05RollaXRS

He meant RT where RC-F is substantially quicker than the M4 (and a tad slower than M3).

Randy Pobst is a professional race car driver. He can extract more out of the car than 99% of the drivers on the road can. If can only get 3/10ths more out of a second out of the M4 on that specific track, majority of the drivers will not be able to do that. Also, remember the M4 had the optional $10K carbon ceramic brakes that made the difference. On standard steel brakes like the RC-F, RC-F would have been quicker.

Besides, the issue is not oversteer. The issue in the M4 is the power delivery. RT said, M4 has a very unpredictable and non-linear power curve (some of it could be attributed to boost lag where there is no power once the throttle is pressed and suddenly gobs of torque available upsetting the chassis resulting in the rear end breaking loose.

Levi68

The RC F is simply fisting its rivals. Awesome car. Toyota over Germany (this coming from a german german car fan).

lobuxracer

iTrader: (2)

On what basis do you make this argument? It certainly isn't stopping power because carbon or steel makes no difference in stopping distance. Tires and available traction make all the difference in stopping power. So you are assuming the small difference in unsprung weight gave the M4 the advantage?

05RollaXRS

Randy does not just sit in the car go for a timed lap right off the bat. He does multiple laps in each car. You do realize the hotter the carbon ceramic brakes get, the better they brake? Completely opposite to how steel brakes perform. The brake fade on the carbon ceramic over steel brakes would have been less giving Randy more ability to brake late in M4. Plus, as 4TehNguyen once posted the specs, M4 carbon ceramic brakes have superior design complete with more clamping force through more pistons (6 front, 6 back) than the steel brake version.

I 100% believe the lighter weight (read 15 lbs per corner on Bimmer forums), having better late braking ability due to better clamping force design and less brake fade over multiple lap all contributed to the M4 lap time.

lobuxracer

iTrader: (2)

Fade? On either of these? Impossible. My IS F doesn't fade in a 20 minute session unless I leave the stability controls on and drive like an utter idiot. Fade didn't enter into the equations for either these cars. Numbers of pistons, swept area, leverage ratios, rubber or stainless lines - all this is marketing BS to sell more expensive brakes. Braking distance is limited by the tire's ability to grip the road unless the braking system is so poorly designed it is incapable of locking the wheel or is uncontrollable at impending lock up. Later braking because the brakes are lighter is in the imagination of the marketing department, not the reality of a track driver. Even if the difference is 60 lbs, it isn't 2% of the total weight of the car. Later braking because the whole car is lighter is definitely NOT in the mind of the marketing department, but in the calculations any basic physics student can understand.

The only advantage is unsprung weight and overall car mass, and that is the big question mark on a track as smooth at Streets. If it were as hashed as the track they set up for the AMCI testing, I'd say there's more of a chance, but there is no inherent fade resistance difference anyone will notice on a track this short and this slow.

NewSpace

The simple facts that ceramic brakes stay cooler over the course of intense use will make them slightly more effective, but it's true that the benefits are marginal on anything but paper.

05RollaXRS

It has better design than the steel brake version installed on M4. According to BMW, it gives more clamping force than steel brakes so stronger braking abilities.

The carbon ceramic brakes are 6 piston front and 6 piston rear. The standard steel brakes are 4 pistons front and 2 pistons back. I personally believe it makes a significant difference.

spwolf

Well, many M4 owners have reported that stock brakes do fade after 5-6 laps... so maybe RC-F's dont (and all reviews said so far that they dont), but M4's sure do.

spwolf

I didnt realize that RC-F was faster than M4 on RT track:
http://www.roadandtrack.com/car-revi...he-motown-mile

Obviously RC-F is such a heavy, terrible car :-)))))

05RollaXRS

In the M4's defense, RT lap times suck badly. M3 and M4 are essentially the same car, yet they have them apart by several seconds (bus lengths). They say the track is extremely bumpy and rough that does not allow the chassis to settle. Stiff cars without adaptive suspension struggle on this tiny little track. They also use several different drivers.

Randy Pobst on Laguna Seca is much much superior to this shoddy effort. We have to wait till the end of the 2015 to see how RC-F does around Laguna Seca.

TimboIS

Uh no! They don't stay cooler. CCB's work better under higher temps, whereas steel will fade. CCB's work at their optimal once they're brought up to temp.

lobuxracer

iTrader: (2)

James Walker, a senior stability and braking systems designer says calipers do not stop the car, and all this chatter about carbon brakes misses the whole reason they exist in racing - they drop unsprung weight dramatically. They have zero advantage in stopping power because the brakes don't stop the car. The tires do. You can believe anything you want, but it is not based in science or engineering, it's just belief.

05RollaXRS

Yes, I can believe what I want and definitely they make a substantial difference. It is not a debate of which brake make the cars stop shorter. It is a debate of which brake works best on the race track. Tons of experts and race car drivers say the something. It is indeed based on science and engineering of how carbon ceramics brake better and better as they get hotter as opposed to steel brakes fading as they got hot.

Not only resistance to brake fade due to carbon ceramics, in the case of M4, if you think clamping force of 6 pistons front and 6 pistons back does not make a difference compared to 4 pistons front and 2 pistons back then that is laughably ridiculous.

I will leave it at that.

lobuxracer

iTrader: (2)

Marketing over science and engineering. Nice pick.

Here's a great primer written by a guy who has forgot more than the sum of Club Lexus knows about braking systems. He wrote it in 1991 for Grassroots Motorsports Magazine, but it is timeless.

http://www.scirocco.org/faq/brakes/p...n/pfpage1.html

05RollaXRS

This video illustrates it best.

LFA on cold brakes with ceramic brakes accelerated quicker, but braked 2 feet longer than the R8 V10 with steel brakes.

Then on the second run, LFA's brake now with some heat in them stopped shorter than its first run while R8 V10 with steel brakes stopped 17 feet longer than its first run.

Pro race car drivers also explaining why LFA was getting better on second run with carbon ceramics and why R8 V10 was getting worse with steel brakes suffering fade after just one run.

Irrefutable real world proof of how carbon ceramic brakes get better and better as they heat up while steel brakes (even as huge as the one's on the R8 V10) rapidly fade.