TH400 rebuild tech
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[[file:T-400_full_manual_loop03.jpg]] | [[file:T-400_full_manual_loop03.jpg]] | ||
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| + | You must also modify the 1-2 shift valve as listed below for FULL manual shift conversion: | ||
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| + | The TH400 has a over-ride shift that will shift out of low gear even if you have manually selected low. It was designed to prevent engine damage. | ||
| + | You can eliminate this feature by performing the following modifications to the valve body. | ||
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| + | You must remove the 1-2 shift valve and grind two flats on the land designated by the arrow. | ||
| + | You must plug the exhaust hole in the valve body also designated. | ||
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| + | [[file:1-2_shift_valve.jpg]] | ||
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| + | Simply grind two flats on the shift valve and deburr them. | ||
| + | You can plug the hole with a brass dowel or a check ball. To use a check ball you will have to first drill the hole larger and then drive the check ball in place. | ||
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| + | Drill the marked holes at .125 for street use. | ||
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| + | For a heavy duty application : 3rd gear shift use .150 drill and leave the 1-2 check ball out. Caution a 34 element sprag needs to used with the 1-2 check ball removed. | ||
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| + | [[file:T-400feed-holes.jpg]] | ||
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| + | Another mod is blocking the 2-3 accumulator. I do this with a set screw. You tap the hole and install the set screw available from any hardware store. | ||
| + | This firms up the 2-3 shift. | ||
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| + | [[file:100_2218-1.jpg]] | ||
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===Boost valve modification=== | ===Boost valve modification=== | ||
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