The Pros and Cons of Putting Aggressive Performance Brake Pads on Your Daily Driver
Sometimes it sounds like you’re dragging a steel pipe underneath your car.
If you want to accumulate significant time on a race track but your disposable income and parking room is limited, you might have to run the same car you use for daily driving on the course. There are inherent risks to that, and a few inconveniences. Like listening to squeaky, loud performance brake pads in traffic.
Keeping an eye on your vehicle’s mechanical condition and having exceptional awareness on track are key to preventing a crash. But even if you’re able to keep your car clean on track, you’ll still have to work out the equation of how much noise, vibration, and harshness you’re willing to endure on your way to work Monday so you can try to drop your lap times on Sunday.
If you’ve got a one track mind for going fast, you’ll be more willing to trade-off comfort for performance. Upgrading your car’s brakes from everyday street pads is a hugely significant step you can take towards improving its track-worthiness, but contrary to what you might imagine, brakes meant for “motorsports” can actually be suboptimal. Especially when they’re not being used, you know, under track conditions.
Upgrading Brakes Efficiently
The great thing about attending track events is that you can genuinely show up with anything as long as it’s in decent mechanical shape and isn’t leaking any fluids.
If you’re going to start upgrading, or want to have a better and safer time in a stock-as-heck car on track, brakes are the best place to start. As important as acceleration and cornering are, brakes are what bring your fast-driving flow altogether. Having strong brakes that stand up to higher temperature due to repeated hard use are crucial. They also as provide more direct feel, make driving on track more fun, and help drop lap times.
DOT 4-rated brake fluid has a higher boiling point than DOT 3, which is what most cars run conventionally. DOT 4 ensures you won’t lose braking strength due to repeated use at higher temperatures, and it has more longevity than convention DOT 3. DOT 4 is more hygroscopic, though, meaning it has a higher tendency to suck up moisture, so it requires more frequent changing. I used to think DOT 3 takes slightly longer to come up to operating temperature, but that's actually a brake-pad-based trait (more on that in a bit).
I started out upgrading the brakes on my Mazda 2 by swapping to Castrol SRF DOT 4 racing brake fluid, using performance street pads, and braided, stainless steel brake lines. Braided lines don’t expand and contract and lose efficiency from higher temperatures like rubber lines. Think of the steel braiding like a binding, or a corset – if the line tries to expand or swell out of shape, which can happen in high-heat situations and diminish braking responsiveness, it’s held in place and your brake pedal feels consistent.
The steel also acts as armor; there’s less chance of a line being damaged from going off-track or hitting debris. Some people disagree and say rubber lines are fine, but for how cheap steel ones are, it’s a why not? mod in my book.
Swapping in performance street pads helps maintain braking strength at higher temperatures than factory-style pads. In general, because performance pads have a more metallic compound, they might wear rotors a tad faster and produce more dust, but they’re a great upgrade over OEM for sure. After trying this mild upgrade, I wanted to upgrade to something more aggressive as I got faster and faster on track. That’s when I experienced an inevitable but annoying side-effect… The stronger, more track-focused my pad choices got, the more annoying they became to use on the street.
Performance Pads To Race Pads
As I got faster on track, performance street pads became overwhelmed and overheated by shorter, more intense braking zones. They weren’t cutting it anymore. They’d fade and lose strength, causing me to either go off the track, understeer off line, or a gloriously terrible combination of both. I then changed up to more aggressive pads that literally did cut it – they were so strong that they ate up and cut grooves into the rotors quite quickly.
After a bit of research and trial and error, I ran G-LOC R10s. These pads are a popular compound in SCCA B-Spec racing; a class where caged, race-prepped versions of my Mazda 2 shine. They had great modulation, were quite strong, and stayed strong all-session-long. They also weren’t harsh on rotors. Modulation is key; being able to feel how much clamping force there is on the rotor, especially while trail-braking into tricky corners, is paramount for holding momentum and getting a 100-horsepower Mazda 2 around a track in decent time.
However, off-track the benefits of these pads quickly faded (pun sort of intended).
When Racing Pads Start To Suck
Like I stated earlier, stronger pads are stronger pads; on the street, they grabbed and slowed my Mazda down significantly better than an OEM pad compound. But since the temperatures for road driving and track driving are different, so are the pads’ characteristics.
The G-LOCs took a bit of time to warm up. This is never an issue on track. Even on an out-lap meant to warm the car up, there’s enough hard braking happening to bring them up to temp before the first flying lap. But the street is different. Cruising through my 25 mph neighborhood after just-firing-up the 2 required a slightly harder pedal push at the first stop sign.
Then there was the noise. Oh my stars, the noise. Easy going street driving, especially on a cold and or damp SoCal morning, meant the G-LOCs were squeaking pretty much all the time until the brake pedal was firmly pressed. Lighter stops of the quarter-to-half-pedal variety made a loud grinding noise that cut right through the eardrums. It was a deep, pronounced grinding; I’m not the type to cringe at nails on a chalkboard, but this noise was brutal. Sometimes it sounded like I was dragging a big, heavy pipe under the car.
The only remedy was to do as many hard of stops as possible, acting like a total dick in the process.
Decent-flowing, mild traffic on the highway was very annoying, too—it puts the pads in a sort of noise purgatory. The temps were too cool to stop the constant squeaking, and feathering the brakes when needed causes slightly-less-annoying grinding.
This was all a lesson in compromise. Or, rather, the stock style brakes were supposed to be a “compromise” between functionality and comfort. The compromise I made was “comfort be damned.” Brakes that perform wonderfully on track mean dealing with downsides on the street—there’s still a lot of meat in the middle of this Venn diagram.
Racing Brakes Can Actually Be Fun on the Street
When racing pads are warmed up, they’ll perform really well. Like, really well. This is very handy for dealing with sloppy drivers who like to get in your way and hate using turn signals. Strong, grabby brake pads are reassuring in these scenarios.
Then, there’s having fun on twisty canyon roads. Strong track pads ensure adequate stopping power for mild enthusiastic driving, as well as any kind of emergency situation. Like massive rocks in the middle of the road that can’t be avoided, or dickheads in cars or or motorcycles crossing the double-yellow line in front of you—being able to stop or change direction quicker means a better chance of avoiding a bad situation.
There’s one more street benefit to share: loud brakes save lives. Like the old saying loud pipes save lives, having something that reminds other drivers of your presence on the road, especially if you’re in a small car, is always a good idea. Asserting one’s presence with loud racing brakes comes in handy, and might even over-power the Nickelback blaring out of some poorly driven lifted bro-dozer or heavily tinted heap of sedan.
Swapping Pads at the Track Is Also an Option
One can also just swap pads in and out at the track, or the night before the event. Most caliper designs are pretty simple, and with the right tools can be removed and re-mounted pretty quickly.
Despite not having the most performance-oriented tendencies, it's nice that both my BMW 128i and previous Mazda 2 have very simple, single-piston front brake calipers. For the 2: unscrew the cap on the brake fluid reservoir, remove two 14mm bolts, slide the caliper off and rest it on the rear shield, pop the pads off, use a caliper spreader if needed, slide the new ones in, re-install the caliper, and screw the reservoir cap back on. Done. This way I can daily on a performance street pad, and track on an aggressive track pad. The rear brakes on the 2 were drums that never needed replacing, and thankfully my 128's rear brakes have done just fine on the street and track with very street-centric performance pads.
There are some risks associated with doing this, though. A lot of OEM and performance street pads require a bit of pad material transferred onto the rotor for optimal performance, so do your research when selecting pads. Track pads remove this material due to their aggressive, mostly-metallic makeup. Redoing this with the OEM or performance street pad is strongly recommended after they’re re-installed, which is done via the pad brand’s listed bed-in procedure.
Another method is to have dedicated rotors for each set of pads. In fact, that might be the move to fully avoid squeaking and having to re-bed.
No matter which, swapping pads before and after track days ensures living a life of less suffering. It does entail factoring in more steps and frequency for prep, which becomes a trade-off on its own. Especially if your time is limited. But heck, write up a thorough checklist and consider it an opportunity to inspect your car's braking system to ensure optimum performance and safety.
Editor's Note 9/21/22: Added a note about brake fluid operating temperature and hygroscopicity.