Bigger brakes cannot stop you faster.

[Jhenson29]

Saw this and immediately thought of @daveo4EV.

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[Archimedes]

It’s a true statement, but not the whole picture when it comes to braking, particularly not in a high performance sportscar, as you (hopefully) are not doing full panic stops that engage ABS much, if at all. It’s about feel and fade. That’s where larger and more advanced braking systems shine. Braking performance cannot be simply boiled down to stopping distance.

Videos like this are just clickbait.

 

[Jhenson29]

It’s a true statement, but not the whole picture when it comes to braking, particularly not in a high performance sportscar, as you (hopefully) are not doing full panic stops that engage ABS much, if at all. It’s about feel and fade. That’s where larger and more advanced braking systems shine. Braking performance cannot be simply boiled down to stopping distance.

Videos like this are just clickbait.

I’m not sure it’s clickbait. Did you watch it?

He covers those things and, in general, it appears to be made as a direct response to comments from a previous video of people “correcting” him that bigger brakes do stop a car faster.

 

[Archimedes]

I did. This is a topic that is repeatedly raised on the Internet because it creates arguments. There’s been a dozen threads about this topic on Rennlist alone, usually started by a link to a clickbait article or YouTube video. Easy way for YouTubers to get clicks is videos on topics like this. Or manual vs. PDK, or ‘Should I follow the break in procedure from the manual?’ Or ‘What oil…

 

[Jhenson29]

This is a topic that is repeatedly raised on the Internet because it creates arguments.

Is it? Or is it to correct misinformation and help misunderstanding? I remember a post on RL earlier this year where someone commented on how happy they were they optioned PCCBs because of how well their car stopped at one red light. So I think sharing the information still has a place. Sorry you disagree.

 

[Mike in CA]

FWIW, I've ceased wondering whether the PCCB's on my car stop better or improve ride/handling due to reduced un-sprung weight or have better feel. The fact is that they look absolutely stunning behind my 21" Mission E wheels. I've never for a second regretted spending the extra money to get them.

 

[andrewh3]

Now I am feeling 'brake envy'!

 

[Dee]

This is also interesting: PCCB vs steel.

 

[f1eng]

Saw this and immediately thought of @daveo4EV.

This is indeed spot on IME.

I have spent years working on making brakes better on Formula 1 cars since it is a BIG influence on lap time.
Having a braking system capable of locking the wheels is all that is needed for stopping distance.

BUT:

For racing thermal resistance and consistency is the most important thing, obviously, because there is, effectively, an emergency stop for each corner and as brakes get hotter their performance changes.
There are multiple potential problems with boiling brake fluid, fade and excess wear being the main ones.
Loads of Formula 1 fans think banning composite brakes will slow the cars down but we tested it and do exactly the same weight adjusted lap time using cast iron discs as composite.
In reality the main gain of composite brakes is weight saving, 10kg lighter was on avarage 0.35 secs per lap faster when I was working on it, (it may be smaller now the cars are so much heavier).

Getting consistent braking and acceptable wear is where the work was concentrated once we went composite, and it was a huge development, small material changes had big effects.

IIRC the first to use composite brakes in F1 were Brabham and they took lifed out composite rotors and pads from fighter aircraft and machined blocks to fix to either side of a steel disc they used in place or the then ubiquitous cast iron brakes.

We were second at Williams with custom designed and made discs and pads by an aerospace specialist. The first test was at Brands Hatch in 1982. I will never forget it. Keke Rosberg came into the pits after a 10 lap run absolutely delighted by the performance but when we took the wheels off they were alredy worn out.
I won't bore you with the next few years of development before they were reliably racable but the thing which surprised me when composite brakes appeared on road cars was how they had achieved an acceptable "cold" performance.

All the racing composite brakes are dire until warmed up quite a lot. The ones with acceptable cold performance had huge wear when racing and cold performance is the most important aspect of road car brakes, obviously.

Anyway 40 years of development has obviously achieved a broad range of performance ranges.

My personal preference for a road car is for cast iron rotors.

 

[smoothound]

For me, and assuming the same road surface conditions...... Superior brakes place full responsibility for ultimate emergency braking on the tyre performance/ABS/driver etc - That is, they are over specced and play their part 100% - so braking performance is all down to tyres and other systems etc.

Whereas inferior brakes that can't quite match tyre/system performance (insufficient stopping or fade etc), take back some of that responsibility; and, because they are inferior, braking performance will be sub-optimal as a result - tyres etc doing all they can - but brakes with insufficient stopping power.

So over-specced brakes are a kind of fail-safe for that component - but are probably overkill economically and weight-wise etc....

So t I am glad I got em.

cheers

 

[Jhenson29]

@Mike in CA Absolutely. No brake/options shaming intended. I felt okay posting the video because it wasn’t a one-note “bigger brakes serve no purpose” view and talked about legitimate reasons to get them, aesthetics being one. it didn’t cover unsprung weight, but I don’t remember it really going into materials at all. I think it focused more on size.

I have sport aero wheels and can’t see my brakes. I think they’re in there somewhere though.

 

[Jhenson29]

@Dee I like that channel and don’t disagree with the general sentiment of that video. But I didn’t catch how many consecutive stop they made (just referred to “first stop” and “last stop”?) so it’s hard to speak to how that may relate to street driving where the duty cycle is possibly lower than their tests.

 

[f1eng]

Whereas inferior brakes that can't quite match tyre/system performance (insufficient stopping or fade etc), take back some of that responsibility; and, because they are inferior, braking performance will be sub-optimal as a result - tyres etc doing all they can - but brakes with insufficient stopping power.

Brakes with inferior stopping power have been illegal in the UK for about 20 years.
Any option on a Taycan over standard spec is entirely cosmetic IMO.

 

[f1eng]

FWIW, I've ceased wondering whether the PCCB's on my car stop better or improve ride/handling due to reduced un-sprung weight or have better feel. The fact is that they look absolutely stunning behind my 21" Mission E wheels. I've never for a second regretted spending the extra money to get them.

That is fair enough.
I never saw an improvement in grip on a Formula 1 car due to reduced unsprung weight, either on the stopwatch or the chassis dyno, so stopped taking it as a key performance design target. I never looked into ride

 

[Jhenson29]

@f1eng thanks for the background. It’s always great to read your stories and experience.

My work is in industrial control systems. The core concepts are universal, but I don’t have your domain knowledge (obviously).

We have different scenarios that cause us to size brakes differently.

A common one is a holding brake which is typically only sized for holding torque and would get destroyed on any significant energy dissipation. But they’re used as a passive brake force (spring on; pneumatic/hydraulic/solenoid off). There’s usually an active braking component (typically AC motor regen) that the holding brake is supplementing*.

The other common one is continuous braking as a resistive load, usually to create tension on a material for some process. Here, in addition to torque, we need to be concerned with continuous energy dissipation. This is getting less common as AC motors get used in more and more applications.

There are a few intermittent duty cycle applications for energy dissipation, but it’s actually not that common. At least not in my domain.

*Note that we typically either have an inverter connected to the grid, appropriately sized braking resistors, or a DC bus connected to another load that uses the energy; so, regen is not battery-limited like the Taycan.

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