markbradford

This article says it does.

Comments everybody?<ul><li><a href="http://www.turnfast.com/tech_brakes/brakes_balancing.lasso">Braking Upgrades and Balance</a></li></ul>

D.C. Lee

No, most of your brake bias is up front.

Clark@turbo5.com

But. On the A4 there is WAY to much rear brake to begin with. If anything its more balanced with a rotor/caliper upgrade.

I run level 3 on my car. I make every road race event held in my area. The difference in braking is simply amazing. I am able to outbrake many cars at the end of the straight.

I feel the main draw back the the system is the rear brakes are still to much on my car. When the car was stock they tend to lock up easy on bumpy track surfaces and pads wear fast. I use stock type rear pads in an effort to reduce rear brake. If I use pagids or other high friction pads on the rear there is to much rear bias. Things are better with the Level 3 kit but I still get over worked rear brakes. Smoke and glowing rear rotors is not uncommon for me at a fast track like PIR.

Of course this is realy only an issue if you are driving the car has fast and as hard as I tend to do at the track.

Clark

zain

I'm sure the math is correct and all. But the author drops in two points as though they are irrelevanty.

"Any brake can lock up a wheel" true I suppose. Until they overheat - as the author observes. And in their front biased case, there is quite a bit more power (torque * angular velocity) being disapated at the front. Symetric pads and rotors imply that the fronts overheat first and lose performance first. An upgrade that does nothing more than disapate heat helps this.

In dismissing the "street" shorter stopping distance as "just an effect of improved response time because the brakes grab sooner" the author overlooks the obvious - shorter is shorter and I'll take my improved reaction time effect thank you. Perhaps if I was perfect my out of balance car could be stopped shorter without the front upgrades, but I'm not perfect, and even if I was, I'd overheat the fronts.

Clark points out that the Audis are rear biased anyway and our upgrades can even help this. I'm not going to argue with him. In my case I'm pretty sure my Tarox kit biases my front strength to the point that they go into ABS first by a little bit.

But there's the last bit, ABS will not allow my braking force to be "wasted" up front by overloading my front tires and having them slide while my rears could have done more. Perhaps in a true race car w/o ABS I'd really have to be sure my brakes all hit the limit at once, but I have a street car. And, I LIKE knwoing which set of tires is going to ABS first.

All things can be taken too far, and I'm sure you can over do the front thing. But it seems far too contradicted by experience to asser that front-only reduces performance.

My clueless $0.02 anyway...

-Z

James R.

ultimately preventing a wheel lockup condition from being allowed...and the circuits are independent therefore the fronts will be released as appropriate and then the, "underutilized" rear brakes will see some action?

Regards,

James R.

2001 A4 1.8TQMSXP (Turbo5 Stage III Brakes, AWE Stainless Steel Lines, Oettinger Pedal Set + Dead, Oettinger RE's 17x8, Yoko AVS Sports 225/45/R17, European Xenon Housings, Bailey BPV & RS4 Grill)

Clark@turbo5.com

I agree.

Clark

StopTech Sales

The design philosophy at STOPTECH is to maintain the OE front to rear balance as much as possible. We coined the term Application Specific (as applied to brake upgrades. We do this in our upgrade kits by using an algorithm that takes into account the increased effective radius and the original piston size. We have the ability to use eight different piston sizes so we can come close to the volume displacement of the OE caliper. You will not see a STOPTECH kit with 200% of OE front torque. For two reasons, the original balance is lost and the ABS may get confused.

So what do you get with our front upgrades? More Heat capacity and a much stiffer caliper under repeated use and heat and a floating hat system that prevents warping. The end result at the track is that you will go faster. The Audi S-4 for example has excellent brakes and can easily lock the brakes with stock tires at 60mph no matter how big the front rotor and caliper are you can't improve on what is already locked;however at the track under the heat of repeated braking our system and other well designed systems will have much better performance(ie less fade, no warping, stiffer pedal)

The STOPTECH front only system is the only one on the market that can claim to maintain the system balance.

RangeR BoB

He seems to forget that switching from single piston stock calipers to 4-pot calipers will create very different clamping forces with the same line pressure. As STOPTECH says in their advertisement below, the size of the pistons in the caliper that RECEIVE the line pressure from the master cylinder have a great effect on the clamping pressure of the caliper. The difference has to be worked out with a bit more complex math than used in the referenced article.

There is a great article, also tragically flawed, in the February 2001 issue of "Grass Roots Motorsports" that illustrates the math in brake systems. It will show you how to do brake pressure calculations, compare the effects of bigger rotors, different pistons etc.

The flaw in the GRM article is that the author tries so hard to convince folks that you should upgrade tires and wheels for better braking before getting bigger binders (which is true), it almost makes it seem like bigger brakes have no advantage. He does not cover the heat management side much at all, just how much brake torque it takes to lock the tires.

Big brake upgrades should not REDUCE the amount of total braking that you get. The master cylinders on ABS cars like the Audi have 2 pistons. One powers the front right and rear left wheel, and the other the front left and rear right. This is different than in the old days when one did the fronts and the others the rears.

Bias is worked out in the hydraulics of the ABS circuit, and I am sure there is a baseline mechanical bias which is then moderated by the ABS. If you pull the fuse on your ABS and stomp the brakes at track speeds you will find the rears of the A4/S4 pair lock far and away earlier than the fronts. This is true still after big brake upgrades. Thus I would not worry that the rears are going to be underworked on our cars.

Bigger brakes = more heat shedding capability. As long as the fronts, which do the lions share of the braking on these cars (heavy engine out front of the axel, above the CG, lots of weight transfer etc) can be brought up to incipient lockup over and over w/o fading, that should give about the best results you can get. Can the rears be optimized? Sure! But since they are already overactive on the B5 platofrm, I don't see the need. I'd rather have vented rotors on the rear, but beyond that they should be fine.

Just my $.02

JeffDavison

whenceforth for the A4 application??????

Kevin K2

The oem bias is based largely on weight distribution and stopping potential of oem type tires. By going with ultra grip tires, or R-compound tires for the track, more front bias is needed. He notes this in last sentence of pt-3.