700R4 transmission swap into 75

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700R4 transmission swap into 75

Postby monza4me » Wed Jul 12, 2006 3:14 am

After blowing up the venerable TH-350 in my street commuter car,[I still won the race] Does anyone have good detailed swapping information for a 7004R? I would like to know just how far back the mount has to be and how much I should shorten the driveshaft. Ive seen somebodys example of extending the crossmember with a heavy gauge C beam to attach the mount and was wondering it the front portion of the original crossmember would hit the rear portion of the 700R4 pan?
As far as the torque arm setup goes, has anyone been able to use the original donut mount or had to switch to the sandwich variety of the F body? Because this is a 75, the xmember is different and the tunnel bigger and *may* cause more fab time. Thanks to all in advance for helpful ideas//
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Postby ColinOpseth » Wed Jul 12, 2006 3:37 am

hey,
I didn't really have much trouble getting a T56 into my '72 Vega. Your tunnel is bigger and the 700R4 is smaller than a T56 6-speed.

You'll probably have to "massage" it a bit, though; if you know what I mean. lmao

As for the crossmember you can do that pretty easily. Bolt the mount up to your existing mounts. Scribe a line where you want to cut the transmission mount. Make your cut and bolt the center section you just cut out to your 700R4. Then weld on extensions to your original trans crossmember.

Later,
Colin
'72 Vega with '93 Camaro LT1/M29 T56/12 bolt 3.31. 16" IROCs all around. Sanderson headers into duals with an H-pipe and Flowmasters. It's loud but at least it's faster than your grandma's Buick. pwned.
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Postby SunbirdMan » Fri Jul 14, 2006 8:56 pm

The h-body.org faq has some info on it.

http://www.h-body.org/library/hbodyfaq/ ... ions.shtml

I've taken measurements and I'm convinced a driveshaft from an 700r4 3rd generation fbody will work. Be sure to double check this. Except that the output shaft spline count was changed sometime in the mid 80's so you'd have to get t the same as your tranny. And the u-joint is bigger by about an 1/16 inch than the h-body so you'd have to get a dual size u-joint . (whatever they call them)Don't take my word on this. Double check the measure ments first.
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