DocWyte

So I ran with the BMWCCA at Mt Tremblant this past weekend. I'd been there twice before and was very impressed with the new track. Much wider, really smooth pavement and way more runoff room.

As those who've been there know, it's a pretty brake intensive track. I thought I was all set (97 A4 1,8Tq) with my A8 rotors, Ferodo DS2000 pads, SS lines and fresh (1 week old) DOT 4 syn fluid. WRONG! I faded the brakes at the end of the 2nd track session, made it thru the 3rd one, then lost the brakes completely the 1st session of the second day.

So I rebled the brakes, then took a drive into town for some gas. Brakes still felt horrible so I grabbed a fresh can of ATE Super Blue from HMS and did a full flush. Brakes were no better. Long pedal travel with very little bite. Much to my disappointment I parked the car for the rest of the event.

On the drive back home in the morning the brakes were still bad and stunk to high heaven. However, by the time I made it back to Boston the brakes were back to normal, and they're fully at 100% today. What the heck is going on? I assume I overheated the pads and/or boiled the fluid, but after I flushed the system everything should've been ok. Thoughts?

What pads should I consider to replace the DS2000's with? I'd prefer to NOT have to swap pads over at events, so something that'll stop me at that 1st stop sign in the winter is a necessity.

Would I be seeing a large gain in brake performance by stepping up to the Porsche Boxster calipers?

I really don't want to fade my brakes on the track again...

GregA

You probably didn't boil the fluid. Sounds like you killed the pads.

When pads overheat, the surface of them melt. This melting causes the surface to glaze over, kinda like how sand turns to glass. What you were feeling is the extra effort you had to use with your leg, 'cause that "glass" doesn't have a very high coefficient of friction.

By the time you got home, you wore off the surface of the pads and now it feels fine.

>>> I'd prefer to NOT have to swap pads over at events, so something that'll stop me at that 1st stop sign in the winter is a necessity.

Problem is, you're asking for too much. You (and Audi) choose the pad compound for the majority of the driving conditions the car is expected to experience in everyday driving. Those pad compounds have a usable heat range, just like tires. Those DS2000 pads are street pads, made for street temperatures; as soon as you exceed those designed material temperatures you start to melt the pads.

Same as a tire, a race pad is made to withstand higher temperatures. Problem is, it doesn't like the lower temperatures of street driving (ESPECIALLY not winter driving) and will not work well until it gets hots. It will likely be noisy as hell on the street and it may machine your brake rotors because it's so damned hard at low temp (Hawk Blues come to mind). Get it hot, though, it it is an awesome track pad that's friendly to brake rotors.

So what you're asking for is a pad that can withstand all the range of temperatures you could possibly toss at it, *and* have a high friction of coefficient at all ranges. It's just not practical. There's compromises for everything, and you just found the compromises you have to make with a street pad on the track (you slow down so you don't over drive your equipment...)

Your compromise is two have two sets of pads:

- one for the street that low dust, no noise, easy on the rotors, and bites right away when you jump on the pedal in 0 degree weather, and

- one for the track that doesn't melt at high temperatures and bites like hell when it gets hot.

Anything else is a compromise in between, don't let anyone kid you otherwise.

Greg Amy
BIRA.ORG

ryoung

Perhaps a different rotor with better cooling might postpone the point of pad meltdown, or is this just asking too much of any rotor?

dingster

Well DocWyte is already running A4 calipers on A8 rotors. I don't think it's possible to go to a larger/thicker rotor without changing the front brakes as a whole. What Greg said is true, many on this board will immediately blame the fluid when they experience fade. Comments like "I can boil my fluid at will" was pretty common. In reality the street pad is the first thing that goes. Going to race pads is one option but given the limited size and cooling of DocWyte's setup I think simply going to race pads won't be good enough for extended track driving.

CP

Geza's homemade ducts are a great way to cool stock brakes.

DocWyte

I agree with Greg, I must've really exceeded the temperature limits of those DS2000 pads. What I'm a little bummed by is that those pads are the "fast road" pads, not the regular street pads. I hoped they'd be enough for the track but evidentally they're not.

Can anyone give me opinions on the Hawk Blues vs Porterfield R4's and Performance Friction pads?

I've got plenty of brake cooling (gotta like those MM emotion wheels!), and the A8 rotors at 12.3" should be an adequate heat sink. I've got the biggest rotor I can go with right now, even the BIRA stage 1 and 2 kits use this rotor....

TM

I would not use street pads on the track, at all.

I have a set of 996 calipers and big rotors waiting to be installed, with Hawk HPS pads for street use. For the track, I plan on replacing the front pads w/ Pagid Blue or Orange, Porterfield R4 or something similar.

I'm also going to add brake ducting- I really doubt you have enough brake cooling, considering you have no brake ducts on an A4, at least for track use.

Then again, take my track/racing comments with a big grain of salt, as I have not BTDT much.

TM