Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Torque converter lock up questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BlueOx, Jan 1, 2003.

  1. BlueOx

    BlueOx 1/2 ton status

    Joined:
    Aug 6, 2000
    Posts:
    239
    Likes Received:
    0
    Location:
    Houston, Tx
    I'm the next step of working the bugs out of my TBI swap. I need to know when does the TC lock up. I was driving the Blazer in "DRIVE" (3rd gear) and found the converter to be locking up. I thought the TC locks up in "OVER DRIVE" (4th gear) at crusing speeds only. Am I wrong in all this?

    Charles
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

    Joined:
    May 30, 2001
    Posts:
    17,669
    Likes Received:
    0
    Location:
    IL, USA
    On my '84, when it had a 700R4, it would lock in 2nd, 3rd, and 4th gears. I've heard not all lock in 2nd, but all lock in 3rd and 4th.

    Now I just take my foot off the pedal and the engine is locked to the wheels. /forums/images/graemlins/smile.gif
     
  3. eds77k5

    eds77k5 1/2 ton status

    Joined:
    Oct 19, 2001
    Posts:
    383
    Likes Received:
    0
    Location:
    washington state
    the torque converter is bolted to the flywheel, so it is spinning at the same speed as the engine, that is the turbine, then ya got the stator and the pump, the other half so to speak, centrifugal force is pumping the fluid and bein redirected and then the transmission turns and then the wheels turn, when you are gettin up to speed the engine is turning faster than the transmission and this "slippage" is what causes poorer fuel performance, when ya get up to speed the transmission almost spins the same as the engine, so you are getting better performance, with a lock up converter they have added a lock up clutch and when the two halves are spinning at the same speed the lock up occurs, thus improving fuel consumption, does that sound right?
     
  4. K05Aggie

    K05Aggie 1/2 ton status

    Joined:
    Feb 22, 2002
    Posts:
    136
    Likes Received:
    0
    Location:
    Dallas, Texas
  5. 95 Silverado

    95 Silverado 1/2 ton status

    Joined:
    Nov 9, 2001
    Posts:
    467
    Likes Received:
    0
    Location:
    Central PA
    It depends on the switch set-up used in your transmission, there have been variations of switches and wiring used, depending on the application and model year. I had an '85 car model 700R4 that had two switches in the valve body, one switch closed when the transmission was in 3rd or 4th gear to allow lock-up, the second switch was a signal wire to the ECM, it's purpose was to signal the ecm when it was in fourth gear, it wasn't wired into the lock-up circuit at all, there are other variations.
     
  6. BlueOx

    BlueOx 1/2 ton status

    Joined:
    Aug 6, 2000
    Posts:
    239
    Likes Received:
    0
    Location:
    Houston, Tx
    Thanks for all the info. I thougt it was only going to lock in 4th gear. When it locked in 3rd gear in thought something was wrong,but now I it's all good

    Thanks again,
    Charles
     

Share This Page