Clarification of Alternator Slip Torque Tension

[CharlieWaffles]

I've got the Slip Torque tension guide from Plane Power on how to tension the alternator belt (http://www.plane-power.com/images/ALTERNATOR BELT TENSIONING.pdf). It specifies to use a torque wrench on alternator pulley-retaining nut. I pull the alternator down the adjustment bracket, tighten the adjustment arm and then use the torque wrench, but I'm not 100% sure of what I am supposed to be looking for. It says the slip torque for a new belt is 11-13 Ft Lbs.

So if I have the alternator at the right tension, then when I move the torque wrench, I am assuming the belt should have enough tension it moves the flywheel. But should it continue to move the belt even if I hold the prop in place up to 11-13 ft lbs?

 

[JonJay]

That is correct. It should slip in that range. If it doesn't, the belt is too tight.

 

[tim2542]

Yeah I think you want to hold the engine still during the test, the belt should not slip below the 11-13. At least that's what I have been doing.
Tim

 

[Kevin Horton]

The numbers are from Lycoming SI 1129A Accessory Drive Belt Tension.

With a new belt, the belt must not slip when you apply 11 ft-lb torque. The belt must slip when you apply 13 ft-lb torque. If it passes both those tests you are done. If it fails, adjust the tension and try again.

If you have a used belt, the correct range is 7 - 9 ft-lb.