RacingBrake aka RB rear replacement rotor review

[Richbot]

I have had these rotors on my car for a little under 6,500 miles and want to provide a brief review.

First, on fitment, and in the interest of full disclosure because I mentioned it elsewhere on here, the rear rotors I was sent, at first, did not fit the car. Over about a month of back-and-forth with me trying to bodge a measurement with feeler gauges and them trying to figure out wtf was up, we realized that there had been a running change in RB's M car rear rotor design and my set of rotors were about 2.5mm too far inboard, which meant they interfered with the rotor bracket.

This might not have been a problem if not for the fact that RB uses a 26mm (thicker than stock 24mm, better, high vane-count) friction ring, but they do, so we had to send them back and forth to finally get me a set that fit. Once Wayne at RB got involved, it resolved really quickly and he says this the only set that shipped with this issue. Glad to have the extra thickness of the rotor, but they use every bit of extra clearance and even recommended taking a bit of material off the bracket to increase clearance if I wanted to be double-sure, but this was NOT necessary on my brackets and there has been no scoring or any other evidence of them ever touching the brackets even when hot.

They were responsive via email service@racingbrake.com though I think we can all agree their website and user interface there could be better, I am satisfied overall with how everything was handled and how it turned out. They clearly were motivated to get the problem resolved as opposed to just taking the rotors back and writing off the sale, and I think they would agree I was patient and realized these are custom race-derived parts and things don't always go perfectly the first time around. Anyway, good attitude, better than some vendors I've dealt with for sure. And it's nice to deal DIRECT with the MANUFACTURER as opposed to going through some parts schlepper middleman no offense to the parts schleppers out there.

Once that was resolved, they fit fine. Note their kit included a set of their own street pads. These also fit just fine. I was not able to get a set of stock pads to fit over the rotors, but I think that's because the stock pads have some additional padding/backing/antirattle on them that takes up all the slack there is when using a thicker rotor. But the RB pads fit fine and are perfectly ok street pad, no sqealing or squeaking or bad behavior at all, not that you'd notice a ton of issues with a rear pad unless really pushing.

I recently bedded in a set of Ferodo DS2500's on my front stoptechs, and the rear RB's got a nice bluing but otherwise never really got hot enough to care. I would want to double-check fitment with an aftermarket track pad before getting caugtht out at the track, but RB also sells a track pad that no doubt would fit the increased thickness if you need it.

Upon install, I sharpied the hardware with telltale marks to watch for any bolts backing out since they're nice bright coated so the sharpie is easy to do a quick visual for loosening, and have experienced none. After adjusting the parking brake, the parking brake works better than with the ECS rotors I had on the car before, but I think that's mostly my laziness not adjusting the ebrake for 100k+ miles.

As you can see from the pictures, taken today, wear so far has been basically negligible. The crosshatching is still present across most of the face on both sides of the car. I may never buy another set of E9xM rear rotors.

Also included a photo of how they look paired with a slotted BBK rotor like Stoptech's 355x35mm front on my car. Looks better than holes, not an exact match, but better.

The party piece (beside the friction ring and airflow being faaar superior to stock) is the weight savings. My car lost nearly 8 lbs (est.) vs. stock and 7lb (measured) vs. ECS rear rotors, for about 1/2-1/3 the cost of some rear BBK kits that either don't lose any weight off the car at all, or lose only a pound or two. THe only way I know of to drop more brake weight out back is the AP Essex kit or going to CCB's. But there's not strictly a need for a multipiston rear brake on these cars for street use, and that's what my car is used for, so, win for me. For reference the wheel/tire setup is 275/30-19 PS4S on square 9.5" 220M with a 5mm rear spacer. Front kit is the Stoptech Trophy STR40 Street kit with more than 55,000 miles on it.

Anyway, endorse.

[bmwfst1]

Is this kit only for the e90? Those look nice.

[Richbot]

E90, E92, E93 M3 and E82 1M all have the exact same brakes. The only exceptions are GT4, GTS, and CRT.

[bmwfst1]

Ok thanks I will definitely get those when I need a rear brake change.

[wyatth]

Nice review. Bummer you’re forced into RB pads in the rear though, perhaps.

[Richbot]

I don't think you are, I think the extra mm or so of anti-NVH padding on the back of the OEM pads makes the difference there, and most aftermarket pads don't have that stuff on them. They were REALLY close to sliding back on but I punted rather than bust a knuckle

[M3 Number 86]

so good to go with these?

I might just FCP the rear rotors lol

[derbo]

Originally Posted by M3 Number 86

so good to go with these?

I might just FCP the rear rotors lol

Be Chinese and do the FCP way

[Richbot]

lol

I have zero data on tracking these yet but I'd have no reservations for a street car and when I finally use up the rotors on our W212 I'll probably use their replacements, but those bastards are 36mm thick with a 33mm minimum thickness so I ought to have at least one more pad change first. The friction ring design is certainly far superior to a stock rotor I'm sure it'd hold up better on track all other things being equal