Adding overdrive to a TH350? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

68GMCCustom · 03-30-2010, 12:14 AM

....or try getting a 200-4r (built up of course). The 200-4r is the same length as a turbo350, has a different ratio for 1st gear(and 2nd?) for a better 1-2 shift w/o the bog, and has a slightly lower (.67) overdrive. I think (not sure) that even the spline count is the same...meaning you can use your old driveshaft. I think the only real change other then the TV cable, is the tail mounting location, meaning slight changes to your tranny crossmember. I'm no expert so I could be off on some of these details.

Conundrum · 03-30-2010, 08:31 AM

Quote:

Originally Posted by 68GMCCustom

....or try getting a 200-4r (built up of course). The 200-4r is the same length as a turbo350, has a different ratio for 1st gear(and 2nd?) for a better 1-2 shift w/o the bog, and has a slightly lower (.67) overdrive. I think (not sure) that even the spline count is the same...meaning you can use your old driveshaft. I think the only real change other then the TV cable, is the tail mounting location, meaning slight changes to your tranny crossmember. I'm no expert so I could be off on some of these details.

The trans mount is in the same place as a th400, so you would only have to move your trans crossmember back a little ways. I found this info....although i'm not to positive on the accuracy of it, I think the 2004Rs 1st gear is a 2.74. Although it came from TCIs site.

TH350_________TH400
Lo 2.52 2.75____2.48 2.75
2 1.52 1.52____1.48 1.57
3 1.00 1.00____1.00 1.00

200-4R__700R4/4L60E__4L80E/4L85E
Lo 2.78______3.06_________2.48
2 1.57______1.63_________1.48
3 1.00______1.00_________1.00
4 0.67______0.70_________0.75

http://www.tciauto.com/Products/Tech...ear_ratios.asp

coater · 03-30-2010, 07:40 PM

I have a TH350 in my '85 and having a motor machined as we speak,but was wanting overdrive also. Are there any computer hook ups for the 700r4? Can you just bolt it up to a mild motor and ride?

03-30-2010, 12:14 AM	#1
68GMCCustom Truck and auto performance nut Join Date: Feb 2007 Location: McKinney,Texas Posts: 3,848	Re: Adding overdrive to a TH350? ....or try getting a 200-4r (built up of course). The 200-4r is the same length as a turbo350, has a different ratio for 1st gear(and 2nd?) for a better 1-2 shift w/o the bog, and has a slightly lower (.67) overdrive. I think (not sure) that even the spline count is the same...meaning you can use your old driveshaft. I think the only real change other then the TV cable, is the tail mounting location, meaning slight changes to your tranny crossmember. I'm no expert so I could be off on some of these details. __________________ Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken

03-30-2010, 07:40 PM	#3
coater Registered User Join Date: Jan 2010 Location: Leesburg,Ga. Posts: 359	Re: Adding overdrive to a TH350? I have a TH350 in my '85 and having a motor machined as we speak,but was wanting overdrive also. Are there any computer hook ups for the 700r4? Can you just bolt it up to a mild motor and ride?



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