1969 el camino 700r4 transmission swap [Archive] - Chevelle Tech

: 1969 el camino 700r4 transmission swap

Jun 29th, 10, 1:17 AM
I have done a lot of research on this swap and I have heard that converting a current TH350 to a 700r4 a lot of guys are saying its some of the best money they have put into their cars. I was wondering because of a lot of speculation on the changes in internal design between many years on what the best year range to get the transmission to slide under my 69 el camino.

-I read somewhere that the pre 1985 ones are junk because of pump failing issues. Is this true or a rumor?

-Shortening the drive shaft by 2 and 7/8" is required but does a '71 nova driveshaft fit perfect? What year would require no fabrication if any do fit?

-Other than having to slide the crossmember back by 2 and 7/8" as well is there any other fabrication that any of you have had to do to make this transmission work?

Thanks as always guys you all are a huge time saver and help me so much with quick solutions to my problems!

Jun 29th, 10, 8:59 AM
I would get a later style with the 31 spline input shaft because there are more available torque converters for that model. I put one in my 66 and it lowered my 70 MPH RPM by 1000. I am getting a new aluminum drive shaft if you are interested my old drive shaft might fit. PM or e-mail me. You have to get the correct attaching brackets for the TV cable and a lock out switch for the converter.

Jun 29th, 10, 11:03 AM
I have been doing research and a lot of people are saying that the 700r4 transmission is great for my 1969 el camino but a lot of people have recommended I go with the 200-4r transmission because it is a longer lasting more durable transmission than the 700r4. What are your thoughts on this?

Jun 29th, 10, 7:01 PM
I have been doing research and a lot of people are saying that the 700r4 transmission is great for my 1969 el camino but a lot of people have recommended I go with the 200-4r transmission because it is a longer lasting more durable transmission than the 700r4. What are your thoughts on this?I cant say here, just that I love my 700r4 now that I have it dialed in. I have a healthy 427 but I dont race so I cant say how durable it would be if I did.The OD drops my rpms 1000 in 4th gear from 3000 to 2000 at 72mph with 3.31 rear gears

Jun 29th, 10, 7:16 PM
I eventually chose the 700r4 because of the hotter 1st gear. I love it, but I'm running a 283 and never racing it. The 2004R's can be built to stand more abuse. Either way, I love the damn OD...

Jun 29th, 10, 7:27 PM

Jun 29th, 10, 10:22 PM
Mike that's a really great link I appreciate that I'll measure any transmission I pull out of the junk yard that is a 700r4. I was also wondering how do you wire that 12-volt torque converter locking switch. This is the only area I am seriously scared to mess up because if I do so I'll blow the transmission. Can you guys give me some tips on how to wire the lock-up switch thingy! I appreciate all this help I want this process to go as quickly and smoothly as possible and all this info is helping immensely.

Jun 29th, 10, 10:35 PM
Link was for mounting and drive shaft dims but use it as you see fit.
Here's some info on cable and electric install for 700r4 - http://purplesagetradingpost.com/sumner/techinfo/700R4p1.html

Here's ID info - http://www.hotrodders.com/articles/TH-700R4_identification.html

You might talk to jakeshoe (username) about a 200-r4.

Jun 30th, 10, 6:25 PM
Last question on this topic(hopefully) I was told that the post 88 700r4's are the best to go with but at the same time you have to make it a non electric ran transmission. I read somewhere that you can for about $20 have the electronics taken out or take them out. How do you make it a non electric transmission?

Jun 30th, 10, 7:03 PM
Garrett I think you have some bad info. I have a 91 700R4 and the only wire to it is to unlock the converter. When you get into OD the converter locks up for maximum efficiency. When you slow down you want the converter to unlock so that it slips and does not push the car. All you need is late model S10 brake light switch. Looks just like your Chevelle switch but has 4 terminals. two the brake lights and two to run 12 volts to the converter. When you step on the brakes you brake the circuit to the converter and it unlocks. I can try to find the number for the switch. I just went to my local Advance Auto and asked for a n S-10 switch.

Jun 30th, 10, 8:40 PM
From all the rebuilt videos and what not that I have seen show roughly a set of 3 or 4 wires that go from one side of the valve body to the other. Those are the wires I am wondering how to remove to make it so the transmission does not run on a ECU. Or do those wires control the torque converter?

thanks guys for the help!

Jun 30th, 10, 8:43 PM
Those 4 wires are shown in the link I posted so you could see how to wire it up.

Jun 30th, 10, 9:00 PM
You don't need an ECU with a 700R4. GM didn't use ECU till the 4L60 series transmissions.

Jul 1st, 10, 8:53 PM
Ok guys I am going to go get my transmission to rebuild tomorrow. While looking through a haynes manual about how to rebuild the transmission and now I am wondering about my speedometer cable. Is there a universal speedometer cable that I can get that will fit both worlds(my old 69 dash with the new trans). I figure I need to get one that will fit into the transmission and will have the proper adapter to slide onto my fitting on my gauge cluster.

I appreciate it guys this help is tremendous!


Jul 1st, 10, 9:39 PM
I used my stock speedo cable with my 700r4. I just bought the correct speedo housing and gear here

Jul 2nd, 10, 9:10 AM
All GM speedo cables are the same except for length. The problem you might have is that later 700R4's came with electronic speedometer senders. Then you have to do as Ron suggested and change tail shaft housings. If your core is set for cable then yours should screw on. The next problem is getting your speedo to read correctly as you may have to change the speedo gears to match your rear axle ratio and tire size but that is a whole nother can of worms.