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Belt slip

Discussion in 'SVT Shelby GT500' started by Andrew33, Jul 14, 2019.

  1. Andrew33

    Andrew33 Member Established Member

    Oct 19, 2018
    2013D978-330E-4810-A860-027A7529349B.jpeg 20971322-D36A-49C1-929F-5CFBE113579C.jpeg

    It certainly looks like I’ve got some belt slip to me. Lots of black dust around the supercharger belt. Set up is a 2.50 vmp pulley and a 90MM idler with the belt van sells for our car that is supposedly the strongest. I went through all the idlers/pulleys and non seem bad. That belt has around 2000 miles on it. I cleaned the supercharger when I put it on last time, so all that dust is from 2000 miles.

    What’s the fix here so I don’t slip?
  2. RedVenom48

    RedVenom48 Ghost Editor-In-Chief Premium Member Established Member

    Sep 29, 2014
    You might have a weakening belt tensioner. Thump Racing and ARS both make excellent upgrades.


    Thump RRR Racing Billet Aluminum Belt Tensioners New Jersey, NJ

    I run a VMP belt tensioner, but it appears that they no longer produce them. If my VMP lets go, Ill be going with the ARS unit.

    Also, consider an Aux idler to help increase belt wrap near the supercharger pulley.

    RBB likes this.
  3. Jam421

    Jam421 Jam421 Established Member

    Sep 15, 2010
    Long Island NY
    Small upper pulleys can create slippage which can sometimes be seen on a boost gauge & certainly on a dyno. Years back there were threads about quick revving, deep geared GT500's having alternator issues due to the instant RPM surge at WOT stabs. Not sure if you're on the stock 331's but I'd guess hard stabs + gears can still cause some belt slippage. What stopped mine from slipping was a Metco Belt tensioner (Aux Idler?) wrapping around 2/3-3/4 of my 2.4 upper.
    I might get flamed for this o_O...but I apply CRC belt conditioner 3-4X each season. My SC whine is louder at WOT after the CRC is applied. But over time I still do see some black soot although way less than years back. Yesterday, I wiped a bit off with metal polish applied the CRC Conditioner then put 100 miles on it including some low roll & highway WOT stabs. The SC is still pretty clean.
    Can your get a belt tensioner that gives you a better wrap up top as suggested by lexustech48 ?

    Attached Files:

    einehund likes this.
  4. GT Premi

    GT Premi Well known member Established Member

    Mar 15, 2011
    OP, you need to add an aux idler to get more belt wrap. A new belt tensioner wouldn't hurt, either, but I recommend starting with an aux idler, if funds are tight.

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