Thread: 700R4 Lockup or Non-lockup

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I have a 700R4 tranny in my 86 Silverado, I just rebuilt the motor and I need a new torque convertor but the ones I've looked at say lockup or non-lockup and I don't really know the differance. How do you tell the differance? Also there is a plug on the drivers side with no wires coming out of it, what is it for and do I need to replace the plug and wires?

Since no one has answered yet I will keep it going until someone does. I don't know the answer except to say that understanding the 700R4 is not as widespread as information on the TH350/400. As far as I know the stock 700R4 required an electrical signal to lock/unlock, but why your trans does not have wires may be a model I do not know about OR an aftermarket replacement unit. If no one else answers try calling:

www.eatmyshift.com

phone 352-683-8384

Monster Motorsports
13743 Linden Dr.
Spring Hill, FL. 34609

I bought a mildly modified 700R4 from them for my '29 roadster BECAUSE they modify the electrical switch and use an internal pressure switch instead to lock the 4th gear, that way I do not have to have any wires. However, I do not know why your unit does not have wires. For the price of a long distance call (if no one else here answers) the Tech guy at Monster Motorsports should be able to answer your question.

Don Shillady
Retired Scientist/teen rodder

The plug has 4 wires on it. yes? it is for the lockup, so yes, you have a lockup trannie and need a lock up converter.

Next, you need to plug this in if yo are still running the factgory harness/computer. Failure to do so will cuse the tans not to lock up, it will run HOT as hell, and burn up.

There are several ways to hook this up if you are not running a \facotry harness / computer. The simplest is (and i have to go look at my trans to answer specifically in wire colors) is to twist two wires together and run the other to hot.

Basically, in the trans is a solenoid (+ and - wires) and a switch that goes to ground when the trans is in 4th gear. - so you run the solenoid + wire to a ign on circuit, and twist the other two together. When the trans hits 4th, the converter locks up.

Kits include a brake switch to go in teh + lead to unlock things when you hit the brake pedal. i have not got that nad see no need for it - hit the brakes, the trans leaves 4th and it unlocks...

there is a delco vac switch that was used on some trucks (included in the painless wiring kit for this trans) that will unlock the converter under loads, like up hills and such. i have a switch installed in the dash and see no need for this either, but on some trip to the 'yard' i'll grab one. About $30 new. I have hte number somewhere or perhaps you can get painless to give it up (hard to do, but it can be done)

Thanks for your info screamer 63, I'm thinking about going with the painless wiring kit from summit for 129.88, unless I can find a cheaper way to fix it. I think mine only had three wires but they were all cut off. I don't have the stock computer either

having the plug from the harness makes it easy. i got mine from my buddies 84 camaro and we have the factory manual to figger out the wiring. It is all in a Jeep now, and the PO had not bothered to hook up the converter lockup and once i did i saw the temps drop tremendously (30+ degrees) at 45-55mph cruise.

There are simpler kits for about $80 out there, but the painless one includes the vac switch. (they all include the brake switch).

My fix cost $0. My one disappointment was i was hoping for a mileage gain and didn;'t get one. the revs will drop about 200rpm with it locked up, so i guess that is not much.

Do you know of any other kits than the one from painless or the b&m in summit

http://www.tciauto.com/gm/gm_4L60E.htm
toward the bottom of the page.

Thanks, the tci switch is priced alot better than both of summits kits so I guess I will go with the TCI harness. My tranny has been overheating, now my current torque convertor howels between shifts. I'm going to run a Tork Master 2000 convertor with a Flex-A-Lite tranny cooler and the TCI harness.

I have a trans cooler - haven't installed it. I plan on doing a cam in may or so, since i think the rad has to come out i'll put it in then. No room to work infront of the rad on a Wrangler!

Overall temps are fine UNTIL i the ambient temps hit 80 or more, then the engine runs hot. I get pinging on the highway at all temps...worse when hot. Still figgerin this beastie out. I thought the pinging was running too hot, now not sure sure. i know the carb is junk, so that is on the list with a cam. Will reevaluate then.

I'm running a 4 bolt main 350 .040 over fully ported polished 305H.O. heads with a performer carb and intake and a comp cams 270H camshaft, exiting through flowtech headers and 2 chamber 3 inch flowmasters.

B&M makes a lockup kit that has the lockup speed adjustable. Take Screamer's advice......dont run it without a lockup!!

Also, you must have the brake switch hookup. Your truck already has the switch. The switch is down by the steering column. It has two sets of contacts, one for the brake lights and one for the converter lockup. The brake light circuit is normally off and the converter circuit is normally on (both with the brake pedal up).

The B&M kit was also cheap and included the trans connector.

mike

Here's another thought.

http://www.bowtieoverdrives.com/cata...php?ITEMID=332

An additional manual switch to lock up in other gears isn't a bad idea in a pickup that might carry a load or tow a trailer.

I agree with Henry -

Bowtie overdrives has one of the simplest easy to use kits available.

I recommend the unlock switchin the brake light circuit, in the case that you lock up the rear wheels on heavy braking it puts a great deal of load on the clutch in the torque converter - much like locking up the rear tires with the clutch out in a manual - that little clutch inside the converter is not designed to hold that much torque - 2-3000 rpm to zero in a second or two.

Also, if you aren't using a oem intake with the bracket for mounting the TV Cable, Bowtie has the best TV cable system on the market. Hands down. TV Made EZ.

Good luck.

Speedy is correct about Bowtie Overdrive's TV cable setup. I looked at several, and theirs is the best out there. Instead of trying to attach something to one carb stud like most others, it's built onto a full carburetor plate. There's no way it's going to move. I did have to make an adaptor for the throttle cable though.

http://www.tvmadeez.com/ez_solution.php

They have some good technical info on the site also.

All 700r4 trans have lockup torqueconverters They also have an orifice in the pump that cuts the flow to the trans cooler when in overdrive GM did this because the converter makes 95% of the heat in a trans but when its locked up it makes no heat GM wants the trans to run a about 280 degrees There a 2 basic 700 wire harnesses in the trans one for fuel injection and one for carbs. The one for carbs. has up to 4 switches in the trans and only one wire to the solonid if you have this type and you put 12 volts to the a terminal on the trans it will lock up in 4th gear only no kit needed If you have a efi unit 1987 and newer you need to drop the pan there is either one or two switches the wire harness needs to be rerouted so power goes through the 4th gear switch then to the solinoid and you need to ground the neg. side of the solinod to the trans this does the same as all those kits and costs nothing I've built 700 since 1982 good luck