New Discs for GLA45

Third factor, flushed the fluid totally with Motul RBF 600. I couldn't get a straight answer from MB about the OEM fluid dry and wet boiling point, so it got swapped out. Took 3 liters since there is a baffle in the tank and we can't siphon old fluid out of the reservoir, just keep adding and bleeding.

Anyway, I need to talk to my colleagues at work who track often. Based on what they say and SpeedSF folks say (and they seem to agree), my takeaway is that brakes should have a healthy ramp through the pedal stroke, implying initial bite is "bad", and braking should be roughly linear.

That is about what I get with the HPS5.0 pads. There is very little brake bite, and certainly noticeably less than the OEMs (not the the OEMs have crazy bite, but they did bite a bit). Braking is predictable through the stroke, all the way to very heavy braking. At no time did my tires ever lose traction from braking (straight line or otherwise). At times there was very heavy braking because my instructor came down super-slow to hit turn 11, and we were getting pretty good at flying out of turn 10.

There was zero fade. absolute zero, and they performed consistent from the first 5 minutes of the first session all the way to the last 5 minutes of the last session. I cannot say the same about my tires which were greasy and crying for help by the middle of the 4th session. Braking consistency was an absolute highlight.

Where I want to consult those with more track time, is how much effort I needed to apply for braking. Since the initial bite is low and the progression is pretty linear, I end up sitting deeper in the brake lever more often to get the braking power I want. And sitting deeper in braking means I am putting more effort into pushing on the pedal. That means I am pushing very hard on the brakes coming into turn 11. Is the increased effort normal, no big deal, even desirable? I don't know. Before HPDE I assumed brakes should hit hard and be effortless, and have learned that is NOT the case at all. But I don't know if effort should be ramping up linear just like the braking force.

I also cannot comment on overall stopping power. As you know, we can stop our small cars in a hurry! Our brakes are already very good. I don't have the right tools to quantify stopping distance, and if TrackAddict can do it, I didn't have that resource with the OEM pads. My butt accelerometer tells me I have a bit more braking power now than with the OEM, but no data.

Overall, I am reflecting on them. Everything I am hearing and feeling tells me these are ideal brakes for my kind of driving (occasional track day). Combined with the Motul Fluid, it seems a recipe for total reliability and predictability for 2 hours of sessions on the track, which is about the peak of my ambition. It's hard for me to justify trying Pagid pads at twice the cost without confidence I will see twice the improvement. I think I'd be better off spending the difference on an extra HDPE day.

You are taking a much different line in turn 2 than my instructor did. The line as I understand it is to take the first apex wide, then hit the second apex and nail it, to set yourself up for the most exit speed before turn 3.

Now, we didn't carry much speed out of turn 1 because he was grossly underpowered, but we still had to brake into turn 2. Looks like we both were going into turn 2 at about the same speed range too.

2:35 is a closer match to the line we were using. your 6:15 lap, you turned way too early and came into the corner in the middle of the track already. 8:15 you didn't even go to the edge of the track, everything was from the middle inward. I know, I know, Monday morning quarterbacking, and your best laps are 8 seconds faster than my best laps...

After my instructor suggested most of the turns start at the white cone, my driving tightened up alot.


About 5:00 in was our line. This video only captures one instance of turn 2.

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The way you describe yellowstuff, I don't think I'm so eager to try them.

Update. My pads finally reached end of life after my last track day at Buttonwillow. I know BKM protocol for Euro cars especially benz is replace pads and rotors together. The OEM's completely eat the rotors.

The Hawk HPS 5.0 didn't. No grooves, no lip. So, I just swapped out the pads and fluid and went about my day.

I in fact bought HPS 5.0 for the rear and swapped them out (I've been running OEM in the back since day-1). My OEM pads are at 90% (swapped out last year) but the rotor is already 2mm lipped and has minor grooving. I'm trying the pads as-is on those rotors since "it's just the rear", though next go I'll definitely swap out the rotors. Only a couple weeks on it but so far so good. Feels much more positive than the OEM.

If the fronts on go #3 still don't eat the rotor then these pads are good candidates for fancy light weight 2 piece rotors.

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That, or I'll play with carbotech XP10/XP8 pads next time. But it might be hard to pull the trigger on that knwing the pads are 3x the cost and that they will fir 100% certain eat the rotors.

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Anyway, interesting datapoint. 2 years of life out of the front pads with HPS 5.0 compound and light track use. Pristine rotors.