- #1
Darth
Hi all
Need help to determine if adapting a pulley from a tapered shaft to straight bore will work. Can the clamping force be calculated for a tapered shaft to bore i/f and straight shaft? I have a professionally modified Porsche crankshaft in which 10mm of the tapered end was cut off creating a straight or snub nose crankshaft allowing earlier version pulleys to be mounted to the end. Previous owner modification allowing the newer 3.6L engine to fit in an earlier model Porsche. I'd like to retain the original 3 sheave pulley because it is also a harmonic damper but is over 50% heavier (i.e. 6.4lbs) than the heaviest pulley (i.e. 4lbs) ever mounted to a straight shaft of previous years. The centre section of the pulley is conveniently held in by 8 bolts making it very easy to replace it with a re-machined straight bore adapter centre section. My concern is whether the lock created by the face of straight shaft is enough to support the heavier pulley which originally had a greater lock created by the interference fit of the tapered shaft? The modified tapered shaft retains the original larger 14mm internal bolt bore threads vs. 12mm allowing greater torque and in turn higher clamping forces. The modified shaft face also has a larger 5mm vs 4mm index pin off centre to the bolt bore. Up until recently I thought the shear strength of this pin was significant but was told otherwise by 3rd party pulley manufacturers that the surface i/f created the majority of the lock. If more details are needed please don't hesitate to ask.
TIA
Need help to determine if adapting a pulley from a tapered shaft to straight bore will work. Can the clamping force be calculated for a tapered shaft to bore i/f and straight shaft? I have a professionally modified Porsche crankshaft in which 10mm of the tapered end was cut off creating a straight or snub nose crankshaft allowing earlier version pulleys to be mounted to the end. Previous owner modification allowing the newer 3.6L engine to fit in an earlier model Porsche. I'd like to retain the original 3 sheave pulley because it is also a harmonic damper but is over 50% heavier (i.e. 6.4lbs) than the heaviest pulley (i.e. 4lbs) ever mounted to a straight shaft of previous years. The centre section of the pulley is conveniently held in by 8 bolts making it very easy to replace it with a re-machined straight bore adapter centre section. My concern is whether the lock created by the face of straight shaft is enough to support the heavier pulley which originally had a greater lock created by the interference fit of the tapered shaft? The modified tapered shaft retains the original larger 14mm internal bolt bore threads vs. 12mm allowing greater torque and in turn higher clamping forces. The modified shaft face also has a larger 5mm vs 4mm index pin off centre to the bolt bore. Up until recently I thought the shear strength of this pin was significant but was told otherwise by 3rd party pulley manufacturers that the surface i/f created the majority of the lock. If more details are needed please don't hesitate to ask.
TIA