How Many Dimples?

[al1dere]

So i've recently bought some brembo slotted and dimpled rotors, and when they arrived the rear rotors weren't in the original box. I know the rear isn't vented, so it would look different, but how many dimples are grouped together, like how the fronts have a slot, then 4 dimples, a slot, etc. how many dimples are supposed to be between each slot on the rear brembo rotors?

 

[herostar]

Could you post some pictures so we can better understand what you're talking about?

 

[al1dere]

the rotor on the left is the rear and the one on the right is the front...notice how the one on the left has 3 dimples and the one on the right has 4 dimples???

 

[ACM]

Styling, nothing more.

Dimples are completely non-functional, other than reducing the rotor mass, so causing the rotor to heat up faster.

Charles

 

[RamenPride]

the rotor on the left is the rear and the one on the right is the front...notice how the one on the left has 3 dimples and the one on the right has 4 dimples???

well the rear rotor is smaller in diameter. keeping the spacing between them the same, there's no way to get 4 dimples on the rear rotor.

 

[herostar]

Dimples are completely non-functional, other than reducing the rotor mass, so causing the rotor to heat up faster.
Charles

Not true, they actually improve braking performance as well as heat dissipation because the dimples are little "pockets" that extract hot gasses trapped between the pad and rotor during breaking. Slotted/drilled rotors work in the same fashion, but do more to evacuate the gasses. This reduces brake fade. They also aide in heat dissipation because of the increase in surface area (This is more theory though, and because of the small ammount of air that flows over the brakes and the small size of the dimples, let alone the extra air that would flow over the dimples, the improvement would be neglegable).



Those rotors are fine. The dimples neither hurt nor help performance in a significant way. The back and front rotors are almost always different because they are different sizes.

 

[ACM]

Sorry herostar, but No and No.

Dimples give gases nowhere to go - holes work for that, and slots too, but dimples don't.

DSM brakes are heat sink mass limited, the removal of that mass hurts the brakes more than the increase in surface area. There's no airflow over the surface inside the dimple, so surface radiation would be the only theoretical improvement.

Charles

 

[al1dere]

well the rear rotor is smaller in diameter. keeping the spacing between them the same, there's no way to get 4 dimples on the rear rotor.

Thank you for answering my question RamenPride, I'm not debating whether or not the dimples have a function or not, good or bad, I've already done my research and wouldn't have bought them if I was still unsure. I was simply figuring out whether or not the rear rotors were brembo because they didn't have the same markings on them. (I only questioned it because the front rotors had "brembo" written on the side, as the rear's didn't, but had all the other writing the similar)...

Anyways, I got my answer, that the number of dimples aren't the same on the front and back...thanks.

 

[Todd TCE]

I won't comment that a dimple is simply an appearance thing to look like holes...but that's not all bad now is it?

The main reasons I can think of here are these;

1. If the slot count is the same then on a smaller rotor you'd have less room between the slots for four holes..err, dimples. Or you could of course make them smaller or close to one another. But then you'd be asking 'why?' then too I suspect!

2. The other issue is the space between the rear hat and the inner most dimple is about as close as most mill heads will come to placing the ball end mill onto the surface of the rotor without crashing the head into the hat. While you could run an extended length ball end mill perhaps to do this and get it close, why? The same one is probably used on both the dimple and the slot, thus the deflection for slotting is too great.

But that's all just my .02