Authored by Wes Vann, last modified on August 14, 1997

PLEASE NOTE; Always use jack stands while working under a car. I would also recommend that you have another person present when lifting a transmission into place.

 

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    This page is written with a 64 Chevelle as an example. Unlike most of the other pages that I've written for this section, this isn't a project that I have personally done. The data stated is as accurate as I can get, however, should you find something that appears wrong, please contact me.

    It's going to be written as a list of items that you have to be aware of in order to do this swap. This should be typical of all GM models. The items are going to be written in real general terms and not as a step by step procedure.

    ITEM #1:

    The 700R4 is larger in width than even the TH350. This means that you will have to massage the floor pan on the passenger side of the tunnel (adjacent to the firewall). This is as told to me by a person that installed one in a 64. Other models may not require as much hammering, but, I'd assume that some is required. You will not know until you trial fit the trans. The idea of having to trial fitting a trans isn't fun, but count on having to do it!

    ITEM #2:

    The driveshaft will have to be shortened. The amount will vary and it's best if once the trans is installed, you follow the instructions of your driveshaft shop in order to measure for the correct length. It may seem like a cop-out that I don't just say that it's 3 inches, but cars vary!

    ITEM #3:

    You will have to add some electrical circuit to control the torque converter lock-up. I talked to the people at B&M (hey, I live in L.A.) and they told me about their kit to do this function. How it works is that there is an electrical sending unit that goes on the trans, where the speedo cable is hooked up, that monitors vehicle speed (the speedo cable then hooks up to it). There is also a wire that gets spliced into the brake light switch. Then a little panel gets mounted under your dash that has a control switch where you can set the desired speed where the lock-up occurs (between 30 and 90 MPH). There is an led that indicates when the trans is "locked up". You also have to provide a ground and 12 volt source.

    ITEM #4:

    You will have to have some kind of trans cooler. This shouldn't be any problem if the car originally had an automatic. What can be a problem is reaching the fittings once the trans is in place. A solution to this problem is to have a short section of hard line installed prior to putting the trans in place.

    ITEM #5:

    Should you desire to run with a non-lock-up torque converter, there are several easy changes that have to be made inside the trans. Per the people at B&M, it's about as easy as doing a shift kit in a TH350. If you don't make the changes, the trans will tend to run hot.

    ITEM #6:

    It's my understanding that the stock rear trans crossmember can be used by just sliding it rearward and drilling some new holes in the frame.

    ITEM #7:

    A 700R4 has what is called a "TV" cable (and not what is called a kick-down cable as in a TH350). It hooks up similar to a kick-down cable and most of the brackets are the same. What it does is give the transmission the throttle position so that it knows when to kick-down. It's adjustable and depending on the cable and brackets you use, the method varies.

    ITEM #8:

    Things to look for when getting your trans (thanks go out to Don Seributra for this information);

    A: Look for a 1987 to 93 core. These should have a #732 as the last three digits on the front pump. These trans have a 10 vane pump, 30 spline input shaft, an auxiliary valve body, and a 28 element inner sprag race.

    B: Avoid the older transmissions unless you plan to retrofit with the 87-present internal hard parts.

    C: Avoid the "E" models due to the fact that they are computer controlled (unless you are going the full computer EFI conversion).

     

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    Good luck and be careful (a transmission falling off the jack onto your hand isn't a pretty site!)

     

    tecref11.html

I am putting a 700r4 in my 72 Lemans....now I am sure the floor pans are different between vehicles, but mine fits with no problems. I moved the trans. crossmember back(frame already had multiple holes)to ones that lined up. The 700 is longer, and will require a shorter driveshaft. The part about the 87-93 trans is correct, before that they were weaker.....and for the lockup portion, Bowtie Overdrives has everything to convert it, and I don't think their price was bad. I was lucky enough to find when I opened mine that mine is only a 1 wire internally, so hook-up is easy. You can wire it to a toggle, or get a vaccum operated switch so it shifts at a certain vaccum. Some older cars had this set-up. I am not done mine yet, but this is what I have found through a pile of research.

Haven't got that far yet..... for the speedo. I think they are still the same as the other trans. with the cable...I just don't know about gearing internally!!!! I got lucky with my trans only having the one-wire running to the plug on the trans....makes it easier to hook-up. Funny thing is on the plug it has 3 prongs????? With no other wires to them!!!!!!!

I believe it controls valve body pressure, It is critical to adjust properly , or they start slipping ,,making heat and then 'toast'

I had read the setup procedure on bow tie overdrives some time ago,,, I have to refresh!

What is the TV cable I have read so much about? Is it really needed?
Yes it is really needed. This is the most misunderstood part of installing a TH-700R4 (and 2004R for that matter) and getting it correct is critical to the very survival of these transmissions. This TV cable system controls the internal hydraulic pumps production of hydraulic pressure and volume, if that isn't enough, it also has a major influence on shift timing, quality and "feel". Thats the bad news, the good news is we have all the necessary pieces to make this easy to get installed and working correctly. These parts are very inexpensive, however you should plan to spend a few hours getting this dialed in. In these two pictures we see a Holley carburetor at idle(1) in the first picture and at wide open throttle(2) in the second picture.

These two pictures below show the plunger on the valve body inside the transmissions pan. This valve is moved in and out by the TV cable connected to the throttle linkage on the carburetor. The first picture shows the plunger all the way out (homed)(3), this should correspond to the first picture above(1): the carburetor at idle. The second picture below shows the plunger all the way buried(4) and this should correspond to the picture above showing the carburetor at wide open throttle(2).
The purpose of these pictures is to show you the relationship that must be established and demonstrate that the TV system is not that difficult to do!

Why is the 200R4 a better choice ? I remember the 200's as being the worst transmission ever produced by GM in the day, but I have read articles on built 200's and they compete??

Elroy wrote:

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Why is the 200R4 a better choice ? I remember the 200's as being the worst transmission ever produced by GM in the day, but I have read articles on built 200's and they compete??

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Elroy, are you maybe thinking of the 200 "metric" which is a 3 speed? If so, agreed, they were awful.  As far as the 200 over drives I would say my own experience at the dealerships since 1980 has been pretty good. Our 87 Grand National had the 200 overdrive and I loved it. That car shifted beautiful, good hard screech into second gear under full throttle, nice sharp firm shifts into each gear under normal driving conditions. Guys did blow them up, yes, but the Grand National is a pretty exceptional engine too.

My personal choice is also a 200 overdrive over a 700 but I know of at least one guy who will disagree with me and we often enjoy debating it!

 

Carl Stevenson wrote:

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Elroy wrote:

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Why is the 200R4 a better choice ? I remember the 200's as being the worst transmission ever produced by GM in the day, but I have read articles on built 200's and they compete??

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Elroy, are you maybe thinking of the 200 "metric" which is a 3 speed? If so, agreed, they were awful.  As far as the 200 over drives I would say my own experience at the dealerships since 1980 has been pretty good. Our 87 Grand National had the 200 overdrive and I loved it. That car shifted beautiful, good hard screech into second gear under full throttle, nice sharp firm shifts into each gear under normal driving conditions. Guys did blow them up, yes, but the Grand National is a pretty exceptional engine too.

My personal choice is also a 200 overdrive over a 700 but I know of at least one guy who will disagree with me and we often enjoy debating it!

 

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Carl, What was the tranny that was used in the pickups in the late 70's early 80's I'm guessing?   It was very weak as I remember my dad and my brother both had them and they didn't get much life out of them.  I think they did some upgrades on them when they were repaired but it was an overdrive transmission.

 

Thanks Ashmore for your info and post ! Theres lots of us old Gm guys out there. What dealership did you work at ?

Uncle Bernie; As you have done this , do you remember on the four prong plug for the TC on the 700R4, as you look at it from the top , which one did you pick for the single wire you ran ?  My 700R4 is 3 inches longer exactly than the shortshaft TH350 and the firewall is fine. THe crossmember works if you redrill the frame brackets to slide it back but the mount needs to be modified to lower the tranny mount 3/8 to 1/2". For the El Camino the shaft length appears to be 57 1/4 center to center on the ujts which is 3 inches shorter. Does anyone know what the driveline angles should be ? I have 2degrees on the diff and 4 degrees on the tranny if its as high as it will go ?  Does that sound right ? I know they shouldnt be the same identical angles or your ujts won't last. Also the press switch location for the switch that runs the TC lockout is not there on the rt side by the accumulator looking thing, so theres a plug on the left side of the case half way up back of the bellhousing, 1/8 pipe thread so is that where it goes ??

-- Edited by Elroy on Wednesday 24th of March 2010 03:51:46 PM

Thanks John for the tips. My slipyoke is really tight, hafta tap it in with a hammer and out but it does go . Not sure why its really smooth in the TH350. I am getting my crossmember modified and I will send pics. The Camino frame is boxed so its a bit different than my Chevelle. There are perches welded about an inch up from the bottom of the frame for the crossmember to mount to . The Chevelle has it bolted to the bottom open side of the frame.