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I will install a PTO that was purchased separately from the transmission. How does one know how many shims to install between the PTO case and the transmission?

Also, this PTO will direct drive a vintage Deming water pump. I need to know the PTO RPM at low idle and full idle of the engine. A friend on this AA site advised me that by counting teeth in the transmission gears and the PTO gear, the output speed of the PTO will be 71% of the crankshaft speed of the engine. However, he would and I would like some verification to our theory. Does anyone know the answer?

Looks like it may depend on the manufacture of the PTO. St.Paul PTO shows 1062RPM per 1000RPM of engine
and Muncie PTO shows 59 percent of engine speed.

Bob

counting the teeth is the sure way to know the gear ratio. Go with that. Shim so that the teeth just have clearance. Plastigage will do the trick.