TC lockup on 700r4's non-computer controlled

[lectric80]

How is the lockup handled on the Blazers with 700r4 and no computer?

I am looking for a simple solution for my Camaro, and I don't have a ton of cash. This got me thinking about the Blazers that didn't have computers, but were factory equipped with 700r4's. Is it the same setup as the vacuum switch setup on my T350?

The Camaro was originally equipped with the CCC, but the carb is long gone, and the distributor is about to disappear along with the wiring harness. This, however, leaves me with no way to easily have the lockup set up on the car. I obviously want this, since this is to be my new DD, and I really can't afford to replace the trans at the moment.

 

[Greg Ducato]

The 350 style vacuum switch set up was also used on 700R4s and works well with stock style camshafts. You may get into some issues of converter lock and unlock shuttle with performance cams that do not produce a lot of vacuum. You can wire the trans to only lock the converter in 4th gear, running the voltage supply to the trans through the brake light switch as it was from the factory. B&M makes a nice speed sensitive adjustable controller you can use to dial in the lockup for what seems the appropriate speed in your particular application.

 

[K85 Octane]

I can only second the 4th gear lockup method. I have a BTO set up (though they are all pretty much the same). It came with a new brake light switch, wire and fuse, and a piece for the inside of the trans. You can install it all yourself, the internal piece IIRC is accessible through the pan.

Mine works perfect, no complaints. I get 1-3 gears, and a locked 4th. There is no unlocked 4th.

 

[dabomb6608]

On my 85 it is controlled thru a vacuum switch on the fire wall and the brake light switch. However mine locks up right around 25+mph in third and in forth. Tap the brake and it unlocks. Give it gas and it unlocks unless im in forth. Then it just kicks down to 3rd gear.

 

[lectric80]

The 350 style vacuum switch set up was also used on 700R4s and works well with stock style camshafts. You may get into some issues of converter lock and unlock shuttle with performance cams that do not produce a lot of vacuum. You can wire the trans to only lock the converter in 4th gear, running the voltage supply to the trans through the brake light switch as it was from the factory. B&M makes a nice speed sensitive adjustable controller you can use to dial in the lockup for what seems the appropriate speed in your particular application.

That gives me the info I need to work on this. I knew there had to be a way, and I have access to a couple wrecked early 80's Blazers that might have just what I need. Including one sitting in my garage right now, that I believe still had the switch on it. Just gotta get through tearing the engine apart in the Camaro.