What rpm do you shift your AT at...

Discussion in 'Street/strip 400/430/455' started by TORQUED455, Aug 18, 2004.

Page 3 of 3
  1. simon1243

    simon1243 Got Torque?

    im pretty sure that the kick down switch is fine because i had it replaced when the tranny was rebuilt. also does it matter that it isint a stage one or gs car?
     
    simon1243, Sep 16, 2004
    #41
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Even a non stage car should shift at around 4800 at wide open throttle. The stage1 cars had a different governor for 5200-5300 RPM shifts. The most common cause for short shifting of a THM 400 is a non operative kickdown. Pretty simple to test. Get up to 40 MPH in high gear, and matt the gas pedal. It either kicks down or it doesn't. If it doesn't, start by checking for 12 volts at the gas pedal switch, check the switch itself, then the wiring down to the transmission(sometimes the wire simply falls off), then the downshift solenoid in the pan. You don't want to shift it yourself. It's a whole lot more precise if the trans does what it's supposed to do itself, and there are potential wear problems if you shift it yourself.
     
    LARRY70GS, Sep 16, 2004
    #42
  3. simon1243

    simon1243 Got Torque?

    the kick down switch works fine i just went and tested it so what else could it be?
     
    simon1243, Sep 16, 2004
    #43
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    LARRY70GS, Sep 16, 2004
    #44
  5. cray1801

    cray1801 Too much is just right.

    Larry, I've heard this before about the TH-400, is the same true for the TH-350? I'm shifting my TH-350 manually at the strip (~5900 rpm vs 4950 rpm's). The improvement in et is ~.42 seconds in the 1/4 mile.
     
    cray1801, Sep 16, 2004
    #45
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Good question Craig, I'm not sure. The wear issue was brought to my attention by Mark DeConti (dcm422). Mark is our resident GS/GN club THM-400 expert. He could answer your question. Try shooting him a pm
     
    LARRY70GS, Sep 16, 2004
    #46
  7. killrbuick66455

    killrbuick66455 Well-Known Member

    The car i had i shifted at 4800 11.78 @112
     
    killrbuick66455, Sep 16, 2004
    #47
  8. Yardley

    Yardley Club Jackass


    What the hell else am I going to do while driving?:Do No:

    And it'll give me a good reason to tear it apart and install the lower 1st and 2nd gears! :TU:
     
    Yardley, Sep 16, 2004
    #48
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Jeff,
    Take your hand out of Dolly :laugh: :laugh: unbolt the governor cover, and adjust the governor so the trans shifts where you want it to all the time. It will be more consistant. Next time we get together, ask Mark Deconti about manually shifting the 400.
     
    LARRY70GS, Sep 17, 2004
    #49
  10. BQUICK

    BQUICK Gold Level Contributor

    1-2 shift automatically at 5500, then shift the 2-3 at 6700 on BQUICK(Stage 2) (Hundreds of runs on the Mark Deconti raffle transmission.) Traps at 6400 to 6700 depending on the air and track.
    Stock rods. :Brow:

    Bruce
     
    BQUICK, Sep 17, 2004
    #50
  11. cray1801

    cray1801 Too much is just right.

    Well, I finally did the governor thing to change my shift points. I ordered the B&M kit (mentioned above #20248). I also PM'ed Mark (thanks Larry). What I found after removing the governor in my original TH-350 from my `72 Skylark, was different from what the kit will fit. The shaft's that were in the kit were different lengths (kit problem #1)? Here is a picture of what was in the kit shown next to the governor cover. :puzzled: The short one is too short and the "C" clamp can not be installed on the second half.
     

    Attached Files:

    cray1801, Oct 1, 2004
    #51
  12. cray1801

    cray1801 Too much is just right.

    Next, the springs in the kit were too small of a diameter to fit over/onto the perch diameter of the outer weight or inner spring (kit problem # 2).

    In the picture the smaller diameter spring from the kit is sitting on the stock inner weight. Notice the perch diameter of the new weight from the kit (#2). The stock spring is the larger diameter one below the inner weight.

    Picture shows the stock inner weights after grinding them.
     

    Attached Files:

    Last edited: Oct 5, 2004
    cray1801, Oct 1, 2004
    #52
  13. cray1801

    cray1801 Too much is just right.

    Kit problem #3, the inner weights with the shaft installed would not rotate due to interfearance with the outer weight.

    Moral of my stroy: none of the parts from the kit could be used. My recommendation is to grind your inner weights yourself a little at a time until you get the shift point you want (assuming you want your trans. to shift later). The spring can be stretched ~somewhat to get earlier shifts if you have to.

    I now have 5900 rpm shifts after grinding my existing inner weights from a combined weight of 22 grams to 16 grams and increasing my 0.50" compressed spring force from a total of 764 g to 855 g. I went slightly too far while grinding the inner weights on the first try :pp

    I've got lots more data, related to weight and springs parameters, if anyone is interested.
     

    Attached Files:

    cray1801, Oct 1, 2004
    #53
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