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700R4 stall math problem


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OK, still having problems with my 700R4. I am just about to say forget it, and buy a heavy duty custom built one. If anyone knows any good source for a reliable 700R4 capable of handling a 400hp sbc, let me know. THE QUESTION IS: I have found a 700R4 with a 2300 stall converter. At what speed will I be out of stall in fourth gear with stock ZX 14" aluminum 6 spokes and a 3.55 rear end? Anyone out there a math wiz? Thanks.

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A little sarcasm, you must be new Cerebus... Anyway, my limited understanding was that the torque converter only locked up when out of the stall range. A 2300 rpm torque converter would lock up at 2300 rpm. Is that incorrect? With the electronic lockup will it lockup anytime you hit the switch? Also, a guy was wanting to build one with a valve to "bypass" the torque converter. The benefits are obviously that I would not have to have the wiring kit that has to be linked to the brake etc. What are the drawback? Will this cause the torque converter to never lock up? Will this generate excess heat? Will this cause decreased gas mileage? Thanks. Lewis

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a search on 700R4's might yield some more info

 

-700R4's lockup ONLY when they get the electrical signal to do so, can be at any rpm. TC rpm figures relate to the gear multiplication the TC can add in. Hence one wants a brake triggered 'kickout' so your TC unlocks before your car stops, or a rpm/speed controller on the lockup.

-bypassing lockup as that fella suggests takes out your lockup completely. You should have a dummy valve and non-locking convertor for that as I understand it (Keith?). If it doesn't ever lockup then yes, it will run hotter if your cooling doesn't keep it below it's happy zone. More wear on the convertor in any event which translates to wear on tranny if convertor is giving up metal particles.

 

Their's a few rpm sheets online, including I believe one link off this initial homepage showing mph/rpm for given combos. If not drop me a line personally as I have excel sheets for comparing combos.

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Guest Anonymous

Yes I be a NEWBIE so sorry .YES I AM BLATANT icon_redface.gif The 700r4 uses a lockup convertor which when current is supplied too a solinoid fluid is directed too a pressure plate in the convertor which engages a clutch providing a solid link too the motor not a fluid one .HAPPY INDI Also you should tap a 4th gear line pressure so it only locks in 4th gear.InDI I have built and blown 700's more than you know I may be a dick but hey we all have r strong points icon_razz.gif

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Well Cerb,

At least nobody is giving you chit for not being honest. twak.gif

 

Indy,

Search the archives, we've discussed the wiring options for the 700R4 a few times in the past. It's very simple to do and worth the extra (minimal) effort.

 

I would tend to agree with Cerberus that you would only really want the lock up in fourth gear. Also, the brake switch is a must. I've got a 3000 RPM stall converter and I never notice the higher stall on the highway while the converter is locked up. However, tap the brakes, and she will instantly flash up at least 500 rpm (1800 - 2300, 2000 - 2500, etc...) There is also a make-shift map sensor that I used to unlock the converter when manifold vacuum drops below about 5 in/Hg. I can still cruise down the highway and speed up / slow down with the flow of traffic and never unlock the converter.

 

Good Luck

-Andy

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