Braking while downshifting

[Darrell]

I've had the same thing happen (dry weather with PSCB's) a few times if I brake, let off and immediately brake again the stopping power is reduced. I read somewhere else on this or another forum about its confusing the regen by braking off/on so quickly and explained it better. I'm no engineer and that may or may not be a reasonable explanation.

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[Dee]

No, it's not the brake booster issue that I am talking about. Brake boosters don't randomly decide not to work well in the rain.

It's the inherent problem with the PCCB when they get wet. They soak up water and the first brake application isn't great.
E.g. highway driving in the rain the first application where you go beyond regen isn't as bad as the car wash but still not progressive with a slight delay.

I see a LOT of these reports to this day on the Audi e-tron GT facebook group for example, and others.

Whatever you say buddy.
I don't have any issue with my PCCB so I don't need an explanation why I should.
They are just fantastic, like a proper Porsche should, in dry and in wet conditions, no problem whatsoever.
But maybe I shouldn't be on this forum cuz I have a Taycan that exactly does what it should do.

 

[prj]

Had the issue entire time on mine, but then the climate is more wet here, and I have driven a few thousand different cars doing calibration, so maybe more sensitive to it.

Doesn't explain all the people complaining about it on social media though.

My J1.2 with steel brakes has a perfect brake pedal (as far as blended braking can be perfect).

 

[SoccerMan94043]

Had the issue entire time on mine, but then the climate is more wet here, and I have driven a few thousand different cars doing calibration, so maybe more sensitive to it.

Doesn't explain all the people complaining about it on social media though.

My J1.2 with steel brakes has a perfect brake pedal (as far as blended braking can be perfect).

I find the transition from Regen (I have it on) to brake at a full stop really rough. The car is still moving too fast when the brake catches and stops the car too abruptly, causing a small surge forward and then rocking back, rather than a smooth stop.

It's better with Regen off, but still happens there too. Tesla is super smooth in comparison.

 

[prj]

I find the transition from Regen (I have it on) to brake at a full stop really rough. The car is still moving too fast when the brake catches and stops the car too abruptly, causing a small surge forward and then rocking back, rather than a smooth stop.

It's better with Regen off, but still happens there too. Tesla is super smooth in comparison.

I always drive regen off and it's quite good for me.

The reason tesla is super smooth is because tesla doesn't do brake blending apart from the very newest Model Y and Model 3.

All the older cars - when you press the brake it's just moving the actual mechanical brake, there's no brake by wire system in them at all.

 

[Dee]

Doesn't explain all the people complaining about it on social media though.

"All the people"...
Kinda exaggerating, isn't it?

Speaking of social media, I'm running the biggest Taycan page on Facebook with 54.632 members for six years now but issues with PCCB (or any other type of brakes) in the wet isn't a common problem.
Heater, battery, charging and app issues (timers/profiles) are far more common.
I don't say there's isn't a problem but it's not a common problem.
If it was a common problem, it's becoming a safety issue rather quickly.
I've seen reports about that at the NHTSA but still, there isn't a recall initiated.
So take it with a grain of salt, especially on social media.
I know a thing or two about braking too as I'm driving cars for over 120 years now, including all the German Autobahns on the whole western hemisphere.

 

[prj]

"All the people"...
Kinda exaggerating, isn't it?

I get English is not your first language, but it does not mean what you think it does.

There is a post from a Porsche engineer responsible for calibrating the brake systems on pff.de, who said exactly the same about PCCB, that I am saying here as well. But you do you.

 

[Mr.Smith]

I find the transition from Regen (I have it on) to brake at a full stop really rough. The car is still moving too fast when the brake catches and stops the car too abruptly, causing a small surge forward and then rocking back, rather than a smooth stop.

It's better with Regen off, but still happens there too. Tesla is super smooth in comparison.

This is when you have Auto Regen on?

I use Regen almost as downshifting when coming to a stop, then disengage Regen when coming to a complete stop and I'm not getting what you're describing.

 

[Dee]

but it does not mean what you think it does.

Yes, it does.
It's a saying to emphasize your opinion, it's just childish.

There is a post from a Porsche engineer responsible for calibrating the brake systems on pff.de

Lol, he makes it looks like the disks are littered with water which isn't even the case.
It's only on a molecular level and disappears within milliseconds when you press the brake, it evaporates very quickly.
I never had such an obvious experience, maybe a fraction of a second but way less than having soap on your disks.
But hé, you are right.
Done.

 

[prj]

Lol, he makes it looks like the disks are littered with water which isn't even the case.
It's only on a molecular level and disappears within milliseconds when you press the brake, it evaporates very quickly.
I never had such an obvious experience, maybe a fraction of a second but way less than having soap on your disks.
But hé, you are right.
Done.

Clearly you know more about the PCCB on Porsche, than their engineer responsible for calibrating the brakes on their cars for over 20 years, have you considered offering them consulting services?

 

[SoccerMan94043]

This is when you have Auto Regen on?

I use Regen almost as downshifting when coming to a stop, then disengage Regen when coming to a complete stop and I'm not getting what you're describing.

I use regen downshift too... it's why I like it so much (10 year Tesla habits are hard to break). If I slow down/stop annoyingly slowly it will come to a halt smoothly.

 

[Dee]

Clearly you know more about the PCCB on Porsche, than their engineer responsible for calibrating the brakes on their cars for over 20 years, have you considered offering them consulting services?

Yes.

 

[TonyR]

I find that on wet, cold days, the brakes are a bit greasy feeling when coming to a stop.
I attribute that to having cold damp brake pads that require warming up.
The situation mitigates as one drives.

Apart from the first mile where it uses the mechanical brakes to clean the pads and discs the braking thereafter uses the electric motors regeneratively

 

[jakeCT]

@freinando I experienced something similar and had my service center look at it closely. There was a ""Found optional update for brake booster. Performed program update for brake booster from software 0131 to 0190"".

You might want to check if you can have this update applied.

 

[Boss Hogg]

I had this random change in brake behaviour after a service visit, happened wet or dry, completely at random. At low speed coming to a stop the pressure required to make the braking work and stop the car had to be very significantly increased, overshot a few junctions and nearly hit a wall. I have covered c. 90k miles in Taycan and never had this before. Anyway, dealer took it back and did some kind of software reset/recalibration and it has been perfect over the last 10k miles.

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