Thread: 700R4 "Lock up" Torque converter

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when general motors designed 700r4 they wanted the trans to run at 280 degrees The part of the trans that makes most of the heat is the converter when it is locked up it make no heat gm put a orifice in the 4th gear curcuit to reduce the flow of oil to the cooler because they thought 98% of the time the converter would be locked-up in 4th. Thats what smokes these puppies when you tow in overdrive There is a solinoid that controls the tcc valve in the trans it needs power and ground to work if you supply 12 volts to the + side of the solinoid and ground the - side you have lock-up To get lock-up in 4th only you connect the neg side to the 4th gear switch But first you have to have a normaly open switch some come this way some do not test the switch in your trans to see which one you have gm sells them and any trans shop can get them.

Ok alittle late but it looks like the other guys have got it covered.
Hope everyone is not really confused now.
Tim

Gusaroo, Here is a site to compute your rpm.

Don Shillady
Retired Scientist/teen rodder