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Drive belt - which way around?

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  • 24-09-2019 9:53am
    #1
    Eireann81
    Registered Users Posts: 262 ✭✭


    The tensioner for my drive belt let go on my N47 520d, so I ordered a new tensioner, idler pulley, and belt. The 2 sides of the new belt (Continental) are different - one side is rubber and the other side is like a cloth material. Both sides were rubber on my old belt. I've changed belts before, but I've never come across one of these before. I've attached photos of the new belt, and a diagram of the route of the belt.

    One side of the belt faces the crank pulley, coolant pump pulley, alternator pulley, and power steering pulley.
    The other side of the belt faces the tensioner pulley, idler pulley, and the A/C pulley.

    I thought Google might help, but I'm none the wiser :confused:

    Any idea which way the new belt should face?
    Tagged:


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    #2
    FDave
    Registered Users Posts: 176 ✭✭FDave


    The outer circumference of the tensioner and idler are smooth and contact the flat surface of the belt. The other pulleys are groved for the ribbed surface of the belt as it increases surface area and contact friction for driving the altenator and power steering etc.


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    #3
    Eireann81
    Registered Users Posts: 262 ✭✭Eireann81


    FDave wrote: »
    The outer circumference of the tensioner and idler are smooth and contact the flat surface of the belt. The other pulleys are groved for the ribbed surface of the belt as it increases surface area and contact friction for driving the altenator and power steering etc. I'd be very surprised if the A/C pulley is not groved aswell.

    Thanks, but both sides of the belt are grooved (one side is rubber and the other is like a cotton fabric). The idler pulley and tensioner pulley have smooth, flat surfaces, but the A/C pulley is grooved. That's why I'm unsure which side (rubber or fabric) should go against certain pulleys...


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    #4
    FDave
    Registered Users Posts: 176 ✭✭FDave


    Eireann81 wrote: »
    Thanks, but both sides of the belt are grooved (one side is rubber and the other is like a cotton fabric). The idler pulley and tensioner pulley have smooth, flat surfaces, but the A/C pulley is grooved. That's why I'm unsure which side (rubber or fabric) should go against certain pulleys...

    Yea I had just edited my post there, i hadn't looked at the belt diagram you posted. Need to read before I reply too. I'd guess the rubber side drives the alternator but not sure


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    #5
    FDave
    Registered Users Posts: 176 ✭✭FDave


    The belts inner circumference will sit on the pump and alternator pulleys unless it somehow got twisted inside out but that would be obvious looking at it. Hope that makes more sense.


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    #6
    Eireann81
    Registered Users Posts: 262 ✭✭Eireann81


    FDave wrote: »
    The belts inner circumference will sit on the pump and alternator pulleys unless it somehow got twisted inside out but that would be obvious looking at it. Hope that makes more sense.

    That's really what I'm asking... which side is the inner circumference - the rubber side or the cloth side?

    Looking at this link, it appears as though the cloth side is the inner circumference, but that's just an assumption: https://www.bestpartstore.co.uk/210215-contitech-v-ribbed-belts


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