Lightened Clutch shoe carrier

GBewley

Well Known and Active Forum User
VOC Member
Mr. Stevens tells us in "Know Thy Beast" that the holes to lighten a clutch shoe carrier should be eight, two pair on 3.125" PCD with centers 0.750 apart, and two pair on 2.125" PCD 1.25 apart. In looking at my stock, I find some variation in this, but some of these shoes may have been drilled by an owner, not the factory. Still, if I place the holes as he says, the webbing between the two holes on the same side of the carrier and on different PCDs seem terribly close to one another, and I have experience breakage of a shoe carrier at that very webbing. Wondering if anyone out there has come up with other measurements. I am right now working at the same figures for the outside holes but have changed from 2.125 PCD to 1.75 PCD on the inside ones, which results in more webbing. I would be very interested in opinions.

Glenn
 

Kansas Bad Man

Well Known and Active Forum User
Non-VOC Member
Hi Glenn

To give you peace of mind, go to your local Auto parts outlet. Ask to see a heavy duty clutch plate from a 454 big block, notice the amount of
metal between the clutch lining and the female spline.

Cheers

excuse the spelling
 

john998

Well Known and Active Forum User
VOC Member
Hello, not sure about where to drill the holes but Glyn Baxter had a carrier disintegrate due to being 'lightened'
also the factory lightened clutch drum meant for lightnings were relegate to rapides as they failed.
John.
 

Kansas Bad Man

Well Known and Active Forum User
Non-VOC Member
Hummm, at least one factory lightning clutch drum held up in the test of time, Sonny has made 0ver 40 passes at Bonneville ,speeds ranging 135 to 150 MPH

Cheers

excuse the spelling
 

GBewley

Well Known and Active Forum User
VOC Member
Thanks, John....Glyn's experience reflects mine. Max, I would argue the stresses are different in a clutch shoe carrier from a clutch plate (454). Further, I would be willing to argue that perhaps the stresses at Bonneville, where one is trying to get to top speed with minimum wheel spin on a surface not particularly good for grip, are different from continuous acceleration and deceleration of a hard ridden road bike. And, yes...I've ridden behind the Baxters...trust me, Glyn can give it the stick!
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Thanks for that John !, I have been running 2 twins with the Factory holes in the clutch drums, I wonder when my luck will run out !! Cheers Bill.
 

bmetcalf

Well Known and Active Forum User
VOC Member
That seems to match what is shown here: https://www.voc.uk.com/net/docs/tl/lightenedclutchcomponents.pdf

Mr. Stevens tells us in "Know Thy Beast" that the holes to lighten a clutch shoe carrier should be eight, two pair on 3.125" PCD with centers 0.750 apart, and two pair on 2.125" PCD 1.25 apart. In looking at my stock, I find some variation in this, but some of these shoes may have been drilled by an owner, not the factory. Still, if I place the holes as he says, the webbing between the two holes on the same side of the carrier and on different PCDs seem terribly close to one another, and I have experience breakage of a shoe carrier at that very webbing. Wondering if anyone out there has come up with other measurements. I am right now working at the same figures for the outside holes but have changed from 2.125 PCD to 1.75 PCD on the inside ones, which results in more webbing. I would be very interested in opinions.

Glenn
 

clevtrev

Well Known and Active Forum User
VOC Member
Hello, not sure about where to drill the holes but Glyn Baxter had a carrier disintegrate due to being 'lightened'
also the factory lightened clutch drum meant for lightnings were relegate to rapides as they failed.
John.
But there are pictures of B Rapides at the factory using those drums before a Lightning was even thought of.
 

Kansas Bad Man

Well Known and Active Forum User
Non-VOC Member
Not to argue but for debate, If the bushings are all in good order, clutch drum and shoes, the load area is the same , 454 to vin , we are talking torque transition area, friction to mechanical. The most torque to the clutch is when the bike is in high gear running as fast as it will go. Hard riding creates kinetic energy shock to metallic parts. In the case of the clutch drum the webbing between the lightning holes would have to go into sheer which is a bunch, maybe some one with a math degree could give us a idea of the tonnage of sheer.
 

GBewley

Well Known and Active Forum User
VOC Member
Seems to me that even with good bushes (actually good fit between the shoes and the pins that carry them, whether bushed or not), there is most like at least some degree of bending force exerted as the pins are only supported at one end, that being the flat of the shoe carrier. This may come into play as well when the shoe carrier self-destructs. No matter really...I'm just saying I like a bit more meat between the holes than ES's figures gave. I do think lightening the shoe carrier leads to quicker disengagement of the shoes, but it may over time be at a cost.
 
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