1947 CJ20A

[cousinmike]

Thanks! There's still lots to do, just need to find the time to work on it.

[cousinmike]

Pic is from Dunefest this summer

[cousinmike]

The Jeep started coasting in manual second gear and was told it was either the band or roller clutch. I removed the transmission and decided to try the rebuild myself after doing days of researching what I was getting into. What I read is all it takes is a good book, keep things in order, check tolerances, and keep everything clean.

[cousinmike]

I bought Ron Sessions TH350 Turbo Hydra-Matic Handbook from Baxters, read it and am even more confident in the rebuild. After reading this book I would highly recommend it to anyone, and if you can rebuild a motor you can rebuild one of these transmissions.

[cousinmike]

I tore down the transmission and inspected all the parts. All the lining on the band was gone and throughout the tranny and both the intermediate roller clutch and low/reverse roller clutch showed signs of wear. Other than that the rest of the tranny seems to be clean and in good shape, but still a stock tranny that had recently rebuilt. No to build a budget performance tranny.

[cousinmike]

Got a 700R4 transmission from Josh to compare parts. There's lots of information on supposedly interchangeable parts with the TH350 on the web, but after comparing the parts only the center support (some call this a case saver) was interchangable without a lot of machining. The good thing about this part is it is hardened where the stock TH350 one is not. The 700R4 first gear planets will fit in the TH350 case, but would need machining. The out-put shaft splines are larger and would need to be custom as well. For a budget build I'm staying away from this.
I'll try to get some pic's.

[chevtech]

Crap!

[cousinmike]

Josh, the tranny I got from you is the second addition 700R4. I would still like to get a first addition (1982 - Feb 1985) and see if there was anything there that might work. They made upgrades in the 700R4 over the years, so there might stilll be hope for a low first gear upgrade. I have another TH350 core so all I need is to find an early 700R4.

[cousinmike]

Here's the TH350 guts. Basically there's the valve body, pump and three sub-assemblies.

[cousinmike]

Here's the first gear differences between the TH350 (parts on right) and 700R4 (parts on left)

Low/reverse clutch piston. This part fits in the TH350 case, and all that needs to be done is modify the parking pawl. The 700R4 is the same on the OD but larger diameter in the ID.



Output ring gear. The 700R4 is larger (hints the larger ID piston it fits in). Also the 700R4 ring gear has splines that match up to the output shaft.



Reaction carrier. The pics tell the story. 700R4 is larger and bearing surfaces would need to be machined down to match TH350 part.





Low/reverse clutch support (some call this a case saver). Both the 700R4 and TH350 parts are identical except the 700R4 is hardened steel and TH350 is not. So I'm using the hardened part.



Output shafts. You can see the obvious. What is hard to see is that the 700R4 splines that lock in first gear are larger than the TH350 shaft. A custom shaft would need to be made.



Why did I go through this? The 700R4 first gear is 3.06:1 and the TH350 is about 2.52:1. This is about like dropping two differential gear ratios. The downfall is you would have a larger split between first and second gear, but if you mainly run first there no worries.

I'd still like to tear into a TH200 and first generation 700R4 to see if the parts are a closer fit with less machining.

[popeye]

out of curiosity do you happen to know how a powerglide would match up? i always thought using one for racing the courses like you do or mud drags might work well but i dont even know if one can be used with a t-case or if they would be worth a darn

[cousinmike]

I thought about this when I started Jeep racing. I've been told by some of the Jeep racers that the Powerglide transmissions are not good for racing if down shifting. You don't down shift in drag racing, or roundy-round racing and only having one shift seems to work when only accelerating. This is probably why you don't see a lot of 4x4 stuff for the powerglide, although they are a strong transmission.

[cousinmike]

Found what looks to be a good place to get tranny parts. They seem pretty knowledgeable too. The only thing I'm leery about is their torque converters. They have a 2000-2600 stall speed for $210, but I've been told that there's a lot to do with quality and you get what you pay for. Does anyone know of a good torque converter at an affordable price?
www.transmissioncenter.net/350_or_400_high_performance.htm

[vegaguy76]

I put a Jeg's brand 2800-3000 stall converter in Ashley's race truck. It's held up great so far, several races and was at last SummerBash as well. Cost was $199. For the price and the fact that I've got another 4wd TH350 should something go wrong, I took the gamble and it seemed to pay out so far.

EDIT: The truck is a 350ci with lots of head work, larger cam, headers, port matched intake. I figure it might be about 300hp. Should be similar to your Vortec 350 if I'm remembering right.

[cousinmike]

Yes, I'm set up about the same as Ashley. I ended up have a place in Louisiana build be a 2600 stall for about the same price. Your tranny should hold up fine, but many places I've been researching have recommended replacing the roller clutches and putting in a hardened sprag gear.
I will post pictures of all the stuff I'm replacing in my tranny build as recommended for my application.

Thanks Charlie