To Shave or Not to Shave the Hubs

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mehiggins101
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To Shave or Not to Shave the Hubs

Post by mehiggins101 » Sun Mar 08, 2015 12:55 pm

My son and I build some decently fast cars, but I haven't bought any of the specialty tools. One tool I've considered is the hub shaver that takes the 2-step outer hub down to one flat surface. Does everyone do this? Is it a must-do step?



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Stan Pope
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Re: To Shave or Not to Shave the Hubs

Post by Stan Pope » Sun Mar 08, 2015 1:10 pm

I hesitate to call it a "must do", but if two cars are otherwise equally prepared, the one that reduces that energy loss (by reducing the friction radius, i.e. torque) wins.


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mehiggins101
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Re: To Shave or Not to Shave the Hubs

Post by mehiggins101 » Sun Mar 08, 2015 5:16 pm

Thank you. Seems like it's worth doing.



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Re: To Shave or Not to Shave the Hubs

Post by sporty » Sun Mar 08, 2015 9:40 pm

Back in late 2098. I modified mine. And I think it's very important to reduce hub to axle head friction.

In fact I had posted on here. How I would polish my hubs to a nice shiny plastic before burnish some graphite.

In graphite racing. Faster car and times don't drop off as fast. In a longer running race format.

It's not a huge difference. But keep in mind. In a close race. It could be the deciding factor.



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Re: To Shave or Not to Shave the Hubs

Post by ngyoung » Sun Mar 08, 2015 9:58 pm

May want to have extra wheels on hand. I have heard mixed reviews on the DW hub shaver. Will likely take a few tries to get a clean cut hub.



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Re: To Shave or Not to Shave the Hubs

Post by Vitamin K » Mon Mar 09, 2015 7:57 am

Stan Pope wrote:I hesitate to call it a "must do", but if two cars are otherwise equally prepared, the one that reduces that energy loss (by reducing the friction radius, i.e. torque) wins.
Would you be willing to expand a little on the concept of the "friction radius" here? How does removing the outer step reduce our energy loss? (I'm not arguing that it does, just trying to get a handle on how .)



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Re: To Shave or Not to Shave the Hubs

Post by ngyoung » Mon Mar 09, 2015 8:26 am

Having the point of friction closer to the axis of rotation of a spinning object reduces it's effect. The center of a wheel is moving slower then the outside of the wheel with regards to linear speed. The outside of the wheel travels a greater distance then the center each rotation. The rim of a wheel is essentially a lever and the farther away your friction point is from the axis the more leverage it has.
Vitamin K wrote:
Stan Pope wrote:I hesitate to call it a "must do", but if two cars are otherwise equally prepared, the one that reduces that energy loss (by reducing the friction radius, i.e. torque) wins.
Would you be willing to expand a little on the concept of the "friction radius" here? How does removing the outer step reduce our energy loss? (I'm not arguing that it does, just trying to get a handle on how .)



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Re: To Shave or Not to Shave the Hubs

Post by Stan Pope » Mon Mar 09, 2015 10:27 am

Without disagreeing with ngyoung, I simply express it as reducing the leverage of the hub/axle head friction braking force.


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Re: To Shave or Not to Shave the Hubs

Post by mehiggins101 » Sat Mar 14, 2015 10:27 am

How are people cleaning up the cut surface after shaving? I'm not too impressed with the final result. I'd love to get in there with some sandpaper (800 to 100 and then 2000), but don't see how to get to the recessed surface



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Re: To Shave or Not to Shave the Hubs

Post by Stan Pope » Sat Mar 14, 2015 2:15 pm

mehiggins101 wrote:How are people cleaning up the cut surface after shaving? I'm not too impressed with the final result. I'd love to get in there with some sandpaper (800 to 100 and then 2000), but don't see how to get to the recessed surface
I have glued small disks of abrasive paper on the end of short dowel rods of comparable diameter. However, you probably want the center of the cut hub to be higher than the outer edges. This suggests a diagonal cut of the dowel. Okay?


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Re: To Shave or Not to Shave the Hubs

Post by mehiggins101 » Sun Mar 15, 2015 10:15 am

Stan Pope wrote:
mehiggins101 wrote:How are people cleaning up the cut surface after shaving? I'm not too impressed with the final result. I'd love to get in there with some sandpaper (800 to 100 and then 2000), but don't see how to get to the recessed surface
I have glued small disks of abrasive paper on the end of short dowel rods of comparable diameter. However, you probably want the center of the cut hub to be higher than the outer edges. This suggests a diagonal cut of the dowel. Okay?
Thanks. Using a dowel seemed to do the trick. The hub surface is flat (no cone), but a lot smoother after sanding with 800-, 1000- and then 2000-grit--probably not perfect but much better. I went from thinking we wrecked some wheels to having some wheels that should be good to go.



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