Tranny swap ?'s

[Mrturner1]

currently have a h400 in my 1970 c10, mild 350 (cam intake carb headers exhaust) and I've been looking at a new TKS i believe is the brand name, th700 R4. will this bolt right up to my motor? anything challenging to expect as i plan on doing this myself. also thinking of doing a 2000-2400 rmp torque converter at the same time

[Mrturner1]

also how much would a h400 with shift kit go for used? would like to get something out of it, its a great tranny and strong

[GASoline71]

A TH700R4 will bolt directly to your SBC. I think the rear tranny mount will be the same too.

I'd think about 500 bucks for the TH400, if it's still in great condition.

Gary

[71meangreenc10]

You will have to change the driveshaft yokes as they are different between the 400 and 700R4. If you had a TH350 you would be fine or 3OTT, but would have to shorten the driveshaft depending on the tail length on the 350. You may have to shorten the shaft anyway. You also will need the metric TC bolts for the TC, buy them at a parts store. You will need an adapter for the TV Cable angle depending on what carb you have. 700R4's hate heat so I would add an additional cooler to the trans lines. How are you going to lock up the TC or are you? Speedo cable is another issue to tackle and you may have some issues depending on what rear gear you are going to run. I have done this so if you want exactly what I did I, please PM me and I will send you every part number I did for my swap. I run 3.42's with my 700's and everything works like GM designed it to do.

Let me know

Smitty

[leftybass209]

Originally Posted by 71meangreenc10

You will have to change the driveshaft yokes as they are different between the 400 and 700R4. If you had a TH350 you would be fine or 3OTT, but would have to shorten the driveshaft depending on the tail length on the 350. You may have to shorten the shaft anyway. You also will need the metric TC bolts for the TC, buy them at a parts store. You will need an adapter for the TV Cable angle depending on what carb you have. 700R4's hate heat so I would add an additional cooler to the trans lines. How are you going to lock up the TC or are you? Speedo cable is another issue to tackle and you may have some issues depending on what rear gear you are going to run. I have done this so if you want exactly what I did I, please PM me and I will send you every part number I did for my swap. I run 3.42's with my 700's and everything works like GM designed it to do.

Let me know

I concur with most all what is said above. As you can see it's not just a trans swap. I could suggest a 2004r as well. It's also an overdrive trans, but is shorter, and has a more usable 1st gear in comparison to the 700r4, especially if you want to run gears lower than 3.73's. I have a 700 myself, and while the OD trans isn't as straightforward as a th350 or 400, it isn't anything to be worried about. How much horsepower and torque you have planned is another thing to check. A stock rebuilt 700, or 200, will only handle safely, between 350 and 400 ft lbs of torque. Numbers vary, I've seen all kinds of numbers thrown out as to what they'll handle stock, but the consensus is it certainly isn't above 400ft lbs, or 400 hp. That's something to keep in mind because it's much cheaper to get a trans built to handle what you will throw at it, rather than be rebuilding something that is blown out after the fact.

[71meangreenc10]

Originally Posted by leftybass209

I concur with most all what is said above. As you can see it's not just a trans swap. I could suggest a 2004r as well. It's also an overdrive trans, but is shorter, and has a more usable 1st gear in comparison to the 700r4, especially if you want to run gears lower than 3.73's. I have a 700 myself, and while the OD trans isn't as straightforward as a th350 or 400, it isn't anything to be worried about. How much horsepower and torque you have planned is another thing to check. A stock rebuilt 700, or 200, will only handle safely, between 350 and 400 ft lbs of torque. Numbers vary, I've seen all kinds of numbers thrown out as to what they'll handle stock, but the consensus is it certainly isn't above 400ft lbs, or 400 hp. That's something to keep in mind because it's much cheaper to get a trans built to handle what you will throw at it, rather than be rebuilding something that is blown out after the fact.

I got more to add, just don't feel like typing . If the 700r4 is built correctly, it is a great trans. My 3.42's make 1st gear get off the line pretty good, but I went above and beyond most people when I did my swap I would love to see the difference between the 1st gears of the 700R4 and the 2004R. You are correct about the 2004R, it is a great transmission.

Smitty