advice on 700r4 conversion

turbo 350 lost drive coming home from nats. and will likely replace with 700r4. i know its longer and i have a driveshaft to fit (2.5" shorter than stock) fabricating mount isnt a problem. my concerns are the wiring and shift points. are they set up decent for our 6 cylinders or do i need a shift kit/governer/? i have seen 2 types of wiring kits. 1 has a switch, relay and wires for external connection, the other has a lot more parts for inside tranny. if anyone has done this swap, please give me advice on what i might be overlooking. john

I have used the simple on that uses a pressure switch that goes
into the valve body at the 4th gear port and then on to the torque
converter clutch soleniod, only applies the tcc when in 4th gear.
the other one that has all the external parts is a little more complex
to install and set up and is more expensive. the shift points are
controlled by the detent cable or tv cable and it is adjustable to
get it right.

I have done this also, Like panelmanrd said the shift points are mostly adjustable with the external TV cable set up at the throtle . The rest is a design function of the valve body and works well. the shifting is all controlled hydraulicly however shift problems can occure if the TCC trys to engage too early, which some people equate as an electrical problem, and it may be cause because of an ellectricl issue with the TCC but shifting is hydraulicly controlled.

I changed up the internal switches and wiring because the 700r4 come with many different internal wiring arrangments suited for whatever it had been used in. The inside changes are not that mysterious. its just a solinoid with power and ground you want the TCC engaged only in fourth gear and under light cruise and light loading.

There are many sensable reasons for all the external set up ot the TCC controls if you want it to work automaticaly, work well and give you best fuel economy then you should consider hooking it all up electricaly as I did.

M1D

did a lot of research on the tv cable tonight and am confident i can get that correct. i found very little on the lock up control, just adds for different kits ranging from 45.00 to 175.00. dont mind paying for everything in one package and simple instructions but i can wire a toggle switch for a lot less than 175.00. what am i missing here?

Have you considered a 200r4, same length as a th350, and better gear split than a 700r4. As far as the tv cable adjustment check out Bowtieoverdrive. They have a lot of good info on the setup.

wanted the lower first gear from 700r4. van came with extra driveshaft for a th400 and is correct length.

Normally you need the TCC solinoid, a manifold vacuum switch that is adjustable which allows the TCC to engage at cruise and dissengage when you give a certain ammount more throtle. Then there should be a switch on the brake pedal that dissengages the TCC the instant you hit the brake. And there should be a oil presure switch in the forth gear oil passage that allows TCC to happen only when the trans applies oil presure to forth gear.

Some other 700r4 trans may have a 3rd gear switch and various models of oil temp switches which can all be removed unless you want the complexaties of why they where put there.

It is all a single wire circuit in series. starts with Batt power through a 10 amp fuse, then through the manifold vacuum switch, then to a "normaly open" brake pedal switch, then into the trans to the fourth gear switch(not sure if its a N.O. or an N.C. type switch, I can check later) , then to the solinoid and the other end of the solinoid is grounded to a bolt inside the trans. you can add in a togle switch if you like however the TCC being enfgaged when it shouldn't can cause other problems and trans premature failure.

I can draw it for you later.

M1D

Here's a couple examples.

ordered a kit from summit for 90.00. has the parts shown in digz post, same parts in the 160.00 kit so i felt safe with summits 'no name' kit. i have heard of people wiring a switch and selenoid/relay only but as m1 stated, the other parts are there to make it work properly.

That second drawing looks good and I would add in the brake switch also.

Doing the little extra work now to hook it up right so its fully automatic with the proper input comands will make driving a lot nicer. And fuel efficiency as best as the TCC can do.

When I'm doing 60mph, my engine is turning 1800 rpm with TCC engaged. if I move the gas down just some to change lanes and get past someone the TCC unlocks, the engine goes to about 2300 to 2400 rpm depending how much gas pedal I put in and the van is right in its power curve and passes no problem. and then when I let up on the gas to cruise the TCC re-engages and I don't have to be jerking with switches and wondering when and if.

I love it.

M1D

I'm running the vac sw and pressure sw set up , Not running a brake sw but I have heard that they may save some tranny damage say like from a panic stop? and disengage the TCC quicker than what the pressure switch will.
I couldn't figure out a decent way to mount a brake sw, most are ment for interior installation out of the weather and that aint where our stuff is. Perhaps a N.C. pressure sw in the brake lines would work well ? if that animal exists.
I am running into one other anomaly, Gently coming up to cruising speed, say around the 45-50 mph area. the trans will want to go back and forth some from 3rd to 4th, kick it down and pick up speed and this gets rid of it, I'm not sure if it's just TVC adjustment or I am up against an engine RPM/ ground speed thing running the 4:11s. It doesnt do it if I just stick my foot in it and go, which is usually the case, LOL

Digz; the trans should just shift. The 411s are not the problem. Assuming no problem inside the trans , the external imputs that effect shift point are #1 the TCC is not trying to engage #2 engine rpm vs road (tail shaft) speed and #3 TV cable adjustment.
I would take a carfull look at the vacuum switch adjustment and I would play with the TV cable adjustment. The TV cable adjustment is to bring ballance between the inputshaft speed (oil pumppreasure) and the out put shaft speed (govenor pressure). In some extreem casses a hot rodder may have to modify or go to a different govenor spring, however not likely in your case.

Brake switch;
I mounted a N.O. whether sealed brake switch I bought at napa for $6.





It works right, I had to increase the spring tension that assist pedal return


M1D

Thanks M1, I had wondered about the Vac sw also, I will play with that first. Will add the brake sw to my off season to do list also. It has to be an "almost there" kind of adjustment. I probably should rig upa a temporay vac guage to see what is happening as it comes up to speed to give me something to go by.

sometimes you need to put a restrictor in the vacuum line to make it less sensative or delayed to overcome an "almost there" issue. Or maybe a different vac source of the carb or intake as some ports have greater or lesser vac signal and at slightly different times. I have used a soup can as a small Vacuum resivior in the line that would delay the vacuum signal decrease to the switch as I push down on the gas. These kinds of ideas I bring up because sometimes the problem is not the adjustment on the vac switch but the problem is something else the vacuum switch adjustment can't deal with. especially because different engines have different MAP values.



You want a vacuum control that is not too sensative because driving condisions might be in strong head on wind gusts or hilly roads or even some dumb ass in front of you that keeps speeding up and slowing down, you want the TCC to stay on or off and not be responding off and on to every little road condition or twitch of the gas pedal.

M1D

My trans guy and I touched on the vacumn cannister idea back in the beginning of my build, I had forgotten about it . Now would a restrictor be different than a vacumn accumulator/resevoir in effect ? I'm also wanting to add filtered vac source for stuff like the bowl vent on the carb for my van, and tank vents and such on the next build. Are there any easy systems to rob or aftermarket pieces that would make a good setup to help with all of it? Sorry this is gettin' a bit off topic.

I can't say for sure how a restrictor can be the same or different from a small resiviour can. There are so many variables. I do think however that the same desired effect can happen although a restriction can get clogged and a can might be some smother. Maybe some setups might need a can and a restrictor??
I need to add a large vacumm resiviour in line with my brake booster because my booster is small and the engine computer dosn't lat the engine right down to idle on a fast decel from high rpm so my booster starves momentarily.
Thats just the way these vans are, everything is a custom build up!!

maybe you need to start a different thread on this other subject/
Are you talking gassoline vapor recovery system on your next build? Like I have now on my 65?




this one is solinoid controlled by the computer when it thinks its time to purge.

You could get a canister from a 70's car when they were controlled by a vacuum signal to a vac valve on top of the can. You can get replacement charcole and filters for them and take the vacuum line diagram from the underhood sticker to figure out how to plumb it and you will also need a gas cap that has presure control in two directions (quite comun).

M1D

Yes that is what I am thinking of, the gas vapors. I am leaning towards a TBI or some kind of EFI set up on the 66 and am wanting to put a larger tank in. Yep . going to have to get another thread going when I get a little further along. LOL

If you are going to FI of some sort I highly recomend you select a donner vehicle that has all the equipment as a complete power plant package. Get it running right and then move it all into your van , wiring, computer and all. and get a proper shop manual for that donner vehicle so you can get it all happening.
By the way , there is very gains in fuel economy if you put in some half of a designed FI system and eliminate all the complimentry imputs that go with it. Those FI systems that have a computer independantly controlled fuell injection ONLY and nothing else computed together with them, donot get any noticably better mialage then a properly set up carb

Its the system "KNOWING" load, throtle position, air temp, coolant temp, air intake presure (density)or flow volume, road speed, rpm, gear, timming and O2 value as well as EGR position, EVAP purge and variable fuel pump voltage that leads to best fuel economy. I ditched the A.I.R. system but the CAT is also important for proper O2 funtion. I even built my exhaust to be like the exaust in the donner car . You can see lot here.

https://s119.photobucket.com/albums/o122/m1dadio/

M1D

tranny is finally in and adjusted right. everything i read says the tv cable is the hardest part. IT WAS!! 20 minutes to remove, 2-3 hours chasing parts and new (used) tranny, 4 hours to install, fab. mount and swap driveshaft yoke and u-joints. 2 days getting tv cable right! factory tb swings 78 degrees as do some 4 barrels, holley and edelbrock are less, but you can buy the correcter. 40.00 for a hunk of aluminum smaller than a bic lighter. on the 6 banger, no such part available. i have several hours calculating and verifying the correct placement of tv cable. if anyone is interested on how to calculate or wants the specs for a 6 cyl. let me know. i can put something in 'how its done' if others feel this is useful info.

Good job;l

M1D