700r4 torque converter lockup

[skysoldier173rd]

I'm using a 86 GMC as a donor vehicle for the 305 and overdrive trans 700r4. I have been told the vacumn/electrical switch for the converter lockup is located on the firewall of the truck. Well, there are several things on the firewall with vacumn lines and wires, and I don't know which one is it. Obviously, i want to move it when the motor and trans come out, so i want to be sure i have the proper item. Does anyone have a picture of the switch?

[Oklahoma]

in my opinion dont waist your time, I did the lock up deal on mine, and at 75 I flip the switch and it only drops it about 100 rpm's, not worth it.

[vin63]

It might be easier to get a toggle TCC lock up switch harness conversion. That's what I usually do for the 700R4 conversions.

[raycow]

I agree with vin63. A manual switch would be friendlier than the vacuum switch. But you don't need an overpriced kit from one of the aftermarket vendors. Just use a toggle switch from a hardware or home supply store.

Definitely make sure you hook up the converter clutch one way or another, though. It isn't just the 100 rpm. The converter puts a lot of heat into the transmission oil when you let it slip continuously.

Ray

[skysoldier173rd]

So, if i go with a simple switch all i need is 12 volts sent down to the solenoid inside the converter and it will lock up. I'd rather have the control over it anyway than the automatic lockup. Also, I'm wondering how would you kick it down other than the switch, or would that be the only way to disengage it.

[fleetsidelarry]

Originally Posted by skysoldier173rd

So, if i go with a simple switch all i need is 12 volts sent down to the solenoid inside the converter and it will lock up. I'd rather have the control over it anyway than the automatic lockup. Also, I'm wondering how would you kick it down other than the switch, or would that be the only way to disengage it.

depends on whether you mean "kick down" to 3rd from 4th (OD) or "disengage". Kicking down is handled differently by your transmission. Mine is set up as a manual lockup and only in 4th, I don't have to disengage it when coming to a stop, for instance, because, as the transmission automatically downshifts out of 4th the lockup no longer is working. The advantage of the vacuum switch is that is disengages the lockup when you accelerate. I really don't use my lockup very often, only when trying loaf along with interstate traffic at 75 or so. Like the guys said before, you do not have to spend big bucks to do this. I also get more of an RPM drop than Oklahoma does, maybe 200-250.

[Russ65C10]

I used the adjustable B&M lockup kit, its around $180 works great.


http://www.streetperformance.com/m/c...-m-racing.html

[low79fx]

Not to hi jack this tread ,but can someone elaborate on whether it is actually necessary to hookup power to lock up converter.Or can it be ran with out any juice going to it as if not even being there i.e non lockup TH350.What I am getting at is I am going to install a TH350C which has a lock up converter but I am not going to hook power to converter yet.Can I run it with no issues as described?

[raycow]

Originally Posted by low79fx

What I am getting at is I am going to install a TH350C which has a lock up converter but I am not going to hook power to converter yet.Can I run it with no issues as described?

Yes, you can certainly run the transmission without power connected to engage the converter clutch. The unanswered question would be about the long-term effect on the tranmission. You would be putting more heat into the transmission oil (from converter slippage) than the oil cooling system was designed to handle.

[skysoldier173rd]

Thanks larry, think i'll go with the manual switch on the dash and retain control. I tow alot with my F250 diesel and it has that manual dash switch, only way to go while towing and i don't want lugging in the low to mid ranges when it's so much easier on the motor/trans to cruise in lower gear.

[skysoldier173rd]

pulled the donor vehicle engine/trans together. everything intact along with carb and vacumn converter lockup switch. the tv cable, electrical plug not disturbed whatsoever. therefore i'm thinking all i will need to do is add 12volts off the key and plug in the vacumn line and the trans should totally function as it did in the donor vehicle including the converter lockup and unlocking. anyone disagree?


www.picturetrail.com/skysoldier173rd

[skysoldier173rd]

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