Over-boosted or Ceramic-Sensitive?

Don't know about the T, but for my 2011, all I can say is that the braking is confidence inspiring without being "grabby". I thought the brakes on my 911 were great (they are IMO), then I drove my Ferrari, and they're greater than great. Again IMO. Impressive considering the Cali is about 700 lb heavier than the Porsche...T

 

I have 3 cars with carbon ceramic brake systems (Mercedes, Porsche, Ferrari) and the Ferrari is definitely the grabbiest and most sensitive to temperature. CCB work best when they get hot.

CCB are noisier than iron brakes, but I really don’t find it that annoying. In the Porsche forums you will find hundreds of complaints about it and Porsche produced a video explainer on why PCCB are so noisy.

 

I have had my '16 Cali T for about 3 months now, and the brakes are definitely "over-sensitive" IMO. I traded in an '07 599, both have CCB's and the 599 was nowhere near as "sticky" when first applying pressure to the pedal. It's something I'm still trying to get used to.

 

It's good that this topic has been raised.

I've been studying how braking and CCM (or Porsche CCB) brakes work. It's a bit more complicated than it appears and is not properly explained by automakers or even brake suppliers. Here's my short take on this issue of "over-boosted" or "ceramic-sensitive" brakes on the Cali or other cars.

At low speeds, (cold) CCM/CCB brakes only work off friction between brake pads and rotor. This is called not surprisingly, "friction braking". More friction = better braking. The "over-boosted" or "ceramic-sensitive" behaviour you refer to is caused by the "initial bite" between the pads and CCM/CCB rotors. Some people just label brakes with high initial bite as "grabby" brakes. Initial bite is mainly controlled by choice of brake pads as some pads are designed to deliver more initial bite than others. You can also swap CCB/CCM rotors but that is much more expensive and not a good way to alter initial bite.

Fast-driving works better with higher initial bite because you'll be braking from higher speeds on what are most likely to be COLD brakes, as in an unanticipated emergency situation. Cold brakes don't stop well. Higher initial bite also inspires more confidence when braking, because your car will slow down faster and Fcars do tend to accelerate faster than most other cars. OTOH, lower initial bite brakes will exhibit lower friction, result in slower braking (on cold brakes) and may leave you needing a change of underwear after emergency braking on cold brakes.

New owners of Pcars and Fcars tend to be different, depending on specific model of car. I suspect Ferrari didn't want first-time Fcar owners to crash their cars because their (cold) brakes weren't aggressive enough. Brakes with high initial bite do challenge drivers to develop greater sensitivity to brake force application but that is usually a good thing and most drivers get use to it. It wakes you up. My old BMW also had very aggressive street brakes and could easily deliver a nose plant to unsuspecting new owners. I recall one time a silly person serviced one of them with Pagid racing pads instead of regular street pads without telling me and I nearly crashed into a car in front of me when I had to brake for a very slow car that turned into my lane. My car behaved completely differently from before. Those racing pads had very low initial bite and only worked properly after achieving high temperatures (on a race track).

Finally, aside from "friction braking", there's also another type of braking "physics" at work after the brakes are properly warmed up under demanding conditions (like after a few laps on the track) and I think pads with high initial bite would facilitate this warming up process but I'll leave that discussion for another day.

BTW, I believe 599 CCMs were Gen-1 (first generation) brakes while Calis use Gen-2 and Gen-3 CCM brakes.

 

Here’s my take:

If you drive my Carrera GTS with PCCB you will find two things to be true, the brakes are also grabby but nowhere near as much as the Ferrari system and, two, the Porsche brakes are far more effective at lower temperatures than the Ferrari brakes. The 911 and California T are very different cars, not just front vs rear engined but also performance profile. The Mercedes system feels just about the same as iron brakes for around town driving.

Porsche and Ferrari have more experience with this technology in production cars than any other manufacturer, and Brembo SGL manufactures their brakes along with those for many other badges. I simply don’t understand why Ferrari tuned the brake system the way they did for a car that is more touring than track car.

 

I have driven a 991.1 Carrera 4, 991.2 Carrera S as well as a 991.2 Carrera 4S on the road and (the latter 2) also on the track, ditto with my Cali30 on the road and track but I've only test driven an early CaliT on the road once for about 20-30 minutes. These Pcars are very competent and pleasurable to drive at high speeds while the Calis are arguably more edgy, entertaining and engaging to drive at the same speeds. None of the Pcars I drove felt grabby to brake but I also don't find my brakes have too much initial bite as I prefer high initial bite. The CaliT I drove did not feel uncomfortable to brake. It felt fine.

Something to consider are the bigger 390 mm front rotors in the Cali vs the 350 mm front rotors in the erstwhile heavier 991 Carrera. The Pcars also have much wider rear tires 305 vs the Cali's 285 and bigger rear tires result in greater rear braking bias (especially given the Carrera's rear engine placement). These factors do affect brake performance behaviour.

As for tuning for the track, I do feel high initial bite is beneficial and I can see how it can be a bit annoying in a GT application for some people. Unfortunately, if the factory took away more of the visceral feel of the Cali, the pundits will add yet another complaint that the Cali and the "new cars" are too soft and "have lost their way". You can't win. Ferraris cannot just be touring cars or else they fail to be Ferraris.

I also do not drive my Cali30 on a daily basis so each outing is an occasion. I pay extra attention when I drive my car and it never becomes routine. That may add to my tolerance of edgy behaviour as my car already has a lot of aftermarket mods which make the car much more edgy than a regular spec car.

At any rate, I think owners have more reason to complain about the touchy throttle of direct-injection DCT-equipped Fcars!

 

I am left to wonder if we are talking about the same cars. My GTS is 500 lbs lighter than my California T (3,362 vs 3,813) and nothing on the latter feels edgy. The steering is a pleasure, I much prefer the hydraulic rack to the electric steering on the Porsche but you can’t ignore the effect fo the larger tires on the Porsche steering, which feels much heavier but with, unfortunately, no feedback. The 3.9 turbo engine is a pleasure, Ferrari has delivered a turbo that drives like a NA and I really enjoy that mid-range power band. The Porsche HP deficit is not fully felt due to the efficiency of rear engine power delivery.

Current generation PCCB rotors are 390mm, which is equivalent to the Cali T rotors, but the Porsche calipers are much larger. The Calfornia T comes standard with 19” wheels, a PCCB equipped 911 requires 20” wheels and there is but a scant 3/16” gap between rotor and wheel. It’s a bit of a problem when rocks get caught between the wheel and caliper. The PCCB is class leading, serial track guys get that option just to get the calipers and then swap out the rotors and pads for Girodisc and Pagid. It is a marvelous track setup.

As for track, I really wouldn’t take the California T on the track. It could represent itself well on the track, but it is clear that Ferrari didn’t engineer this model for track use. Don’t mistake my comments, it is a thoroughly enjoyable car to drive but I would characterize this Ferrari as an emotionally fulfilling experience while the GTS (and GT3, 911T, C2S) is a drivers car. Every input on the Porsche results in the car doing something. PDCC and RAS is a really special combination on track day. And yes, the Ferrari brakes are way too grabby but I suspect that they level out when they get up to a higher temperature than one will experience driving on the street. I suspect there a difference in the formulation of rotors and compounds that optimizes the Ferrari brakes for higher tempertures and on a 458/488 this is probably a real advantage.

Hehe, your comments on Ferrari can’t win is just spot on. It seems like every enthusiast badge carries a degree of can’t win when it comes to change.

 

Jeff, I realize this issue of the high initial bite of CaliT brakes is of significant importance to you and perhaps the brakes in your car are particularly grabby. I wish we lived close to each other and could compare our experiences first hand. Have you already brought up the issue with your dealer? I should also address some of the points you just brought up.

First, I agree the steering feel of these cars do differ a lot. I understand what Ferrari is trying to achieve with very light steering effort (neutral, NO understeer) but on the downside the light steering ends up removing some of the (tire adhesion loss) feel as you approach the limits of their grip. I also suspect the CaliT's rack is faster than the GTS's. Whether that works depends on personal preferences and the kind of roads being drive on.

Next, my apologies regarding what I thought was the curb weight for the 991.2 GTS. Apparently Ferrari and Porsche publish different weight measurements - Ferrari publishes DRY and CURB weight, whereas Porsche advertises CURB and GROSS weight. I accidentally took the GTS gross weight as curb weight. Gross weight is the maximum specified weight (max passenger/cargo weight), whereas curb weight is akin to WET weight or the car with all lubricants, hydraulic fluids, full tank of fuel (see below for relevant hot links and screen scrapes). So you're right, the CaliT is actually about 420 lbs heavier in curb weight configuration if we are comparing both cars as convertibles.

The reasons for the CaliT's heft are probably the heavier roof panels and mechanism, larger engine compartment (in the GTS, the compartment is so small, you cannot even see the engine). You get the sense the Cali's design puts more emphasis on aesthetics than the 911's.

California T specs hotlink

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GTS Cabriolet specs hotlink

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As for the brake rotors, you and I seem to quote different figures. California T rotors, from the same hotlink as above (15.4" = 391.16 mm). FWIW, the rear 14.2"=360.7", is also bigger than the GTS's rear

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991.2 GTS from the same hotlink as above clearly says 350 mm

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So according to Porsche, the GTS has significantly smaller front brake rotors. This makes sense as the CaliT is a very fast front-engine car and is heavier so its larger front brakes are not surprising. The GTS does not need large front brakes as it's a lighter car with a lighter front end. Overly-large brakes can cause unwanted understeer when trail braking and larger brakes = extra unsprung weight.

At any rate, I didn't mean to say larger brakes are better in my earlier message. The point I was trying to make was that, at low speeds (street driving), the braking action of larger front brakes on the CaliT will be more obviously felt than the smaller GTS front brakes. I suspect ALL complaints of grabby brakes stem from the feel of the FRONT brakes, not the rear brakes so at very low street speeds (e.g. in the parking lot), the CaliT's front brakes may feel "over-spec'd" for this reason.

I agree the Cali models (and the PF) were not designed for regular track use. They are too heavy and the springs softer than suitable for track use, resulting slower, often vague suspension responses and too much leaning which overload the outside tires, not inspiring faster cornering speeds. The GTS is much better at the track. However, the HS versions of the Cali are a lot more agile than the standard Calis and I can attest to the HS Cali30 being a fun car for the occasional track day drive. Another thing about the Cali is that it behaves very differently (much better) when pushed hard. At legal speeds, it can feel a bit pedestrian and not really at ease because the MagneRide is set for comfort and its suspension is unloaded. However, when you really hammer it, responses sharpen significantly and the car becomes "electric". It's transformed. However, you need to have MagneRide and the HS Pack.

As for the standard 19" wheels of the Calis, I only quoted the 20" wheels because they are the wheel size most often used by Cali owners and since we are discussing real world differences, I felt it more relevant to quote 20" wheel sizes. At any rate, for the consideration of "grabbiness" the 245/40-19 tires are 9.6" tread width, exactly the same as the 245/35-20. FWIW, I believe the 19" wheels are forged aluminium and so are actually lighter though their sidewalls are higher, which neutralizes benefits for responsive turn-in and deliver a softer, more compliant ride.

Finally, regarding edginess, I was only pointing out that my particular Cali30, with numerous aftermarket modifications, is indeed a lot edgier than the standard car (and my experiences with regular 911s). I like the edgy feeling because as I emphasized, my Fcar is not my daily driver.

 

Where do you live? It would be fun to compare cars!

The California T steering is amazing, I think it is much faster than the GTS but it's a bit apples-to-oranges because Porsche has gone with electric steering that is progressive. It definitely gets fast when you need it to be fast, but it is not nearly as lively as the Ferrari rack. A bit dead stick, at times. It's a big complaint in the Porsche community, which values steering feedback.

I'm not surprised the California is heavier, it is a much more comfortable car (insulation) and the retractable roof is a serious piece of hardware. More drivetrain and it's a bigger vehicle. It doesn't feel 420 lbs heavier when driving it.

The brake sizes you linked to are for iron brakes (PCCB is an option on most models). The current PCCB rotor size is (we were both incorrect) 410mm up front and 390 in the back. https://www.porsche.com/usa/models/911/911-gts-models/. (click on the Safety tab for details on the brake systems offered)

So, the GTS is a lighter car with bigger brakes, but it really should be considering that it is a track car first, daily driver second. I flip back and forth between the California T and the GTS, which definitely draws my attention to the contrast between the two cars. I also have an E63S wagon and appreciate that car for what it is, but don't enjoy it nearly as much as the Ferrari or the Porsche.

 

Yeah, I live in the Toronto GTA and while I do go on club rides and the odd track days, the other drivers I know live about an hour away so it's not like someone down the street whom I can just shoot the breeze with on an ad hoc basis. Let me know if you also live in the GTA.

Thanks for informing me of the differences in brake sizes for the GTS. I do try to make correct references in discussions by referring to proper sources but unfortunately the Porsche GTS spec page I picked omitted mention of any options. I also assumed incorrectly that Carrera GTS models, being top-of-the-line, would also have PCCBs as standard equipment.

Yes track cars do of course work better when they are lighter. Unlike the many, many 911 models that Porsche offers, the Cali model tries to present a broader performance appeal and application, all in one single model. I have experienced the track with a much more track-oriented car and it's nice to have the extra performance envelope but such cars are more focused so public roads manners tend to require some compromise in the other direction. I like the Cali30 because by using the mods I made it's become more focused and "more typical Ferrari" while still keeping the basic modern advantages of the platform.

 

Factory weight figures are normally too low,especially with Italian machines. I use the figures from the major car magazines who usually weigh vehicles themselves with a full tank. C/D June 2015 weighed a California T at 4064 pounds. For a 2010 California,R&T got 3925 and M/T got 3916.

 

Is the C/D 4064 lb CaliT figure for DRY or CURB weight? Yes, I've read similar stories in the past and they do make me wonder.

However, the factory numbers may differ if they measured a European model which probably has less or different emissions conformance equipment than N. American cars measured by the US magazines. North American cars also have extra DOT-mandated side markers, certain body part variations, perhaps different lights, ...etc. You will see this noted in the parts catalogue where certain parts only apply to cars in a certain market. You really need everyone to weigh an identical car or the exact same car to get a fair assessment on this issue. I also suspect factories would use the lowest weight numbers they can justify but then they don't tell you how they actually arrived at those numbers. In the end, unless you can weigh the cars you are buying for yourself you are really better off just to assume all numbers can vary a bit and just use them as "ballpark" estimates.

The different weights from R&T and M/T for the 2010 Cali would also make me wonder if they measured the same car or if one or both of the weigh scales had issues.

 

I'm talking about what a car weighs with a full tank,ready to drive,no people or luggage. What it weighs when I put it on a state-certified moving-company scale (which magazines sometimes use).

You are concerned about nine pounds difference with 2-ton cars? Different options could easily account for that.

 

So you're assuming the difference is due to the cars being different? If they were indeed different, how do you know if the actual weight difference was not actually 100 lbs instead of 9 lbs? You are making all kinds of assumptions without realizing it.

The difference in measurements between magazine reports may indicate they either weighed different cars, or if they actually weighed the same car, then one or both measurements were wrong. If they were indeed both wrong, we have no idea HOW WRONG they may have been. We cannot assume the degree of error. I'm also not sure about the reliability of "state-certified moving-company scales" unless they are calibrated against a known standard before they are used. I'm not new to using certified test equipment. I was once a cancer and transplantation research scientist.

At any rate, base car configurations in different international markets usually include different options. Base cars in Europe will likely weigh quite differently from base cars in N. America.