73 Teach's Pet

Guys,
I just spent $96 to install TCI's lockup converter wiring harness that operates without the use of the computer in an 1986 700R4 tranny that will be put in my 86 Trans Am (for use as a winter car and 1/4 mile performance parts test bed car.) I have eliminated the computer and all the smog crap which is why I have to find an alternate method of engaging the lock up converter.
I read where the Chevy used a vacuum switch to operate the early 700R4 tranny's, but moved away from that method of engaging the lock up converter because of the lack of maintenance and up keep associated with the vacuum hoses and all problems associated with a vacuum operated system. The TCI kit uses a vacuum switch to engage the lock up converter, which sounds pretty much like the early method that Chevy used when they first brought out the 700R4 tranny, prior to engaging the lockup converter with the computer.
What year and models was this vacuum engagement method used in, early 80's Vettes perhaps, and any others?
Does the early 700R4 Vette trannies use a vacuum operated switch to engage the lock up converter?
Does anyone know where I can get a vacuum operated micro switch that would have been used in the early 700R4 trannies, or any other vacuum operated micro switch that may engage the lock up converter for me?

TCI has there vac. micro switch set to 8-10 inches of mercury, or 8-10 what ever the proper units of vacuum are measured in.

By having the micro switch and TCI wiring diagram, you could really save yourself a pile of money by doing your own wiring harness conversion if you needed your lock up converter to engage without using a computer, like in an early C3 tranny swap.
Can anyone help me save big bucks by telling the "do it yourselfer secret" to the lock up converter engaging arrangement?
Thanks for insight and help, and above all.....Be Cool!
"TEACH"

Apeiron

One way to do it is to use a 140141519 vacuum switch, 8627332 or 8642473 pressure switch, and 12085533 connector.

tommelton

82 Corvette - first year for 700R4 in Corvettes, first year (I think) of use by GM in any US car. 700R4 in 82 Vette was computer controlled, not vacuum. ECM had complete control of the torque converter.

Tom Melton
82 CE
86 Z51 Coupe

Apeiron

Only some passenger cars for export and some pickup trucks had non-computer controlled TCC.

Ingar, Norway

It's very simple, the brake and vacuum switches are connected in series feeding 12v to the lockup solenoid connector.
The complete 1980 shop manual electrical section is at my page.

I have a LED indicator in my car and it shows that the vacuum switch is always closed except when motor is idling. (ported vacuum).
Maybe an advantage when going down hill, but I don't think the switch is really necessary.
It 's not shown at the Bowtie lockup drawing either.

But it's not possible to say how to hook it up unless you know how the 700r4 is internally wired. (I'm still searching for information on that, apparently there are lots of different configurations).

Apeiron

Yes there are a lot of different internal wiring arrangements. Most non-computer TCC setups used the brake switch to interrupt the +12v, and the vacuum switch interrupted the ground.

73 Teach's Pet

Great info guys, but keep it coming. Please be specific in your descriptions of the parts you are mentioning, where they are located and what job they peform in the system.

Apeiron, what is a brake switch, what does it look like and what job does it perform in the system? Is that the switch that would be mounted to the brake pedal assembly under the dash? I have never heard of such and item and need a beginners lesson. Your description of the funtion of the vacuum micro switch helps clearify what that part does.

Keep on teaching the "teacher" a lesson students of speed and performance!
Be cool!
"TEACH"

Ingar, Norway

The schematics/drawings at my site give an description on both electrical hookup and mounting of the switches.

The 700r4 page shows some examples of 700r4 internal configuration.

Apeiron

The brake switch is on the pedal. Pressing the pedal opens the switch and forces the TCC to unlock when the brake is applied. The vacuum switch is closed when vacuum is applied, and opens when vacuum falls, to unlock the TCC at W.O.T. and prevent premature wear-out.

A brake switch is probably not essnetial, especially if the vacuum switch is connected to a ported vacuum source.