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How to tell if TC is locking up in 700r4??

Discussion in 'The Garage' started by 85mudblazin, Feb 7, 2005.

  1. 85mudblazin

    85mudblazin 1/2 ton status

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    I dont think my TC is locking up because it shifts into 4th very early like 50 MPH at only about 2500 RPM, is there some type of test I can do?? I think I want to just wire up a manual lock up switch so info on that would be helpful. BTW this is with 4.88's and 35" tires.
    Thanks
    -Chris
     
  2. dirtwarrior17

    dirtwarrior17 Banned

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    2500 with 4.88 sounds right to me. You should be able to feel it just in how the pedal responds and you will barely be able to hear the motor at all(couldn't hear mine with stock motor, gears, and 35's. Mine was locking up right around 50 if i was off the gas and let it shift into od.

    I'm sure one of the ck5 vets has an answer for the tests but I'm stumped.
     
  3. 1979jimmy350

    1979jimmy350 1/2 ton status

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    as long as there is 12v going to the transmission it locks up when it goes in to forth. try getting it to do a 4-3 down shift and see if you hear it unhook. YOu could manual wire it there are many advantage to this

    you can wire a led in to light up when locked up
    you can have lock up in 2nd & 3rd also
    you can turn off all lock up
     
  4. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    here is a good easy way for lock up wiring, i have it in my truck.
    http://www.highperformancecars.com/crosley/lockup1.htm

    lockup has nothing to do with at what speed it shifts into 4th gear. from a stop you should feel/hear 4 gear changes (1-2, 2-3, 3-4, converter lock).

    the factory wiring has a vacuum switch, a temp switch on the motor and a temp switch in the tranny, all have to be working for lockup. the vacuum switch is near the brake booster, so check the vacuum lines. the temp switch IIRC is on the tstat housing. you don't really need this one as the temp switch in the tranny does the same. if you don't use it, it needs to be connected
     
  5. 85mudblazin

    85mudblazin 1/2 ton status

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    I do not hear any sound change when it goes into 4th besides the RPM drop, I was looking at the connector that is on the tranny and it is all full of mud and doesnt want to "snap" in so that may be my problem, what can I clean it out with??
     
  6. Jonny-K5

    Jonny-K5 1/2 ton status

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    easiest way to check for lockup is the brake test. the lockup function is designed to unlock when you apply the brakes. so while your cruising down the the freeway, keep steady pressure on the gas to keep a steady speed. with your left foot push on the brake lightly, just enough to turn the brake lights on. the engine should speed up 200rpms. if it doesnt either the wiring is screwed up, or more likely the lockup function in the converter is burned up.
     
  7. 85mudblazin

    85mudblazin 1/2 ton status

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    cool thanks ill try that out
     
  8. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Thats the test.
     

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