MovIt Carbon Silicon Carbide Rotors as PCCB Replacement?

[Gator Bite]

Good stuff. I don't mean to accuse you of 'guerrilla marketing'. I just want to understand all the dynamics.

I'm not sure I totally buy the whole theory on tapered pad wear. If it were caused by a structural weakness in the caliper and it flexing, wouldn't the pads wear in a curve, less wear in the middle of the pad, more on each end where the caliper is clearly stronger because that's where the front and back are connected?

I would expect tapered wear on any large surface area brake pad that is mounted in a multi piston caliper. On any brake pad, there is going to be a certain amount of torque applied to the pad during braking. What will a motorcycle do if it brakes too hard? It will flip forward because of that torque. That torque is normal.

When we have a multi piston caliper, like the 6 piston units on your car, the pistons can move independently from one another, which allows the torque to turn the pad over time and wear the pad unevenly. Now the best way to compensate for this is to stagger the piston size with smaller pistons close to the leading edge and larger pistons closer to the trailing edge. I know Porsche does this on my 4 piston unit, I'm guessing they do the same on the 6 piston unit. But apparently they haven't staggered the sizes enough.

If the MovIt calipers stagger the pistons differently, this may have an effect on the tapered pad wear.

[FTS]

Originally Posted by Gator Bite

If it were caused by a structural weakness in the caliper and it flexing, wouldn't the pads wear in a curve, less wear in the middle of the pad, more on each end where the caliper is clearly stronger because that's where the front and back are connected?

I would expect tapered wear on any large surface area brake pad that is mounted in a multi piston caliper. On any brake pad, there is going to be a certain amount of torque applied to the pad during braking. What will a motorcycle do if it brakes too hard? It will flip forward because of that torque. That torque is normal.

When we have a multi piston caliper, like the 6 piston units on your car, the pistons can move independently from one another, which allows the torque to turn the pad over time and wear the pad unevenly. Now the best way to compensate for this is to stagger the piston size with smaller pistons close to the leading edge and larger pistons closer to the trailing edge. I know Porsche does this on my 4 piston unit, I'm guessing they do the same on the 6 piston unit. But apparently they haven't staggered the sizes enough.

Well not necessarily. The caliper shape, its metallurgical construct, piston design, all play a significant role in how heat is spread across the caliper and dissipated. Few years ago, Racecar Engineering mag pushed some technical articles from PFC on their NASCAR calipers and how the new Z-rated designs were making noticeable performance differences. I could not locate the article on their web site, but the following thesis is a very close approximation of what PFC was claiming:

http://soar.wichita.edu/dspace/bitst...pdf?sequence=1

I find Pete's adventures in testing "stuff" to satisfy his curiosity quite interesting, I really appreciate you taking the leading on finding and using these rare products Pete, thanks

[Trackrat]

Originally Posted by FTS

I could not locate the article on their web site, but the following thesis is a very close approximation of what PFC was claiming:

http://soar.wichita.edu/dspace/bitst...pdf?sequence=1

I am only to page 35 of the thesis and look forward to finishing it and fully digesting it this weekend. One thing immediately learned- don't throw away those "useless" metal plates clipped onto back of pads Unless you want to play with overheating your calipers!

[mdrums]

Originally Posted by Trackrat

I am only to page 35 of the thesis and look forward to finishing it and fully digesting it this weekend. One thing immediately learned- don't throw away those "useless" metal plates clipped onto back of pads Unless you want to play with overheating your calipers!

That is some very interesting stuff! I've been using Ti inserts on the back of my pads from TiSpeed and they really do work at keeping the heat out of my stock calipers.

[Terry L]

FWIW, an observation on pad tapering - when I use Pagid RS29s on my steel brake GT3.1, they will taper every time. I once switched to Pagid Blacks, which destroyed the stock rotors (rings of Saturn big time) but no taper wear at all. I have no idea why this should be.