How can I accurately measure the deflection on an alternator belt? How much pressure should there be on the belt when it is measured? Thanks for any help you can give me.

Tom

 

I believe the "spec" is 10-15 lb of pressure in the middle of the longest run on the belt..

usually I just crank 'em down until they're snug and start the car.. if it squeals, crank it down another turn or two. and do it again.