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Thread: TREMEC Magnum Swap VSS Issue(s)

  1. #1
    Tuner in Training Blockade Runner's Avatar
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    TREMEC Magnum Swap VSS Issue(s)

    Greetings Gentlemen,
    I am here because my speedometer is +- 60% off and I get an ABS warning after a few miles after installing a new Tremec Magnum 6-speed transmission. I was told the reluctor gear on the new Magnum is different from the one on the factory NV3500 5-speed.
    I have no problems or issues with my engine. The transmission works perfectly, and I have new brakes/calipers/rotors all the way around. Brakes are perfect, and I am also told the ABS warning is related to the reluctor issue. I am relying on the experience of you fine Gentlemen to steer me to the truth.
    I wanted to post this thread before my initial scan because of the ABS warning and known speedometer error, lest my naivete on these matters gets me into a world of poo poo that could otherwise be avoided by consulting the experienced men on this forum.
    The facts y'all need to know:
    The VSS reluctor on the new TREMEC is 12 tooth.
    Vehicle is a 2003 Chevrolet Silverado 4.8L V8
    Factory Transmission is Getrag NV3500; I do not know the NV3500 reluctor gear tooth count, but believe it may me 40.
    Engine has stage 2 cam and long tube headers, and is tuned great. No complaints.
    Ring/Pinion is 3.73
    Tire size is 29.7" - (275/45/20)
    Please advise if I missed something.

    I just received the MVPI2 today, and this issue is why it was purchased. Truck was so much fun to build and restore that I am certain I will do it again.
    All help is greatly appreciated, and don't be afraid to use idiot-proof guidance. I don't know jack, but that's about to change thanks to you Gentlemen.
    If any of you have solved this puzzle yourselves, I am interested in hearing from you regardless if you arrived at a solution via different routes.
    I thank you in advance, and look forward to having you all save my ass.
    Sincerely,
    The Blockade Runner

  2. #2
    Senior Tuner TheMechanic's Avatar
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    Yikes. 12 tooth is pretty bad resolution. Not sure if you won't get some issues with your ABS etc. Even though the calculation will be correct the amount of pulses per might be on the light side. You may need to go with a GPS converter.

    EDIT ADDITION
    You would want to change that "Hardware" to whatever tooth you have. You said 12 so that is what it would be.
    Last edited by TheMechanic; 01-28-2021 at 03:30 PM.

  3. #3
    Tuner in Training Blockade Runner's Avatar
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    The T56 folks, including vendors all say HPTuners is the solution. I am certain there have been many before me, I just need to find them. If they aren't on this forum, I will dive in regardless and solve the puzzle. 12 tooth reluctors are the most common in Tremec Magnums these days, and may in fact be in every 6-speed currently made. I am grateful for your response. Thank you!