Celicasaur

Figured I'd post here since the W212 forum is so dull.

Do you C63 guys have 2pc front rotors on your models? My friend has a PP C63 (MY2013) but he doesn't have 2pc rotors, although his fronts do look a little lighter than the usual 1pc disks because they have some odd cut-outs and indentations around the hub of the disc.

Have any of you done the conversion to a 2pc rotor and did you feel an improvement in acceleration due to the lower rotational mass?

My car already has front 2pc rotors and while the rears look like they've made an effort to reduce the weight with the strange indentation around the disc hubs, I'm wondering if I'd benefit a notable amount from buy 2pc rears from Girodisc...?

I did lighter tyres on my car a couple of weeks ago and it made a noticeable different considering that each tyre was probably only around...2kg lighter each! I went from the original Bridgestone RE05A to Continental CS3 in a marginally narrower size. I'll most probably go for Michelin Cup 2 tyres as the summer dawns on us.

Supposedly their front rotors are worth around 8lbs in weight savings on the front, but the rear is a lot smaller, so I'm guessing the difference won't be as big on the rear....but perhaps you folks can share any experiences...



As for pads...I'm probably going to stick with the OEM MB units...they seem to be good enough. Any others worth taking me away? The OEM's don't squeal and they stop the car nicely....they create loads of dust, but....meh

Mort

The PP rotors are two part rotors cast together and they are lighter than the one piece base rotors. The hats are aluminum and the rings are cast iron. You will not gain nearly as much of a weight savings with the two piece rotors as you would over the none PP one piece rotors. They are often referred to as 1.5 piece rotors. The rear will definitely offer some weight savings.

Wobble64

Please check the FAQ section for brake info.
https://mbworld.org/forums/c63-amg-w...-stickies.html

561design

Im heading up to a shop to have my 1.5 measured and they'll convert it over to a two piece. Supposedly this shop can produce these significantly cheaper than what's out in the market today. I'll post my findings tomorrow.

Wobble64

Hope you don't mind me asking: Why would you go to a local shop to have a 2 piece rotor custom made instead of going to a reputed brake supplier and buy their tested 2 piece offering? If your custom brake was cheaper than one from, say RacingBrake or Girodisc, where would the savings come from if not from the quality of the raw materials? I do not quite get the rationale.....

561design

Well, the shop has made brake rotors for Indy car and nascar. So I'm pretty sure they can make a great rotor for me. They claim a two piece can be made for around $500 where as the shops retail for well over $1000. I don't consider myself cheap, but that's enough of a savings for me to look into it.

Wobble64

Interesting, thanks! Yes, a set of 2 piece fronts is around 1000$, so that is a good price. The RacingBrake fronts (2 piece, standard size 360x36) are 1246$ including a set of pads on their website.
Well, please keep us posted on how that goes! It would be interesting to hear who they use as supplier for the blank rotors and whether they buy blanks or subcontract it complete including fabrication (again, with who)?

Celicasaur

Thank you, that's really insightful.

When you say 1.5 piece rotors...you're referring to the C63 PP front rotors aren't you? The one on my E63 is the one with the black hat and little bolts around the edge, so I'm guessing that's a genuine 2 piece rotor....?

Here's an example of my front discs:


And this i assume are the 1.5 discs on the C class:




These are my rear rotors...I think they're the same on the C class...right?


So these ones, are the ones most likely to give me the best gains in terms of reducing rotational mass? Seems they at least made the effort from the factory to remove as much dead weight as possible though. I wonder if the savings are going to be worth justifying the cost purely on the weight savings. For me...i would consider it worthwhile to save 2-2.5kg per rotor.

Celicasaur

Thanks man, I didn't know of this. I'll read it through now

Mort

Your first pic is a two piece rotor. Your second pic is what is referred to as a 1.5 piece rotor as used on the PP C-Class after 2009MY. The third pic is a solid rotor.

Here is an example of Racing Brake OEM replacement rotors for your E-Class. There is chart for weight savings included.

http://www.racingbrake.com/RB-Two-pi.../mb-irk-21.htm

561design

so it looks like I have to be a Guinea pig for these rotors. The type of metal they use is for track performance and not street longevity. With that said he claims the rotors can be noiser than the street versions and will wear faster. They have a foundry they source their rotors and they have to order extremely large quantities to change the metal. They're apprehensive about doing a road formula because they're already doing well with what they have and it appears to be a pain for them. He also claimed concern for the rotor heating and cooling quickly on track and then switching to road use. To the extent a rotor might blow up. He recommended doing a slotted only rotor to reduce this and a few other tips to consider to mitigate these troubles. He didn't even quote me a proper estimate after he sized my rotors. He said he has to work with his guys to generate a quote. I'll keep you guys updated on what happens.

BLKROKT

You lost me at the "might blow up" part

561design

He said he's known a couple cars used for track and street where the rotors ended up getting cracked and in one cause blew up into pieces when the guy was driving home from the track. Something about extreme cooling from driving in the highway and then having to slam the brakes in an emergency stop. He believed the rotors possibly got cracks from heavy track use. The long cooling that occurred from the highway drive home didn't help.

Wobble64

You do not really HAVE to be a guinea pig. You could just buy a proven rotor for the same kind of money from RacingBrake or Girodisc. Or get Brembos from FCP - with lifelong replacement warranty. You have options..... :-)

Just sayin.

561design

They are the ones that make the rotors for Girodisc. So I'm confused why they're giving me a different story in regards to product quality. They're the same exact rings and hats I saw while they were giving me a tour of their facility.

Celicasaur

Thanks man


So, it looks like the rear saves around 3lbs per disc...hmmm.....i'm on the borderline with this one...that might not be enough of a weight saving for me to justify the cost tbh.

Wobble64

The weights are per rotor. 23-16.6=6.4 lbs weight reduction per disc for the rears

Celicasaur

Oh wow really? I just remember that one time in a thread by Evosport, the overall weight saving gains we said to be per axel, so I assumed it would be the same here. 6.4lbs per rotor is a decent enough loss of weight for me...hmmm....This may be my next engine mod after I get the cams done on my engine.

Celicasaur

Hey guys,

So i did my brakes this week - had them skimmed by a local machine shop and they were fitted yesterday along with a suite of OEM brembo pads.

For reference I weighed my rotors - granted they've been used and lightly skimmed, so they will be slightly lighter than a fresh set.

The front two-piece rotor came in bang on at 10kg == 22lbs
The rear one-piece rotor came in bang on at 9kg == 19.8lbs



Looking at the weights above posted by Racing Brake, there's quite a discrepancy in the OEM weights, isn't there? They're 3lbs off from the rear and let's assume 6lbs off from the front. Makes me question the accuracy of the weights posted for their two-piece rotors now.

thesaintusa

How did you weigh the rotors?

Place them on a bathroom scale by themselves?

Weigh yourself with and without the rotors on a bathroom scale?

Take them to the grocery store?

Just wondering if your scale is the issue rather than the reported OEM weights.

Celicasaur

Bathroom scale several times and ensuring that it's showing a clean zero every time before the measurement.

Bear in mind, the weights I posted were after many miles of use and after I had just had them skimmed.

The car has done 79k. I'm reasonably sure that they hadn't been changed before....but then it's hard to tell. Maybe they were changed around 40k or so.

ENVē

Between the Girodisk and RB offerings which have been more widely used by guys on here with no bad reviews?

Gerry_M

You are probably not going to get much in terms of acceleration with lighter rotors. Their weight savings come from the HUB, unlike the tires where it comes from the wheels perimeter.

Celicasaur

oh, that's a good point. yeah, the further away the distance from the hub the greater the improvement.

i'm quite happy with how the car is braking now and given that i can't see the benefit of the two piece upgrade vs stock by comparing against their own numbers, i'm going to hold fire for now until/unless another member can prove that they're lighter.