Belt size

[brr]

I am wondering how to figure out the correct belt size for a Max IV with a 18hp Vanguard motor. There are no shims between the motor and the mounting plate. Currently it has a 43" x 1 1/4" belt. It seems tight. When I turn the clutch on the motor by hand the clutch on the shaft to the drive turns as well. There is no slippage at all. I believe this is what is causing the machine to take off as soon as I put it into forward and is making it very difficult trying to get it into reverse. Should the belt be slipping on the clutch on the motor when turned by hand? Should I move to the next larger in diameter belt?

[thebuggyman1]

How much deflection do you have on your belt now? Can you turn the primary by hand and hold the secondary from turning? With the machine in neutral it is normal for the secondary to spin as there is very little resistance...you should be able to reach in with a stick and stop the secondary from turning with the engine running. Be very careful here!

[brr]

I cannot turn the primary by hand and hold the secondary from turning. I tried a stick on the secondary and could not get it to stop turning. There are no spacers/washers between the engine and the engine bracket. If I need a larger belt is there a way to figure out what size I need besides trial and error which would cost a ton of money?

[thebuggyman1]

Trial and error is probably your only choice, not having access to the original belt.
If you are 43" now, I would try 45" next. That 2" of extra length only means 1" of spacer(s) to get it to the same over tight condition you have now.

The other alternative is to cut your current belt and guess at when the gap would give you the right tension.

[msafi65]

The stock belt for a Briggs IV is 42 1/2" x 1 3/16". Most had two washers between the engine and mount, about 1/4" total. 1 1/4" wide belts are to wide and make the belt tight. A daco 1092M3 is the belt I use for replacements. The Salisbury manual said to tension the belt so that when pulled away from the driven clutch and pinched around the inner part of the engine clutch should have 1/16" clearance to shaft. Any tighter than that and vehicles creep or belts squeal at idle. Good luck the correct belt makes all the difference in performance.