700R4 Questions

[misslemanid]

First of all, is it worth the cost and effort to install a 700R4? I will have a TH400 but I was just wondering if the overdrive is worth it. Also, there a quite a few for sale around here but they are all advertised as 4x4 transmissions. I have a 2wd. Does it make a difference?
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[veinbar]

Yes, it makes a difference. You will need a 2wd trans. Upgrading the transmission is only one element to this O/D equation. More than likely you will need to rebuild or replace your rear end so that it has proper gearing for an overdrive transmission. I am undergoing this mod right now, and it is expensive. $1000 for the rear rebuild, and $1500 for the 700r4 rebuild and install. Not to mention you have to get a driveshaft because your TH400 has a yoke and the 700r4 doesn't.

In the end, overdrive + proper rear gearing makes for a more modern / efficient vehicle, but it comes with a price tag. Like I said, I'm going through this process right now, and I cannot wait to see and feel the end results.

[misslemanid]

Originally Posted by veinbar

Yes, it makes a difference. You will need a 2wd trans. Upgrading the transmission is only one element to this O/D equation. More than likely you will need to rebuild or replace your rear end so that it has proper gearing for an overdrive transmission. I am undergoing this mod right now, and it is expensive. $1000 for the rear rebuild, and $1500 for the 700r4 rebuild and install. Not to mention you have to get a driveshaft because your TH400 has a yoke and the 700r4 doesn't.

In the end, overdrive + proper rear gearing makes for a more modern / efficient vehicle, but it comes with a price tag. Like I said, I'm going through this process right now, and I cannot wait to see and feel the end results.

Ok that all makes sense. Thanks for the quick reply. Currently my 78 is a 4 speed but I am going to convert it to an auto. I will either be going to a 454 or a 350 with a TH400. I was just inquiring about the 700R4 because it had crossed my mind. But in the spirit of saving money and time, I think I'll stick with the TH400. Thanks for the help.
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[johnnypop]

I dumped a TH350 and fulltime transfer case for a 700r4 and NP241 and went from 6-8mpg's to 10-12mpg's... Not a bad investment if you plan on owning the truck for a long time.

*EDIT* - this is all with 4.56's on 35 inch mud terrains... a 2wd will probably show much better gains.

[misslemanid]

Originally Posted by johnnypop

I dumped a TH350 and fulltime transfer case for a 700r4 and NP241 and went from 6-8mpg's to 10-12mpg's... Not a bad investment if you plan on owning the truck for a long time.

*EDIT* - this is all with 4.56's on 35 inch mud terrains... a 2wd will probably show much better gains.

Ya, gas mileage was one of my motivations but cash on hand is unfortunately one of my limitations. Maybe someday I could make the swap. My ultimate goal is to build a sort of pro touring pickup. I want it to be something my wife and I can enjoy. This is sort of off topic but how hard is it to convert a non a/c cab into an a/c cab?
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[veinbar]

visit vintageair.com... They've got some A/C solutions for you.

[johnnypop]

Money is key! haha, I was able to get a donor Suburban for 1,000 with a blown motor, so the transfer case, transmission and fuel injection all made a one way flight to my truck.