F1 Brake Discs

[DaveKillens]

One factor that is relevant is the clutch. A Formula One clutch is minimal in every aspect, fragile, and I seriously doubt it could be effectively used in partnership with the engine in braking.

Sure, you could enlarge and beefup the chutch so that it could withstand being used in engine braking, but right now, it's not up to the task. Of course, if you did beef it up, it would wreak havoc with everything in the drive train, from increased mass and inertia to having to relocate the centerline of the crankshaft to accomodate the larger clutch.

So if the clutch isn't used, then the transmission has to match the engine revs to the speed in order to avoid turing the entire transmission into an exposion of metal fragments. It does that right now, but is doesn't engage any engine braking.

It's amazing how much energy and heat the brakes have to deal with, and this year it will be interesting. Due to changes in regulations, the "frisbees" are now illegal, and thus airlow within the wheel won't be as effective, and due to the need to carry a lot more fuel, the brakes will be severly taxed, especially in tracks such as Circuit Gilles Villeneuve.

Please remember that not only are brakes used for performance, they are a vital and critical part of safety. There's no better way to render a dangerous situation into one of safety than stopping the car. Right now, the simple system in place is just that, simple and reliable. The only thing I can think of that is safer and more reliable is an anchor and chain. If brake-by-wire is intended to be used, I will accept it only it it can demonstrate the same level of reliability as what we now have.

[autogyro]

One factor that is relevant is the clutch. A Formula One clutch is minimal in every aspect, fragile, and I seriously doubt it could be effectively used in partnership with the engine in braking.

Sure, you could enlarge and beefup the chutch so that it could withstand being used in engine braking, but right now, it's not up to the task. Of course, if you did beef it up, it would wreak havoc with everything in the drive train, from increased mass and inertia to having to relocate the centerline of the crankshaft to accomodate the larger clutch.

So if the clutch isn't used, then the transmission has to match the engine revs to the speed in order to avoid turing the entire transmission into an exposion of metal fragments. It does that right now, but is doesn't engage any engine braking.

It's amazing how much energy and heat the brakes have to deal with, and this year it will be interesting. Due to changes in regulations, the "frisbees" are now illegal, and thus airlow within the wheel won't be as effective, and due to the need to carry a lot more fuel, the brakes will be severly taxed, especially in tracks such as Circuit Gilles Villeneuve.

Please remember that not only are brakes used for performance, they are a vital and critical part of safety. There's no better way to render a dangerous situation into one of safety than stopping the car. Right now, the simple system in place is just that, simple and reliable. The only thing I can think of that is safer and more reliable is an anchor and chain. If brake-by-wire is intended to be used, I will accept it only it it can demonstrate the same level of reliability as what we now have.

Of course it would be better if the 'clutch' was thrown away, leaving the engine free to either remain connected solidly to the gearbox input shaft or alternately drive it through a OWC (disengage on overrun) and allow the gearbox itself to handle a powertrain braking task and harvest some of the braking energy as well as saving fuel. It would also shorten the car by at least 12cm and reduce the weight by at least 1 kg.

[horse]

So if the clutch isn't used, then the transmission has to match the engine revs to the speed in order to avoid turing the entire transmission into an exposion of metal fragments. It does that right now, but is doesn't engage any engine braking.

Sorry, this is a dumb question. Is this process what is happening in an over-torque (but in reverse)? Can the power consumption of the idle (don't know if that is the right word) engine really do this to the gearbox? Or is this more to do with the mechanics of engaging the downshifts?

[autogyro]

So if the clutch isn't used, then the transmission has to match the engine revs to the speed in order to avoid turing the entire transmission into an exposion of metal fragments. It does that right now, but is doesn't engage any engine braking.

Sorry, this is a dumb question. Is this process what is happening in an over-torque (but in reverse)? Can the power consumption of the idle (don't know if that is the right word) engine really do this to the gearbox? Or is this more to do with the mechanics of engaging the downshifts?

It is simply the difference in rpm between the crankshaft and the input shaft of the gearbox if a clutched gearchange occurs, or the difference between the input and output components in the gearbox if a clutchless gearchange is made.
In either case the engine torque is negated during the shift through the EMS, so that the engine rpm can be altered to match the different component speeds. Because F1 engines (and many other performance engines such as rally engines to a degree) have little inertia, such rapid changes in rpm are possible without damage.
In a car with conventional flywheel and clutch, the clutch itself deals with the inertia from these components and has to be beefier to survive.
Unfortunately this results in an engine that is easy to stall on the start line because there is no inertia to keep the engine turning.
Not so with my clutchless system even though the engine still has no seperate flwheel and not even a clutch.

[riff_raff]

Friction devices, whether clutches or brakes, are usually sized by thermal capacity. A brake must convert kinetic energy into thermal energy via friction, and then dissipate that thermal energy into the passing airflow. The brake rotor mass is sized based on how effectively it can transfer the braking heat load to the passing airflow without exceeding an acceptable temperature rise. Carbon brakes can achieve this with a much lower weight than steel brakes.

Clutches are designed the same way. But the function of a clutch is somewhat different. The function of a clutch is to synchronize the rotational speeds between the two torque transmitting elements of the transmission, such as synchro rings or dog rings. Which are ultimately connected to the engine and rear wheels of the car. Dog ring racing gearboxes don't really need a clutch to shift up or down, since the driver (or ECU) is usually very good at synchronizing the engine speed via the throttle, and the dog rings are very durable devices. But even with an F1 car, the clutch is needed to sync the transmission and engine speeds as the car moves from a standing stop. It must slip, and thus absorb power, until the transmission speed is brought up to match the engine speed. As with brakes, the thermal mass of the clutch pack must be sufficient to absorb the energy that must be dissipated during a standing start without overheating the materials.

Carbon clutch materials tend to have very aggressive friction characteristics. They slip initially, but as they quickly build up friction heat, their friction coefficient rapidly increases which causes the clutch to instantly grab and lock up. That's why you see even very experienced drivers commonly stall when leaving the pits in a car with a carbon clutch. A carbon clutch has no modulation or slip, it's basically like an "on/off" switch.

I would disagree with DaveKillens, a carbon clutch is definitely not a fragile device. They're very durable.

Regards,
riff_raff

[autogyro]

Agreed but it is the 'static' friction capability of a clutch rather than the dynamic friction of a brake.
It is the lack of rotating flywheel and clutch assembly weight that gives a low enough inertia for racing 'dog' engagement gear changes under power.
Dont try it with a lorry engine the dogs will instantly break.
The engine managment system takes out the engines torque delivery during a clutchless shift in F1 cars. It allows design of the dogs and or engagement synchronisers to be light without breaking. Dual shaft gearboxes disengage one shaft as they engage the other. However there is still a delay and a torque gap.
The twin shaft is also at the expense of extra torque loss from an extra layshaft.
Guess what, my ESERU does not 'gap' the torque delivery during a shift in fact extra torque is applies and there is NO gap, plus only one shaft.
Sorry.

[riff_raff]

autogyro,

Agreed but it is the 'static' friction capability of a clutch rather than the dynamic friction of a brake.

As I noted, both brakes and clutches are sized by thermal capacity. The clutch is a rotational speed synchronizing device. It must endure "slippage" between its stators and rotors as the transmission input shaft and engine flywheel speeds are synchronized closely enough to engage the shift dog rings or permit direct drive. This "slippage" function requires the clutch pack to absorb energy in the form of heat. The amount of thermal energy the clutch pack can absorb is a function of the clutch material's specific heat value, thermal conductivity rate away from the friction interface, and allowable safe structural temperature limits of the materials. CRC clutch materials begin to oxidize above about 1500degF, so that would be the thermal limit at the sliding interface.

A properly designed clutch normally has far more static friction capability than necessary by nature, so once locked-up there is very little chance it will ever slip. Carbon-carbon materials have an unusual friction characteristic in that its sliding coefficient of friction value changes significantly as it heats up, which is the exact opposite of how other friction materials behave.

Dual shaft gearboxes disengage one shaft as they engage the other.

I believe you mean dual clutch gearboxes? The principle behind dual clutch gearboxes is that they allow one (de-clutched) gear ratio to be engaged and ready while another (clutched) gear ratio is being driven. This allows faster and less complicated shift events, but also requires more complex transmission assemblies. Dual clutch transmissions are also normally three shaft arrangements, not twin shafts.

Regards,
riff_raff

[autogyro]

No I meant dual shaft gearboxes. (dual not two)
It does not matter if one of the shafts is inside another or seperate.
True, Dual clutches with a layshaft gearbox of any layout means three shafts.
Using two clutches and three shafts is of course a very high torque loss arrangement and far worse than the Model T epicyclic gearbox of nearly a century ago in this respect.

[autogyro]

To be fair riff raff and to keep the posts up to standard, you are correct and I am wrong. These are three shaft gearboxes with two clutches.
The reference to them as 'dual shaft' is pretty much accepted in gearbox definition however. It comes from the 'layshaft' part of the definition.
A conventional layshaft box is often refered to as 'single' shaft.
Technicaly incorrect I know.

[riff_raff]

autogyro,

No problem with your terminology. Besides, I design aircraft transmissions, not automotive transmissions. So my use of terminology may not be technically correct either!

Regards,
riff_raff

[autogyro]

autogyro,

No problem with your terminology. Besides, I design aircraft transmissions, not automotive transmissions. So my use of terminology may not be technically correct either!

Regards,
riff_raff

Hahahaha
At least I can pull over and adjust mine, yours have to be right first time.
I think your technical descriptions are the most important aircraft transmissions do have to be very reliable.

[FW17]

Singapore is one of the toughest races on the calendar for brakes. Red Bull and Ferrari are using new discs at Marina Bay, which they previously tested at Spa and Monza. Featuring more than 1000 holes (five holes per row), the new discs are supplied by Brembo. Made from a new material, CER, they lose only 1mm of thickness by the end of the race in comparison to the 4mm worn away on the older CCR discs. Red Bull also used new front brake ducts in Singapore to aid cooling.

So what is CER and who else is running them?



Comparison with

[adam2003]

Whats the reason some teams dont position the calipers at the bottom? surly reduces cog, but they are brainy than me so their must be a explanation why

[Scootin159]

Whats the reason some teams dont position the calipers at the bottom? surly reduces cog, but they are brainy than me so their must be a explanation why

Primarily because it's hard to do, as that space is generally occupied by the lower control arm mounting point. It's not so much that the teams are unwilling to invest the time to correct for this, but it makes it difficult to produce an upright that is just as light and strong as one with the brake caliper at a 90* clock position.

[olefud]

If you keep the brakes cool, the wear rate increases rapidly”.

Why is this? With cast iron rotors if the rotor is overcooled a transfer layer of pad material forms on the rotor and causes bad things to happen. The problem isn’t running cool but rather a mismatch of temps and materials. But carbon rotors run with similar carbon pads so the dissimilar material problem shouldn’t on the face of it exist.