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View Full Version : Crankshaft Pulley Problem and Solution



RonzSC
06-17-2005, 02:43 PM
The fact that my stock crankshaft pulley was made using two power pressed pieces did come as surprise to me. Evidence of the pressing procedure can be seen near the bolting holes in the form of four equally spaced round spots. The outer pulley surface has a beead lock near it's base and locks to the other smaller pulley diameter. The interior and fat portion of the pulley is hollow. I presume this configuration is meant to save weight.
The problematic issues arose for me as the outer ring (diameter) will flex under high rpm's and the overall crankshaft pulley is significantly out-of-balance.
It made me wonder is this out-of-balance condition contributes to harmonic balancer and crankshaft failure. If the crankshaft is inducing vibration at one end and the crankshaft pulley induing harmonics at the other, something has to give.
To machine a on-piece steel part would be expensive and heavy. The the original pulley in it's present form (a lightened two-piece part) weighs a hefty 6 pounds amd 3 ounces. If machined from a solid piece of steel it might weigh 13-15 pounds. A
Getting a six pound mass moving out-of-balance at the top end of our rpm range doesn't sound too goog.
A one-piece aluminum crankshaft pulley weighs 4 pounds 7 ounches.
I machined a one-piece unit for my SC.

David Neibert
06-17-2005, 04:53 PM
The fact that my stock crankshaft pulley was made using two power pressed pieces did come as surprise to me. Evidence of the pressing procedure can be seen near the bolting holes in the form of four equally spaced round spots. The outer pulley surface has a beead lock near it's base and locks to the other smaller pulley diameter. The interior and fat portion of the pulley is hollow. I presume this configuration is meant to save weight.
The problematic issues arose for me as the outer ring (diameter) will flex under high rpm's and the overall crankshaft pulley is significantly out-of-balance.
It made me wonder is this out-of-balance condition contributes to harmonic balancer and crankshaft failure. If the crankshaft is inducing vibration at one end and the crankshaft pulley induing harmonics at the other, something has to give.
To machine a on-piece steel part would be expensive and heavy. The the original pulley in it's present form (a lightened two-piece part) weighs a hefty 6 pounds amd 3 ounces. If machined from a solid piece of steel it might weigh 13-15 pounds. A
Getting a six pound mass moving out-of-balance at the top end of our rpm range doesn't sound too goog.
A one-piece aluminum crankshaft pulley weighs 4 pounds 7 ounches.
I machined a one-piece unit for my SC.

Ron,

An aluminum underdrive crank pulley weighs even less. BTW, I think Ryan Harris makes/sells an aluminum stock size crank pulley.

David

Joisey Jim
06-18-2005, 09:51 AM
I would be interested in an alum. stock size pulley to install on the BHJ balancer. Do you have any contact info for Ryan.
Tx,Jim.


Ron,

An aluminum underdrive crank pulley weighs even less. BTW, I think Ryan Harris makes/sells an aluminum stock size crank pulley.

David

XxSlowpokexX
06-18-2005, 04:18 PM
Guys,

I think what hes saying is that he made one...Not that he wants to buy one.

Seems we may have another person able to procure pulleys for us