Actual Brake Improvement

[djwimbo]

IIRC our cars are diagonal split system. Meaning if you lose brake pressure on one wheel you will still maintain a relatively straight stop b/c opposite corners are applying pressure at the same time.

[rogerius]

So,after I scrolled to post#64 as advised,I quote this:
==================
EBD – Electronic Brakeforce Distribution (also referred to as DRP, dynamic rear proportioning) – An electro-mechanical control system designed to monitor and influence rear wheel dynamics, and ultimately foundation brake (front-rear) balance. In so many words, the EBD utilizes the ABS hardware to function as an "intelligent brake proportioning valve." Unlike a traditional mechanical proportioning valve which is limited by design to one kneepoint and slope, the EBD algorithm relies on closed-loop feedback to continuously monitor rear wheel slip, adjusting brake line pressure to the rear wheels as appropriate.
====================

and I conclude this: is good to have BBK in the rear,the system will exhaust the braking power of the rear BBK and then transfer to the Front BABK, which may exhaust or not depending on the tyres and road quality.So the bigger in the rear,the better.And the biggest in the front,the best.....if the asphalt is good and the tyres new,one will stop faster and could do repeated stops before fade.

Now comment this asgain please!

[onemoremile]

That it what it is supposed to do but it isn't so seamless in real life. The systems are digital and math based. If the system makes a physical change and gets a result that it didn't expect and can't trim it's values to compensate then things could get rough.

[Tigu]

There was a time when me and my buddy were making streetrace cars out of golf gti-s. We had one project where we swapped the front brakes for bigger vento Vr6 brakes. I remember there was no improvement to be noticed.
Then we also swapped the rear brakes for something bigger that I don't remember ( sorry was about 10 years ago). The car totally transformed. It was like a rallycar on tarmac slicks. but since it had no ABS nor any other assistance for braking force, the getting use to these brakes ended up smashing the side of the car. It kept on locking up very suddenly. but we also measured the braking distance before and after. it was 43m before and 38,7 after. both were 3 separate measurements and done with borrowed equipment. so things are supposed to be balanced. if we get bigger brakes for front we should also get them for rear.
The OEM solutions... yes, some modifications of cars have bigger on front but same on rear. But there are so many different parts in the system that we usually oversee. Including somewhat differently balanced EBD or ABS or some other electronic bllsht. ( sorry again, hate the damn things).

[audiFUEGO]

sooooooooooooooooo....

A8 rotors in the front and rear

Boxster calipers in the front

S4 calipers in the rear

PBR ceramics and SS brake lines

Would this be the "best/cheapest" setup?

[$teady$upreme]

I definitely think so. I just don't have the boxster calipers for now~

sooooooooooooooooo....

A8 rotors in the front and rear

Boxster calipers in the front

S4 calipers in the rear

PBR ceramics and SS brake lines

Would this be the "best/cheapest" setup?

[hoganalley]

sooooooooooooooooo....

A8 rotors in the front and rear

Boxster calipers in the front

S4 calipers in the rear

PBR ceramics and SS brake lines

Would this be the "best/cheapest" setup?

This is my exact setup minus the Boxster Calipers and SS brake lines....didn't see the need. When I pulled off my rubber ones they were WAY more spongy than the new rubber one's I put on. Plus, just in case, I didn't want to swap SS lines in a few years if they broke.

I love it. It feels balanced, the rear end doesn't kick out on me and it stops well. Haven't tried it on the track but for the street it's perfect. I would recommend this to anyone.

[audiFUEGO]

This is my exact setup minus the Boxster Calipers and SS brake lines....didn't see the need. When I pulled off my rubber ones they were WAY more spongy than the new rubber one's I put on. Plus, just in case, I didn't want to swap SS lines in a few years if they broke.

I love it. It feels balanced, the rear end doesn't kick out on me and it stops well. Haven't tried it on the track but for the street it's perfect. I would recommend this to anyone.

So which front calipers are you using then?

[mysman]

Perhaps some of the mixed results for the Porsche BBK is from mounting the calipers backwards, ie, larger piston leading instead of trailing?

[Kyle H]

Wow! Great thread... bookmarked.

[rogerius]

Perhaps some of the mixed results for the Porsche BBK is from mounting the calipers backwards, ie, larger piston leading instead of trailing?

u have to mount them corectly=smaller piston leading.Therefore u unscrew the bleeder valves and the conecting pipe and switch them over.Voila!

[mysman]

Yeah, I knew that, lol. But if you don't, and piece together a kit, you get it backwards. Besides tapered pad wear, it would probably be harder to modulate the pedal during rapid stops.

u have to mount them corectly=smaller piston leading.Therefore u unscrew the bleeder valves and the conecting pipe and switch them over.Voila!

[onemoremile]

instead you brag about patents (i have one too whoopeedeedoo)

FWIW, I now have 29 patents.

[VTAudiA4]

So basically upgrading to A8 rotors in the front while keeping the rears stock will not affect braking negativly. Correct?

But here is another question. Let's say I decided to upgrade to A8 rotors up front, will there be a huge difference between getting rotors that are plain and rotors that are slotted?

[onemoremile]

I like plain after running D/S rotors and seeing no improvement. The holes and slots also caked with pad material rendering them useless.

The Tyrol bushings made a nice improvement in feel. With the A8 stuff up front, stock rears, and track tires, I've outbraked 996 turbos and a Z06 on Hoosiers. Don't really know how but it did. The stock system is surprisingly capable when properly set up.

Here is a pic of my old D/S rotors with the holes and slots full of pad material. I cleaned them out with a scratch awl and drill bit several times. They look pretty when new but I see no real world benefit and would not run them on a track again.

[Adie89]

Wow! you guys whine at each other a lot.
But facts are facts, to say you would increase stopping distance by putting too larger brakes on the front compared to the back is rubbish. Ask any world touring car team, they all use massive 330mm discs up front and standard discs on the back. By your theory they'd make the car worse!
Bigger discs will always increase the torque even with standard pads because its like using a tyre bar on a nut instead of a wrench. The further away the force is applied the more torque is created for less force applied ie the pad squeezing.
Like someone said fluid amount has nothing to do with it, fluid dynamics states that the pressure is constant in a liquid all your doing is moving the fluid with levers and pistons, not adding to the system or taking any away.
A point in case i've got RS6 discs and calipers on my S4 and that sucker stops on a dime, and the rears are still standard.
Stop blowing smoke up each others asses like kids in a school yard and answer the guys question instead of confusing the issue.
Squarrl if the rotors and pads are bigger they'll be better. Bigger rotors means less torque required to stop, bigger pads means a greater amount of force can be applied to the rotor and stop faster. And generally your toyos will be more than enough for grip.
As for the rear i've been told reliably that S8 discs and calipers bolt straight on the back of an A4

[Kyle H]

Squarrl if the rotors and pads are bigger they'll be better. Bigger rotors means less torque required to stop, bigger pads means a greater amount of force can be applied to the rotor and stop faster. A

And here’s a free tip – effects of poor brake bias on the street not only include sub-optimal stopping distances, but also include sub-optimal brake pad life. If a car is too heavily front-biased in the deceleration range it typically operates in, it will wear front pads more quickly due to the fact that the rear brakes aren’t doing as much of the stopping work as they could be. However, the rear brake pads will probably last forever…

The most dramatic front-bias impacts are usually brought about by “big brake kits” which are not properly matched to the intended vehicle. Any time that a bigger front rotor is installed, there is a simultaneous need to decrease the effective clamping force of the caliper (installing smaller pistons is the easiest method) to offset the increased torque created by larger rotor effective radius. The objective is to maintain a constant amount of brake corner output (torque) for a given brake line pressure as Figure 6 illustrates. Unfortunately, too many upgrades do not take this factor into account, and those poor cars end up with both bigger rotors and larger pistons which serve to drastically shift the bias even more forward. While rock-solid stable under braking, stopping distances will go up dramatically.

http://www.stoptech.com/tech_info/wp...formance.shtml

[Altech75]

Awesome, a four month old thread that probably should have been locked or turned into a sticky demonstrating how NOT to conduct yourself on the Zine (not meaning onemoremile)

[AudiTurbo]

Just did my a8 upgrade today and so far love it! To do the rear upgrade what is my best route? Why can't I post pics on here?
A8 rear rotors with s4 calipers? That's all?

[.Mad Hatter.]

Don't bother with the Carbotech Bobcats. I had them and they are so not worth the 160 bucks. For about $60 the Axxis Ultimate Ceramics are a crazy value and outperformed the Bobcats in every way. The AUC are silent where the CB would occasionally squeal like a garbage truck. The CB would slip when cold just like when driving on the freeway in the rain whereas the AUC have a grip that feels consistent and predictable regardless of temperature. If the prices were reversed it would reflect the actual real world performance of the pads.

I have been considering Hawk HP+, would you say that for half the cost the AUC pads are worth it? I dont want to chew through pads in a summer let alone a weekend, but I also want something that will bite. Keep in mind its auto x now (season is basically over) and hopefully solo 1 next year, so a mix of track, slalom, and DD use.

TIA Jim!

[hoganalley]

Just did my a8 upgrade today and so far love it! To do the rear upgrade what is my best route? Why can't I post pics on here?
A8 rear rotors with s4 calipers? That's all?

You can do any of the big brake upgrades...depends on cash. If you don't want to spend a ton of money, go with the S4 rears. If you have a bit more (~$100 more) go with A8 rears. I have them, and I love them.

If you want to spend tons, then go ahead and get 300mm+ rotors. You'll need new everything to make this work.

BTW.....A8 rears (269mm) won't fit behind 15" wheels...has to be 16" or bigger

[AudiTurbo]

Yeah I just did the 12.3 fronts under my stock 16's, and looks good.
I'm just confused on what I need for the rears if I'm only doing the s4 or a8 upgrade?
Thanks!

[jrock]

Doing my 996 upgrade up front and 300mm rears at the moment and I agree that the rears cant get quite expensive. Just the rotors alone are turnin out to be more than I thought (b7 s4 rears are a biatch!) but I will let you all know how it ends up feelin when its all said and done.

[.Mad Hatter.]

Yeah I just did the 12.3 fronts under my stock 16's, and looks good.
I'm just confused on what I need for the rears if I'm only doing the s4 or a8 upgrade?
Thanks!

best bet is the A8 rear rotor, S4 caliper and A8 caliper carrier. thats what im doing eventually at least. (best bias)

[AudiTurbo]

Is there a kit out there? What about TT setup?

[.Mad Hatter.]

the TT uses a completely different hub, so no.

I think there is a kit from either parts4euro, PureMS or something that sells the entire kit. All you really need to do is watch for a parted out B5 S4 for calipers (~$100) and an A8 for the carriers. FWIW, A8 guys dont like to let parts go for cheap. Some guy wanted $50 each carrier, they are only $65 new!

[AudiTurbo]

A8 rotors same as s4 for the rear?

[$teady$upreme]

i think so (correct me if i am wrong), unless if you want to go b7 rears.

I have the S4 rear carrier, calipers and rotors. They work with my A8 fronts fine~

[.Mad Hatter.]

S4 rear rotors are 256mm, A8 are 269mm.

The A8 front and rear, no matter what, offers the closest bias (out of the OEM options) to the stock setup

[$teady$upreme]

Hi, so what exactly are needed for the A8 rears? A8 carrier and rotors, how about calipers?

[.Mad Hatter.]

best bet is the A8 rear rotor, S4 caliper and A8 caliper carrier. thats what im doing eventually at least. (best bias)

...

[hoganalley]

best bet is the A8 rear rotor, S4 caliper and A8 caliper carrier. thats what im doing eventually at least. (best bias)

This is what I have. Search my name and brakes and you'll see what I've done. I've also posted in here a couple of times that this is the best balanced setup mathematically to the stock dimensions. Do it, it's great. You won't regret it.

My mechanic thought I was nuts....didn't understand why I did this. He had my car about 3 weeks ago and took it for a test drive. Didn't have his belt on and almost put himself through the windsheild. Definately was not expecting the grab he got!

[malanca]

A moderate and affordable improvement is de 312 disc replacement with A6 parts.

I've used TAROX rotors, Ferodo DS2500 pads and Goodridge stainless brakelines. The rear rotors are still the OEM-size 245.

The next mod will be the 986/987 clamps on the front...

[lotusgardener]

sooooooooooooooooo....

A8 rotors in the front and rear

Boxster calipers in the front

S4 calipers in the rear

PBR ceramics and SS brake lines

Would this be the "best/cheapest" setup?

I think that's my exact setup, except I have Boxster S and S4 rotors

[onemoremile]

I have been considering Hawk HP+, would you say that for half the cost the AUC pads are worth it? I dont want to chew through pads in a summer let alone a weekend, but I also want something that will bite. Keep in mind its auto x now (season is basically over) and hopefully solo 1 next year, so a mix of track, slalom, and DD use.

TIA Jim!

I've been running the same set of AUC pads for a few years now. No problems.

[.Mad Hatter.]

wow, thats impressive.

thanks Jim.

[.Mad Hatter.]

Jim, where did you find the Axxis pads for that price, I cant find them for anything less than ~$150???