praedet

Please keep this on the topic of brake biasing...

hmmm, so EBD never worries about too much front bias? I am going to leave the threshold vs. ABS out of this one. I would like to keep it on the the topic of what BBKs are out there, how their biasing compares to stock, and what pads are out there... Any Stoptech owners want to measure pistons? Ted

Fixed Where does it say that? I thought the EBD used the ABS sensors and some of its logic...

confused about the question...

Just added pad info to the first page. Please PM me if you want to add a pad and have the info on it, or if you uhave info for the ones I already have listed... Ted

Haven't tried them. From talking with Keefe/RaceComp, they don't have quite the temp range. SS-Y has the highest mu of the three (0.38-0.48) w/ the lowest temp capability (716 F) and SS-S has a mu between SS-Y and M (0.35-0.43), with a max temp closer to SS-M (932 F). SS-M will have the least dust by far, and has a max temp of 986 F and a mu from 0.3-0.4. Here is the post where I got that info... Ted

Well, ebd only turns on once ABS comes on. When threshold braking, if your bias is perfect you will stop faster w/ no ABS activation. The same force applied to a poorly biased car would activate ABS and EBD. As PGT mentioned earlier, it is like snow tires with a stability control systems. The limits become higher... Ted

Street pads I like my Endless SS-Ms, but they are expensive... I have run Bobcats on other cars and really liked them. I have never tried any Hawk pads... I definitely recommend trying pads, lines, and fluid first. You can always sell the stock set-up to a WRX owner if you do go to a BBK. Ted

It'd be nice to find out about both set-ups since the outback version would fit the Legacy's stock rims also...

I need the piston sizes and effective rotor diameter. It would be nice to have the mu of the pad they ship with also... Ted

^^^Just a little, you are correct. It is very dependent on the springs in front also. Next though, you need to track down info on the Legacy's Brake systems proportioning. I know in the past, it was different between the wagon and sedan... Ted

updated... Shows data for each kit including the mu of the pad shipped with the kit. Bias is based on a mu of 0.35 for all pads shown. Ted

Dan, Thanks for the post! I agree with every point you made. I am just trying to compile a list that will add a piece of information to the puzzle... It is very true that suspension can have a major effect on braking, as can tire pressure, tire grip, tire temperature, and sidewall strength. The empirical data would be great! I am working on going back to one mu now... Ted

Well, I was actually using the mu of the pad a few of them ship with, but I agree with you. I was just trying to easily illustrate how having stock rear pads and a BBK w/ upgraded pads can get vey poor... I will work on this in a little while. Is the code format better or worse? Ted

OK, I have redone the format. I will typr exactly what everything means later tonight, but I added a comparison of what "ships" vs. matching pads. Matched pads are a mu = 0.5. Stock pads are now mu = 0.35... Hope this is better! Ted

real quick, Do you all want the stock brake pads to stay at 0.3, or move to 0.35?

Yeah, I will do that set-up. I am also going to be adding some stuff to the first post, so give me an hour or 2. iON was cool enough to check the thread and give me some more info! Ted

What Hawk pad is one step down from HP+? Ted

That is a really funny, and sad, response. With mildly aggressive Hawk pads, the mu should be at least 0.45. Using that with the stock rears gives you a set-up that is more front biased than stock. Going to a mu of 0.5 w/ stock rears, gets near 80/20. If they have a specific set-up that is best, they should let people know when they buy the kit... Ted

Great points Joel, and I agree with everything you have said. The best part, is that the LGT has a good bit larger brakes and doesn't weigh that much more than the WRX, so heat capacity and fade resistance should be even higher! Adding in better 2-piece rotors gives even greater heat capacity w/ less chance of frying the bearings... But, mu for the WRX is generally documented between 0.35 and 0.39. The LGT is thought to have an even lower mu, somewhere between 0.25 and 0.35. That is why I used the numbers I did. I can go to the upper limit, 0.35, but a mu of 0.5 on the front w/ 0.35 on the rear will still push the bias to the front a great deal. Thanks, Ted

He typed faster than me Great question too! Because EBD functions only when the tires lock... If you have it set up perfect, you can go further before they lock and EBD starts to send the biasing around. I wish it was a truly intelligent system, but it is not. But, this is truly a dynamic problem, that is why we don't have a 55/45 bias to match the car's weight bias. This also doesn't take into account the large flex of a sliding caliper, or the almost zero flex of an AP racing caliper vs. a Brembo caliper. Those are variables that come into play, but do not affect things so much that it changes the end result. Does that help? Ted

Interesting. That makes me think the proportioning valve on the STi is set-up quite different. Subaru also might take into account the EBD on the Legacy and tune closer to the edge of a perfect bias since if the rears do lock the LGT will send more to the front and less to the rear... Ted

What is the weight distribution of a stock STi?

Good question! No. For these calculations I was mainly trying to show what you would do to your bias. I am working on building in the MC/piston size problems...

Dan, Here is one of the articles that talks about brake biasing. I will look for more. In it, they tested an Audi S4. (twin-turbo) A ratio of 2.5, or 71.5%/28.5% was ideal for that car. While the LGT is different, it is close enough to the same, that the numbers from the S4 should be close. Factor in that we have a better F/R weight distribution, and the lower center of gravity due to the boxer, and that is why 70/30 (2.3333 using their convention) is likely ideal for our car. All manufacturers design in front bias so the tail doesn’t get happy during braking. Shifting closer to a 4 wheel lock-up equates to shorter stopping distances. The STi Brembo front w/ stock rear and stock pads is a 4.56 using their convention. Take a look where that puts you on the chart… Make sense? Ted