brake circuits

[tonycarguy]

All cars have 2 brake circuits for redundancy. I was under the impression they're always diagonal, but I just read on a website that only FWD cars are done this way; they implied RWD cars are split front/back. Is this generally true? I'm still a bit doubtful...

What about AWD cars?

 

[rshunter]

There is no standard. I believe it depends as much on the manufacturer's philosophy, as anything else.

 

[rshunter]

I should have added that I believe most have migrated to the diagonal design, though. It is a safer system if you suffer a circuit failure. You'll always have a front brake working with a rear, which will be more effective than having just two rear brakes. Having the front braking circuit fail at speed isn't fun, trust me...

 

[Silk]

You need negative scrub radius for diagonal split braking,which is why more front wheel drives have diagonal split,as they are normally set up with negative scrub radius (KPI,SAI).This makes the braked wheel pull to the centre of the vehicle,not to the outside....and so is easier to control with a single front brake (or flat tyre)

 

[Ken42]

Don't forget you do still have the E-brake if it works

Ken

 

[Rick in PA]

Originally Posted By: Ken42
Don't forget you do still have the E-brake if it works

Ken


Yes, but... you reaaaallly have to plan ahead using e-brake only.

Years ago, I had a drum front brake de-bond it's shoes mid-trip.

This rendered the hydraulic brakes useless, so I had to rely on the e-brake. I clearly remember sailing through the first stop light I encountered, fortunately it was late and no one was at the intersection.

This got me to thinking, my current car has 4-wheel disk brakes, the e-brake (really only a parking brake) is a tiny set of drum shoes inside the rear disk brake hubs.
Man, would I hate to have to rely on those to stop the car.

 

[eljefino]

I've popped a few brake lines/ wheel cylinders. Pretty sure they were all front/rear splits. Even though you're still supposed to have some pedal, my pedal was in the carpet.

My pickup trucks have had just one line for the rear, it goes to a flex hose above the differential then gets split by a Tee to go off to each wheel. Single-channel Rear wheel ABS.

 

[morris]

are you talking about e-brake that will stop a moving car? there are two kinds of brakes ,e-brake that stops the moving car, and a parking brake that will not stop a moving car but holds it in place. they are not the same thing.

 

[eljefino]

It's part of the US motor vehicle safety standard that the e/parking brake stop the car in a certain number of feet all by itself.

 

[rslifkin]

Eljefino - The single rear brake line, 1 abs channel for the rear is exactly how my Jeep is set up.

I have 4 wheel disks, and the e-brake is really weak, although I think something is broken in the mechanism. It won't hold the Jeep at idle in drive, but I can practically floor it in reverse and it holds fine.

 

[mechtech2]

Whereas there are many diagonal brake systems, there are also loads of front/back split systems. FWD or not.

In real life, a sudden massive leak is a very rare occurrence.