Under slung brake calipers?

[sovietspybob]

While watching some of the F1 testing i saw this on the back of one of the cars

Got me thinking why do sports cars not have their brakes mounted on the bottom of the disc? In my head it lowers the centre of mavity and when you turn the wheel its rotating around the centre of the caliper so should have some kind of gain for steering feel as your not slinging a caliper around with the wheel?

Do they not do this because:
- There aren't any real benefits
- It's too difficult to mount it there with various other gubbins being in the way
- ??? = Profit?

 

[Clarkey]

Because that's where the bottom ball joint goes.

 

[tigerstyle]

Defying convention there Clarkey

 

[Jonnycoupe]

While watching some of the F1 testing i saw this on the back of one of the cars

Got me thinking why do sports cars not have their brakes mounted on the bottom of the disc? In my head it lowers the centre of mavity and when you turn the wheel its rotating around the centre of the caliper so should have some kind of gain for steering feel as your not slinging a caliper around with the wheel?

Think is thats the rear axle so the benefit you have defined doesnt exist with regard to steering.

Probably easier to get air to a lower mounted caliper on an F1 car.

 

[tigerstyle]

Similarly; when did F1 move away from inboard mounted discs? Or did they not ever have those, I know 50's GP cars did, so seems strange to have lost them or it's rule enforced.

 

[Clarkey]

Don't know but presumably they can use much lighter duty drive shafts with normal brakes.

 

[tigerstyle]

Don't know but presumably they can use much lighter duty drive shafts with normal brakes.

In my head the loads on the drive shafts would be the same? The mass of the vehicle doesn't change, nor the braking forces so they are all transferred through the tyres/car car/tyres vice versa?

(But I don't know! Perhaps move this thread to Motorpsorts and we'll get a lot more answers )

 

[Clarkey]

Err how? Inboard the braking torque is applied through the shaft, otherwise it's directly to the hub. These cars can generate 5g+ in braking so that's a huge amount of torque to apply to a skinny lightweight driveshaft.

 

[Building Candy]

I would think it could provide a little low platform for small stones etc to be flicked up and sit on, this would be right on the brake pad, could cause a problem.

 

[K.C. Leblanc]

I also expect the moved away from inbound brakes because they can get better cooling with the disk in the wheel. I also wonder if they've contemplated building the brake into the wheel in such a way that the brake disc will be replaced with the wheel and tyre.

I will echo others, I suspect the caliper isn't at the bottom because brake dust, tyre marbles and other crud could get caught in there more easily.

 

[tigerstyle]

Err how?

I think my hub is connected to my driveshaft.

 

[Jonnycoupe]

I think my hub is connected to my driveshaft.

But the brakes retard vehicle mass through the tyres, which is a system that the driveshaft is not involved in.

 

[touch]

I think my hub is connected to my driveshaft.

Braking forces wont be transferred from the hub to the driveshaft though.
The force will be transferred through the hub to the wheel.

Engine braking force will be transferred through the driveshaft, but thats significantly less than the force of the brakes.

edit: beaten :/

 

[Lashout_UK]

Production car calipers have to (arguably) last the life of the vehicle too. Putting them low down may make them more prone to being regularly doused in water, shrapnel and mud (etc), reducing their lifespan.

You'd have to route the brake lines down too, placing them lower as well, which could make them more prone to damage.

 

[tigerstyle]

hmmm I had more of an engine braking feeling going on in my head.
Similarly though, you could brake the output of the gearbox, into an inboard hub, then again the driveshaft isn't taking the load as the disk isn't right onto it ala a gokart?

 

[Lashout_UK]

hmmm I had more of an engine braking feeling going on in my head.
Similarly though, you could brake the output of the gearbox, into an inboard hub, then again the driveshaft isn't taking the load as the disk isn't right onto it ala a gokart?

The driveshaft still has to transfer that braking effect to the wheel, remember.

 

[Alibaba99]

Having a horizontal caliper makes them a swine to bleed as well. RBR had quite a few issues when they were first introduced.

F1 cars have them mounted that way as it reduces the CofG.

 

[Dogbreath]

hmmm I had more of an engine braking feeling going on in my head.
Similarly though, you could brake the output of the gearbox, into an inboard hub, then again the driveshaft isn't taking the load as the disk isn't right onto it ala a gokart?

What connects the output of the gearbox to the wheels? If you have inboard brakes of any description the driveshafts have to carry those braking forces.

I suspect the driveshafts would be up to the job on the rear of an F1 car, but cooling tends to be problematic with inboard brakes.

 

[Simon]

The shafts would have to be much stronger for reasons above and the fact they would be constantly being 'wound' and 'un wound'. Fatigue life would be a potential issue.

Regarding low down, many reasons why not on a road car. Water and dirt for one but also bleeding them would be more difficult.

Youll notice some car makers put the cailper nearer to the centre rather than at the front of the car, helps being the mass closer to the centre, reducing polar moment of interia (helping the car turn)

 

[Clarkey]

That means putting the steering gear forward though, which is just as heavy. Swings and roundabouts...