Brake System On F1 Cars

[gruntguru]

However. The rules that cover torque variation across the axle are:

9.9 Torque transfer systems :
9.9.1 Any system or device the design of which is capable of transferring or diverting torque from a
slower to a faster rotating wheel is not permitted.

If I created a system that used a cyclic variation in the direction of MGU-K torque to one side of the diff I don’t think it would infringe either rule.

Surely such a system would be capable of transferring torque to the faster spinning wheel.

[henry]

However. The rules that cover torque variation across the axle are:

9.9 Torque transfer systems :
9.9.1 Any system or device the design of which is capable of transferring or diverting torque from a
slower to a faster rotating wheel is not permitted.

If I created a system that used a cyclic variation in the direction of MGU-K torque to one side of the diff I don’t think it would infringe either rule.

Surely such a system would be capable of transferring torque to the faster spinning wheel.

Yes but it’s not transfer from the other wheel, it’s apportioning of torque from the MGU-K.

[gruntguru]

Well worded Henry. I wonder if the FIA would read it that way?

[henry]

Well worded Henry. I wonder if the FIA would read it that way?

Who knows? But it does seem grey. Given the importance of diff control to the drivers there is remarkably little in the regulations concerning it. Or maybe I’m not reading the regs thoroughly enough.

Sometimes we see the outer, more heavily loaded, front wheel lock up on corner entry. That might be explained if the yaw rate was increased by differential braking across the rear axle.

[Jolle]

Well worded Henry. I wonder if the FIA would read it that way?

Who knows? But it does seem grey. Given the importance of diff control to the drivers there is remarkably little in the regulations concerning it. Or maybe I’m not reading the regs thoroughly enough.

Sometimes we see the outer, more heavily loaded, front wheel lock up on corner entry. That might be explained if the yaw rate was increased by differential braking across the rear axle.

The outside wheel is more prone to lock up on corner entry because of under steering. They fully load the tire with turn in while still gently on the brakes.

[henry]

Well worded Henry. I wonder if the FIA would read it that way?

Who knows? But it does seem grey. Given the importance of diff control to the drivers there is remarkably little in the regulations concerning it. Or maybe I’m not reading the regs thoroughly enough.

Sometimes we see the outer, more heavily loaded, front wheel lock up on corner entry. That might be explained if the yaw rate was increased by differential braking across the rear axle.

The outside wheel is more prone to lock up on corner entry because of under steering. They fully load the tire with turn in while still gently on the brakes.

Thanks. I can see how the outer tyre might be asked to do a higher proportion of steering duty than load transfer allows.

I guess since there is a significant aero effect there might also be some influences from wind direction.

[Jolle]

Who knows? But it does seem grey. Given the importance of diff control to the drivers there is remarkably little in the regulations concerning it. Or maybe I’m not reading the regs thoroughly enough.

Sometimes we see the outer, more heavily loaded, front wheel lock up on corner entry. That might be explained if the yaw rate was increased by differential braking across the rear axle.

The outside wheel is more prone to lock up on corner entry because of under steering. They fully load the tire with turn in while still gently on the brakes.

Thanks. I can see how the outer tyre might be asked to do a higher proportion of steering duty than load transfer allows.

I guess since there is a significant aero effect there might also be some influences from wind direction.

You'll have the same thing on a pre-ABS road car if you tried to brake into the corner. because on the road we are much more (especially with stick shift) "brake/shift down, match revs and then turn in" instead of gently coming off the brakes after steering in until you come to the apex. And since ABS locking a wheel is out of the question anyway, EPS even brakes the inside wheel a bit more to guide the car around the corner.

with the onboard graphs is really fun to see that they really brake all the way to the apex (on most corners).

[henry]

@jolle I’ve never driven hard enough in any of my non-ABS cars to notice which wheel locks under trail braking.

The wheel that locks is more often the inside, I guess it all depends on the car, conditions and driver.

Speaking of driver I noticed on the quali laps from Brazil that Vettel, Hamilton and LeClerc all roll off the throttle during braking so that for some time they are driving against the rear brakes. In fact on a couple of occasions LeClerc never comes off the throttle fully. As you say it’s interesting to see the onboards.

[Jolle]

@jolle I’ve never driven hard enough in any of my non-ABS cars to notice which wheel locks under trail braking.

The wheel that locks is more often the inside, I guess it all depends on the car, conditions and driver.

Speaking of driver I noticed on the quali laps from Brazil that Vettel, Hamilton and LeClerc all roll off the throttle during braking so that for some time they are driving against the rear brakes. In fact on a couple of occasions LeClerc never comes off the throttle fully. As you say it’s interesting to see the onboards.

You lock the inside when the balance is more towards hard braking then hefty cornering forces. That’s why us mortals lock inside tires while F1 drivers lock outside tires. The outside tire is already so much on the limit that too much brake force will lock it, while the inside still has grip to spare.

[gruntguru]

I don't believe it is that simple. The ideal Ackerman/Suspension setup will laterally load each front tyre in proportion to the normal force (weight) on the contact patch during cornering. Equal braking will then lock the inside tyre first.

[strad]

less weight on the inside tire causes it to want to lock up first.

[Slo Poke]

Well worded Henry. I wonder if the FIA would read it that way?

Who knows? But it does seem grey. Given the importance of diff control to the drivers there is remarkably little in the regulations concerning it. Or maybe I’m not reading the regs thoroughly enough.

Sometimes we see the outer, more heavily loaded, front wheel lock up on corner entry. That might be explained if the yaw rate was increased by differential braking across the rear axle.

You are definitely on the right line Henry but make your Goal more towards a permanently locked differential.
Ask any articulated truck driver which drive wheel spins first on any type of road surface and all will state the left or near side wheel. That’s because of different length drive shafts, the left one is a little shorter. The mercs and fezzas have developed an improved arrangement in their differentials that enables the use of equal length drive shafts. If you were able to see the arrangement in animation, you’d probably claim, that’s torque vectoring but the goal is actually far more towards creating and maintaining an unbiased and locked differential.

[AJI]

I don't believe it is that simple. The ideal Ackerman/Suspension setup will laterally load each front tyre in proportion to the normal force (weight) on the contact patch during cornering. Equal braking will then lock the inside tyre first.

Could it be an Ackerman vs. anti-Ackerman thing?

[saviour stivala]

Well worded Henry. I wonder if the FIA would read it that way?

Who knows? But it does seem grey. Given the importance of diff control to the drivers there is remarkably little in the regulations concerning it. Or maybe I’m not reading the regs thoroughly enough.

Sometimes we see the outer, more heavily loaded, front wheel lock up on corner entry. That might be explained if the yaw rate was increased by differential braking across the rear axle.

You are definitely on the right line Henry but make your Goal more towards a permanently locked differential.
Ask any articulated truck driver which drive wheel spins first on any type of road surface and all will state the left or near side wheel. That’s because of different length drive shafts, the left one is a little shorter. The mercs and fezzas have developed an improved arrangement in their differentials that enables the use of equal length drive shafts. If you were able to see the arrangement in animation, you’d probably claim, that’s torque vectoring but the goal is actually far more towards creating and maintaining an unbiased and locked differential.

Which formula one car ever had an unequal length drive-shafts?.

[Tommy Cookers]

.... Ask any articulated truck driver which drive wheel spins first on any type of road surface and all will state the left or near side wheel. That’s because of different length drive shafts, the left one is a little shorter. ....

imo not so
fundamentally which wheel spins when driving straight .....
(best shown in a traditional ie Hotchkiss drive vehicle) is due to the direction of rotation of the prop shaft
ie the crown wheel is trying to dive or climb - this causing contact load increase on one wheel and decrease on the other

torque tubes (diluting this effect) were common (before chassis-mounted CWPs eg IRS or De Dion did the same)
or it was cancelled in some race cars eg 20s M-Bs and 30s Alfa Romeos by using 2 'handed' propshafts/CWPs


regarding cornering
remember there's lots of toe effects eg rear wheel (not just Ackerman)