700r4 electrical help needed...

[patmckinneyracing]

I am swapping from a TH350 to a 700r4 and have read most of the 700r4 tech I could possibly read. My driveshaft snapped in half and destroyed the TH350 bellhousing and a section of my flooring. Lesson learned...use a driveshaft safety loop.

The 700r4 I have is from 1985 and does not have the auxiliary valve body. I have spent 850$ in getting it fully rebuilt. I wanted to keep the lockup and this trans was owned by 2 different guys prior to me getting it. Here are the parts in it:

-Full rebuild kit (3-4 gear uses 6 clutches)
-Kevlar band
-13 vein pump
-Corvette Servo
-New lockup solenoid
-New Reverse input drum
-"Beast" Sunshell
-.500 input boost valve with larger output valve
-Transgo shift kit
-New TV cable

My question is dealing with the wiring itself. I was reading installation instructions for the painless wiring kit (http://www.painlesswiring.com/Manuals/60109.pdf). What confuses me is that I don't have the 4th gear pressure switch or any wiring by the servo. The only wiring I have in the pan is going from the lockup solenoid to the factory plug.

So is the 4th gear pressure switch necessary? Am I missing anything, as far as you can see by the pics, that is a necessity for the electrical system that is paramount to operating this transmission? Is it possible to put in an auxiliary valve body and are there any benefits or will I be fine with what I have?

My plan was to route the 12v source wire from the transmission up to the brake pedal then to the toggle switch. But looking at painless wiring, there is a vacuum operated switch as well which threw a wrench into my thought process.

 

[SSedan64]

It's not possible to install an auxillary Valvebody into the older design Trans Case. I'd stick with what you have since the $$ have been spent.

The 4th gear Pr. switch is only needed if you want automatic TCC Lockup when the Trans shifts to 4th. There are several styles available, 2-Pin, 1-Pin, N/O=NormallyOpen, N/C=Normally Closed.
The Manifold Vacuum switch will engage TCC Lockup when vacuum is high and disengage Lockup when the throttle is opened and vacuum drops. It helps if you need Passing gear quickly.

Looks like it's wired correctly for what you are wanting, Manual (Toggle + Brake) switch use. It will also Lockup the TCC in 2nd, 3rd & 4th gears this way if the Toggle switch is on.

Lots of good TCC Lockup Info here>> http://www.rowand.net/Shop/Tech/LockupTCCWiring.htm
More & Parts >> http://www.rowand.net/Shop/Tech/AutomaticOverdriveTransmissionSwap.htm

 

[SSedan64]

There's also a Hydraulic Lockup Kit, No electrical needed.
TransGo Part# 700-LU >> http://www.transgo.com/valve_bushing.php

 

[patmckinneyracing]

I've read that while in forth gear, the TC needs to be locked or risk burning up the transmission from overheating. Is this true?

If I go with the 4th gear pressure switch, where would I hook that up to and how exactly does it work?

 

[SSedan64]

Yes, the TCC/TorqueConverterClutch does need to be Locked in 4th. Short periods unlocked wont hurt it but, cruising on the freeway etc.. with the TCC unlocked will cause the Trans to overheat.

The Brass plug closest to the Accumulator housing or bottom plug in your Pics above is where the 4th pressure switch will go. You could install a 2-Terminal N/O= Normally Open switch there. When the Trans shifts to 4th the pressure activates the switch & completes the circuit which applies 12V to the TCC, when the Trans downshifts out of 4th the pressure drops which causes the switch contacts to open and breaks the circuit.

Several wiring diagrams/Pics etc.. here >> http://www.rowand.net/Shop/Tech/LockupTCCWiring.htm

Todd