Brake Rotors Effect on Stopping Power

JHZR2

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I highly doubt you want slotted or drilled rotors. Get the heaviest rotors you can. The increased thermal mass is what you want. The car isn’t never going to be a super handler so marginally more unsprung mass won’t matter. A more aggressive compound will have more bite, but can do different things including chances of lockup, more suspension stress, nosedive, etc.

The other option may be if there are larger wheel cylinders for the rear. A slightly larger cylinder could add benefit to the rear stopping power, but also could lock up easier….
 
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OK, so now I know, a track car. Go big, way bigger than stock. I knew a guy who tracked a turbo'ed BMW E24. He had a pair of C 6 Corvette rotors machined to fit, and used 4 piston calipers so he could run with 911s. :cool:
 
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OK, so now I know, a track car. Go big, way bigger than stock. I knew a guy who tracked a turbo'ed BMW E24. He had a pair of C 6 Corvette rotors machined to fit, and used 4 piston calipers so he could run with 911s. :cool:
Thickness of rotors and proper air supply to calipers.
On BMW’s last 17 years knuckle is same, so much larger rotors fit models that came with smaller ones. I am doing that on mine now. Going from 312x24mm to 340x30.
 

Pew

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Rotors have no affect on stopping power (except rotor diameter) but good quality rotors will cool faster/more evenly; and from that the rotors will stay more true. Pads and caliper rigidity have more affect on stopping power. +1 on what everyone else says about not using drilled and slotted.
 
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Which BMW is that? I use regular solid rotors on track and don’t have issues. Last time i did 1 1/2hrs session on track and brakes worked great. Both front snd rear solid ones.
Aftermarket pads? Rotors?
That was my 2013 328i. Brembo MAX slotted rotors and XTRA pads vs stock.
 
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Rotors have no affect on stopping power (except rotor diameter) but good quality rotors will cool faster/more evenly; and from that the rotors will stay more true. Pads and caliper rigidity have more affect on stopping power. +1 on what everyone else says about not using drilled and slotted.
True. Quality of rotor is what matters. There is a lot of junk on the market and then that junk even comes slotted or worse, drilled.
Pads, caliper design, shims (titanium!), air flow to calipers, is where tricks are how to improve performance on track.
 
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That was my 2013 328i. Brembo MAX slotted rotors and XTRA pads vs stock.
So, problem were not rotors but your pads. Brembo is really good rotor and caliper wise. But pads they offer for cars like 328 are not anything special.
How about your brake fluid?
The reason why I think brake design is not reason is that i drove F30 328 a lot here in the Rockies and few times up/down the Pikes Peak pushing it really hard with OE brakes, and performed excellent fading wise. I am though not fan of pad material on them which is designed for less dust.
I use on track ATE front rotors, Pagid rear ones, solid ones, EBC yellostuff pads, and no issues at all. I managed in one track day to wear half of rear pads (compliments of ediff.) but no fade or rotor issues.
 
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If you're talking slotted/drilled vs solid no difference for 98% of brake use... But it sure looks cool so I always get them lol. I did one her aluminum hat rotors which cut unsprung weight several lbs per side. Otherwise the only place to spend money on rotors is coating to slow rust.
 
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Pads and rotors aren’t the biggest consideration. Get decent pads and rotors drums and shoes. Put the work into making sure all the hardware works smoothly and adjust properly. Drum brakes benefit from occasional hard braking to keep the surface good and hard braking while backing to keep them adjusted. Had to do this routine every month or so on my manual transmission S10 to keep the brakes good enough to stop in an emergency.
 
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Seems to me that there are different metallurgies. The euro makes for instance seem to use softer pad and rotor combos when oem. It contributes to very powerful braking with less pedal effort, at the expense of faster wear. Slap standard pads from the corner store on a Volvo rotor, and the rotor wears even faster. Replace the pads and rotors with corner store parts so the rotor doesn’t get chewed up, and then it feels like a Honda or Toyota instead of a Volvo. I’ve heard the same from bmw owners.

as to whether or not the aftermarket suppliers vary in metallurgy, I’ve found zero data, and just a few testimonies of staying “in brand,” like using raybestos rotors with their pads, being very good combinations. I’ve never done it. Like so many here, I go with solid rotors, having had the best luck with raybestos AT, and have tried different pads. My fav pad of late has been the raybestos element 3. Prior to that Hawk, and on certain makes, akebono.

i tried slotted rotors for a season looking for better stopping power without extra cooling, and after 2 sets of rotors couldnt quite keep pads bedded well with them, and they had a “noisy” stop which never felt right to me.

old rotors, cleaned and painted, make great stands for small speakers, and floor lamps.
 
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Seems to me that there are different metallurgies. The euro makes for instance seem to use softer pad and rotor combos when oem. It contributes to very powerful braking with less pedal effort, at the expense of faster wear. Slap standard pads from the corner store on a Volvo rotor, and the rotor wears even faster. Replace the pads and rotors with corner store parts so the rotor doesn’t get chewed up, and then it feels like a Honda or Toyota instead of a Volvo. I’ve heard the same from bmw owners.

as to whether or not the aftermarket suppliers vary in metallurgy, I’ve found zero data, and just a few testimonies of staying “in brand,” like using raybestos rotors with their pads, being very good combinations. I’ve never done it. Like so many here, I go with solid rotors, having had the best luck with raybestos AT, and have tried different pads. My fav pad of late has been the raybestos element 3. Prior to that Hawk, and on certain makes, akebono.

i tried slotted rotors for a season looking for better stopping power without extra cooling, and after 2 sets of rotors couldnt quite keep pads bedded well with them, and they had a “noisy” stop which never felt right to me.

old rotors, cleaned and painted, make great stands for small speakers, and floor lamps.
The trick is not in rotors but pads, and it is not as simple.
1. European manufacturers generally pay much more attention to braking performance. Both my BMW and VW have larger brake rotor surface than my Toyota which packs 1,100lbs more than BMW or VW.
2. Rotors are much more durable. They are generally thicker too. Put “whatever “ pad from store down the street is not indicative of “softness.”
3. Pad material is where initial bite comes from. More bite=more dust. Have you seen BMW’s with super dirty/black wheels? Comes from pad material.
That is the biggest discussion among owners of European vehicles, especially owners of BMW’s. Those that buy BMW’s for ahow, hate those pads. Enter Akebono who offered cermic pads strictly for European vehicles and look, rotor longevity increased. No dust at all! But they are POS is performance department.
BMW actually in 2012 with introduction of F series models introduced three different set of pad material. Base pad strictly made for North American drivers. No dust, long life of pad and rotors. Sport pad (base in Europe) have extremely strong bite but also dust a lot. And M sport pads with also extreme bute but also more resistance to heat. Last two dust like crazy.
First two share same rotor while third has same rotor material but it is bigger.
Now, manufacturers do have different material, but key is pad when it comes to feeling, bite, generally performance. Rotors either do job good or not. When rotor becomes too hot to perform properly that means that other parts (pads, pistons) already exceeded its limits.
 
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Excellent explanation! But are you sure they are using the same metallurgy? I ask because in my own experience and the local folks I know here, the oem European rotors wear faster than the Japanese makes and the typical non-oem aftermarket?
 
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Excellent explanation! But are you sure they are using the same metallurgy? I ask because in my own experience and the local folks I know here, the oem European rotors wear faster than the Japanese makes and the typical non-oem aftermarket?
That is due to pad material, not the rotor.
 

twouvakind

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I was not only interested the slotted vs unslotted, but if the metallurgy between the high end rotors and low end rotors made any difference. For example Centric has the CTEK line rotors and StopTech slotted rotors for this car. The StopTech description reads as follows:



While the CTEK desciption is as follows:



The StopTech rotors are also 3 times the cost of the CTEKs. Unfortunately, the specs for the StopTech rotor are not listed, because I was interested in comparing the weight.

Also, for the car itself, it has makes around 400 hp and 450 ft-lbs of torque. It also has a fully overhauled suspension with high rate springs, upgraded bushings, large anti-sway bars and Bilstein performance shocks. So brake dive is not an issue at all, it is better than some modern cars. This car looks almost 100% stock, but I have managed to make huge improvements utilizing upgrade "stockish" parts. I want to do the same with the brakes, keep it stock appearing but perform much better than original.

It's not that I don't want to hear about tires and brake dive, it's just that I am aware of that stuff and have addressed it. I want to keep this discussion focuses entirely on the brakes. Thank you!
 
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Oldswagon

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Thanks for all the replies. As I suspected, the slots and metallurgy don't seem to have any significant effect on stopping power. So I will just stick with plain rotors and put my money into high end pads like porterfields.
 

UncleDave

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Ive had all three types of rotors on my trucks and of the three, the slotted ones outperform the solid and cross drilled ones.

There are prices to pay for this though - reduced pad life as the slots increase the friction, they make a buzzing sound, and the rotors performance reduces to that of a standard rotor over time as the depth of the slot diminishes or when you have to turn the rotor.

Without the right pad combo the rotor choice is moot.
 
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Excellent explanation! But are you sure they are using the same metallurgy? I ask because in my own experience and the local folks I know here, the oem European rotors wear faster than the Japanese makes and the typical non-oem aftermarket?
Pads are the issue.
 

X15

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Excellent explanation! But are you sure they are using the same metallurgy? I ask because in my own experience and the local folks I know here, the oem European rotors wear faster than the Japanese makes and the typical non-oem aftermarket?

My limited understanding is that your typical OEM performance High Carbon rotor does wear a little faster than a low carbon aftermarket one.


Very few of the aftermarket manufacturers make it clear what grade of iron they use for what, many of them could be accused of being intentionally misleading....
 
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interesting link from DBA with lots of info BUT of course better is $$$$. i put EBC rotors + yellow stuff on my 2011 fronty + it stops much better than OE + a bit dusty + will need pads at 25,000 miles! daily driver in a hilly area + a few loads of coal yearly, in fact got one today on this nice 40 some degree day!! i believe there are variables in quality depending on $$$$$. EBC advertises higher carbon rotors + lots of pad choices, not the cheapest but worth it IMO!!
 
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