Brake Pad Chunking from Track

[radon55]

Hello all,

So far I've been fortunate to get to 6 track days this year. I have a 2017 non-PP BRZ with Project Mu Club Racer pads. Club Racer Advanced up front, and Club Racer in rear.
I've been looking at the pads after each weekend, and they've held up pretty well, but I started seeing some deterioration at the leading edge of the front pads after weekend #2.

I just took a look after weekend #3 and am wondering if I should be concerned about this chunking off the leading edge. The pads still stop the car very well and consistently on track.
Thanks for any feedback!

https://imgur.com/a/T6ZnY3G

[GrabTheWheel]

Those look cooked. I would replace them. Looks like they got too hot. Are you sure you did a sufficient cool down after each session before parking in the pits? (hopefully with the ebrake down). I'd put temp stickers on your calipers and monitor temps next track day.

Also, depending on the number of laps 6 days isn't bad for pads although you'd get more on those if they weren't falling apart.

[radon55]

Originally Posted by GrabTheWheel

Those look cooked. I would replace them. Looks like they got too hot. Are you sure you did a sufficient cool down after each session before parking in the pits? (hopefully with the ebrake down). I'd put temp stickers on your calipers and monitor temps next track day.

Also, depending on the number of laps 6 days isn't bad for pads although you'd get more on those if they weren't falling apart.

I try to do the normal in-lap where you don't touch the brakes at all. It's been very hot the last two weekends I've done though.
Just very annoying to toss them since there's so much pad thickness left.

Good idea on the temp stickers. I'll pick some up.

[CounterSpace Garage]

Those look normal with a lot of ABS action and a bit of overcooking. There are other well known brake pad compounds that completely crumble and fall apart. Project Mu pads tend to have higher friction so it gives the initial impression of super nice bite. This does come at a slight detriment of getting users to initiate ABS a little sooner than usual. There are companies that mitigate this by having higher friction values but with squishier compounds to give a sense of "modulation". In reality, it's just deforming under heat kind of like how you can heat up a sheet of metal (such as aluminum) and be able to bend it giving you a sense of strength, but in reality the material was just deforming under handicapped circumstances.

[radon55]

Originally Posted by CounterSpace Garage

Those look normal with a lot of ABS action and a bit of overcooking. There are other well known brake pad compounds that completely crumble and fall apart. Project Mu pads tend to have higher friction so it gives the initial impression of super nice bite. This does come at a slight detriment of getting users to initiate ABS a little sooner than usual. There are companies that mitigate this by having higher friction values but with squishier compounds to give a sense of "modulation". In reality, it's just deforming under heat kind of like how you can heat up a sheet of metal (such as aluminum) and be able to bend it giving you a sense of strength, but in reality the material was just deforming under handicapped circumstances.

So theoretically if I'm able to nail threshold braking more the crumble resistance should be improved? This is my first track season so I do need improvement for sure getting my braking correct.
Are you also in agreement that the pad should be replaced at this point?

This squishier compound some companies use, as it is more pliable, is there an improvement in crumble resistance? Or is it more just of a driver preference type feel for the pedal adjustment.

[CounterSpace Garage]

Originally Posted by radon55

So theoretically if I'm able to nail threshold braking more the crumble resistance should be improved? This is my first track season so I do need improvement for sure getting my braking correct.
Are you also in agreement that the pad should be replaced at this point?

This squishier compound some companies use, as it is more pliable, is there an improvement in crumble resistance? Or is it more just of a driver preference type feel for the pedal adjustment.

1. Not necessarily. Crumbling is normal for certain compounds. This is perfectly fine and can be reused again. What's not fine is if the pads have half the compound chunked off.

2. Squishier is manufacturing process based. Higher end manufacturing capabilities can get the pads to be more consistent and "stiffer". Squishier means pads operate less consistently with different pedal pressures and temperature. In other words, it's like pressing against a sponge and the friction characteristic changes. It's not that extreme, but as you drive more and experience more pads, you'll find that every manufacturer has unique characteristics.

For reference, our CSG pads are extremely stiff and the friction values are much lower than what other brands advertise, however the bite, consistency, modulation, etc. are very intuitive. Granted, our specified processes are very unique, hence the price point is much higher.

Back on topic, if this is your first season, enjoy the pads for what they are. Crumbling is normal and keep using the pads. If you're interested in trying a spectrum of brake pads, let us know. We can tailor the driving experience accordingly.

[rice_classic]

After every couple sessions on track I will flip my pads on the rotor. Just (1) 14mm wrench to swing up the caliper and swap the inside pad with the outside pad. This will help them even out the taper and last much longer and will likely help reduce the crumble as well.

[redlined600]

My club sports always crumbled as well. I just keep running them until they are used up, with no issues. They usually look worse than that by the end.

[CSG Mike]

Originally Posted by rice_classic

After every couple sessions on track I will flip my pads on the rotor. Just (1) 14mm wrench to swing up the caliper and swap the inside pad with the outside pad. This will help them even out the taper and last much longer and will likely help reduce the crumble as well.

Taper is a sign you're over the MOT of the pad!

[rice_classic]

Originally Posted by CSG Mike

Taper is a sign you're over the MOT of the pad!

Taper from exceeding pad MOT is predominately longitudinal. Radial tapering is predominately a function of floating caliper flex.

You'll see many monoblock (4 pot/6pot) have different piston sizes from the leading side to the trailing side to mitigate longitudinal taper and I think the dual piston calipers on our cars do a lot to reduce this as well. The longitudinal taper on our cars is negligible.

The radial taper - that is the taper from the innermost radius to the rotor to the outermost radius - is not negligible. This is functionally unavoidable on a floating caliper once enough pedal pressure has been exerted to induce flex (which is always on a racetrack).

I think the OP is exceeding the MOT on the leading edge from a longitudinal perspective and would doubly benefit from pad rotation.

Edit: CSG Mike if you think there's a pad that out performs the ST47 in a meaningful way, send me a set and I'll provide an honest review. Better yet, be my pad supplier and I'll run a CounterSpace Garage windshield banner for the rest of the season including the Runoffs in exchange!

[CSG Mike]

Originally Posted by rice_classic

Taper from exceeding pad MOT is predominately longitudinal. Radial tapering is predominately a function of floating caliper flex.

You'll see many monoblock (4 pot/6pot) have different piston sizes from the leading side to the trailing side to mitigate longitudinal taper and I think the dual piston calipers on our cars do a lot to reduce this as well. The longitudinal taper on our cars is negligible.

The radial taper - that is the taper from the innermost radius to the rotor to the outermost radius - is not negligible. This is functionally unavoidable on a floating caliper once enough pedal pressure has been exerted to induce flex (which is always on a racetrack).

I think the OP is exceeding the MOT on the leading edge from a longitudinal perspective and would doubly benefit from pad rotation.

Edit: CSG Mike if you think there's a pad that out performs the ST47 in a meaningful way, send me a set and I'll provide an honest review. Better yet, be my pad supplier and I'll run a CounterSpace Garage windshield banner for the rest of the season including the Runoffs in exchange!

The CSG pads are already proven. I would encourage you to try them, but if you find the ST47 does the job for you regardless of tapering, then there's nothing wrong with sticking with what works for you!

Given the current life/cost ratio of the CSG pads, and your proven driving history, taking advantage of the CSG contingency program may effectively cut the cost of your program significantly

There are many factors involved in pad taper, but we all already agree on how, when, where, and why they taper on this platform, so that only adds to our evidence.

[radon55]

Originally Posted by CSG Mike

Taper is a sign you're over the MOT of the pad!

Uh, what's MOT?
From a quick google I keep getting a UK braking test lol

Thanks for the feedback from everyone. I have flipped the pads for my next weekend and I'll see how they go from there! Definitely bringing my spare pads just in case the crumbling gets significantly worse after a single day.

[nico_rsx]

Originally Posted by radon55

Uh, what's MOT?

From context, I'm pretty sure it's "maximum operating temperature" (of the pads).

[CSG Mike]

Originally Posted by radon55

Uh, what's MOT?
From a quick google I keep getting a UK braking test lol

Thanks for the feedback from everyone. I have flipped the pads for my next weekend and I'll see how they go from there! Definitely bringing my spare pads just in case the crumbling gets significantly worse after a single day.

Maximum Operating Temperature. Actual observed temperature is the result of a few factors, primarily in order, ABS use, kinetic energy converted, and pedal pressure (which contributes/causes ABS).