TH400 to 700R4 Swap? - Impala Tech
Transmission & Driveline Transmissions & Differentials

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post #1 of 4 (permalink) Old 03-16-2011, 11:31 PM Thread Starter
Join Date: Jun 2010
Location: Venice, FL
Posts: 36
TH400 to 700R4 Swap?

I have tried to look up and research information regarding a TH400 to 700R4 swap and have read a lot on powerglides to TH400's and powerglides to 700R4's, but I can't seem to find a source for TH400 to 700r4. I think I am missing something.
I have an all original car that needs a transmission rebuild (seals are leaking real bad after the car sat 10+ years in a garage...) The transmission works as long as I top off the fluid every now and then. I like the idea of having overdrive....and I am wondering how much more expensive it would be to swap out the TH400 for a 700R4 rather than just rebuild (*and with a move in the not too distant future I cannot afford to have the transmission torn apart and rebuild on my own).
How much would need to be modified to adapt a 700R4 to my all original 327ci car?
Could anyone recommend a transmission specialist in the Sarasota area? I can drive the car, so even a little distance would not be out of the question.
Is anyone on here using and enjoying the gear vendors OD? Thoughts?
68Impala4drsportsedan is offline  
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post #2 of 4 (permalink) Old 03-17-2011, 07:30 AM
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Join Date: Jul 2006
Location: Estero, FL
Posts: 471
Very commonly done. Check Lots of rebuilders in Tampa area, check eBay, figure on $1500


1965 Impala SS 396
1967 SS427
Michael9040 is offline  
post #3 of 4 (permalink) Old 03-17-2011, 08:20 PM Thread Starter
Join Date: Jun 2010
Location: Venice, FL
Posts: 36
Just got a quote from a transmission specialist I've used and trust. He will pull/rebuild/reinstall my TH400 for $700-1200 depending on what I want beefed up etc or $2995 for a complete swap for a 700R4. Sound like the norm?

I will probably just get the rebuild TH400 since I am not sure swmbo will approve of spending $3k...

Thanks for any extra input. I want to get my Impala on the road~
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post #4 of 4 (permalink) Old 03-17-2011, 08:47 PM
Join Date: Jan 2006
Posts: 12,455
You can talk to my favorite tranny builder at J&W Performance Transmissions.

You can buy a heavy duty rebuilt transmission (part number 85210-L for a lock-up torque converter) able to handle the power of a big block for about $1602.72. A new 1,900-2,300 RPM stall 12" 30 spline torque converter is going to run you about $338.20 (part number 85441-L3).

JW Performance
1826 Baldwin St.
Rockledge, FL 32955
Phone: 321-632-6205
Fax: 321-632-0247

It will require a shifter modification to find the extra gear you get with the OD, but aside from a change of out-put yoke to the smaller 27 splines (same as on a TH350 Muncie or PowerGlide) you are ready to go.

Big Dave
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