alternately, just take the parts to a trans shop for bushing replacement.

Gunfreak25

Great, I already have a set of snap ring pliers, a micrometer for measurements, slide hammer and plenty of C clamps laying around. I also found a large plastic tub in the shed that is only 5 or 6 inches deep so it would be perfect for the disassembly. I have 1 table inside where I do my gun work I can clean off. Then I have my large steel electricians table outside as well as a set of sawhorses I use to make portable tables. Also have the large plastic picnic table to work off of.

I think I might do this then! I saw a complete tear down and reassembly on one of the K5 forums and it didn't look too challenging since everything comes out in "sections" so to speak.

I will definately pickup the manuals in the meantime, my biggest fear is dirt getting inside the components upon reassembly. I will have to put all my skills to the test on this one. Walmart bags are quite handy and I suppose I could store all the surgically clean parts in my bedroom corner where they are protected from the elements. Yuma has some fairly dusty air all the time.

Now, I am always on a budget. Most of the rebuild kits seem to run $100 to $200. Can you guys recommend a decent kit for my application? It's a big 13,000lb Army truck so firmer shifts are okay. Just want it rock solid and reliable without spending bookoo bucks.

MDchanic

ZipLock bags are a gift from Heaven!

- Eric

Gunfreak25

I really like the Jakesperformance website. Great tips, I will be doing the same mods to mine to firm up the shifts as well as making sure it stays properly cooled for long life. While I have the pan off i'll have NAPA put a drain plug on it and I can put a T fitting on the trans cooler outlet for a temperature gauge.

defiant1

What brand rebuild kits do you all recommend?

d1

Gunfreak25

I see a kit for $100 on Egay that has all the necessary parts for a ful rebuild. It looks like it's of decent quality. Contains steels, modulator and clutch plates. Is there such thing as a POS kit?

Aceshigh

Can you buy junk tools off Ebay ?? Yes, and Yes. Call Jake and order your parts through him.
If you do this, you also get some of his free expertise on where to do simple upgrades to prolong the life of the trans.

He's a huge sponsor of the LS1Tech forum and Nastyz28 forum as well.
Most forums out there have heard of Jakeshoe.

The guys that do performance rebuilds are the one's you want to talk to.
Not the guy who buys kits from whoever and slaps it in trans.

Gunfreak25

Will do! Thanks for the input. I'll talk with him about my specific application and see what he thinks.

Yellowstatue

I'm behind you 100%...my suggestion is a good, small magnet...preferably telescopic...but not the 10X type...

Aceshigh

In regards to this.....

When I went to my buddy's transmission repair shop all I used was his 2 ton Arbor press to
push out many of the old bushings, and push the new one's in.

Obviously he had all the correct bushing tools, but technically they're not really necessary for
MOST of the bushings. You can be creative and just get something round about the same size
and push most of these in without those tools. Getting them out, either use a large screwdriver
with dulled out corners and bang it out, or press them out.

Don't use a chisel, because you'll just damage the soft metal parts and end up having to use
emery cloth to buff out your botch work. Learned that one the hard way......