TH350 rebuild tech
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Once it is pushed into place, install the snap ring, with the ends on each side of the spring or case-saver. | Once it is pushed into place, install the snap ring, with the ends on each side of the spring or case-saver. | ||
Now is the time to air check the low clutches. You do so by applying pressurized air to the passage at the rear pan area of the worm casting in the case. | Now is the time to air check the low clutches. You do so by applying pressurized air to the passage at the rear pan area of the worm casting in the case. | ||
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| + | Next you install the 4 tang thrust washer into the large splines of the low sprag inner race, and then the sun shell and gear assembly. | ||
| + | Before this step, for HD use, you would have wanted to install additional sun gear bushings, 2 on each end, and re-drilled the lube holes. | ||
| + | Shown here. | ||
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| + | [[file:TH350sungearbushings.jpg]] | ||
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| + | Drop the sun shell/gear in, spinning in the output carrier until it falls in place. | ||
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| + | [[file:TH350inputplanetthrust.jpg]] | ||
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| + | Install the input planet next, already pictured. | ||
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| + | Now, | ||
| + | To prevent excessive endplay, a pump thrust washer can be installed on top of the input planet, then the regular thrust washer. Then install the small outside snap ring to hold it all in place. | ||
| + | Check the output shaft for proper rotation, there will be some drag, especially in one direction. | ||
| + | Check for excessive output endplay. If endplay is excessive, it can be tightened up by dis-assembling and shimming up the output ring gear bearing from the case. | ||
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| + | Now you drop the input ring gear on, spinning into place. | ||
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| + | photos needed | ||
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| + | Then install the 3 tang thrust. | ||
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| + | For racing and heavy towing use, you will want to machine the direct clutch piston down approximately .160" to allow for one extra friction and steel plate for a total of 5 frictions, and 5 steels in the directs. This can be accomplished on a brake lathe. I try to keep a few machined on hand, and machine several at a time when I do so. If you need one email me and if you can supply a core, I MAY be able to sell you a piston. | ||
| + | Stock measurement is ~.835, I cut them to .675". Ideally you would pre-assemble, and check clearance using a 4 clutch pack, meaure the additonal thickness of the extra friction and steel, then cut the exact amount needed to leave you the exact clearance you desire. Rule of thumb on most auto trans friction clearances is ~.010" clearance per friction. So a 5 friction direct setup would work great with .050" clearance. It will work with less, I wouldn't go less than .040", and will work with quite a bit more, but excessive clearance can result in delayed engagement, busted lip seals, and unsatisfactory shift quality. | ||
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| + | Stock 4 piston direct piston vs. machined for 5. | ||
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| + | [[file:TH350directpistons.jpg]] | ||
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| + | Next, | ||
| + | HD applications should also get a hardened intermediate sprag race. It is darker colored than a stock piece. | ||
| + | The intermediate sprag race and intermediate sprag (actually roller clutch) take a brutal amount of force on a 1-2 shift at high rpm. Even more so with harsher shift calibrations. It is the weakest single part of a TH350. | ||
| + | This is not to say a TH350 is not tough, they are under-rated and can reliably handle in the 600HP or lb/ft range based on my experience. | ||
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| + | I also like to always use a NEW intermediate roller clutch for HD builds. My theory on a long lived setup is that the springs that force the rollers against the race must be in good condition to helps the rollers grab quicker and more evenly on apply. | ||
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| + | The parts go on the direct drum. | ||
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| + | Edit/Delete Message | ||
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