upgrading rotors
 

recommendations for cross drilled and maybe slotted rotors for the c55? Can I increase my rotor size while keeping the same calipers? I'm not really trying to spend like 4k on c63 brakes either...:nix:

Racing Brake has some swell two-piece hardware.

Are yours suffering fade, or are they just too heavy?

I just read that racing brake post.

Actually; I didn't notice any fade at the track in 15 minute sessions with 45-60 minutes of cool down in between but i believe i warped my rotors just a tiny bit. There's just a little bit of more vibration in the brake pedal under braking and the rotor doesn't feel as flat as it should be. So, if I'm going to replace my rotor might as well upgrade it?

The stock rotors are nice and big already. The slight brake judder you are experiencing since your track event is likely some uneven deposits of brake pad material on your rotors. Give it a few weeks, and it should go away (it always goes away when it happened to me after tracking my C55).

In my opinion, there are 3 reasons to upgrade to better brakes: 1) if you feel you need better stopping power, or 2) if you are experiencing fade during track events, or 3) you simply want to reduce unsprung weight.

From my experience on the track, the stock C55 brake system is very adequate when it comes to stopping power. On very tight courses where there is a lot of braking and lack of straights for cooling, the pads/rotors could over heat a bit, but for the most part the only side effect is that uneven deposition of brake pad material which I talked about. For the first 2 reasons listed above, a simple change to better brake pads and upgrading the brake fluid (with higher boiling temp) will achieve what you want at a fraction of the cost of upgrading the whole brake rotor/caliper setup. I would try that first to see if you get the desired effect.

With regards to reducing unsprung weight, you can start by simply replacing the heavy stock rims with lighter ones.

Sure, there are fancy rotors/bigger calipers/big brake kits which look cool, but ask yourself what you are really aiming for.

Thanks for the information! The brakes don't feel any different in terms of stopping power after the track day but yeah, I was concerned about the judder. I was suprised that the c55 brakes had no fade during the 15 minute long sessions on a tight, large, gokart track (80+mph was the fastest I got on the straight away).

As for the brake pad material stuck within the drilled holes in the brake pads; does that go away naturally as well or should I take off my wheels and try to clean them out manually? I've only auto-crossed before so I never have pushed my car this hard.

What about the softness of the pedal? I feel like that brakes on the c55 are too spongy compared to my friends 335i. I had the brake fluid flushed a while ago and it felt the same afterwards...would the SS lines help with that or is that just under heat?

I really can't say enough good things about the RacingBrake rotors. I have the open slotted ones and love them as much as the day I bought them. They've held up really well too. They look and feel like the day I bought them.

The brake dust/material within the rotor holes will eventually fall out. Note that the powdery brake dust in your rotor holes is not the cause of the brake judder. You may or may not be able to see a layer of brake pad deposit material on the rotor itself. If there are more deposits in a certain area compared to another, that's the cause of the brake judder.

And yes, I forgot to mention stainless steel brake lines. When the system gets hot, the rubber brake lines expand, causing that "mushy" feeling at times when you are pushing it. Upgrading to stainless steel brake lines are another cheap way to get rid of that.

I'm still happy with Racing Brake rotors; have not had any problems. I just wish they would make two piece rears to match.

+1 I dream about that at night :y

+1 on what PC said-I took my C55 out to BIR last year with a stock set up and had very few probs after 30min sessions (130+mph top speed at the time)-then went and talked to the gys at EVOsport and got a diff set of rotors (lighter), slotted-not drilled, pads, lines and fluid-made a great improvment on consistancy and longer time out on the track-

What kind of pads do you guys use on the Racing Brake 2-piece rotors? I've had Akebono ceramics since I installed them last summer, and have had some vibrations while braking. Called Racing Brake and they told me that I shouldn't be using ceramics on their rotors. Was surprised to hear that.

So, I'm thinking about switching them out; car's mostly driven on street, except an autox two a year (though will probably be doing Starfest this September :zoom: ).

I have Akebono's on there as well. They seem to be the least aggressive ceramic around. RacingBrake recommended I not use ceramics when I bought them, but there aren't many good non-ceramic options for our cars. I know the vibration you're talking about, but it's not that bad on my car and doesn't really bother me. I just kinda think of it as what "bite" feels like. (if that makes any sense) If I find a nice non ceramic pad, I'll probably use that next. I just can't stand all the powder the OEM pads produce.

Feddoro S2000s are what I left my C55 with-loved them-looking at ST-43's for the Pcar track-OEM's are Brembo pads iirc-not great when compared to official track pads-but certainly better then most OEM you'll find on cars!

You should check out the Stoptech rotors. They now offer their 2 piece rotors in stock sizes for many cars. Just an idea.

Les

Thanks for the info. Just got an email from Racing Brake - they recommend Axxis. Might try their XBG's; Porterfield's R4-S are always there as well. I'll pick one or the other.

Porterfield R4-S were the best pads I ever had but, then again, I don't race on a track.

I had Porterfield R4-S's on my car for almost an entire season. They make some noise first thing in the morning and don't stop as good as the stock pads when cold. Just driving around produces very little dust. Get them a little warm and they stop great and are silent. I tracked them with success until the track configuration was changed and the braking zone went from 115 to 45 to 130 to 45 and they got too hot and melted. A person I trust recommend's DS2500 Ferodo but I've never used them myself. I'm going to lots of track days so I'm going with Carbotech XP8 for my next pads.

Les

I ran the Axxiss pads for a month-hated them-dirty pads-very dirty-slight squeek at low speed stops-

Oops - ordered Axxis two hours ago. :eek:

Dirty's ok; have gunmetal powdercoated rims. Squeek is ok too, since my Eisenmann race will pretty much drown out anything. :y

Will be on this time next week, and will post thoughts then.

Well, the juddering is gone just like you said but the brakes have always felt a little soft compared to bimmer's..but thats under normal driving and not when they're hot...i've driven other mercs and they all kind of feel the same too. I think if I track my car more I'll upgrade to semi metallic pads and steel lines?

I'm also using Akebono's, way less dust than stock.

"I know the vibration you're talking about, but it's not that bad on my car and doesn't really bother me. I just kinda think of it as what "bite" feels like. (if that makes any sense)"

I know what you're talking about as far as the feel under heavy braking. I don't think of it as a vibration, but can't think of a better way to describe it. I didn't know RacingBrake discouraged them, I guess I'll try something else when it come time.

I think that's just an inherent difference between Bimmers and Mercs. I had a 328i MT and the brakes on even that basic model bit harder than my C55. I'm certain the C55 stops better than the 328 but you could never surmise that from just the feeling.

Although I did drive my friends new 135i 6speed and his brakes were TOO sensitive. I braked normally in it like I did with my car and we were almost flung into the dash lol.:eek: