Why do some rear brakes have 2 calipers?

[amdforever]

Why do some rear brakes have 2 calipers?

You usually see this on supercars, e.g. Aston DB9/Vanquish or Ferrari F430/Enzo.

Here is a capture from a DB9:

 

[matt_shaw]

uhhhhhh

 

[Magnet]

parking brake

 

[stapler123]

indeed, most cars have the parking brake built into the back of the disk, kindof a small drum brake solution, I guess it doesnt help to add all that to super duper cars.

 

[bone]

can you still pull the E-brake when driving? the caliper looks like it would brake off any time

 

[Viper007Bond]

Are you sure it isn't just for better braking power? I mean, why not just make the e-brake use the main caliper?

 

[Magnet]

No, the parking brake does not rely on the hydraulics to pull the car up because of safety issues, etc. Especially if the system were to fail. It is usually cable-operated to avoid this.

To increase braking power, they would normally increase the surface area of the original caliper, and perhaps increase the number of pistons used, but introducing a secondary caliper running off the same system would simply add to costs unnecessarily.

 

[Viper007Bond]

Mmm, right, right.

 

[Magnet]

Although having said that, it could actually be an electronically operated parking brake, as seems to be the fashion these days (don't know what happens when the battery dies and the car needs to be towed).

 

[amdforever]

Here is what I still don't understand:


Why do you see this 2nd caliper only on supercars but not on normal cars?

Where is the wire-actuated emergency brake on normal cars ??? :?

 

[stapler123]

once again.. on normal cars it's usually on the other side of the disks.. in the form of a old drum brake system. Using shoes, not calipers.

 

[MXM]

I'm very positive it's NOT used as regular brake. Not even because of cost, but bigger trouble would be making both calipers press on disk with absolutely same force, which is necessary. My guess it's handbrake.

EDIT: http://www.astonmartin.com/thecars/v12vanquishs/specification

"Rear: Ventilated and grooved steel discs 330 mm diameter with four piston calipers and separate handbrake caliper"

 

[VUK]

handbrake, or as you americans call it parking brake

 

[asthenia]

handbrake, or as you americans call it parking brake

That's because many American cars don't have a handbrake, they have a foot-operated parking brake pedal.

Makes you look extra cool, stomping on the parking brake, or pulling the release handle and hearing it go SCHWANG.

American cars. Heh.

 

[Blythy]

If there was two braking callipers on earch disk there would be pretty dire cooling issues.

 

[Renesis]

moved to questions and answers

 

[Viper007Bond]

handbrake, or as you americans call it parking brake

That's because many American cars don't have a handbrake, they have a foot-operated parking brake pedal.

Makes you look extra cool, stomping on the parking brake, or pulling the release handle and hearing it go SCHWANG.

American cars. Heh.

Canadian cars. Heh. Wait, you guys don't make any cars...

Anyway, only automatics have the floor pedal and not even all autos have it. It's basically to free up space in the center console.

 

[matt_shaw]

Canadian cars. Heh. Wait, you guys don't make any cars...

Anyway, only automatics have the floor pedal and not even all autos have it. It's basically to free up space in the center console.

we used to make cars but we gave up when we realized that they were shit. sadly americans have not yet come to that conclusion


my old 1989 ford ranger was a manual and it had a floor pedal for the parking brake

 

[BlaRo]

Canadian cars. Heh. Wait, you guys don't make any cars...

Anyway, only automatics have the floor pedal and not even all autos have it. It's basically to free up space in the center console.

we used to make cars but we gave up when we realized that they were shit. sadly americans have not yet come to that conclusion


my old 1989 ford ranger was a manual and it had a floor pedal for the parking brake

The Bricklin? Does that count?

My (father's) Xterra has a foot brake as well. My guess is that it's to save space; console property is precious. Gotta have those cupholders!

 

[stapler123]

handbrake, or as you americans call it parking brake

That's because many American cars don't have a handbrake, they have a foot-operated parking brake pedal.

Makes you look extra cool, stomping on the parking brake, or pulling the release handle and hearing it go SCHWANG.

American cars. Heh.

Yeah, like the e38 740i