how to determine belt size 70 tooth rear pulley, 32 tooth transmission/front

V

vtwin_doc

New member
What kind of FRAME is the bike you are doing????
THAT is what we need to know......all current models use a 32/70 ration.....it is the chassis and drivetrain dimensions that will determine the belt length......you will also need to know the WIDTH of the belt.

Just so you know ....belts are measured by # of teeth, not by length
 
if its the same pulleys the same belt wil fit al lyou need to know is rear 70 or year of bike now if you have replace pulleys with different guessing would be a way count old pulley teeth and new pulley teeth count old belt add
 
We need to know what model Harley to help give you an answer.You could also go to a dealer and get a broken belt from the service department to use as a measure.Make a mark on each pulley then set the pulleys with the marks opposite each other.In other words the mark on the front pulley to the front and the wheel pulley to the rear exactly opposite each other.Lay the belt on the pulleys and mark it at each pulley mark.Then count the teeth.Double the number you get and it should be the right size.Just make sure the pulley marks are exactly opposite from each other.
 
Take a metal take measure (or your wife's cloth seamstress tape measure) and wrap around both pullies just like the belt would.

Or, with the rear axle in the middle of the adjustment slot, measure from the center of the axle to the center of the output shaft and multiply that by 2. Better write that number down. Measure the diameter of both sprockets to where the outside of the belt would be were it on there. Better write those down also. One at a time, take the diameter times 3.14 and divide that by 2. Add those numbers to the first and you should have a pretty close estimate of the length required. See how that compares to your measurement with a tape.

For example, the axles are 24 inchs apart with a 4 inch diameter front pully and 10 inch rear.

Axle measurement is 24X2=48"
Countershaft sprocket 4X3.14/2=6.28"
Axle sprocket 10X3.14/2=15.7
48+6.28+15.7=69.98"
 
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