I've been running the Racing Brake 2-piece rotors (front and rear) for a little over 30k miles now, and I wondered if anyone else is having problems with roughness and short rotor life. Mine have not seen track use, but they regularly see high-speed braking on the street from spirited driving. They feel fine and are quiet in normal daily driving, although they have much less initial bite than the factory rotors and pads did. But when I get the fronts hot from just one hard 120-to-60 slow-down, they start making considerable noise and feel rough.

The original front pads were the ones supplied by RB with the rotors, but since RB didn't have matching rear pads, I ordered a set of Porterfield R4-S as per their suggestion. The front pads bedded-in fine, but by about 5k miles, they were making a lot of noise and were quite rough when doing a really hard 120-to-60 slow-down. I put up with it, and the RB pads lasted about 20k miles, but I think they trashed the front rotors in that timespan because the surfaces began showing noticeable cracks and hot spots. I did a pad-slap and replaced both front and rear pads with factory MB pads, and those have been reasonable smooth and have lasted roughly 10k miles, but now they are getting quite rough again when the rotors are hot and they're due for a change. The rotors are now showing significant cracks and hot spots, and they don't look like they ever have any chance of being smooth again.

I have not contacted RB yet, but these rotors were touted as having longer life than factory and my feeling is that they should have lasted more than 30k miles. Hell, I got 30k out of the factory rotors, having gone through three sets of front pads without any more maintenance than swapping-in new factory pads at about 10k and 20k. I'm certainly not happy with the feel of these RB rotors, so either I have to replace the rings and try them again with a pad other than the crap RB sent me in the first place, or I need to discard them and swap-in the 2-piece Brembos from FCP Euro and new factory one-piece rear rotors.

So, I'll call RB and discuss, but I'd love to know how anyone else is doing with their RB two-piece rotors.


I took these pics of the front rotors a few weeks ago. I have a little more than 30k on these RB rotors, having gone through the RB-supplied pads plus one set of factory pads.

I took these pics of the front rotors a few weeks ago. I have a little more than 30k on these RB rotors, having gone through the RB-supplied pads plus one set of factory pads.

 

I'm running RacingBrake's two-piece rotors but only at the track. If you have 30k miles on those rotors, they look a lot better than my OEM rotors at 26k miles, granted my OEM rotors have 6 track days on them.

 

It looks like you're getting a lot of uneven pad deposit on your rotors. This is most likely the cause of your noise and rough feel. I would try to re-bed your brakes again.

How do the edges of the pads look? Are there any white spots? A possible cause of the uneven pad deposits could be the fact that you're overheating them and need a pad that can withstand higher temperatures.

 

I see your point, so I'll assume the discs are still ok and try honing them before slapping-on a new set of pads. After the first set of pads from RB, I scrubbed with brake clean and Scotchbrite, but it's nearly impossible to remove pad deposits that way. My factory rotors and pads never built up deposits like this, but the pads that RB supplied with their 2-piece front rotors started doing this fairly early (they were getting rough by 5k). I would definitely not recommend the RB pads for street use after my experience with them. The other thing about the RB pads is that they wore very unevenly and were tapered when I removed them, but the caliper pistons all compressed easily and smoothly back into the calipers, and the factory pads that I have in there now are wearing evenly. I pulled the fronts recently to inspect, fearing that I may have calipers that need to be rebuilt, but all four pads all extremely uniform in thickness.

No white spots on the factory pads. Compared to the repeated abuse that track time puts on them with limited cool-down time, my infrequent hard stops on the street don't seem to be abusing them much. So after seeing how well the factory pads are wearing with the same rotors, I can only assume the RB pads suck for street use and must deposit material unevenly at the lower usage temps on the street. I'll hone them lightly and go with another set of factory pads and see how they do. Thanks

 

Agreed that looks like uneven pad deposits. Problem is once you have them, they are hard to get off. You'd basically have to run a very aggressive pad for a while that scrapes the rotors clean. Sounds like it was the RB pads that caused this and the OE pads are probably softer so they did not remove the uneven deposits. My OE front brakes are down to about 3mm and have started to make a noise at very slow speed under light braking. I'm at almost 19k miles and I've looked at the RB rotors, but I'm most likely going with the Brembo set from FCP as well with fresh OE pads. It looks like the Brembos are true-float rotors, while the RB like OE rotors are only semi-float.

 

I'm not sure that the pads that came from RacingBrake are made for the track. My impression was OEM compound equivalent.

For the record, I run Raybestos ST-47 on the front and ST-45 on the rear for track days. Zero complaints! For street use, currently I'm running OEM on the front and RacingBrake's pads on the rear. I have new fronts from RacingBrake and those will likely go on after weekend at the track next month. Car has 26k miles and the front pads are original, but thin, so about time.

 

superswiss, aren't the front calipers fixed and the rear, float?

Unsolicited editorial comment: Why AMG dropped the 4 piston Brembos for the rear brakes is beyond me to understand and a real disappointment.

 

superswiss, I think that's a great assumption.Clearly I didn't get all of the deposits the RB pads left on the rotors, and it must have compounded itself further with the factory pads. I've never run another compound to clean rotors, but that sounds interesting. I'm going to pull the rotors and clean with a brake hone on a cordless drill, and rig-up some sort of spindle to spin the rotors properly so not to trash a 2k set of rotors

W213e63s, the one comment I'll add about the RB rotors and pads that I ran... I never got 100% braking force out of them from high speeds - never. With factory rotors and pads, I could stomp on the brakes at 120 and I'd get immediate ABS intervention, but with the RB pads and rotors, I never got lock-up at speed. I would say I got 90-95% of the friction that the factory brakes provided, and this occurred even after a B maintenance with fresh brake fluid bled through the system. However, the RB never went away from fade. I always got the same braking force immediately after running back up to speed and hammering on them again. I just think that they're pad compound isn't a good match for the rotor material, or they require some god-like bedding process that if it isn't absolutely perfect, it leaves the rotor with deposits that diminish braking friction. Not sure what it is, but I will never pair another set of whatever-they-sent-me pads with their rotors.

 

Anyone have any experience with Girodisc rotors?????????
Mine will need replacing soon and I was planning on Racing Brake until reading this thread....

 

Doesn't sound like you're overheating the pad compound. How did you bed in the RB pads and did you re-bed after reinstalling OE pads? I'm thinking that the RB pads didn't get bed in correctly and you didn't get the all important even transfer layer on the rotor for proper adherent friction. If you didn't re-bed after installing OE pads, the pad compound difference between the RB and OE pads could also be amplifying the problem.

I'd avoid trying to remove uneven pad deposits by any means other than re-bedding or properly turning your rotors if they are above the minimum thickness. Its going to be very hard to keep the rotors surface even which is most likely going to further amplify your problem.

I would try re-bedding your brakes using the procedure outlined in this link.

 

I would (and did) go with the Brembo 2-piece floating front rotors (from FCP Euro). They work very well and run a lot cooler for track running, especially if you fit some brake cooling ducts (because they capture the injected cooling air _much_ better than stock rotors).

This thread is a good on for this topic:
https://mbworld.org/forums/c63-c63s-...nt-rotors.html

 

how do the brembo’s compare in weight vs oem? I went with racingbrake specifically for unsprung weight reduction.

 

The (worn) OEM rotors weighed 31.25 lb and the (new) 2-piece Brembo replacements weighed 30.85 lb (weighed on a certified scale). Given the wear on the OEM rotors, I'd guess the 2-piece rotors were about 2.5 lb lighter. Not a huge weight reduction, but they do have good braking and better heat-dissipation performance and I like the fact that they're designed by Brembo and used on other Mercedes and AMG vehicles.

I've also weighed tire/rim combos and typically see about 51 lbs for front 19" and 56 lbs for rear 19" ... so this plus 31-33 lb of rotor plus the hub weight means there's 85/90 lb of spinning front/rear mass per corner. A 245/35x19" tire runs about 784 revs/mi and at 125 mph/201 kph you're covering a mile in about 29 sec so that 85/90 lb mass is spinning at about 1,570 rpm ... or say 1,000+ rpm at common corner/turn-in speeds!

If you've ever started up a side-grinder (or other hand-held spinning tool) that has a relatively heavy spinning mass (e.g., a diamond cup-grinder wheel), you've felt both the "kick" from the accelerating mass _and_ the ongoing gyroscopic effect that causes the entire tool to resist direction changes. When I weighed the rotors and thought about it, I had a new-found respect for the idea of turn-in response, forces on steering components, etc. because of all that spinning mass (yeah, OK, I'm a geek).

 

I have had RacingBrake rotors on multiple AMG I have owned. I was one of the first to ever run them & even been guinea pig development tester for many of their product lines. Their stuff is bulletproof if you use them properly with the CORRECT type of brake pad. I am insanely Abusive on my brakes never had a set of their rotors go bad on me and I’ve put over 60K on them. I have always run stoptech fronts and factory rear pads and never had any issues. Had them on the heavier chassis too which is way tougher on them that Cclass chassis which is much lighter. Something is off, my rotors have been insanely hard and last forever with zero pad deposits and wear perfectly evenly. The weight savings on the larger Mercedes chassis is insanely high (often almost 40lbs of rotating unsprung mass reduction which makes a massive improvement in both handling, performance, steering feel, and even better/softer ride quality with improved rebound speeds).

for what it’s worth you should not be having issues, contact them directly

 

I did a lot of research on racing brake and their products when i did my c43 brake upgrade to the c63s calipers. i trust my life on the track/street and family's life on the street with the brembo/oem mercedes 2 piece rotors with oem pads or porterfield r4s pads. The weight difference between the racing brake rotors and the oem brembo rotors was enough to scare me off to get the oem brembo setup. iron is iron. the 2 piece design already saves the weight. their "proprietary" iron compound which is somehow stronger and lighter seems like advertising fake news to me. sounds like less structural integrity to me. if you do a search you will see a few of the racing brake discs failing on the track. I havent seen any reported fail daily driving but a few corvette owners didnt have a great track day with them. You dont see brembo rotors failing like that. just my .02. Why redesign the wheel, brake*. Mercedes/Brembo has probably millions of hours tested on these brake setups as they span multiple generations of cars and models. if you really want lighter brakes just get the CCBs. Otherwise stick to oem or equivalent. and a cool trick, FCP euro literally replaces your used brakes for free* that you buy from them. send them in buy new ones and they refund the new ones once old used stuff is received. so essentially new brakes whenever you want for the cost of shipping. put that difference you saved on brakes into a pair of forged wheels and youll get even better results since you are reducing more weight away from the center of the axle.

 

Talk about fake news advertising. I run the racing brake rotors only at the track with Raybestos ST-47 (front) and ST-43 (rear). Brembo rotors fail, too. All rotors fail at some point. Just do a quick Google for Brembo rotor failures.

This whole idea that FCP Euro replaces rotors for free is BS! Or...is it? As I was writing this I decided to call FCP Euro, and what OP and others have said is true! I said to the guy on the phone: "say I buy a set of Brembo rotors, daily drive and track the car and after two years the rotors start to crack (they all do, BTW), you're saying I can buy a new set, send in the old ones and you'll refund my purchase?" Guy says, "yes, that's absolutely right." I said, "I don't understand how this works but okay. It's like Nike saying buy a pair of our shoes and after you've worn them for three years, just buy a new pair, return the old ones and we'll refund your money. I still don't understand why you would do this but okay. I'm buying my next set of rotors from FCP." Guy says, "I don't exactly understand either but that's the way it works."

Hot damn!

 

Figured I'd post an update after almost 75k miles with the Racing Brake rotors on my 2016 C63S...

Never again... Period. I got about 40k out of the first set of rotor rings, then I changed them out with a new set of rings onto the original hats. The rotors last longer than the factory iron by about 4-to-3 in mileage, but I never found a pad compound that was properly matched/compatible with whatever iron RB used in these rotors. No matter what the compound, they would never bed-in and remain smooth with heavy use. They would be fine for normal driving, but any heavy use would cause them to hot-spot and get very rough when braking hard from high speed. I have run the RB pads originally supplied with the rotors, MB factory pads, Porterfield R4-S, EBC Yellow, EBC Blue, and Brembo Low-Metallic pads. The RB pads were the worst of all with really crappy braking performance. The EBC Blue were the best in performance, but they would still hot-spot and be rough until enough regular street usage would smooth-out the bedded coating again. The latest choice of Brembo P50127 Low-Metallic pads has been the best of all with pretty good performance and very little hot-spotting and unevenness after heavy braking, but the kicker is this...

I have had a loud knock develop in the front left suspension, and myself and the dealership have been unable to find it until just recently... Turns out, the hardware securing the rotors to the hats has either been worn down or it has wallowed-out the holes in the rotor tabs, causing the rotor ring to float around :/ The hats were wiped clean, and the new rotor rings were installed using the supplied new hardware torqued to the designated specs. They have about 35k on them now, but they have been making noise for probably 5k, and the looseness has not been evident during the last pad slap nor when troubleshooting at the dealership. I'd surmise that there's too little load-bearing area for the stresses induced on the hat by the rotors, and the hardware screws are likely the sacrificial parts, but I won't know for sure until I pull them next weekend and inspect. If the rotor tabs are ok, I could order new hardware and remount the rings, but they are nearly worn-out again plus they have been a fairly miserable and rough street experience, so I'm wiping my hands of them and going with Brembos from FCP Euro.