What size short belt for this combo ?

Discussion in 'Fox 5.0 Mustang Tech' started by Katmandu, Nov 21, 2007.


  1. Katmandu

    Katmandu Founding Member

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    Ok, I just did the 3G alternator upgrade along with a smog delete and installed an underdrive crank pulley on my 5.0.

    In addition, I swapped pulleys with my stock alternater (50mm) Vs the 3Gs (60mm).

    My chart shows an 84.5" belt (which I just tried) and it's a bit too long.

    I don't feel like running back and forth to the parts store chasing belts down and reinstalling them.

    Would anyone know the exact size with my underdrive pulleys and smog delete ? :shrug:

    [​IMG]
  2. 90topdown

    90topdown New Member

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    You gotta measure it.

    Borrow a fabric tape measure from your woman's sewing box. Run the tape measure around the pulleys just as the belt would run. That will give you the measurement.

    Just to be safe get that size belt and the next smaller and next larger one. Then just take the 2 back that don't fit.


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  3. white99gt

    white99gt Founding Member

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    DOnt have the part number here(its at work).I pretty sure i run a 81" belt.
    I can get you the part number on friday.

    I run the 3g ,underdrives (kept the a/c) and smog delete.
  4. MrXCESSIVESPEED

    MrXCESSIVESPEED Member

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    An 81" 6 rib serpentine belt would have a part number of 810K6

    The easiest thisng to do would be like mentioned about and measure it....be it with a fabric tape measure or so twine, rope, string, or something similar. Run it the route the belt wouldt take then lay it straight on the floor and measure it. I usually get that measurement as well as half inch longer and shorter. The return the two you dont need. :nice:
  5. Katmandu

    Katmandu Founding Member

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    Great idea!! :nice:
  6. blackened88lx

    blackened88lx Active Member

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    Wouldn't that be a complete pain in the balls? Do you hold the auto tensioner up in the "operating range" while measuring?? I'm guessing you would need 2 people. My no smog belt is 84.5" just like the diagram says, and the diagram says that's for underdrives, but mine has stock pulleys. Does the 3g need a shorter belt for some reason?? I wouldn't see needing anything shorter than 84" unless you're routing it differently or the 3g needs a much shorter belt. I usually just park outside the parts store and get about 20 belts and find one that fits.
  7. Darkwriter77

    Darkwriter77 Resident Ranting Negative Nancy

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    FWIW, an alternate part number for an 81" belt would be 5060810 in a Dayco. I dunno what the "50" denotes, but the "60" means 6-ribbed belt and the last three numbers are the length ... just add a decimel point. (Ex: 81" = 5060810, and 84.5" = 5060845)

    Goodyear Gatorbacks have a funky prefix number like "70" or something, but it works about the same way in that they include the number of ribs and belt length in the part number.

    EDIT: Knowing the part number for a belt you want to try will save you a headache sometimes with some of the clueless counter 'tards they hire in some parts stores. Unless you give them an exact part number, they usually only know what they can find on their computer listings for stock sizes and they'll just try to tell you that there's no such belt, if you're looking for a custom size.
  8. MrXCESSIVESPEED

    MrXCESSIVESPEED Member

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    Not really a pain at all...and i usually do it by myself. I just did it a little over a month ago when I put my LX back together, and it worked out just fine. Its almost always once of the three...either the measurement you got initially, half inch longer. or half inch shorter. Sure beats trying a million different belts IMO.
  9. blackened88lx

    blackened88lx Active Member

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    Hmm. I just figured it would be a pain while holding the tensioner up and measuring at the same time. So is it a shorter belt with the 3g??
  10. SuperStang83

    SuperStang83 Founding Member

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    I always just used a string and measured it then.

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