2wd 700r4

[2deuce]

I'll be looking at a 2wd 700r4 for sale. It is in a 91 1500 6.2 the engine is bad. Will the 2wd 700r4 be a good swap into a m1009? Does anyone know what the spline count is on this trans. Can the tailshaft housing be changed? Will I need to look for a different TC? My daughter fried her turbo 400. She didn't check her radiator. What will it need to work? I appreciate your advice.
Thanks

 

[rlwm211]

Unless I am grossly mistaken,

The 2WD version of the 700R4 has the long tail shaft
which WILL NOT WORK with a 4WD set up.

RL

 

[2deuce]

That was one of the things I was worried about. I was hoping it was adaptable without dismantling it too far.

 

[popacom]

Hey 2deuce ,popacom / BILL in Ky. here. I been into that before when I used to work installing
parts people bought at the salvage firm I worked for. The output shaft on the 700r4 is the same diameter and spline count as the Turbo 350 transmissions and the 4l80 & 4l80E are the same as the
Turbo 400 in the CUCV's. I think there are several companies that make an adapter collar to get you in play on the different diameters ,but as rlwm211 said there is a difference in length of the tail housings and output shafts. The only hope you have of it working without changing the out put shaft is if the 700R4 you get is the short 2WD version "AND" it happens to be one of the few that the shaft is splined far enough up the shaft to allow it to be cut off to the 4WD shaft length.
I have done this so I know it is possible. But if the tranny you get has the longer 2WD tailhousing and shaft the only option is a shaft change which involves tras. dis assembly. to make the change. Hope this info is helpful,and good luck!!!

popacom / BILL in KY.

 

[sht2kll]

Howdy POPACOM: You said the 4L80 and the TH400 have the same spline output shaft? Do you know if the NP208 will bolt up to the 4L80, or is there an adaptor available? Thanks. Tom

 

[2deuce]

Thanks Bill for that info. I do have a turbo 350 with a broken case that came out of a 77 chevy 4x4. If the spline count works would that be a swap possibility to make it work?
Thanks again,
Greg

 

[nhdiesel]

To use ANY 700R4, you will be looking at swapping driveshafts because the lengths are different. To make the 2wd 700r4 into a 4x4, you need to swap tailshafts and the tailhousing, and you will still need new driveshafts. And in the end, you get a crappy 700r4 that won't last nearly as long as that th400.

You say she "didn't check her radiator". Did the truck overheat bad? If so, the engine probably has more problems than the trans. But if the engine didn't overheat, why do you suspect that anything happed to the trans because of this?

If the trans is toast, the cheapest, most reliable thing to do would be to either find a used TH400, or rebuild that one. Its by far the easiest and cheapest trans to rebuild, and the most durable trans you will find for that truck.

Jim

 

[popacom]

I am not an expert on tranny's by any means, but my transmission Guru says the easiest way to
say it is The turbo 350 and the 700r4 share a lot of things,out put shaft size and count etc.
To bring it down to basics the 700r4is a turbo 350 with overdrive. The 4l80 is a Turbo 400 with
overdrive The turbo 400 is a tried and true HD tranny the 700r4 is really a lighter duty(Without upgrades) tranny. The problem you run into trying to put a 4l80 where a Turbo 400 was is they require a stand alone computer to run their electronic valve body. Unless you are doing a heep of high speed highway driving with this truck I would overhaul the Turbo 400 and call it good. That's
my opinion anyway.

popacom / BILL in KY.

 

[2deuce]

NH, The trans is slipping bad and the oil is burnt. The rad was half full so I'm thinking the trans cooler wasn't doing much cooling. The engine may have gotten hot but not fried like the trans. It seems to run as usual. I'll know more when I get the truck running again. I'll probably put the 400 back in. I'll cross my fingers about the engine for now. Thanks