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Belt Measurement Help!

Aftermarket replacement belts can successfully replace many original equipment belts. If aftermarket model listing information is not available, then measurements can be used to select a replacement. Proceed as follows to develop measurements to search for the belt(s) you need.
 

Measurements Required
 
For each belt to be replaced, determine its belt type and size as follows:

    • A Type of Belt - Round cross section, square cross section, flat belt or fabric belt.

    • B Inner Circumference (IC) – The length of the belt along its inside (driving) surface.

    • C Thickness – How thick the belt is from the inside driving surface to its outside surface.

If a “flat” belt then also need:

    • D Height - How tall the belt is if sitting on a flat surface.

Note: Some “square” belts are really slightly rectangular and may have unique values for thickness and height.

How to Measure

The Inner Circumference (IC) is the most difficult to measure. Two methods are provided as follows:

    • Quick method (for belts with a thin thickness only)

        Press the belt halves together and measure the length and multiply by 2. Take the result
        and multiply by .95 to compensate for belt stretch.


    • More precise method

        1 - Gather two pencils and a thin piece of string.
        2 - Put the old belt across the two pencils and move them apart until all the slack is gone.
             Do not overstretch.
        3 - With the two pencils still in their same position, put the string around the two pencils so that it
             is taught, and mark where the two ends of the string come together.
        4 - Remove the string and measure its length from marked end to marked end. Measure as precisely
             as you can in inches using either fractions or decimal equivalent.
        5 - Multiply by .95 to compensate for belt stretch.

Height and Thickness - Measure as precisely as you can.
 

Special Situations

    • If the old belt is damaged such that its IC cannot be measured, use the string on the mating parts driven by the belt, mark where the string meets, and measure from marked end to marked end. Take the result and modify by .95 to account for the fact that the belt has to be smaller than the string.

    • If the old belt has a non-regular construction and does not fit any of the types discussed, please email a .jpg photo.

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