I was wondering if there was anyway that I could make my th700r4 (87 model) lock up in 1st gear? Thanks,
Tyler

 

Why would you?

 

The 700's I have messed with will lock up a few seconds after the 1-2 shift, no earlier. I don't know why you would want this either, it will be rough on the torque converter clutch especially with a shift kit.

 

I wouldn't recommend it but if you have your own prom burning equipment you could set the minimum mph for TCC to something like 10mph.

 

Well actually I am in the process of putting a TPI motor in my jeep and would love to get my compression braking back. I learn more about my firebird from you guys and I figured since it is a Firebird engine and tranny I should ask you guys. So can I program my prom to lock it at 1 mph or change my speedo gears to make the computer think that it is at 10 mph? I am willing to give up the speedo if I can lock my TQ. Thanks,

 

far as I'm aware, the 700r4 is not capable of feeding pressure to the TCC in 1st gear, period, regardless of TCC solenoid position. that hydraulic circuit is not active in 1st.

you'd have to modify the tranny itself to get pressure to the tcc solenoid in 1st. how? i don't know.

and like everyone else, i have to ask: why? you should still get plenty of compression braking in 1st even without a locked converter, unless it's a loose converter. Even so, you are only in 1st until 15mph or so under normal driving conditions. compression breaking is ususally used in the 35mph-80mph range...not below 15?
or is there something i'm missing here?

 

I just want the compression breaking so that I can go down hill at 1/8th of a mile an hour if I want (Jeep thing). I have very low gears and everything else it would just be nice if I could lock the TQ in 1st. Thanks for the help everybody and if you hear of a way to mod the tranny to do this please let me know.
Tyler

 

If you were to have lockup in first gear and you got below (let's say) 750 rpm, the front pump could no longer put out the volume of oil to hold the two sets of clutch packs needed to hold manual low (and the torque converter clutch being on) because of the transmission torque converter being locked up.

 

Isn't the 87 lock up controlled by the computer? If it is you would have to program the prom to keep it locked at 0 % throttle, then you would have to set the MPH to some low number to unlock it, if the tranny TCC is computer controlled it could be easly done by burning a new prom. But I'm going to assume that u don't burn your own proms or u would have already known this.

 

The circuit that feeds L/U comes from the 2nd gear oil. Period.