Semi dumb belt question
 

I know this sounds stupid on the surface but I am not close to a parts store and don’t want to make a million trips back and forth getting belts. I have to get custom belts for my CVF Racing accessory drive setup and I have seen custom belt measurement done two ways. One is to take yarn and run it around the pulleys and tie it off and take it to the parts store to be put on the good old fashioned v belt measurer if they even still have one. The other is to take a sewing measuring tape and measure the distance and write it down. What method do you use for custom belts? What do you think is gonna result in me having to make the least number of trips?

Assuming you are running V-belts, I think twine would be better, but first wrap something on the pulleys to simulate where the inside of the belt would actually ride. Otherwise the twine falls too far into the groove and your belts will end up too short. I'd position the adjustments close to as short as they can go, leaving a little to allow you to get the belt on but not stretch out so far that they don't have enough tension. Longer belts stretch more than shorter belts.

If it's the serpentine style with multiple belts, the twine should work well right on top the pulleys. But have someone hold the tension device in the right position while you work the twine.

I would want to measure all the new belts with the same device I measure the twine with.

Yarn I suppose would be OK if it didn't stretch.

Weather you need a v belt or serpentine belt i perfer to use an old belt that is too long. I cut it square, then wrap it around the pulleys and mark the end at max length. Subtract 3/4"-1" and you've got your length. For me this works better cause the belt is sitting excatly how it should be in the pulleys.

This is what I do. Tape measure, string, rope etc. did not work for me.

This:
 

I do this also but I set the adjustment at halfway to give me some leeway.

From CVF;
Q. What belts do I use?
A. Our V-belt pulleys all use the Series 15 belts (except for Toyota Landcruiser Pulleys). The best way to get the right length is to cut your old belt or use a rope to measure the length with the bracket fully compressed. Most auto parts stores sell the belts in 1/2" increments.

Dayco V-belts are carried by many local, and online sources (Rock Auto, etc).

Dayco belt number breakdown =

First 2 numbers = Series (2 common series available, 15 & 17, and applies to the width of the belt)

Last 3 numbers = Length

So, a 15465 is a 15 series, 46.5" long.

15470 - 47" long

15475 - 47.5" long

Rinse, repeat.

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