TH400 conversion to overdrive unit

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January 12th, 2010, 10:59 AM

steve terry

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TH400 conversion to overdrive unit

Is it possible to either convert from original '76 SB tranny to an updated OD tranny? OR, change trans gearing to get better top end fuel economy while still maintaining low end torque?

Thanks.
Steve

January 12th, 2010, 11:37 AM

wjustinmartin

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steve - it is common - do a search and you can get some specifics

January 12th, 2010, 11:46 AM

steve terry

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Thanks wjustinmartin. I'll do some searching around.
Steve

January 12th, 2010, 03:05 PM

joe_padavano

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Quote:

Originally Posted by steve terry

If "original '76 SB tranny" means the original small block transmission, then it is not the TH400 in your title but a TH350. The swap to a 200-4R is easy in this case. As noted, search for "200-4R".

January 13th, 2010, 06:20 AM

steve terry

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Thanks Joe.
My mistake. TH350 is correct.
Is the 200-4R as strong as the TH350?
Steve

January 13th, 2010, 07:14 AM

joe_padavano

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Quote:

Originally Posted by steve terry

Thanks Joe.
My mistake. TH350 is correct.
Is the 200-4R as strong as the TH350?
Steve

Certainly not in stock form. The turbo Buick community has found and fixed all the weak points in the 200-4R, but you must build one correctly to live behind any real HP.