[oceanview]

Originally Posted by sqwinny

That was the original/question I was developing as well but then found a deal too good to pass up. M4 brake setup with power slot rotors. Car feels braking wise a little "stronger" compared to the stock M Sport brakes (330/300 single piston all around). 60-0 feels firm and confident. Currently have the standard "soft" brake pads in. Will be bedding in the stock pads before swapping to a more aggressive pad for daily use as well as track pads too.

Easy simple swap, the hardest part is bending the damn brake shields so they don't rub on the bigger rotors. That was it honestly.

It's all about friction and heat handling.
Upgrade with a good pad like EBC YellowStuff and you will be fine for street and track.
https://ebcbrakes.com/product/yellow...nd-track-pads/
(Accept some cold brake noise on low speed in certain situations.)

370 and 340 rotors use the same pads. So they have the same brake surface size. The larger rotor allows to mount the caliper further from the axle center which gives a greater leverage.
Or the other way around. With the same brake pressure applied from the driver to the caliper/pad to the rotor, the 370 rotor will have a greater brake power. (due to the larger leverage)
Now, high power to the pad is only useful if you have a good brake friction. (high power applied to a low friction surface like an oiled brake surface wouldn't be helpful)
That's where a high friction pad makes the difference of how effective the brake pressure can be transferred to the brake rotor.

But high friction will generate high temperatures. For track use, also go with a brake fluid having a higher dry boiling point. (as already mentioned in another post.)
Higher temperatures can also be a problem for pad and rotors. But with the 370 you are on the safer side.
But once you've overheated the pad or the rotor, you will have to change them. So you want to avoid that.

I also recommend to cool down the brakes after tracking or hard street driving before stopping the car.

And, don't forget about the tires and tire pressure.
The performance in dry and wet stopping power are immense.

[Logicoeur]

Since the 340mm rotors already have less mass and thermal capacity than the 370mm counterpart, is it safe to say that floating or semifloating rotors would have even less? (All things similar in upgraded brake pads and fluid)

[brigade24]

Originally Posted by oceanview

370 and 340 rotors use the same pads. So they have the same brake surface size. The larger rotor allows to mount the caliper further from the axle center which gives a greater leverage.
Or the other way around. With the same brake pressure applied from the driver to the caliper/pad to the rotor, the 370 rotor will have a greater brake power. (due to the larger leverage)

i don't get this. how is it that by mounting the caliper further away from the axle increase brake torque? I get that it would be more effective for managing heat when using the 370mm rotor, but increasing brake torque? and if both setups use the same pads, the difference would be miniscule, no?

[oceanview]

Originally Posted by brigade24

i don't get this. how is it that by mounting the caliper further away from the axle increase brake torque? I get that it would be more effective for managing heat when using the 370mm rotor, but increasing brake torque? and if both setups use the same pads, the difference would be miniscule, no?

Read reason 3#
https://mtbphd.com/2019/08/18/3-reas...20temperatures.

Ok, that's probably not a killer reason to go from 340 to 370 rotors.
(But it is almost 10% gain in lever arm however)
But if you look at the entry level 312mm front rotor for some of the F3x cars, the advantage for the 370 rotor would be about 20% lever arm gain.

[brigade24]

Originally Posted by oceanview

Read reason 3#
https://mtbphd.com/2019/08/18/3-reas...20temperatures.

Ok, that's probably not a killer reason to go from 340 to 370 rotors.
(But it is almost 10% gain in lever arm however)
But if you look at the entry level 312mm front rotor for some of the F3x cars, the advantage for the 370 rotor would be about 20% lever arm gain.

So I read the article, Damn bro,...bicycle rotors!??! really?? some of it transfers to cars but certainly not all of it...in cars, you deal with more heat and with bigger rotors, more weight . when that rotor is turning, that extra weight is multiplied the faster it turns which semi-negates any benefit of going with a bigger rotor in the first place with respect to brake torque. this is a non-issue for bikes because the rotor is exposed to the elements and they weigh...almost nil.

The 312mm rotor setup uses floating calipers...so going to a 370mm setup, it would be impossible to not have an impact.

sorry, i'm still not convinced.

[oceanview]

Originally Posted by brigade24

So I read the article, Damn bro,...bicycle rotors!??! really?? some of it transfers to cars but certainly not all of it...in cars, you deal with more heat and with bigger rotors, more weight . when that rotor is turning, that extra weight is multiplied the faster it turns which semi-negates any benefit of going with a bigger rotor in the first place with respect to brake torque. this is a non-issue for bikes because the rotor is exposed to the elements and they weigh...almost nil.

The 312mm rotor setup uses floating calipers...so going to a 370mm setup, it would be impossible to not have an impact.

sorry, i'm still not convinced.

I just used this link because it explains the principle advantage of a larger rotor/lever.

But I found another one:
https://ebcbrakes.com/how-to-choose-...big-brake-kit/

Braking Torque = 2µFr
Where µ = friction coefficient of pads, r = torque arm radius of pad on the rotor (which is taken as the midpoint on the rotors pad track), F = force applied by brake caliper (NOTE: the constant 2 comes from the fact that the caliper force F clamps the pads onto both sides of the brake rotor)

From this equation it can be seen that:

- Use of a higher friction brake pad = higher braking torque (EBC’s speciality)
- Fitment of a brake caliper with larger clamping force (i.e. a caliper that uses larger pistons) = higher braking torque
- A larger torque arm radius (i.e. fitting a larger brake rotor) = higher braking torque
.
.
.
The torque arm radius r is determined by the size of brake rotor fitted

convinced?

[brigade24]

Originally Posted by oceanview

I just used this link because it explains the principle advantage of a larger rotor/lever.

But I found another one:
https://ebcbrakes.com/how-to-choose-...big-brake-kit/

Braking Torque = 2µFr
Where µ = friction coefficient of pads, r = torque arm radius of pad on the rotor (which is taken as the midpoint on the rotors pad track), F = force applied by brake caliper (NOTE: the constant 2 comes from the fact that the caliper force F clamps the pads onto both sides of the brake rotor)

From this equation it can be seen that:

- Use of a higher friction brake pad = higher braking torque (EBC’s speciality)
- Fitment of a brake caliper with larger clamping force (i.e. a caliper that uses larger pistons) = higher braking torque
- A larger torque arm radius (i.e. fitting a larger brake rotor) = higher braking torque
.
.
.
The torque arm radius r is determined by the size of brake rotor fitted

convinced?

lol no.

Again here, this article is just saying that a larger rotor increases brake torque. there is no demonstration or evidence to suggest it in the article. They do however mention that what does increase brake torque...the friction material of the pad and clamping force (ie. caliper piston size). They go into this in good detail. what they didn't do was provide details on how a larger rotor contributes to increasing brake torque.

They also mention nothing about the extra rotational mass that comes with mounting a larger rotor and whether or not it negates the benefit with respect to brake torque.

I wasn't sure if i was reading a fact sheet on brakes or an EBC marketing pamphlet...good read none the less. thanks for posting it!

[MacklinUSOB]

I have tracked on my 312mm single piston brakes for years with SS lines, pads and fluid. I have not been able to overdrive the brakes before I overdrive the tires and I haven't even touched the stock cooling solution. The only F30's that ever saw NA competition were on the single piston setup with PFC pads and cooling ducts.

Always always always exhaust those upgrades before adding more unsprung mass to the vehicle. Try a uni/monoball front control arm bushing to remove braking deflection and increase feel.

I have had the EBC Reds and Yellows on my car, I would not suggest either of them. The yellows literally fell apart with track use. Their brochure that is being spoken about above is accurate, though. As the distance of a force applied from the center of a rotational mass increases torque is multiplied. Thank Newton for that one!

Now is it worth the increase in unsprung weight? It can be. The kit bolts up to every F2/3 but there is a very wide range of weight and power on F2/3X. My 328 with aftermarket wheels is around 3300 pounds, many models are around 3800.

[propwash5]

Originally Posted by MacklinUSOB

I have tracked on my 312mm single piston brakes for years with SS lines, pads and fluid. I have not been able to overdrive the brakes before I overdrive the tires and I haven't even touched the stock cooling solution. The only F30's that ever saw NA competition were on the single piston setup with PFC pads and cooling ducts.

Always always always exhaust those upgrades before adding more unsprung mass to the vehicle. Try a uni/monoball front control arm bushing to remove braking deflection and increase feel.

I have had the EBC Reds and Yellows on my car, I would not suggest either of them. The yellows literally fell apart with track use. Their brochure that is being spoken about above is accurate, though. As the distance of a force applied from the center of a rotational mass increases torque is multiplied. Thank Newton for that one!

Now is it worth the increase in unsprung weight? It can be. The kit bolts up to every F2/3 but there is a very wide range of weight and power on F2/3X. My 328 with aftermarket wheels is around 3300 pounds, many models are around 3800.

Agreed that the stock system has pretty good heat capacity once you replace the pads and fluid. I swapped my 330mm m sport fronts with 340mm fixed calipers because the fixed calipers make it easy to swap out race pads. But I never noticed a problem beforehand. I only run in intermediate groups on street tires so maybe a more competent driver with more grip could find the limits of the system.

[sqwinny]

I am curious which tracks have you been running ? Road América would boil my nissans brakes pretty easily. Thus I upgraded this car that makes around the same power, but weighs 1100 pounds more.

[oceanview]

Originally Posted by brigade24

lol no.

Again here, this article is just saying that a larger rotor increases brake torque. there is no demonstration or evidence to suggest it in the article. They do however mention that what does increase brake torque...the friction material of the pad and clamping force (ie. caliper piston size). They go into this in good detail. what they didn't do was provide details on how a larger rotor contributes to increasing brake torque.

They also mention nothing about the extra rotational mass that comes with mounting a larger rotor and whether or not it negates the benefit with respect to brake torque.

I wasn't sure if i was reading a fact sheet on brakes or an EBC marketing pamphlet...good read none the less. thanks for posting it!

Well, the formula 2µFr refers to to the rotor radius as one of the parameters!
But if you don't belive in physic formulas, I don't know how else to convince you then.

You are right, that the weight of the rotor has it's down sides.
In general the more rotating mass you have to stop, the more force you need.
(The flywheel in a car on the other side uses it's rotating mass as an advantage. But in a brake rotor, you actually don't want that.)
That's why you see many sports cars also with compound material or carbon rotor. They bring down the rotor weight (less unsprung mass, less rotating mass) AND have thermal advantages as well.
(not only rotor, but the whole brake unsprung mass, like calipers and brake pad)

But I'm with you, every change/setup will give some effects/results. Depending on what you would like to achieve, one or the other setup decision could be positive or negative with respect to what you want to achieve.

[itsrichierich]

Have you guys tried using Zimmermann slotted and dimpled rotors on the track?

[MacklinUSOB]

Originally Posted by itsrichierich

Have you guys tried using Zimmermann slotted and dimpled rotors on the track?

Not a fan of slotted and dimpled rotors but I have run Zimmerman blanks on all of my BMWs and never had an issue.

[itsrichierich]

Originally Posted by MacklinUSOB

Not a fan of slotted and dimpled rotors but I have run Zimmerman blanks on all of my BMWs and never had an issue.

I would like just slotted rotors (not a fan of drilled) but Zimmermann only offers blank or slotted with dimples.

So it's either R1 Concepts Carbon Geomet slotted or Zimmerman slotted with dimples. Stoptech is asking too much for something that I don't think will perform better than the rest.