12200411 set up for 700R4

[Buzz]

...Back to 700R4 and lock up only in fourth gear...doesn't it need some kind of VSS from PCM to lock? This vehicle trans was controlled by ECM that has speed, no vacuum switch which IIRC only came in pre 87 Chevy Truck 700R4 ...

The 700R4 shifts are 100% mechanical (not controlled by any PCM / ECM). The TCC lockup is a simple 12 volt supply (no PWM etc.). It can be as simple or as complicated as you wish.

The most simple means is a 12 volt ignition circuit, routed through a brake switch that interrupts the voltage, connected to a normal open pressure switch on the 4th gear circuit of the valve body (most / all 700R4 came with this switch in place). With this method the TCC is locked in 4th gear at all times - except when the brakes are applied.

The next most complicated method adds a vacuum switch, which interrupts the the voltage when the vacuum drops (under load).

The most complicated method adds a speed component - which in a TPI / TBI vehicle was controlled by the OBD1 ECM. If memory serves B&M used to offer such a kit.

As long as the vehicle is not dreadfully underpowered the most simple method works just fine.

[Fast355]

The 700R4 shifts are 100% mechanical (not controlled by any PCM / ECM). The TCC lockup is a simple 12 volt supply (no PWM etc.). It can be as simple or as complicated as you wish.

The most simple means is a 12 volt ignition circuit, routed through a brake switch that interrupts the voltage, connected to a normal open pressure switch on the 4th gear circuit of the valve body (most / all 700R4 came with this switch in place). With this method the TCC is locked in 4th gear at all times - except when the brakes are applied.

The next most complicated method adds a vacuum switch, which interrupts the the voltage when the vacuum drops (under load).

The most complicated method adds a speed component - which in a TPI / TBI vehicle was controlled by the OBD1 ECM. If memory serves B&M used to offer such a kit.

As long as the vehicle is not dreadfully underpowered the most simple method works just fine.

Except the simple method is a great way to smoke the tcc linings.

[EagleMark]

Except the simple method is a great way to smoke the tcc linings.

How's that?

I could see if it were used improperly... or am I missing something?

[dave w]

I've successfully used the Superior Transmission K058 ( http://www.superior-transmission.com...age.cfm?ID=186 ) with a modified 700R4. The 700R4 had been modified so a manual toggle switch (wired in series with the brake switch) could be used to lockup the torque converter. The vacuum switch replaced the manual toggle switch.

dave w

[EagleMark]

Well since Dave has one solution I figured I'd add another idea to this thread for future reference. It may be the answer to all proper signals of gear postion to 0411 to operate TCC lock in 2 through 4 if someone wanted to spend $100.

http://www.dakotadigital.com/index.c...prod/prd60.htm

[Buzz]

In post #10 I mentioned that the PCM receives an input from the transmission with respect to the current gear the transmission is in. The PCM may also receive an input from a transmission mounted Park / Neutral Position Switch with respect to the current shifter position. These are not the same thing.

For example, with the shifter in the 4th or overdrive position, the transmission is free to shift up and down through all 4 forward gears - the shifter position however would have never changed.

That kit could send a signal to the instrument cluster to show what position the gear shift was in, but this is not synonymous with the gear that the transmission may be in.

The short answer is - that kit will not be of assistance with respect to TCC lockup.

[cmaje72]

Bringing this one back from the dead since I am wondering if you guys ever got a 411 to control the TC lockup on a 700R4. I am swapping out a LT1 for a 5.3.
I know I can easily control lockup with a switch (already have this) but ECU control would be cool so I don't have to remember to flip the switch.

[Buzz]

Except the simple method is a great way to smoke the tcc linings.

Keeping the TCC locked up at highway speeds reduces / eliminates TC slip, and thereby reduces overall transmission temperatures.

The OEM strategy generally follows this principle.

In the late 1980s / early 1990s I ran a 355 / 700R4 combination in as S10 pickup wired just like this - 200K later when I sold it, the drivetrain still worked just fine.

[EagleMark]

As long as the vehicle is not dreadfully underpowered the most simple method works just fine.

The 5.3L should do fine even with the 35 inch tires as it was re-geared to 4:88 gear ratio. Although the aerodynamics of a brick at highway speed is a factor.

So at 70 MPH should be forth and TCC locked I think it'll be fine. Now start pulling a mountain pass and? Seems like this is where the simple switch to unlock could be a benifit? If not it may be a lot of throttle and a harsh downshift to third?