700r4 swap out

[jeffro788]

Hey guys, I am wanting to swap out my TH400 for a 700r4. I know that the kickdown will have to be changed, but will the drive shaft length be a problem? If so will any other model match up to what I need instead of having one cut to length?

[jeffro788]

forgot to mention, my truck is a 72 swb c/10

[jay6891]

Welcome from a little south of ya. I just took mine to Glovers in Little Rock and had it cut and balanced. Not sure on length of your 400. I had a long tail 350 and needed I think 4" inches cut out. Been about 8 years ago so my memory may be wrong.

[chevy_mike]

700R4's are longer then T350's or T400's. You will need to shorten your driveshaft. Make sure you get the TV cable set 100% correctly our your 700R4 is not going to last long.

Check www.bowtieoverdrives.com for a lot of good info and the correct cable to carb bracket.

Also run an external tranny cooler as they do not like heat.

Good luck.

[cdowns]

plus i think the 400 has a different driveshaft yoke than the 700r4

[jeffro788]

what are the tv cables? is that for the kick down?

[john]

Heres some tv cable education.
http://www.tvmadeez.com/article/index.html

[chevy_mike]

Originally Posted by jeffro788

what are the tv cables? is that for the kick down?

Unlike a 350, who's cable is a kick down cable, the 700R4 uses a TV cable which controls shift points, firmness and kick down. It basically indicated where the throttle is and moves a vavle inside the tranny to control the flow of fluid. If you have this set wrong or doesn't move correctly with the movement of the throttle, it can cause a major slippage problem and can burn up the tranny in a few hundred miles. This is the #1 reason 700R4's fail when putting them into a car/truck that never had one before.

GM vehicles that had 700R4's originally, have the correct mounting brackets for the cable so it is basically plug and play but if the vehicle never had it, you have to set everything up very specificily if you want it to work and last.

[smoky02]

I've been told that the drive shaft for an 88 and up chevy full size short bed will work. But I had to just get mine cut down a few inches. Good luck to either way.

[jeffro788]

I was thinking that a newer like the 88's and up would work. I think I am about to get serious on the transmission project and appreciate all the info. Looks like other than tranny I need tv cable, bracket, crossmember, and lockout. I read something about a transmission cooler though. Is this for sure needed?

[smoky02]

I would suggest that you get one. Also if you are running a TH350 you can use that cross member, you just have to fabricate new holes in the frame. And you can buy a T.V. bracket at most local part stores. Also if you just google T.V. cable adjustments there is an abundance of information on that out there. And on here you will find a few different ways that you can hook that up. I have a thread on here about it, you should be able to find that as well if you search for it. If not I will try and dig it up and link you to it.

[2ndCIB]

If you plan on using a lock-up torque converter, use the kit that Summit sells for less than $90. The transmission shop that rebuilt my 700 reccommended it to me. Easy to hook up and is adjustable for when the vacuum locks the converter. I even put in a single-pole/double -throw switch that allows me to lock the converter anytime, have it operate auto by vacuum or have it unlocked all the time with just a flick of the switch inside the cab.

[oldblue1968chevy]

I currently have 3spd manual tranny. Id like to go to 700r4 this summer. Are you folks buying new trannys? Or going with a craigslist deal and having them rebuilt of putting them right in? How much $$$$ am i looking at spending? And how much mpg difference will I see. thanks

[capev86]

with 3.73 gears in the back, you should get a 3 or 4 mpg improvement provided you drive steady at 65mph. my dad gets 17-18mpg with his 87 burb 350tbi 700-r4 3.73 1/2 ton 2wd. the other nice thing is the engine isn't turning so fast.....longer engine life and less noise inside the cab. the overdrive is great, but combined with the lockup converter, you eliminate any slippage when you are cruising and thus waste as little fuel as possible. less t/c slippage means less heat build up too.

[oldblue1968chevy]

ok..

are you guys buying brand new trannys or a used one what should i expect to pay for one..and should i take it to be rebuilt or what? i gotta read up for a bout 8 months before i make this swap this summer...(aiming for cab swap and auto/700r4)

[chevy_mike]

Personally, I consider ALL used trannys as junk and will need a rebuild. Many, many people have been burnt over the years by buying a "works great" or "fresh rebuild" only to find the tranny completely trash.

I would buy from a well known tranny vendor, like Bowtie Overdrives, Gear Star, Art Carr, even B&M or TCI.

[PHAT TONY]

I used a B&M lock-up gizmo=awsome!(Summit) Little flywheel gadget run by the speedo cable wired to an in-cab adjustable controller that locks/un-locks converter from 35-90ish mph. 1 ground wire, 1 power wire and a dual function brake light switch; 45 mins and I was driving!

[Indyuke]

I must confess I went the craigslist route and it's lasted me 22k miles so far, however, I agree with mike. When this one goes, I'll go with a freshly remaned on next time. And I'll switch to the 200-4r rather than the 700-r4... first gear is too steep for me on the 700.

[jeffro788]

I think I am going to find a cheap one, making sure the bell housing and other important parts are not cracked or bad, and we have a friend that was a mechanic and built race cars, etc... that I am going to see if he can rebuild it with heavy duty parts. I am running a ZZ4 crate motor so it won't be to much horsepower, but I plan to get the comp cams ZZ4 kit that should put it close to 415 h.p.
Other than that I can spend about $1200 for the conversion kit and tranny off the internet.
I kinda like the idea of building it to match my motor and not buying one already built, will probably save a little money.

[smoky02]

I bought mine from a guy on this site, and he was saying that it was freshly rebuilt and so far it's lasted almost 18 months, with no problems what so ever.