700R4 MD8 valvebody problem.

[Peer81]

Hello everbody,

To tell the short version, I have a '81 and put in a 700R4 from a '90 Corvette. I'm working on the lockup wiring so the lockup can be controlled by the '81 ECM. I wanted the lockup to kickin at 3rd and 4th.

The '81 ECM gives the following readings on the lockup wiring.
Wire A has a continues 12v.
Wire B gives 12v under 25mph and when braking.
Wire C is for the high gear don't know.

I ordered a vacuum switch to lockup at high intake vacuum.
Ordered a 3th gear switch 2 prong, normally open.
4th gear switch 1 prong, normally open.
4-3 downshift switch 2 prong, normally closed.
solenoid switch 1 prong, normally open.

The idea was to connect wire A to the 4-3 pulse switch, then the solenoid and returning in wire B the 3rd gear switch. Wire C would have the 4th gear switch (as original for this transmission).
Yesterday I dropped the pan and today I wanted to put in the extra switches. But under the trans I found out there isn't any thread left or stops (with thread behind it) left to remove in this valvebody.



You can see on the right the place where I removed the 4th gear switch (above the connector). I had the idea this would be an easy switch of switches but didn't expect this. Am I overseeing something or is there just no easy way to install the switches? As I look at it now my entire lockup wiring is down the drain...

The problem I have now is that the transmission will lockup the second we go over 25mph so I need a switch that is only closed it 3rd and/or 4th gear. As I see it I can switch the single prong 4th gear switch for one with 2 prongs, but I don't find it on the net (normally open). Does anybody have an idea were I can find them? Or as I already have a 2 prong 3rd gear switch (normally open) can I also use that one and place it in the 4th gear switch opening?



Btw. I already have a aftermarket lockup kit but don't want to cut wires when my ECM can do the same and I don't want to use a manual switch to control the lockup.

Greetings Peter

[Peer81]

I checked the switches today. Lucky I did because the 4-3 downshift switch isn't normally closed but normally open!... On the other hand now I can use two different switches to go into the 4th gear location.

The 3th gear switch 2 prong, normally open, closes at 40 psi.
The "4-3 downshift" switch 2 prong, normally also open closes at 30 psi.

Which is better to use to lockup the 4th gear?
I hope some auto tramission guys can shime in

Greetings Peter