700 R4 Tranny lockup function - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 09-18-2002, 03:54 AM
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700 R4 Tranny lockup function

What does the lockup function do on a 700 R4 tranny? I am rewiring my computer harness with a new Painless harness and it gives me the optional lockup wire to hook to a solenoid somewhere or I can just tape it off and not use it.
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post #2 of (permalink) Old 09-18-2002, 11:55 AM
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Re: 700 R4 Tranny lockup function

The lockup function locks the torque converter so there is no slippage at highway speeds. This helps keep the heat down in the tranny and also improves mileage (depending on gears of course) and acts like a 4th gear. I would recommend allowing the lockup to function.
post #3 of (permalink) Old 09-18-2002, 01:41 PM
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Re: 700 R4 Tranny lockup function

I would highly suggest wiring it in. It locks up the converter in 3rd and 4th gear to make it a direct drive to stop slippage. I think not having mine working for almost a month was part of the reason my last 700 blew up. If it isn't locked up it slips the whole time and causes heat with fry's tranny's.
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post #4 of (permalink) Old 09-18-2002, 03:23 PM
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Re: 700 R4 Tranny lockup function

ok, well my friend has a 91 k-5 350\700r4\np241. 31's stock 10 bolt axles, now when he wams on the gas the trans slips and dosnt go anyware, now is this an electrical problem, or is the trans just wore out, the trans was done 2 years ago, i mean when he races me in my 87 4x4 chevy shortbed tbi350\sm465\np208, i beat the pants off of hime with 33's. when im next to him and he keeps up with me but then all of the sudden you just hear this roar, sounds like a fan explodeing or somthing, i think it could be somthing with the toruqe converter, if you can clear me up on the 700r4 trans issue
post #5 of (permalink) Old 09-18-2002, 03:40 PM
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Re: 700 R4 Tranny lockup function

Unlike a TH400 or TH350, the 700R4 will die a horrible death without the torque converter locking up. The only time people don't use one on a 700R4 is when it's a drag-only vehicle.

Why? Because the 700R4 is a 70hp stealing heat monger. It generates a lot of heat and with the torque converter unlocked it generates even more. People towing in overdrive is what usually kills a 700R4. The torque converter repeatedly locks and unlocks and eventually the 3/4 clutchpack gets crispy crittered.
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post #6 of (permalink) Old 09-18-2002, 03:52 PM
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Re: 700 R4 Tranny lockup function

All together now.....

"Clutch packs roasting on the open road"
post #7 of (permalink) Old 09-18-2002, 05:05 PM
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Re: 700 R4 Tranny lockup function

Yes I would hook it up. The 700r4 in my jimmy crispy fried the 4th gear. Just short 100 km drives at about 120 it would heat up so bad all I could smell was burnt ATF (with an aftermarket cooler). Eventually it wouldn't shift into 4th. The 1st to 2nd shift wouldn't happen until like 5800 rpm and about 65 kmh, or something and then BANG like a shift kit. I went and put a sm465 in it instead. Wish I had looked into the torque converter lockup thing before I changed it. Miss the overdrive, but its worth it. Seemed alot more powerful with the stick. City driving is a big P.I.T.A
post #8 of (permalink) Old 09-19-2002, 03:43 AM
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Re: 700 R4 Tranny lockup function

O.K. where does it hook up to. I'm talking about the brown wire in my new fuel injection kit labeled VSS. I already have the plug from the harness going into the torque converter. VSS is vehicle speed sensor, Where is it?
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