Do the rear brakes activate before the front?

**Bubu** · 25-12-2008, 01:27 AM

I was just reading an interesting article regarding braking.

According to this article, on MK4 Golfs' the rear brakes are applied first by the electronic brake distribution system under light braking. And rear brakes tend to wear out quicker on these cars.

Does the brake system on the Polo perform the same way? Has anyone here had their rear brakes wear out before the fronts or more so than the fronts?

Here is the article if you want to read it.

http://www.myturbodiesel.com/1000q/brake_FAQ.htm

**Jmac** · 25-12-2008, 05:21 AM

Works the same way mate, interesting read.
Cheers
Jmac

**Kai** · 25-12-2008, 07:35 AM

That would explain alot of stuff. I never thought about the rears coming on first tho.

**NickZ** · 25-12-2008, 08:44 AM

How come the front wheels get so much more brake dust than the rear wheels? Is that because the brakes are bigger in the front?

**Kai** · 25-12-2008, 10:26 AM

The rear brakes may come on first. But thats where it stops.

There is more force at the front. And yeah. Bigger brakes.

**gerhard** · 25-12-2008, 10:33 AM

I have noticed that when I "poodle" around, there is more crap on the rear wheels, especially noticeable just after washing the car.

The article is a great read.

I'd love to see an updated one by the same author incorporating the complexities of ESP when the ABS system is used to brake individual wheels.
The ABS would have to be tuned to match the clamping pressure and changes to the piston size could throw the ESP tuning out the window.

**Bubu** · 25-12-2008, 07:16 PM

Originally Posted by gerhard

I'd love to see an updated one by the same author incorporating the complexities of ESP when the ABS system is used to brake individual wheels.
The ABS would have to be tuned to match the clamping pressure and changes to the piston size could throw the ESP tuning out the window.

I always thought the ABS calculates the amount of braking as it is engaged. In another words if the piston size is bigger and/or the pads are better it dosent make any difference to the way the ABS works. The ABS system uses a sensor to determine how much loss of traction combined with steering angle and brake pressure and adjusts the braking to each individual wheel at a fraction of a second. So even changes to piston size dosent matter as it will calculate it all while its activated.

Thats the way I always thought it works, there are to many variables (tyres, pads, discs etc.) to simply tune the system once and leave it at that so it would have to be able adjust the ABS as required. Correct me if im wrong...

**Bukefal** · 26-12-2008, 12:44 PM

interesting article. while i was reading it i was reminded of a question that i've been wondering about for a long time. why do different cars have their brake calipers in different positions? this thread gave some answers. there's a lots of nice pics there, too. this was the best response:

"Yes, to some it does matter. It's not like it constitues of a huge difference, but still...

Firstly the callipers does weigh a little bit, som by positioning the fron callipers on the rearside of the front discs, and the rear ones on the front side of the disc they get more wight positioned inside the wheelbase. Furthermore this does reduce the cars polar moment of intertia. On most performance cars they use this position. Furthermore, on the Carrera GT Porsche postioned the callipers like this, and did it as low down to lower the centre of gravity in the same stroke.

The second slight advantage is shorter brake line piping, which leads to a quicker response time on the system when the brake pedal is pressed. It also makes the brakes slightly ligher, enabling the engineers to reduce the brake assistment, which in its turn gives the car more brake feel. Also, shorter piping also means less weight and by simply using less of it also means less costs.

(This has been up a couple of times in the Q&A section in EVO)"

the full thread is here:

http://forums.finalgear.com/general-...alipers-21269/

check out the caliper/wheel combination on the 2nd pic

**gerhard** · 26-12-2008, 02:14 PM

Originally Posted by Bubu

I always thought the ABS calculates the amount of braking as it is engaged. In another words if the piston size is bigger and/or the pads are better it dosent make any difference to the way the ABS works. The ABS system uses a sensor to determine how much loss of traction combined with steering angle and brake pressure and adjusts the braking to each individual wheel at a fraction of a second. So even changes to piston size dosent matter as it will calculate it all while its activated.

Thats the way I always thought it works, there are to many variables (tyres, pads, discs etc.) to simply tune the system once and leave it at that so it would have to be able adjust the ABS as required. Correct me if im wrong...

My comment was about ESP and the effect of larger rotors/pistons/calipers/pads on the correct application of braking effort to correct a skid. That's quite different to ABS alone.