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th350 to 700r4 swap?

wage92

wage92

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Im sure someone has done this before, just looking for an overall summary of what i will run into. I have a th350/np203 right now and i wanna switch over to a 700r4 and np241 or 208. Do i need to move the cross member that was under the transfer case and what other problems will i run into?

Has anyone done that in their build and have pictures?
 
I'm pretty sure you'll need the crossmember from the same or similar truck with a 700r4, tv cable bracket for the motor, driveshafts. Maybe move trans lines if they mount any differently but that shouldn't be necessary. And make sure you get the torque converter if you're just swapping in a used unit.
 
700r4 throttle valve cable ( NOT KICK DOWN CABLE ) bracket .

all parts related to 700r4 from doner .

shifter indicator in dash. pull cluster and few screws its out easy .

floor shifter bracket and parts for transfer case . diffrent shifter all together.

as said all drive shafts best to have on hand.

might need to move crossmember . but best to get the doner one as 85-up diffrent than older stuff.

plug off the vac port on intake that feed the old th350 vac modulator.

tranny dip stick tube .

check the flex plate on engine for pattern correct to the 700r4 convotor . some are diffrent for hd stuff . hate to get it all up in and find you need to swap it.
 
Find a junk truck with a TH700R4 and buy the whole truck.

Martin
 
okay thanks guys, looks like there is a little more to it than i thought. ill have to do my research and make sure i get everything :waytogo:
 
And make sure you install a large cooler on it, the 700 doesnt tolerate heat at all. And get a later year one, 88 and up, it has a better pump and some other stuff. You will like the swap, its a better low and OD.

You can just take the column apart, and buy a sticker that reads P-R-N-OD-3-2-1 instead of P-R-N-3-2-1. Thats what I did when I pulled out my 700 to swap in my TH400.

You will have to drill new holes for the crossmember as the 700 is a few inches longer and it scoots the t-case back.
 
okay, so let me get this straight. The 700r4 will bolt up to the 400sbc no problem. I will need a new torque converter, i need a transfer case that matches the tranny (208 or 241), i need to move the cross member back a couple inches (i assume you just do that once you have the transfer case bolted up?), change the shift indicator, and then make sure the tv cable is hooked up right?

Did i miss anything?
 
Trams to t-case adapter. Buddy of mine just did this. The th350-208 adapted is different then the 700r4-208 adapter.
 
Chevy bellhousings are all the same, so your good there. You should be able to use the 700 converter, and more than likely it will bolt up to the flexplate no prob, you will have to find the t-case adapter and a 700 friendly t-case which both are common. I would recommend the 241 as its stronger and a better low over the 208, but thats just me.

And yes, thats how I moved my crossmember, bolted everything up and held it up with a piece of wood and a jack, bolted my new crossmember on and jacked up the whole thing and drilled the new holes in the frame through the existing holes in the crossmember.

And I am reading that Hotrod right now, you can pick a single issue up at the local wall-mart
 
The way I wired up mine, there's only one were going to the transmission. It's a 12 volt that comes from the brake switch, and is interrupted when you press the brake (opposite effect of brake lights) then it passes through a toggle switch on the dash. That way I can keep it off until I hit cruising speed then switch on the lockup. I'll need to see which of the pins the wire goes to.
 
plyr2k said:
Trams to t-case adapter. Buddy of mine just did this. The th350-208 adapted is different then the 700r4-208 adapter.
Click to expand...

right. if i was to do the swap id get the tranny out of a parts truck with the transfer case most likely.
 
So to get this straight, Once the tranny is bolted up to the engine, i would need to wire up the lockout for the torque converter, attach the shift cable, and then attach the tv cable...those are the only connections going to the tranny right? (other than fluid lines and whatnot)
 
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