Belt Length

Discussion in 'Fox 5.0 Mustang Tech' started by John Dirks Jr, Aug 15, 2013.


  1. John Dirks Jr

    John Dirks Jr Active Member

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    I'm going to remove the smog pump eventually. I'll be keeping the factory AC (still blows nice and cold). I've been reading and understand I'll need an 84.5" belt after the smog pump is removed.

    To expand, under-drive pulleys might be in the mix too. Will that affect the belt length? I see the vendors offering them and they don't mention the need for a different belt. I figure that since the crank pulley is smaller, and the alt and water pump pulleys are larger, the belt length from a typical pulley swap basically stays the same?

    Is this correct?
     
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  2. newskool

    newskool Active Member

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    The best thing you can d is measure it with a string. Run it around the pulleys like you would the belt then measure it.Take tha measurement to the parts store of your choice and voila you will have the correct belt length.
     
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  3. RsStanG1987

    RsStanG1987 I shaved all my pubes playing this game.

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    The only pulley smaller than stock is the crank.. The 84.5 will work
     
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  4. 84Ttop

    84Ttop They make new pistons every day, so why worry?
    SN Certified Technician Mod Dude

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    Leave your stock pulleys alone, in my opinion. I was never a fan of underdrive pulleys. Something about spinning all of your accessories slower just doesn't sit well with me...
     
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  5. mikestang63

    mikestang63 Mustang Master

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    I have used U/D pulleys on several cars and they work fine. The key is you must have a 130 amp 3G alternator and your cooling system needs to be in good working order. Also, do not use a race crank pulley. You should use the same length belt but I would check with the pulley vendor. Stay away from the cheap off brand sets as their quality and tolerances are questionable.
     
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  6. cevtv

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    Unless he uses one of the kits with an overdrive alternator pulley.....
     
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  7. RsStanG1987

    RsStanG1987 I shaved all my pubes playing this game.

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    They all come with a bigger alt pulley bigger water pump pulley and a smaller crank. I've used the same belt with the stick pulleys and the alt pulley
     
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  8. cevtv

    Founding Member

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    :sigh: No....the March Power & Amp series pulley set has a smaller, overdrive alternator pulley (1 11/16").
     
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  9. mikestang63

    mikestang63 Mustang Master

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    Correct. I am running that on my car- recommended for automatics- as the stock alt pulley (2 3/8'?) will not spin the alt fast enough to maintain a proper charge. Just go to the vendor's website and it should tell you the appropriate belt. I needed a slightly shorter belt do to the smog pump delete pulley.
     
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  10. stykthyn

    stykthyn Commander of the snuggie cultists

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    Make sure your tensioner is up to snuff as well
     
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  11. John Dirks Jr

    John Dirks Jr Active Member

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    Dayco 5060845 on the way.
     
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  12. mikestang63

    mikestang63 Mustang Master

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    That's 84.5" which should fit as long as your alt pulley isn't overdrive, but again, best to measure or better yet pull up to the parts store, pop the hood and try out a few belt lengths while you are there.
     
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  13. cevtv

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    I believe I needed an 82.5 with the overdrive alt. 84.5 with regular under drives.
     
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  14. Grabbin' Asphalt

    Grabbin' Asphalt Mustang Master

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    Same here, when I got my '95 130amp 3g, it was a little tight. But I HAVE to use the crowbar on the tension pulley to left it up, socket won't slide past the belt for sure.
     
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  15. John Dirks Jr

    John Dirks Jr Active Member

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    My conclusion is such.

    The 84.5 worked with the smog pump delete. It also worked when the UD pulleys were installed but the tensioner was sprung all the way down (completely vertical).

    I went a got a 83.5 and it fits perfect with smog pump delete and UD pulley combined.
     
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