Drilled and slotted rotors

[GT_MTL]

Oui monsieur

Sent you an MP, just in case you didn't see it

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[Mike Pfeifer]

I always thought the holes and slots were there solely for gasses to escape under high speed braking, otherwise the pad will “float” on the gas causing brake fade.

 

[shogun32]

I always thought the holes and slots were there solely for gasses to escape under high speed braking, otherwise the pad will “float” on the gas causing brake fade.

Outgassing pads is a relic of history

 

[Mike Pfeifer]

Outgassing pads is a relic of history

Fair enough, but I can’t see how there could be any benefit beyond that. Besides esthetics anyway.

 

[Flyhalf]

Drill rotors have the tendency to crack way more than slotted.
But THE MOST IMPORTANT THING IS:
you will not see any drop in Temps Because the REVERSE ROTOR DESIGN. the cooler vains are outside while should be inside.
This is a issue mustang has also in the front of not PP cars. (Wrong choice made in 2015)
If you really are concern of rotor Temps. Find a not reverse rotor or/and a 2 piece
However
If you daily driven only. There is not a lot of stress on these. And you will be good.

 

[MAGS1]

REVERSE ROTOR DESIGN. the cooler vains are outside while should be inside.

Ford fixed this is the later years of S550. I have a non-PP 2022 and I have the proper rotors. So they are available for the earlier cars that have the reverse rotor design

 

[Flyhalf]

Ford fixed this is the later years of S550. I have a non-PP 2022 and I have the proper rotors. So they are available for the earlier cars that have the reverse rotor design

Good info here. Thanks for sharing.
What about the rear?
Still reversed or not?

 

[MAGS1]

Good info here. Thanks for sharing.
What about the rear?
Still reversed or not?

Rears are still reversed. Couldn’t get a good pic on my car with the wheels on, but LMR sells them (including so others can see the design you’re talking about)

https://lmr.com/item/LRS-32026K/mustang-rear-13-brake-rotors-performance-pack-15-20

 

[Hack]

Ahhhhhh.... but it can be described by a single simple formula: F=μη

μ = friction
F = the horizontial force to slide the object
η = the normal force (what the thing sliding weighs)

Area only comes into play with a totally different formula: F=PA

F = force to slide the object
P = the pressure the object is putting on the ground
A = the area the object has in contact with the ground

The Coefficient of Friction formula assumes ZERO wearing or abrasion of the material.

The second formula is a shear formula... it uses the area in contact as it assumes the entire surface area is going to be sheared (wearing or abrasion). This is how the "marbles" end up on the race track.

Friction doesn't cause marbles or tire wear... shearing does.

I like your thoughts and approach on this @Hack




ENGINEERING FORMULA DISCLAIMER
I did not Google and cut paste this info… it was forced into my brain in the late 80’s by relentless Ph.D’s.

I agree that's the formula they give out for friction and that's what you'll find in a physics book from the time I went to school as well.

I equate mu to Reynold's number - AKA fudge factor. Meaning, "sorry guys, we really have no idea how this stuff works, but here's something that gets you in a basic ballpark of the vicinity of an answer."

We try (mostly unsuccessfully) at work to simulate systems that have waaaay too much unpredictable friction in them, so I can tell you the struggle is real. I really don't know much of anything about this stuff, but in my head I think that mu is like Reynold's number where there really need to be curves and surfaces to describe how it changes when temperature, pressure and other things vary. It's not just a number like the formula implies.

And I'm sure you know static friction is different than the friction after relative motion between the surfaces begins. Yada, yada..

 

[shogun32]

And I'm sure you know static friction is different than the friction after relative motion between the surfaces begins. Yada, yada..

man, I was expecting a 300-level dissertation and all I got was "yada, yada".

 

[dpAtlanta]

And I'm sure you know static friction is different than the friction after relative motion between the surfaces begins. Yada, yada..

Static friction vs. dynamic friction… that still doesn’t change my formulas.

 

[dpAtlanta]

I equate mu to Reynold's number

This one has my interest.

but in my head I think that mu is like Reynold's number where there really need to be curves and surfaces to describe how it changes when temperature, pressure and other things vary. It's not just a number like the formula implies.

I would love to hear more info on this… I am interested in the physics.

 

[Hack]

This one has my interest.



I would love to hear more info on this… I am interested in the physics.

Ha, ha!

You know how they use PV for wear rate? Do you think there's a relationship between friction and wear?

But hey, PV has AREA in it!?!? What the heck?

Edit: I was serious when I said I don't know anything about this stuff. I really don't know much about brakes either. I can only parrot what I've read. It would be interesting to see some brake dyno test results.

 

[WildHorse]

As long as the brake fluid doesn't boil.. shouldn't matter what the temps get up too.
Just look at F1 rotors. Regularly 1000+ degrees. The priority is not to have the fluid boil.

 

[Hack]

I think if any company had some magic sauce in rotor design and construction that improved braking significantly, they would publish numbers that show the improvement.

Lower temperatures, higher braking torque, etc. All of it can be measured and compared between different rotors.

But they don't provide any performance numbers, or comparisons. Draw your own conclusions, but it makes me think there isn't a lot of difference.

I understand the light weight two-piece rotors benefit handling, which is not easy to demonstrate.

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