Manual Torque Convertor Lock-up 700r4

[HotRodPC]

It's all up to you. It's really not a bad concept IMO. It's my understanding you're wanting it ONLY for when you're towing something and in D going down the internstate in D and don't want to use OD correct? If that's the case, I say go for it. Reason being, you're going to do alot more justice for that 700r4 by using D on the highway instead of OD, and it would be nice to be able to recover those 200-400 rpms on the highway, not to mention as you said, keep the trans cooler. And that is a fact. You will keep the trans cooler with the converter locked up going down the highway, and especially when towing. I wouldn't jack with the manual locking up in town, but if you're on the highway and not in stop and go traffic by all means, I do see the benefit.

 

[austinado16]

How 'bout shooting the trans pan with an infrared temp gun and seeing what your real trans temps are when towing in town, and then decide if you have a problem that needs to be addressed.

I'd pop an 11x11x1.5" Tru-Cool (same as B&M Super Cooler) on it before I'd play with how TCC works.

 

[Jims86]

How 'bout shooting the trans pan with an infrared temp gun and seeing what your real trans temps are when towing in town, and then decide if you have a problem that needs to be addressed.

I'd pop an 11x11x1.5" Tru-Cool (same as B&M Super Cooler) on it before I'd play with how TCC works.

^^^^this. and unless someone has ****** with the TCC wiring, all TBI overdrive transmission are to Lock up in 3rd gear....usually happens around 33ish mph. Heat is a 700r4s enemy, nothing else.

 

[austinado16]

Here's how I keep my trans heat under control....

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Here's what I'm trying to protect....

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Here's where I tow.....

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[HotRodPC]

^^^^this. and unless someone has ****** with the TCC wiring, all TBI overdrive transmission are to Lock up in 3rd gear....usually happens around 33ish mph. Heat is a 700r4s enemy, nothing else.

I'll have to dig out my misplaced 700r4 ATSG manual. I was certain some later models DO NOT lock up in 3rd. That's according to some of the wiring diagrams IIRC.

 

[Jims86]

I'll have to dig out my misplaced 700r4 ATSG manual. I was certain some later models DO NOT lock up in 3rd. That's according to some of the wiring diagrams IIRC.

Im not sure if they did pre 87, but I think the wring on all the Aux valve body models are all the same. On e the ecm gets the activation sig from the high gear switch, which I believe is on the 3rd gear circuit, the ecm waits for the lockup command speed to be reached, then activates lockup....dunno why they would do away with it.

 

[austinado16]

My '90 locks in 3rd and 4th, and I swear it feels like it does it in 2nd too when I'm towing. I know that's not possible though. Maybe it's doing some sort of "coasting" mod on the sprags when I let up on the gas, and then hooks up again when I put my foot back? Like when I let up a little on the twisties shown above, and then add throttle as I come out of a tight turn.

 

[Jims86]

My '90 locks in 3rd and 4th, and I swear it feels like it does it in 2nd too when I'm towing. I know that's not possible though. Maybe it's doing some sort of "coasting" mod on the sprags when I let up on the gas, and then hooks up again when I put my foot back? Like when I let up a little on the twisties shown above, and then add throttle as I come out of a tight turn.

Oh, its possible if the lockup wire is grounding.

 

[HotRodPC]

Oh, its possible if the lockup wire is grounding.

Very true. And if it's getting the go ahead signal from within the trans too and has the ECM convinced it's in 3 or 4 it can lock up. But then again, it would be getting around the VSS to do that too wouldn't it? Maybe not. The ECM is the boss, so what it says goes regardless of where it gets the go ahead info from.

 

[Jims86]

Very true. And if it's getting the go ahead signal from within the trans too and has the ECM convinced it's in 3 or 4 it can lock up. But then again, it would be getting around the VSS to do that too wouldn't it? Maybe not. The ECM is the boss, so what it says goes regardless of where it gets the go ahead info from.

The ECM activates lockup via the ground, once it gets signal from the high gear switch. If that wire is chaffing anywhere and grounding out, the ECM is being bypassed all together. ****, When i was testing after I got the TBi installed, I overlooked the lock up test wire going to the ALDL port, and the stripped end was rubbing against the ECM, and locking in 1st.