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Thread: Tire/Gear Limits? Modification for DEEP gears/tall tires.

  1. #1
    Potential Tuner
    Join Date
    Jul 2017
    Location
    Tampa, FL
    Posts
    9

    Tire/Gear Limits? Modification for DEEP gears/tall tires.

    Hey Guys,

    My neigbor (sucker me) has a 2002 Yukon (5.3 2wd) mud truck running a divorced SCS transfer case (3:1) and rockwell axles (6.72 gears) on 49" tires. Needless to say the speedometer couldn't be more incorrect as it basically has a "20.16" ratio and 49" tires. The gear/tire wizard obviously isn't going to help me out with this. What is my best course for adjusting the speedometer without messing up anything? Transmission controls will obviously need to be heavily modified, but was wondering if it was even possible to adjust the speedometer accordingly. Any thoughts/input much appreciated!

  2. #2
    Potential Tuner
    Join Date
    Jul 2017
    Location
    Tampa, FL
    Posts
    9
    Update, messed with the truck today. I am mxed out on the trans revs/mile, ratio and VSS pulses/mile. Still need some more, anyone have any ideas? I'm not 100% sure on the PCM output calibration's exact function.