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Offline Rexelstar

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Re: Anyone interested in lightweight rear brake disc?
« Reply #10 on: December 06, 2018, 10:08:50 AM »
Thanks for the info. Never had physics but still learning;)

BTW the front disk seems to be from Sunstar, mentioned in the partsmanual. Rear disk no reference is given..
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Offline Oyabun

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Re: Anyone interested in lightweight rear brake disc?
« Reply #11 on: December 06, 2018, 10:10:21 AM »
My bad, I took it granted. Thank tou for broadening my perspective.
In our education system everyone has to study Physics in both elementary and secondary education. Some study further.

Oem rear disc is made by sunstar too. Quite surprised to be priced at a whopping 99+shipping  :033:
(ref: https://www.bike-parts-honda.com/honda-motorcycle/assignment_spare_parts/43251MGZJ02)
« Last Edit: December 06, 2018, 10:34:44 AM by Oyabun »

Offline hilldweller

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Re: Anyone interested in lightweight rear brake disc?
« Reply #12 on: December 06, 2018, 10:21:01 AM »
*Originally Posted by Oyabun [+]
Surface area affects mass, heat dissipation, heat absorption capacity, longevity

Even at my age I remember different sized wooden blocks, a string over a pulley and a weight.

But what scares me with these skeleton designs is heat. A big solid disk is a good heat sink and radiator. I can picture that tiny scrap of metal glowing white hot with the minimum of braking.

I also suspect no-one would detect the small decrease in unsprung mass.

So sorry, you asked the question and that is my honest considered answer.
Brian.

Offline Rexelstar

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Re: Anyone interested in lightweight rear brake disc?
« Reply #13 on: December 06, 2018, 10:26:14 AM »
Thanks, your never to old to learn. Wish I had the right education when I grey up.
Takes some more time with age, but find it most interesting to learn in time. And seeing physics more and more like magic;)


« Last Edit: December 06, 2018, 10:32:49 AM by Rexelstar »
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Offline Oyabun

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Re: Anyone interested in lightweight rear brake disc?
« Reply #14 on: December 06, 2018, 10:33:05 AM »
*Originally Posted by hilldweller [+]
But what scares me with these skeleton designs is heat. A big solid disk is a good heat sink and radiator. I can picture that tiny scrap of metal glowing white hot with the minimum of braking.

I also suspect no-one would detect the small decrease in unsprung mass.

So sorry, you asked the question and that is my honest considered answer.

To be very precise I've asked if anyone would be interested, not if anyone has concerns, but your comments are still welcome. ;-)

Good thing is, that these skeletons dissipate heat as quick as they absorb it. My concern would be rather the fast heat cycling, or heat transfer to the fluid rather than the temperature of the disc - but I'm quite sure it should be no concern with proper fluid and sinter metallic pads.

As per my calculation I can go down as much as a kilogram on the rear wheel (combining spacers, axle mods, brake disc, lighter sprocket, etc). All of it being rotating and unsprung im sure I'll notice it.

As I've mentioned before it might not be for everyone, never intendet to be. Just asked if anyone else would be interested.

Offline Irishrover

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Re: Anyone interested in lightweight rear brake disc?
« Reply #15 on: December 06, 2018, 10:40:45 AM »
*Originally Posted by Rexelstar [+]
Thanks for the info. Never had physics but still learning;)

BTW the front disk seems to be from Sunstar, mentioned in the partsmanual. Rear disk no reference is given..

The front and rear are cut from the same piece of metal. if you have the rear disc and front disc off at anytime, the rear disc will fit inside the front disc space.

Offline Oyabun

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Re: Anyone interested in lightweight rear brake disc?
« Reply #16 on: December 06, 2018, 10:41:44 AM »
*Originally Posted by Rexelstar [+]
And seeing physics more and more like magic;)

I just Love physics. My second favourite quote I usually say ro my students is that "I love physics as it is reliably fairly consistent and doesn't sleep even during weekends"
My most favourite one is that "I'm an Engineer, trasferred to the dark side of the force" having equal number of economics degrees by now than engineering (college degree in mechanical engineering, MSC in electrical engineerig, BSC in management and finance and an MBA major in innovation and technology management)

Offline Irishrover

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Re: Anyone interested in lightweight rear brake disc?
« Reply #17 on: December 06, 2018, 10:43:46 AM »
I would have been interested if I knew it was as safe as the original and half the price. Paying 90 for a new disc isn't cheap.
But if it does the same as this piss poor after market disc, then I have concerns.


Offline Oyabun

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Re: Anyone interested in lightweight rear brake disc?
« Reply #18 on: December 06, 2018, 10:45:43 AM »
*Originally Posted by Irishrover [+]
The front and rear are cut from the same piece of metal. if you have the rear disc and front disc off at anytime, the rear disc will fit inside the front disc space.
Yup was one of the feats of ingenious cost saving engineering from Honda when the bike came out. It is not only reducing wste material and simplifies manufacturing, but also decreasing parts count as the mounting for the front brake is integrated to the wheel, and does not require a separate spider to mount.
But it it is highly irrelevant to the original topic. ;-)

Offline Irishrover

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Re: Anyone interested in lightweight rear brake disc?
« Reply #19 on: December 06, 2018, 10:50:28 AM »
*Originally Posted by Oyabun [+]
Yup was one of the feats of ingenious cost saving engineering from Honda when the bike came out. It is not only reducing wste material and simplifies manufacturing, but also decreasing parts count as the mounting for the front brake is integrated to the wheel, and does not require a separate spider to mount.
But it it is highly irrelevant to the original topic. ;-)

The reply was aimed at our Spanish friend who was wondering what make the rear disc was.
He probably didn't know that the two discs came from the same piece of metal.
A relevant reply to his question in my opinion.

 


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