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Old 09-14-2018, 01:22 PM   #1
RDrancher
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700r4 Lock Up?

I'm yanking all the computer gizmos in the '88 and installing a new carbed L31.
I need (or don't need) to address the lock up torque converter. I've heard everything from don't worry about it, to use a lock up kit, to it's easier to run a no lock up converter. The trans has the four hole electrical plug in, but I'm seeing this included in the lock up kits, so...just ground and power? Dunno, I need some direction here.
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Old 09-15-2018, 11:58 AM   #2
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Re: 700r4 Lock Up?

In '88 the TCC was computer controlled. On the transmission there is a power supply from a NC brake switch, ground from the computer to control the TCC solenoid and there is a wire from the 4th gear pressure switch to tell the computer when you are in high gear.

You can home brew your own setup or buy a kit from a vendor. On a really light weight vehicle you might get away without hooking it up but on something like a truck it needs to be working to keep the fluid from overheating
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Old 09-15-2018, 04:43 PM   #3
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Re: 700r4 Lock Up?

Check out the offerings here, https://www.bowtieoverdrives.com/cat...SUBCAT&CATID=B
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Old 09-16-2018, 10:01 AM   #4
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Re: 700r4 Lock Up?

I just put a 700R4 in my truck, the electrical plug on the driver side of my transmission was removed and replaced with a solid plug. The Torque converter clutch (TCC) is applied in the Valve body thru a shift valve.
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Old 09-16-2018, 10:16 AM   #5
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Re: 700r4 Lock Up?

unfortunately that kit doesn't work on an '88 model transmission
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Old 09-16-2018, 10:29 AM   #6
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Re: 700r4 Lock Up?

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Originally Posted by Bigdav160 View Post
unfortunately that kit doesn't work on an '88 model transmission
Hmmm...I had only seen the conversion kits with wiring through the 4-plug to somewhere outside the trans. Full hydraulic lock up? I like the sound of that. I need to check this out more.
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Old 09-16-2018, 11:07 AM   #7
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Re: 700r4 Lock Up?

I put 700r4 electric vs hydraulic lock up in the search engine and came up with some interesting discussions. From https://www.hotrodders.com/forum/700...ed-115199.html. "The "hydraulic lockup" works off the pump pressure and is so simple and fool proof. The kit is a steel ball and a set of colored springs to choose from. I just happen to select the mid range spring and it seems to work fine for my set up. As you accelerate the motor, the pump pressure builds and overcomes the spring pressure, allowing the hydraulic fluid to redirect into the lockup valving to lock the converter. As you decelerate the motor, and wheel speed allows the pump pressure to decrease, the spring overcomes the reduced pressure and the torque converter unlocks. I have never experienced any failure to unlock and I have experienced lock up in other gears, under heavy acceleration, but you would never notice this if you were not really looking for it to do so. It is not a malfunction and no unusual wear and tear will occur."

But then this..."a ball goes into the solenoid. I like lockup at 55-60. I like to unlock for hill pulls sometimes I like extra rpms until 70-75. Go for a toggle
total driver control." That would be electrical lock up.

So I guess I have to make a decision as to how I want it to function...By toggle switch or hands off.
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Old 09-16-2018, 11:56 AM   #8
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Re: 700r4 Lock Up?

Life is wonderful when you understand your options. Choose the option that best fits your needs.
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Old 09-16-2018, 12:39 PM   #9
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Re: 700r4 Lock Up?

I found a great post describing different aftermarket company's paths to electrical lock up. https://www.hotrodders.com/forum/put...nglepost8.html
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Old 09-16-2018, 01:40 PM   #10
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Re: 700r4 Lock Up?

I also have been thinking about installing a 700-4r in my truck. The toggle switch sure looks simple. Yes, it requires a simple electrical switch to toggle it off and on but in my case I've been driving a 5 speed manual for many years anyway. A toggle switch wouldn't be anymore than I do now -off on hilly roads and on when driving flatter terrain.
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Old 09-16-2018, 02:12 PM   #11
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Re: 700r4 Lock Up?

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I also have been thinking about installing a 700-4r in my truck. The toggle switch sure looks simple. Yes, it requires a simple electrical switch to toggle it off and on but in my case I've been driving a 5 speed manual for many years anyway. A toggle switch wouldn't be anymore than I do now -off on hilly roads and on when driving flatter terrain.
Yeah, after reading a bunch I'm leaning towards the TCI style switched lockup. The switch allows manual lockup in 3rd and even 2nd if the need was there. This page https://www.thirdgen.org/forums/carb...c-control.html has a lot of good info.
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Old 09-16-2018, 04:04 PM   #12
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Re: 700r4 Lock Up?

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Originally Posted by Bigdav160 View Post
unfortunately that kit doesn't work on an '88 model transmission
The way it works is with the type of valve body that has the TCC shift valve. Not all 700r4 Valve bodies have this, earlier years did.

Not for sure exactly if ALL 1988 did or not.... but the valve body is interchangeable within the years.

The type 1 Valve body can be used with or without the aux valve body which has the TCC shift valve or has the dummy plugs which can be removed to install TCC shift valve assembly.
Read the "700r4 rebuild thread" on this site, it has pictures so it will help out for anyone needing some understanding of this.
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