Where to get cross drilled Rotors E70

[JCL]

Originally Posted by Quicksilver

This part struck my funny bone. I didn't know drilled
or slotted expelled gas............

Well, they do provide a path to expel gases produced by the pads. Only problem with that marketing claim is, modern brake pads don't produce gases like the pads from the 1960s did, due to different bonding agents in the pad material. So, drilled rotors had a real benefit when they debuted in the '60s. Now, with modern pad compositions, they make as much sense as a whale tail spoiler on a Honda Civic.

[JCL]

Originally Posted by Penguin

Please educated me as to why being lighter would provide superior braking? I can see there would be suspension advantages to keeping unsprung weight down, but the only effect I can see a lighter or heavier disk would have on actual braking performance would be the moment of inertial, which on the top of my head would not be a very big energy difference, considering the diameter of the disk and the weight involved, in relation to the total mass you are slowing down.

What am I missing here?

P.S. Perhaps my guess as to the rotational inertial/energy of a rotating brake disk is wrong... when I get some spare time maybe I'll do the calculation and see if I've underestimated the delta effect of the mass removed by drilling/slotting. But if somebody already knows, you could save me some time and effort by chiming-in with the answer.

I don't think the difference in rotational energy is at all significant. The rim, yes, due to the greater diameter, but the brake disk is much smaller.

I do think that lowering unsprung weight allows the suspension to work better, and keeps the tire in contact with the road surface. This may have more to do with braking performance than rotational energy.

[Penguin]

Originally Posted by JCL

I do think that lowering unsprung weight allows the suspension to work better, and keeps the tire in contact with the road surface. This may have more to do with braking performance than rotational energy.

Good point, I can see that the benefit of lower unsprung weight on the suspension could improve tire contact at times, thus improving the effective braking performance.

But I wonder what the measurable impact of the weight saved by drilling would actually be on the suspension, considering the overall weight of the wheel, tire, and caliper..

[JCL]

Originally Posted by Penguin

But I wonder what the measurable impact of the weight saved by drilling would actually be on the suspension, considering the overall weight of the wheel, tire, and caliper..

On an M3CSL, a vehicle that got all sorts of weight-saving features, it can matter. On an E70? Not measurable, IMO. Especially on the vehicle the OP asked about, a 3.0 diesel. Travelling the superhighways of Panama, yet.

[Quicksilver]

You completely side stepped my sarcastic implication. But that's OK...

Originally Posted by JCL

Well, they do provide a path to expel gases produced by the pads. Only problem with that marketing claim is, modern brake pads don't produce gases like the pads from the 1960s did, due to different bonding agents in the pad material. So, drilled rotors had a real benefit when they debuted in the '60s. Now, with modern pad compositions, they make as much sense as a whale tail spoiler on a Honda Civic.