Are inboard brakes outlawed ?

[woohoo]

Hello!
Many years ago, some F1 cars had inboard brakes.
Now, they all have brakes inside the wheels.

Have the inboard brakes become illegal ?
Or it is simply because of convenience that the teams are using outboard brakes ?
Was the trouble of inboard brakes simply not enough of a performance gain ?

[Scotracer]

The torsional strain on a wishbone when you're decelerating a 605kg mass at 5G over a length of 300mm is...erm, A LOT. That'll be one factor and probably packaging too (you'd need a much larger nose structure).

[ReubenG]

The motivation for in board brakes is to reduce unsprung mass and hence improve suspension performance. Carbon disks do not add as much to unsprung mass as steel disks - so less motivation to move them inboard.

At the front, in board brakes would require the addition of a drive shaft from wheel to chassis. This adds mass and complicates aero issues - neither is desirable.

Front or rear, F1 brakes require substantial air flow for cooling. Putting them inboard would mean modifying / adding ducting to direct cooling flow to the brakes - again the aero guys are unhappy.

I'm not sure about this next idea: after a braking event, some of the heat from the brakes is absorbed by the tyres, helping keep them warm. Inboard brakes would remove this heat source for the tyres - so during a safety car period, the driver would have to work much harder to maintain tyre temperatures.

So with carbon disk brakes, the benefits of moving in board are overshadowed by the complications.

[Scotracer]

Yes, I forgot the heat radiated from the brakes keeps the tyres heated. Big bonus.

[Jersey Tom]

Yes, I forgot the heat radiated from the brakes keeps the tyres heated. Big bonus.

Brake heat will cook the bead area of the tire... not heat the tread. Generally a bad thing.

[ISLAMATRON]

cant wait till the brakes are gone and we have hub motors that turn the braking into energy. Those Siemens electric brakes seem cool too, F1 needs to catch up on some new technology!

[DaveKillens]

The current regulations imply that there is a brake on each wheel, but they are vague and leave room for interpretation.

F1 Technical Regulations 31 of 60 22nd February 2008
ARTICLE 11 : BRAKE SYSTEM
11.1 Brake circuits and pressure distribution :
11.1.1 All cars must be equipped with only one brake system. This system must comprise solely of two separate hydraulic circuits operated by one pedal, one circuit operating on the two front wheels and the other on the two rear wheels. This system must be designed so that if a failure occurs in one circuit the pedal will still operate the brakes in the other.
11.1.2 The brake system must be designed in order that the force exerted on the brake pads within each circuit are the same at all times.
11.1.3 Any powered device which is capable of altering the configuration or affecting the performance of any part of the brake system is forbidden.
11.1.4 Any change to, or modulation of, the brake system whilst the car is moving must be made by the driver's direct physical input, may not be pre-set and must be under his complete control at all times.
11.2 Brake calipers :
11.2.1 All brake calipers must be made from aluminium materials with a modulus of elasticity no greater than 80Gpa.
11.2.2 No more than two attachments may be used to secure each brake caliper to the car.
11.2.3 No more than one caliper, with a maximum of six pistons, is permitted on each wheel.
11.2.4 The section of each caliper piston must be circular.
11.3 Brake discs and pads :
11.3.1 No more than one brake disc is permitted on each wheel.
11.3.2 All discs must have a maximum thickness of 28mm and a maximum outside diameter of 278mm.
11.3.3 No more than two brake pads are permitted on each wheel.
11.4 Air ducts :
Air ducts around the front and rear brakes will be considered part of the braking system and shall not protrude beyond :
- a plane parallel to the ground situated at a distance of 160mm above the horizontal centre line of the wheel ;
- a plane parallel to the ground situated at a distance of 160mm below the horizontal centre line of the wheel ;
- a vertical plane parallel to the inner face of the wheel rim and displaced from it by 120mm toward the centre line of the car.


My personal interpretaion is that brakes can be mounted on the wheels or chassis. The choice is up to the designers. But if the brakes are not mounted in the wheel, then any wheel shrouds are not allowed.

[woohoo]

Ahh

Thanks for your replies, especially Dave and Reuben!

[persovik]

The torsional strain on a wishbone when you're decelerating a 605kg mass at 5G over a length of 300mm is...erm, A LOT. That'll be one factor and probably packaging too (you'd need a much larger nose structure).

Actually, having the brakes inboard would remove the strain on the wishbones, a big bonus.

[Belatti]

Yes, I forgot the heat radiated from the brakes keeps the tyres heated. Big bonus.

Brake heat will cook the bead area of the tire... not heat the tread. Generally a bad thing.

I wonder what kind of thermal insulation is used in the wheel rims. Some reflective coating?

[DaveKillens]

There's also another reason.

The great Lotis 72 had inboard brakes, and was a very successful car. But in 1970 at Monza, Rindt was killed, while driving a 72.

On Rindt's fifth lap of the final practice session, Hulme, who was following, reported that under braking for the Parabolica corner: 'Jochen's car weaved slightly and then swerved sharp left into the crash barrier.' A joint in the crash barrier parted, the suspension dug in under the barrier and the car hit a stanchion head on. The front end of the car was destroyed. Although Rindt was rushed to hospital, he was pronounced dead. Rindt had only recently acquiesced to wearing a simple lap belt, and had slid underneath where the belt buckle cut his throat. He was the second Lotus team leader to be killed in two years, as Jim Clark had been killed in 1968 in a Formula 2 race at Hockenheim. An Italian court later found that the accident was initiated by a failure of the car's right front brakeshaft, but that Rindt's death was caused by poorly installed crash barriers.

http://en.wikipedia.org/wiki/Jochen_Rindt

In other words, the shaft failed, and was instrumental in Rindt's death. Today's cars have the brake disk firmly attached to the wheel, and it's simple and reliable because of that.

Sometimes, the classic engineer's mantra of "keep it simple, stupid" (KISS) does make sense.

[xpensive]

The torsional strain on a wishbone when you're decelerating a 605kg mass at 5G over a length of 300mm is...erm, A LOT. That'll be one factor and probably packaging too (you'd need a much larger nose structure).

Actually, having the brakes inboard would remove the strain on the wishbones, a big bonus.

I was thinking the same thing, afraid you got it backwards this time Scot.

Anyway, I think the shape and width of today's tub's front-end would make it virtually impossible to room the brakes,
but I would love to see it. Together with small front wheels of course!

[Roland Ehnström]

Oh I'd hate to see them back, I'd be nervous every time a driver touched the brake pedal. Inboard brakes are suicide devices. Rindt's death is only one of many huge accidents caused by this horrible idea to but a driveshaft between the brake disc and the wheel. It should have been outlawed 40 years ago.

[CMSMJ1]

nobody would want the shaft in the airflow anyways...and the carbon brakes would take too much cooling hidden away in the chassis...

[xpensive]

Oh I'd hate to see them back, I'd be nervous every time a driver touched the brake pedal. Inboard brakes are suicide devices. Rindt's death is only one of many huge accidents caused by this horrible idea to but a driveshaft between the brake disc and the wheel. It should have been outlawed 40 years ago.

You must learn to trust the engineers Roland, just like your namesake did...oops!

Sorry about that one, but racing att 300 km/h is dangerous and just about anything can happen in terms of a technical failure, ask Rubens. The Lotus 72 was one of the very first cars with inboard frontbrakes at a time when F1 cars were built in a garage, pretty much like USF1 actually...darn, ooops again, why today's drver should trust a shaft the same way he trusts a wishbone, wheel-bearing or wingsupport.