I know the twin rotor design of the P30 brakes help prevent brake fade, which is great at the track, but has anyone ever seen any braking specs specific to that option? Different pads, different rotors should equal different results, no?

Also, can anyone say definitively if non P30 rotors fit P30 cars? I'm just trying to sort out if they are really worth the extra money given that at approx 24000 miles I've been told my brakes are at 40% and these rotors cannot be machined (this is from an independent shop). If they are all about fade resistance than I'm not sure as i only get a couple track days per year, but if they have a shorter stopping distance or better wet braking than its a no brainer as that can turn an accident into a close call. But......perhaps a better pad would help make up the monster differential on rotor cost.

Also, with brakes at 40%, at what percentage would you replace? I want to get full value but I also am aware of the declining performance and I'm not sure where x meets y as it were.

In a perfect world or in other times it would be cost be damned, but unfortunately life's not like that right now and so I need to save some nickels and hope the dollars take care of themselves. Having said that if I need to invest I will ie if aftermarket rotors that cost more up front (ie evosport) last longer and are cheaper in the long run then that's an option too.

BTW some will wonder what fool gets a p30 knowing (or not) what a brake job costs. Short answer is when I bought this car (used from MB dealer) I checked on pricing but was told they had an 80000km (approx 48000 miles) life span and just got new pads. 10 months later here I am. I am all city driving and I have a lead foot, and I have tracked 2 or 3 times, but I did sort of expect to get through til next summer and replace for the 2013 track season.

I'm not a chump in an Aventador with no money for insurance, but I sure have other places to spend my dough.

 

replace when the light comes on.

How many KM on the two piece rotors??

I had 60K KM on mine and there was still tons left.

Id say you could do 120k km on them easy.

I did a few track days as well.

Measure rotors with calipers to see how much meat is left. Min thickness is stamped on them, no need to machine them unless they are pulsing. Just throw on new pads.

 

If you don't care about fade resistance, but want to shorten braking distances, tires will make a bigger difference than brake system hardware.

 

If you can lock up the brakes/activate ABS on a dry road, it's your tires that are the weak link. Typically any old set of brakes can do this and stop fast once. Fancy brakes are for track days.

 

I understand what you are saying, but I am not asking about tires. I am on Dunlop Direzza Star Specs in the summer and Continental ExtremeContact DWS the rest of the year. My tires are fine.

I am asking specific questions about brakes as replacement is on the horizon and not looking for tires. Does anyone actually read the post or do they just glance at the title and toss out any answer they please? I try to give specific answers to members specific questions but sometimes it feels like talking to a cranky, hard of hearing grandpa at Xmas dinner in a loud room.

A real life example I experienced;

Me: I hope I get some speakers for Xmas cos mine aren't working.
Grandpa: you don't need speakers. Problem is that crap music you listen to. Forget the speakers and get yourself some better music.
Me: No, grandpa, it's not the music. My speakers aren't working.
Grandpa: What you do isn't work. Typing away and staring at a screen all day isn't working. I was raised on a farm. Now that"s work. THATs what's wrong with kids today.

Wouldn't mind some actual answers to some actual questions.

 

And actually, the notion that if you can activate abs in a dry stop that means you need better tires is malarkey. If you want to say that's at xxx mph maybe, but any car on any tires can lock its brakes if you jam on a full stop.

 

To address your first question, I've read/collected probably 15 domestic and Euro road tests of the the C63. Under those test conditions the 60-0 mph braking distances have been remarkably consistent across the tests, generally falling in 110'-115' range. The only problem is that every single test has been with either P30 or P31, so there is no statistical baseline I'm aware of for blank non-PP rotors. My understanding anyway is that in normal dry conditions there would be basically no difference between the two types under normal usage. Many seem to concede a possible benefit to cross-drilled rotors in wet conditions though. I don't think you'll find a definitive answer to your question here.

 

Although I have no empirical evidence to back this up, I highly doubt rotors will make any difference in stopping distances. Fade resistance yes, but distances & feel are more a function of the pads. As for the P30 vs non-P30, other than cost, I'd be VERY surprised if there was any measurable difference in stopping distances.

I believe there was a thread a while back where an Indy shop owner did say that the rotors are interchangeable but until an actual owner can chime in with such an experience, you may have to find out for yourself. The non-P30 rotors are dirt cheap, comparatively speaking, if you get them from getmercedesparts.com and have them shipped to Pt. Roberts ($130 per rotor if I recall). There are pad options as well - Racing Brake has 6 compounds for the C63. I'm currently using their Xt-910 and was previously on their ET-500 compound. Initial impressions are that the OEM pads are VERY good all around but they dust like a ****! The ET-500s were OK but I'm liking and feel that the XT-910 offers more comparable performance to the OEM pads but without all that nasty black dust.

One final note, my front non-P30 rotors lasted 70K kms and my rears are pretty much done now too at 80K. I had two Indy shops, in addition to an MB dealer verify this so unless you have some magical rotors, 120K kms doesn't seem possible. And I'm about as specific as you can get as I'm in the 604 and drive pretty much in the city 95% of the time and the same way you do - pretty irresponsibly lol

 

It all depends from what speed you are stopping. On few occasion I have applied the full anchors from 300km/h with my P30 car and there was zero fade all the way down with no cracking on the discs. Not sure if anyone has done this type of emergency breaking with a non p30 car?

 

^
As the rotors/discs get older and wear down more, there usually will be some minor radial cracks - nothing to be overly alarmed about. I recently did a track day with my non-P30 rotors and they held up perfectly fine & performed well.

 

I would think - if for no other reason than product liability (but cost too) - that these are cast holes and not true cross-drilled. I'd be surprised to see many cracking issues with the OE PP rotors.