[Maxendeddy]

I have some questions to throw into the group.

1. Has anyone ever tried to start the car with your keyfob in the same pocket as your iPhone?
Me found that the car wouldn't start, then putting the keyfob away from the proximity of the
phone, the car found the key and started. Am I alone in this?
2. Why cannot tyre pressure be calibrated? Now we have to follow the pressure fork
as programmed, although sometimes ie on track it is easier to start at a lower pressure,
and now that gives rise to a whole number of tyre pressure errors, until pressure rises and
they disappear.
3. I found that my car was a bit unstable at high speeds, turns out the right rear brake cooling
duct was broken off and had taken a piece of a deflector with it. I had no idea this had
happened, didn't have any recollection. So, Iwould like to know if any of you regurarly
inspect the bottom of the car?

 

[andy c]

I have some questions to throw into the group.

1. Has anyone ever tried to start the car with your keyfob in the same pocket as your iPhone?
Me found that the car wouldn't start, then putting the keyfob away from the proximity of the
phone, the car found the key and started. Am I alone in this?
2. Why cannot tyre pressure be calibrated? Now we have to follow the pressure fork
as programmed, although sometimes ie on track it is easier to start at a lower pressure,
and now that gives rise to a whole number of tyre pressure errors, until pressure rises and
they disappear.
3. I found that my car was a bit unstable at high speeds, turns out the right rear brake cooling
duct was broken off and had taken a piece of a deflector with it. I had no idea this had
happened, didn't have any recollection. So, Iwould like to know if any of you regurarly
inspect the bottom of the car?

Max,i check the front deflectors as they are easy to see,but never the back,its amazing that such a small piece would make the car feel unstable,i think most of us still have problems with the keyfob,but on my last visit to the MTC,they did say the 8.3 upgrade was mainly to fix this problem.As for the trye pressures,we did ask why they hadnt put a stable gas in them and they did say it was something they hadnt thought about,so i think this might help

 

[Maxendeddy]

Thanks for the reply.
The strange thing is, with the key it's only when I put it next to my phone, for the rest it works
beautifully. So my advise, keep em in seperate pockets and ron's your uncle.
The deflector only made a slight impact primarely on the raidaillon and the blanchimont parts of Francorchamps, but still noticeable. There was also another little thing that could have contributed, but that's between me and the dealership.
Here's another fun question: Does break steer work under trail braking? So does it work in concordance with the brake pedal input or does it only work when you aren't braking?
I still have a bundle of these.

 

[6th element]

Here's another fun question: Does break steer work under trail braking? So does it work in concordance with the brake pedal input or does it only work when you aren't braking?

Not certain, but I'm gonna guess that yes Brake Steer works during trail braking. Essentially, I think you will end up with more braking torque apportioned to the inside rear wheel than the outside wheel. Can't think of any other way that it would work.

I have also thought quite a bit about the straight line braking and why the performance as tested by several publications seems to be only average among supercar competitors. I think that the 12C is biased towards ultimate track performance and thus the anti-dive characteristics of the hydraulic suspension and the Air Brake contribute to keeping the car flatter throughout the braking zone. This might actually prevent the front brakes from being applied to their maximum. As evidence for this, I have done some really hard braking from speed and I have yet to trigger ABS. The key, however, is that at the end of the braking phase, the car is already relatively flat and less time is needed in the next phase of the corner, which is the measured release of brake pedal pressure and subsequent measured application of throttle pedal pressure. In essence, you can get off the brake and onto the gas with a much quicker transition, without causing excessive front to rear weight transfer that would upset the car. So, while you may have needed a few more feet to slow the car to entry speed (vs. a 911 GT3 RS or Corvette using its front brakes to the max, for example), you more than gain that deficit back with a flatter chassis precisely when it is really needed.

Is this making any sense?

 

[Maxendeddy]

The brake steer issue under braking is still a bit unsure, but like you I already did a fair bit of hard braking, and I found that you can easily rely on the car's elctronics. First off, I really think the car is a far better car on a dry track with all traction control switched off, but really off, so try it. Five seconds of courage and then confirm it. Don't think the car is going to morph into an 80's Porsche turbo, I can assure you that it will be a revelation. Of course, I take track driving experience as a premise, because with 600 bhp and no experience stay away from the track.
Back to the braking, the brake pre-fill and the brake assist system make it so you don't have to stomp the brake pedal like you want to kill it and still have the full braking force, without any ABS coming in. You can brake later than anybody else in a production car, a lot later, even a GT2RS. I am talking of the composite brakes of course. But then begins my cunundrum, because you brake later, you tend to trail brake and I would like to know for sure that this doesn't interfere with the brake steer. Or is it better to deliberately carry a bit too much speed into the corner after braking and rely on the brake steer?

 

[andy c]

Not certain, but I'm gonna guess that yes Brake Steer works during trail braking. Essentially, I think you will end up with more braking torque apportioned to the inside rear wheel than the outside wheel. Can't think of any other way that it would work.

I have also thought quite a bit about the straight line braking and why the performance as tested by several publications seems to be only average among supercar competitors. I think that the 12C is biased towards ultimate track performance and thus the anti-dive characteristics of the hydraulic suspension and the Air Brake contribute to keeping the car flatter throughout the braking zone. This might actually prevent the front brakes from being applied to their maximum. As evidence for this, I have done some really hard braking from speed and I have yet to trigger ABS. The key, however, is that at the end of the braking phase, the car is already relatively flat and less time is needed in the next phase of the corner, which is the measured release of brake pedal pressure and subsequent measured application of throttle pedal pressure. In essence, you can get off the brake and onto the gas with a much quicker transition, without causing excessive front to rear weight transfer that would upset the car. So, while you may have needed a few more feet to slow the car to entry speed (vs. a 911 GT3 RS or Corvette using its front brakes to the max, for example), you more than gain that deficit back with a flatter chassis precisely when it is really needed.

Is this making any sense?

As to the braking,im going on partly the fact that brake tests are done from 60-0,and in this range the airbrake dosent deploy!! As you know once deployed it stays active till the last 5mph ,so on that reasoning i think you stop quicker from 65-0,just an idea
It certainly feels like it when i try,but i can see your idea too

 

[6th element]

The brake steer issue under braking is still a bit unsure, but like you I already did a fair bit of hard braking, and I found that you can easily rely on the car's elctronics. First off, I really think the car is a far better car on a dry track with all traction control switched off, but really off, so try it. Five seconds of courage and then confirm it. Don't think the car is going to morph into an 80's Porsche turbo, I can assure you that it will be a revelation. Of course, I take track driving experience as a premise, because with 600 bhp and no experience stay away from the track.
Back to the braking, the brake pre-fill and the brake assist system make it so you don't have to stomp the brake pedal like you want to kill it and still have the full braking force, without any ABS coming in. You can brake later than anybody else in a production car, a lot later, even a GT2RS. I am talking of the composite brakes of course. But then begins my cunundrum, because you brake later, you tend to trail brake and I would like to know for sure that this doesn't interfere with the brake steer. Or is it better to deliberately carry a bit too much speed into the corner after braking and rely on the brake steer?

You ask tough questions Max! My gut says don't alter your trail-braking style. If the corner naturally lends itself to trail-braking (decreasing radius, etc.) then continue to trail-brake. But, if you are tempted to trail brake on a corner that you wouldn't normally otherwise (i.e. increasing radius and/or followed by long straight), you are probably going to ultimately lose time, since you could have got back on the throttle earlier, with Brake Steer helping on the way out. Just thinking it through- haven't had my 12C on track, yet.

 

[6th element]

As to the braking,im going on partly the fact that brake tests are done from 60-0,and in this range the airbrake dosent deploy!! As you know once deployed it stays active till the last 5mph ,so on that reasoning i think you stop quicker from 65-0,just an idea
It certainly feels like it when i try,but i can see your idea too

That's what I thought, too, but the Inside Line test video clearly shows the Air Brake deploying in their 60-0mph braking tests: http://www.insideline.com/mclaren/mp4-12c/2012/2012-mclaren-mp4-12c-full-test.html

Honestly, when I mash the brake pedal I don't feel excessive braking torque at the front axle. I think that is ultimately a good thing, as it will spare the front rotors to some extent. But, I bet the braking distance from 60-0 would be shorter if the Air Brake wasn't deployed and the suspension was conventional, allowing the car to dive onto the front and really max out the front binders. Still much rather have it the way it is, especially for the track.