akula-ssh

If that's the reason for explaning the brake wear (and dust) at the back, can somebody with aftermarket pads of the same material front and back comment on whether brake wear at the back is indeed not worse than the front as much as stock?

HighPSI

my rear pads were almost metal to metal on the rotors when i changed, fronts had about 40% left

akula-ssh

What pads did you have when you noticed this?

rovision

Recently replaced rears, new oem pads are TRW black

HighPSI

stockers

bhvrdr

Correct. I put ceramics on the back and use an aggressive front.

Bob Petruska

The A4 comes with Electronic Brake Distribution(EBD) control. This definitely applies more force to the rear brakes to maintain more stability control. Now my Hawk Ceramics are almost dustless(don't need to wash wheels for 2 weeks). But I do see more dust on the rear wheels than the fronts when there is dust.

akula-ssh

Unless Audi has "undersized" the rear brakes so that they have to always work more than the fronts, it just doesn't seem to make much sense... Now then the question is why would Audi choose to put on rear brakes that are too small? :T

Bob Petruska

and I shouldn't have said "more force". I believe that the rear brakes are applied "more often" at light pressure to stablize the car. The ESP, traction control may work the rear brakes more than the fronts. There was an article posted here years ago that describes the functionality of the system.

Bob Petruska

Tech. explanation follows:
User account number (aid): 2311
Posted by Spinnetti on 2002-03-28 12:22:08
In Reply to: Why are my rear wheels dirtier than my fronts? Do I have a bizzarro A4? posted by Big D on 2002-03-28 10:24:58

ok, Heres the deal.

1. A vehicles tires carry all of the load for turning, braking and accelerating. The total force available through the tire contact patch is never greater than the weight of the vehicle displaced over the number of tire contact patches, each tire supporting weight based on the weight distribution of the vehicle.

2. When you press the brakes in any vehicle, weight is transferred forward. The harder you brake, the more quickly weight is transferred (though the total amount of transfer is fixed by the weight of the vehicle). As the weight is transferred forward, the front tires support more weight, and the rears support less. If the braking force is applied equally to all the wheels, the rears will lock up before the front under hard braking.

3.In a conventional pre-EBD (electronic brake distribution) system, The manufacturer had to determine the maximum weight transfer, and usually using a mechanical proportioning valve, adjust how much pressure the rear brakes get based on how much the vehicle body rises off the rear suspension (pickup trucks use this same idea in reverse). The problem is that the response time of these fluid systems is slower than needed to assign force as needed (hysterisis), so the static system needs a bias towards the front brakes.

The result is that under normal conditions, the front brakes do a whole lot more work than the rear brakes, hence lots of front dust.

4.In the new EBD era, electronics determine where the force needs to go, and hence the rears can be assigned a lot more of the total force under normal driving conditions (thus the greater rear dust now), yet still have the fronts do the work as needed.

Conclusion:
The benefit of all this is that you should see more even front-to-rear wear on the brakes, and that the front brakes don't need to be quite as big (and heavy) as previously to get the same total braking performance.

Once again, progress through technology. Yeah Audi!