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th350 - Hardened Sprag

bbtank45

bbtank45

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So i am in the process of gathering parts for my th350. I am very inexperience with auto's in general and have spent most of my time with w56's, nv4500's etc.

Generally speaking, because i will only be running a 4.3, the th350 in stock form fairs pretty well against abuse. I want to build this trans one time and have the option to put it behind a 400hp 5.3 in the future. I am rebuilding the transmission rebuilt to include:

th350 4x4 "K" Case
TCI Ultimate Master Racing Overhaul Kit (http://www.jegs.com/i/TCI/890/329015/10002/-1)
TCI Manual Valve Bodies (Reverse with Comp. Braking)
Hughes Performance Converter
Derale Cooler (Electric Fan)

Anyway, i am struggling to find out exactly what i need for the sprag race upgrade?........Does upgrading this require machining? Should i even do it?

I can call a trans shop but thought i would have some more knowledgeable recommendations on here.

Thanks,

Ben B.
 
In my option if you are planning to run a 5.3 in the future and or an aggressive driver, I would run a hardened roller sprag race. Summit and Jegs have them. They are a drop in upgrade no machine work needed.
I also run a 4.3 - TH350-205. I broke mine in a Dirt Riot race last year. Shifting from forward to rev is often what breaks them.
I ran a 2500 stall converter for a while. Hated it. When back to a stock converter, much happier.

I would also suggest replacing every bushing in the transmission. Get a second set of sun gear bushing and double stack them. Be sure to drill through the second bushing at the oil hole. Also try to align the spiral oil grooves in the bushing to allow lube oil to pass through. The clutch pistons can be machine down to be able to run extra frictions also.

Ron Session wrote a great book on building if you DIY.



 
Thanks for the reply; i need all the help i can get.

My converter is an 1800 stall i believe.

It is likely that i will be working with someone to do the rebuild; a friend of mine that has a good deal of experience rebuilding trans.

Do you have a recommendation on which roller sprag race & bushings?...I see there are different elements and several different brands of course.
 
I had a TH350 built with a hardened sprag one time. Transmission worked for a couple months.
I took the pan off and the entire sprag was in pieces laying in the pan. :puke:
I have not put another one in.
 
If your close to winchester tn. Just look up Mike blackburn. Builds them the way they should be from the factory with a few little extras...you won't ever have trouble
 
The bushing are standard OEM stuff. A lot of builders won't replace them because of the added labor and bushing drivers needed. Also ask your builder to use the metal thrust washers where they can instead of plastic ones. The plastic needle bearings were used to help increase fuel economy but are not as strong.
Using new bushings and thrust washers and shimming the case get the end play on the tight side of spec really helps keep the rotating assembly in line. I am just using a standard sprag. It is my understanding that the more elements in the sprag the more places the load is applied, which would spread out the load better thus stronger.
 
RustyC said:
The bushing are standard OEM stuff. A lot of builders won't replace them because of the added labor and bushing drivers needed. Also ask your builder to use the metal thrust washers where they can instead of plastic ones. The plastic needle bearings were used to help increase fuel economy but are not as strong.
Using new bushings and thrust washers and shimming the case get the end play on the tight side of spec really helps keep the rotating assembly in line. I am just using a standard sprag. It is my understanding that the more elements in the sprag the more places the load is applied, which would spread out the load better thus stronger.
Click to expand...

Oh ok, that makes more sense to me. So, i think ive identified the items below (Bushing Kit, Hardened Sprag, Thrust Washer Kit).....Seem like what youre referring to?

http://www.summitracing.com/parts/tci-328910/overview/

http://www.summitracing.com/parts/tci-313700/overview/

http://www.summitracing.com/parts/tci-313600/overview/

Thanks a lot for all your guys help. I am very much a simple yota guy thats trying to make a jump to the next level!!
 
Yep you're on the right track. You will love crawling with an auto trans too. :dblthumb:
If you have a Transtar store near you they will have all the parts except the sprag race for less $$
 

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