Manual Torque Convertor Lock-up 700r4

[Jake292]

What are yall's thaughts on this? My plan is to use a kit form Bowtie Overdrives(http://www.bowtieoverdrives.com/catalog/catalog_inc/viewitem.php?ITEMID=338) and wire it with a switch similer to the Highbeam switch on the older squares. This would go into my 87 with a 700r4. This should improve gas mileage and trans heat. Let me know what yall think.

 

[Jake292]

Anyone?

 

[CorvairGeek]

A full manual mode scares me. If you forget or someone else drives the vehicle, the possiblity is there to overheat the torque converter/entire transmission when running for long periods of time in over drive with the converter unlocked.

 

[foamypirate]

The factory computer is pretty good with the lock-up as is. I don't really think there is much improvment to be seen by going manual.

 

[Jake292]

I have adjusted my idea from my original post. it would be a switch in parallel with the computer so that when the switch is in the off position, the computer decides when the torque convertor locks up.

This would be beneficial during towing in town. the torque convertor wont lock up in 2nd or 3rd, the gear that it is in when towing at lower speeds.

 

[foamypirate]

I have adjusted my idea from my original post. it would be a switch in parallel with the computer so that when the switch is in the off position, the computer decides when the torque convertor locks up.

This would be beneficial during towing in town. the torque convertor wont lock up in 2nd or 3rd, the gear that it is in when towing at lower speeds.

The ECM won't command lockup in 2nd gear, and some 87's won't even lock up in 3rd. Mine did, however.

 

[CorvairGeek]

It is a funky feeling to have one lock up in 2nd gear, '84 Caprice LG4, 2.73.

 

[philjafo]

As long as its working correctly, manually controlling the tcc won't get you any more mpg. It might actually cause problems if its locked up in 2 or 3 then it trys to shift. As for temp, an auxiliary cooler will do way better at keeping the temps in line. The 700 r4 can be a fussy transmission and I wouldn't risk something that might do more harm then good. But I'm no transmission expert.

 

[HotRodPC]

Depends on the year model of the 700r4. You can only get lock up in 3rd or 4th and many models are lock up in 4th only. There are pressure switches in the transmission on the valve body. Those pressure switches detect when you get into a certain gear and have to give the go ahead for lock up to happen. This is how you avoid lock up in 1st and 2nd. If you decide want lock up in 3rd also, you'd have to look at your valve body to see if it is tapped where there is a plug in the 3rd gear switch area and plugged. If it's got a plug in it, then you can pull the plug, put in the pressure switch and wire it in with the loom or best to get another harness, then you can have lock up in 3rd also.

Here are 2 different wiring examples. One will allow 3rd gear lock up, one will not. And these are ECM controlled TCC units. Both diagrams are from 1993 models.

 

[Jake292]

the only reason that I want to wire a switch in is so that when towing in the city I can lock up the torque convertor. I usually have it in drive (not overdrive) when towing at speeds less then highway speeds so that I don't hurt the sprags. my 700r4 doesn't have 3rd lock up and I was looking for a cheap and simple way to lock up in 3rd to keep temps down. I wouldn't be locking it up until it is in 3rd and unlocking before slowing down, much like the computer does in overdrive

 

[MrMarty51]

Probably need to install another relay, hook a switched wire beyond the CL switch in the pan.
I want mine to unlock sooner than the kickdown switch. I guess that is rough on the overdrive sun/planetaries though.

 

[HotRodPC]

the only reason that I want to wire a switch in is so that when towing in the city I can lock up the torque convertor. I usually have it in drive (not overdrive) when towing at speeds less then highway speeds so that I don't hurt the sprags. my 700r4 doesn't have 3rd lock up and I was looking for a cheap and simple way to lock up in 3rd to keep temps down. I wouldn't be locking it up until it is in 3rd and unlocking before slowing down, much like the computer does in overdrive

And how does locking up the converter help the sprags?


BTW, you can add the 3rd pressure switch to your manual non ECM set up and wire it in and still have auto lock up in D. (If the VB has the provision).

 

[Jake292]

And how does locking up the converter help the sprags?


BTW, you can add the 3rd pressure switch to your manual non ECM set up and wire it in and still have auto lock up in D. (If the VB has the provision).

the sprags are helped by the gear selector not being in overdrive.

I don't want to have to pull the pan to do this, that would cost a lot more than my $10 switch.

 

[HotRodPC]

the sprags are helped by the gear selector not being in overdrive.

I don't want to have to pull the pan to do this, that would cost a lot more than my $10 switch.

Got news for you. Not sure if you got into the crack, or if whoever gave you that info got into some crack. But someone got into it and needs to say No to drugs.

All sprags/roller clutches are used throughout manual 1, 2 and D, in OD the intermediate roller is NOT used but the other 2 are even in OD. So how that makes a difference is wayyyyyyyyyyy beyond me. One other thing to consider. If the EARLY 700r4's locked up in 3rd and OD, but GM later changed it to OD only, might there be a reason why they did that? I'd get it IF you had an EARLY unit where they only locked up in OD and GM later added the lock up in D capability as an improvement then yes, by all means, take the update. Just Sayin'

 

[Jake292]

Got news for you. Not sure if you got into the crack, or if whoever gave you that info got into some crack. But someone got into it and needs to say No to drugs.

All sprags/roller clutches are used throughout manual 1, 2 and D, in OD the intermediate roller is NOT used but the other 2 are even in OD. So how that makes a difference is wayyyyyyyyyyy beyond me. One other thing to consider. If the EARLY 700r4's locked up in 3rd and OD, but GM later changed it to OD only, might there be a reason why they did that? I'd get it IF you had an EARLY unit where they only locked up in OD and GM later added the lock up in D capability as an improvement then yes, by all means, take the update. Just Sayin'

That's interesting...did some research and it checks out. Guess I miss understood.

so it looks like this is a bad idea?