Disc masses

[HornetMaX]

Out of curiosity, is the mass of the disc indicated for a single disc or for two discs (for bikes having 2 discs on front) ?

E.g. murasama:

   Rear = 1.02

   Front = 1.256 (carbon)

So on the front, assuming carbon discs, do we have 1.256 total or 1.256 x 2 ?

MaX.

[Ddinit]

Hello HornetMax

It's probably that,  1,2 kg is already light for one disc of this diameter. And also for the rear, surely more small and made of steel...



You think about the effect on the front wheel

Please to meet the forum,  i'm newbe

Regards

[HornetMaX]

It's probably that,  1,2 kg is already light for one disc of this diameter. And also for the rear, surely more small and made of steel...

But the problem is: how does GPB know that the 990 has 2 front discs while the 125cc has only one ?

MaX.

[BozoCRO]

Carbon is much lighter then steel, so probably sum of masses

[HornetMaX]

Carbon is much lighter then steel, so probably sum of masses

You don't get the point.

For the front disc (or discs) there's a weight specified: is that for 1 disc or for both ?
Independently if it is carbon or steel, the weight seems to be correct for 1 disc. But now how does GPB know that a 990 bike has 2 front discs (so it has to count the weight twice) while a 125 bike has 1 front disc (so it has to count the weight only once) ?

It seems written nowhere in the bike's physics files. Or maybe I'm missing something.

Also reading this (http://www.brembo.com/it/Documents/One%20year%20of%20F1%20and%20MotoGP%20in%20Brembo%20infographics.pdf) in the MotoGp section, the difference in weight between steel and carbon seems to be much less that what GPB thinks: page 35, carbon = 1-1.2 Kg per disc (with support), steel = 1.4 Kg. GPB on the 990 says carbon = 1.2 Kg, steel = 2.5 Kg.

MaX.

[BozoCRO]

What Iam saying is that it doesnt matter how many discs are there. The number represents total weight of the brakes. Maybe Piboso just got it wrong? Maybe I got it wrong?

[PiBoSo]

Out of curiosity, is the mass of the disc indicated for a single disc or for two discs (for bikes having 2 discs on front) ?

E.g. murasama:

   Rear = 1.02

   Front = 1.256 (carbon)

So on the front, assuming carbon discs, do we have 1.256 total or 1.256 x 2 ?

MaX.

Was this thread really necessary?
Of course it's the combined mass, just like the springs of the forks are combined 
Thank you for pointing out the carbon discs weight error, though.

[HornetMaX]

Was this thread really necessary?
Of course it's the combined mass, just like the springs of the forks are combined 
Thank you for pointing out the carbon discs weight error, though.

The wrong values were the problem: I was 99.99% sure the weight is combined (as the number of discs is nowhere specified), but the value didn't make sense as combined weight.
So yes, the thread was somewhat necessary to bring the little problem to your attention.

Was a PM more appropriate for this kind of discussion ?

MaX.

[HornetMaX]

Hmmm ... this seems to say something different compared to the Brembo document:

http://www.motogp.com/en/MotoGP+Basics/brakes

Weird ...

EDIT: And that too: http://www.braketech.com/index.php?option=com_content&view=article&id=50&Itemid=95

Well, maybe there's nothing to change in GPB data.

MaX.

[HornetMaX]

Just thought about another detail around that: when the disc mass changes, does the corresponding inertia change too ?

Didn't check the math, maybe the change is numerically not very relevant.

MaX.