700r4 lock up question

[Topher-x-01]

hey all i am getting ready to install my 700r4 into my truck.... the 700r4 in the truck does not have anything plugged into the lock up sensor deal... the truck originaly was a 3 speed i guess.. but the guy drove the 700r4 the way it is until the tranny dumped on him now it only has 1st.. since there is nothinng and no wiring in the truck to plug in this lock up sensor thing.. obviously i dont need to worry about it?

[INSIDIOUS '86]

Yes you do if it's not plugged in the trans will will not lock up and will overheat. Buy a manual lockup wiring kit from b&m or such they aren't real spendy and it let's you control when the converter locks up
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[Hubscrub]

yes it will help it run cooler but you don't have to have it. My 700 was built and under warrenty for my 71 and he told me that is not absoulty ness. to have it, i would think if it did he would want it to because he will be fixing it if i fails. The one in my 85 4x4 is on a toggle switch that i lock up only on long highways it has been fine. THE MAIN THING IS HAVEING YOUR TV CABLE ADJUSTED PROPERLY FOR TRANS LIFE AND TO FUNCTION PROPERLY.

[Meatman]

This is how I did mine with a relay. Pin A is the signal wire from the relay. Then youll also need a ground which is pin B. Doing it this way once you hit 4th gear it will automatically lock and stay lock unless you come out of 4th or hit the brakes.

[Topher-x-01]

well i guess i also just dont understand even what it does? why does it need to be locked? sounds like a pain having to flip a switch everytime i hit 4th gear?
so confused! i am putting this tranny in my truck saturday... without the one in the truck being hooked up is probably why the one in the truck is bad!
truck used to be a 3 speed, then they must have burned up the 700r4...

[Meatman]

When converter isnt locked it causes alot more heat. Excessive heat will kill a trans really fast. When you lockup the converter it locked so solid and no slippage. It also drops the rpms by a few hundred which helps gas mileage on the highway.

[Topher-x-01]

so many things just make it seem to be easier to put a th350 back into it or whatever it came with... alwell i have the tranny already!
so say in town cruisin the street etc I would leave it unlocked? mostly unlocked until using 4th gear?

[DetroitDan]

I'm interested in this too, I have a 454 with a th400 and I would seriously consider swapping to a 700r4 if I could be convinced it would be strong enough. I've always heard bad things about the 700s, but I've also heard it was due to people towing in OD, and other heat related lockup issues. My 83 owners manual actually recommended driving and towing in OD all the time. Maybe that's why by 1985 all the 700s were blown and they had a bad rep. I like the idea of wiring it into the brakelight circuit for automatic on and off, but honestly I wouldn't mind having to switch it either. Anything to try to improve the fuel economy at this point.
I had a 66 Impala with a 2004r in it with a toggle switch operated OD, seemed simple enough, basically just provided 12v to the trans plug iirc.
Will a 700 bolt up to a 205 case? I'm already leery about losing the strength of the th400, if I have to give up the 205 and change to a 208 I don't think I'd even bother. I'm pretty hard on drivelines, that's why I have 1 tons for daily drivers in the first place. I know the 4l80s are stronger, but I think they require a computer to run the electronic OD.

[Pop's C-10]

Originally Posted by Meatman

This is how I did mine with a relay. Pin A is the signal wire from the relay. Then youll also need a ground which is pin B. Doing it this way once you hit 4th gear it will automatically lock and stay lock unless you come out of 4th or hit the brakes.

Thanks for tha break down

[Meatman]

Best place to put a switch would be on the ground wire to the trans or on pin 86 of the relay. That way your switch wont burn up because all your doing is taking ground out the the equation. Or you can just drive around in 3rd but rpms will be higher. In the diagram the little round thing at the bottom is a 4th gear switch which is before the lockup solenoid. So truck has to be in forth gear so that closes or converter will not lockup.

I have personally had good lock with 700r4s. I have a 4l60e which is the same thing just more wires in my TA with a 4400 convertor. Granted its got a 2k worth of parts in it....But with the right parts you can build one really cheap and itll hold up. Like was said before a trans cooler is a must. Buy the biggest one you can find or fit. I have an oil cooler with a 1800 cfm fan on my TA, but this would be overkill for a truck with a stock convertor.