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About 850 miles ago, I replaced my worn original front rotors with Racing Brake 2-piece units. Because I don't track my car (yet) and never got near the thermal limits of the stock brakes, I won't be able to review anything related to heat management. However, there is a thing or two worth posting. I’ll add to the thread if I ever do get to push them hard.
Before you ask why I wanted these in the first place if I never got near the limits of the stock brakes:
- To help keep brake heat out of the wheel hubs
- Weight reduction, bro
- Wear resistance
Some pics – nothing much to see, but this is the Internet after all. Hope you all like dirty wheels.
I'm using these rotors with OE pads.
So, things worth noting:
1. Yes, they're black out of the box but normal-looking after some driving. They ship with a coating to prevent rust during storage. It's is just supposed to come off as you drive. More on that below.
2. During the install, pushing the caliper with pads over the rotor was tough. It was a REALLY tight fit. After pushing the piston all the way in – or what I thought was all the way in – it still took more effort than I had expected to get the caliper on. Maybe these rotors are half a millimeter too thick or something. Or maybe it's the paint. Or maybe that's entirely normal for this car. If it is, forget I said anything.
3. I've read that some people have seen very little clearance between the caliper bracket and the hardware on the rotor that attaches the hat to the friction ring. There's even a note about this on RB's product page, which says you might have to shave down the caliper bracket. When I first did the install, after reassembling the brakes but BEFORE mounting the wheels, that clearance definitely looked way tighter than I'd be comfortable with (like 1 mm). However, after mounting the wheels, there seems to be a lot more clearance, and there have been no signs of interference. I suspect that the only reason the clearance seemed low was that rotors hadn't fully seated on the hubs until I mounted the wheels.
4. Braking away the black coating took me something like 50 miles of driving more or less like a normal human being (notwithstanding a couple of hard stops). There were a few... interesting effects before the coating was gone. Every time I braked to a stop with more than the lightest pedal pressure, decelerating through the last 1-2 MPH generated the loudest, most resonant groaning vibration I've ever experienced from a car's brakes. When warm, the brakes sometimes stuck very slightly when I was stopped, and I could feel and hear them coming unstuck when I started moving. And after hard braking, there was definitely a weird smell and some white smoke. All of that weirdness went away with the coating. Just be prepared for it if you decide to go for these rotors.
5. Bedding in the rotors seems to have taken a while. Probably because I didn't follow any bed-in procedure. Maybe also because of the supposedly harder-than-normal alloy in the friction ring. Either way, there was some pulsation for a while, mainly when braking from high highway speeds. That seems to have subsided to a dull whirr – much higher frequency and lower amplitude. And again, that's only when braking fairly hard at high highway speeds.
6. Because these rotors reduced my car's unsprung rotating mass by 4.4 lbs per corner, my car is now fast enough to tear a hole in the universe. I raced a McLaren P1 on a twisty backroad and it fell farther and farther behind until it got sucked into the black hole produced by my car's crushingly low inertia.
7. That last point is definitely not true. In fact, I can't say with confidence that I've noticed anything from the weight savings. At least, nothing I could distinguish from placebo. Oh well.
Dannobre... to counter that... I probably have at least 20+ track days on my OE rotors... still holding up fine =P though with all the crazing I have, I carry spares with me to every track day, lol!
I do like the idea of those rotors though...! just can't justify it yet...
what pads are you using? that to me means a lot when talking rotor life
For me....mostly DTC 60's or Combo DTC60 and HT10's I tried a set of Blues early on cause I got them cheap...and a set of HP+ cause that's all I could get on short notice once
I had blues because I got a great deal on them. ATE my rotors. I see you all are running quite aggresive pads, so it must true that the blues really are bad for rotor life.
Seems I've been wrestling with pad deposit issues.... basically since I got these rotors. Still using OE pads. The vibration comes and goes, but it's mainly there when the brakes are hot, which means summer has brought it back with a vengeance. I tried cleaning the rotors with steel wool and brake cleaner and then re-bedding them as RB suggests; that improved things, but didn't eliminate the problem.
I've called RacingBrake support about this a few times, and here's what really gets me. At first, they told me that OE pads should be fine. Now, just today, I'm hearing a different story: OE pads might meet their definition of "ceramic", which they say is a no-go for their rotors. I'm now considering other options, none of which I'm happy to pay for. I threw Porterfield's "carbon kevlar" compounds out as an example to the guy on the phone, and he said it'll be fine. But in light of the failure of their previous advice, I'm skeptical.
I'll try giving the rotors another good cleaning when I can, and see if that finally does the trick. But as of now, I kind of wish I had stuck with OE rotors.
Fingers crossed that I'll have another positive update...
Racing Brake would love to sell you a set of pads. I'm quite sure of it!
Centric and Raybestos (among others) sell inexpensive pads labeled as semi-metallic. See here.
I think Mazda has variously supplied semi-metallic and ceramic pads as OE over the years. The pads that came with my car were most likely semi-metallic. The replacement Mazda pads I bought a few years ago were most likely ceramic and were definitely not the same.
Sites like Rock Auto and O'Reilly attempt to list the OE material, and both sites list both compounds as OE. Go figure.
Racing Brake would love to sell you a set of pads. I'm quite sure of it!
Centric and Raybestos (among others) sell inexpensive pads labeled as semi-metallic. See here.
I think Mazda has variously supplied semi-metallic and ceramic pads as OE over the years. The pads that came with my car were most likely semi-metallic. The replacement Mazda pads I bought a few years ago were most likely ceramic and were definitely not the same.
Sites like Rock Auto and O'Reilly attempt to list the OE material, and both sites list both compounds as OE. Go figure.
Thanks, Steve.
Plot twists:
1. RB support told me the Hawk pads on their site would work... but one of them is the Performance Ceramic.
2. Race Roots has posted here saying RB's ET500 compound is ceramic.
Even if I assume their no-ceramic advice is real, trying to find another pad compound is a real pain in my ***. I don't track the car as of now, but I do drive pretty hard when I can (previous OE front pads were basically done after 20k miles). But I don't want to sacrifice initial bite or cold performance vs. OE. And it has to have no (or minimal) ceramic content. Gah.
This is way, way too much trouble and worry for a $700 pair of rotors.
I'm willing to pay if I think there's a good chance of benefits. The difference between $80 and $180 looks huge, but as a fraction of the car's operating budget over the pads' lifetime, it's not that big.
Went at the RB rotors with heavy scouring pads and sandpaper this weekend. Got the friction surfaces as clean as I could. Then I cleaned and greased all the pins and clips, threw on Porterfield R4-S pads all around, and headed out for a bed-in run.
I've clocked about 80 miles so far, and the warm-braking rumble is basically gone. It still creeps in sometimes, but it's mild enough and rare enough that I consider the problem resolved.
The rotors' friction surfaces look noticeably more uniform and less streaky than with the OE pads. I suspect that's another artifact of the R4-S compound being a better match for the rotors.
I'm not much of a fan of the R4-S so far, mainly because the pedal feel at low-to-moderate temps and pressures isn't what I want. But the car hauls down nice and strongly without feeling like it's on a rumble strip, so I'm probably not going to touch anything until something wears out or I win the lottery.
Aaaaaand we're back to having intolerable NVH. I've tried another cleaning with the same result: good for a few hundred miles, and then the NVH comes back. It's now worse than it's ever been.
Not going to get into my conversations with RB support, except to say they have not been helpful.
Few options at this point beyond resurfacing them or just taking a bath on the purchase price and going back to OE. Either way, really regretting this purchase. Even if by some miracle I can fix the problem, this was way too much trouble and headache for a rotor that costs >3x as much as OE.
The only bright spot is that thickness seems to be indistinguishable from new. If they're wearing, they're wearing SLOWLY. So at least there's that.
Aaaaaand we're back to having intolerable NVH. I've tried another cleaning with the same result: good for a few hundred miles, and then the NVH comes back. It's now worse than it's ever been.
Not going to get into my conversations with RB support, except to say they have not been helpful.
Few options at this point beyond resurfacing them or just taking a bath on the purchase price and going back to OE. Either way, really regretting this purchase. Even if by some miracle I can fix the problem, this was way too much trouble and headache for a rotor that costs >3x as much as OE.
The only bright spot is that thickness seems to be indistinguishable from new. If they're wearing, they're wearing SLOWLY. So at least there's that.
Trying to figure out whether to try resurfacing them as a last resort. Need to find someone who understands I'm not trying to fix warpage and will only take a tiny bit of material off.
If that seems unwise or doesn't work, they'll be for sale soon.
And of course, if someone gives me a good offer, I'll ship them out ASAP without doing anything to them.
So I went back to OE rotors and have been running them for several thousand miles now. Zero pedal pulsation, ever. Weirdly, initial bite and pedal feel seem to have improved slightly, so I'm no longer underwhelmed by the Porterfield R4-S.
Looking back at this thread, I realize I may have understated the NVH issue with the RB rotors. It wasn't some mild vibration or squeal. It was pedal pulsation that felt like riding a jackhammer. Thoroughly cleaning the rotors made it go away, and it'd stay gone until the first brisk stop in warm weather; after that, it'd gradually come back until it felt like it was going to shake the car apart.
Either way, I'm happy now, and looking forward to trying some different pad compounds in the future without having to wring my hands over whether the rotors will like them.
Glad some of you are having such success with these rotors. If the pads you're running were on my list, I'm sure my experience would have been different.
05-29-2016, 12:44 PM
