rm21

A few months ago, I installed the AP Racing Radi-Cal calipers with the Ferodo DS 1.11 pads on my 991.2 GT3. In terms of the on-track performance, and ease of pad changes, I've been very pleased with the setup. After two days at VIR, I wrote a post about how little pad I had used. But after another two days at Road Atlanta, the pads were shot. I've attached an image of the front drivers side pads. In addition to the high rate of wear, there was noticeable tapering. I was driving the car very hard, trying to break 1:30, but nonetheless, that seems like some pretty rapid wear. Most of the other reviews of this setup have had pretty good things to say about wear rates, but I think those were with Cup2s, not R7s. I had the RE10 pads on my 991.1 GT3 and thought they were fantastic - I would get between 10-12 days per set, but that was also with Cup2s. Has anyone tried a different pad with the Radi-Cal setup that produced better wear? Or do I just need to adjust to the reality of higher rates of wear if running R7s?

orthojoe

More grip means you are taxing the brakes more with later and harder braking. The pads will wear much faster as a result regardless of which pads you use. I'm surprised about the tapering, but since we don't have ceramic pucks to crack, not a big deal

thebishman

TRAKCAR

jadski

Mech33

krell

I'm surprised there is any taper considering the different bores of the pistons in the kit should eliminate that. My Brembo GT kit for my M3 has zero pad taper.

I was discussing brake setups today with a friend and he thought the DS1.11 are Ferodo's sprint pad, and the UNO is the endurance pad. That may or may not change expectations for this pad.

mdrums

MaxLTV

I think this is how these pads work. I had the same situation with 3 sets already - everything is great up to about 50-60% left and then they turn into something so soft it can be crumbled with bare fingers and either wear out within a session or just crumble off the backing plates. I don't know what causes it - could be some kind of heat-cycling. But I'm done with them.

Also, surprised about the taper - I have no taper with them in stock calipers.

CDinSing

mdrums

JRitt@essex

Hello Gents,
I'm currently working on article about pad wear, but I have no idea when I'll have a chance to complete and publish it. In the meantime, I'll address each of the topics below.

Temperature, Mu, Fade
Pads typically work optimally under a specific set of conditions. That goes for street pads or race pads. If you look at a brake dyno plot, a good race pad will in most cases have a fairly flat torque curve over a specific temperature range. That torque is measured as mu. For example, at 1000F a pad has a mu of 0.43, and at 1300F it has a mu of .45. A good race pad gradually tapers off in mu as it gets hotter. That means it is still generating friction as the temperature climbs, but you need to press harder to get the response you want out of them. If you exceed the pad's maximum operating temperature, the mu drops substantially and that is pad fade. You press the brake pedal, it remains firm, but the pads aren't generating mu any longer and the car doesn't slow. A poor race pad abruptly loses its mu. The curve on many of the brake pads we evaluate on our brake dyno drop precipitously when they reach a certain temp. That is scary, and not something we've ever seen with a Ferodo compound, including the DS1.11. The Ferodo pads maintain mu up to the highest temps that our customers are seeing. As noted in the quote above, the DS1.11 pads perform well, don't fade, etc.

Taper
We see pad taper on all fixed caliper brake systems, across all platforms, at all levels of racing. That includes the pinnacle of pro racing such as IMSA, NASCAR Cup, etc. Pad taper is unavoidable. As the disc spins and the pads are clamped against them, particles of the pad are ripped off the pad face and they travel back along the length of the pad, and the pad floats a bit on that material towards the rear of the pad. As the discs contact the pad on the front edge, the spinning disc tips the pad in a bit on the leading edge and the trailing side gets wedged against the abutment plate and the edge of the pad cavity. The differential pistons are arrayed to apply slightly uneven pressure across the length of the pad. They put less pressure on the leading edge with a smaller piston, and more on the trailing edge with a larger piston in an attempt to even out the longitudinal taper described above. The longer and thicker a pad is, the more likely it is that you'll see some of this type of taper.

At what appears to be a couple mm, the pad taper shown in the pic above is extremely minor. I actually have some pads from other manufacturers sitting on my desk that show taper to a much more severe degree. I'll try to snap some pics of them. Helpful tip: The simple way to even out pad wear is to swap the pads around between events. Move inners to outers, and swap the sides of the car. On our calipers, doing so is quick and simple. That will help even out pad wear and allow you to squeeze some more miles out of them.

Also note that changing conditions such as the track will have an impact on whether or not, and how much, taper occurs. You may see no taper on VIR, but may see considerably more at Road Atlanta.

Pad Wear Rates
Pad wear rates are incredibly hard to predict. As I noted above, a pad tends to have a temperature range in which it generates a certain level of mu. Just as mu changes with temperature, so do wear rates. Sticky tires and different tracks dramatically change the operating conditions for the pads. Sticky tires generate more grip with the track, shorten stopping distances, and place greater demands on your brakes. Switching to a different track will alter how long you're on the brakes, how far apart the brake zones are, how much time the brakes have to cool between stops, etc. These factors can dramatically alter the temperature window in which a pad is operating, along with its wear rates.
As pads go through numerous heat cycles, it's normal for them to have a bit of flaking, crumbling, etc. on the edges. All of the binding agents in the pad will break down a bit with enough heat and pressure. This is not a brand-specific issue. We see this all the time on pads from a wide array of manufacturers. Helpful tip: Race pads that have been heat cycled a bunch of times should be treated with care. Don't use your pads like a lever to push the pistons back into the bores. Don't drop the pads on the concrete in the pits or in the garage. I've seen people chuck them around, use them as tools, etc. While the backing plate is a solid piece of steel, the pad material isn't. They can be damaged, fractured, chipped, etc. I wouldn't call them delicate, but they aren't indestructible either.

Pad and DISC wear rates
Pads and discs are essentially two pieces of metal that you're rubbing against each other with a great deal of force at incredible temperatures (we see 1600F in NASCAR, and most people on this forum likely operate at 1000-1350F at track days, club races, etc.). We you rub to hard materials together, one of them is going to wear faster than the other, and the one that wears out first is typically the softer of the two. In the case of the Ferodo DS1.11, it is not a particularly hard material. That means the DS1.11 is easy on discs. We've seen customers run the DS1.11 on all types of discs (OEM, other brands, AP Racing) on all types of cars and get tremendous number of track miles from their discs. We've had a few customers tell us that they had better PAD wear rates from the RE10 pads the OP noted, but based on everything we've seen, those pads are more abrasive and your discs aren't going to last nearly as long.

Again, note that pad and disc wear change with temperature. When abrasive race pads are run cold, they can chew through discs extremely quickly. One of the reasons many of our customers love the DS1.11 is because they can get away with leaving them in the car at all times. They drive them to and from the track, at the track, on Sunday morning jaunts, canyon carving, to the grocery store, etc. The DS1.11 generates mu across a very wide temperature range. They generate bite/mu when cold (not always the case with race pads), they don't make a ton of noise, and they don't devour discs at day-to-day temperatures.

Pad choice comes down to tradeoffs. There is no magic pad that can work optimally in all conditions. The Ferodo DS1.11 works extremely well under an incredibly wide range of operating conditions, and that's why it is our most popular race pad compound. Other pad compounds may last longer, but that might be at the expense of disc wear, noise, difficulty bedding them in, price,

All of my comments above exemplify why you see dramatically different feedback on brake pads from different users. We deal with this everyday. I'll have a Subaru BRZ customer call and tell me his Ferodo DS2500 were silent driving to the supermarket, and an M3 owner will tell me that his DS2500 were squealing on the way back from his track day. We've already seen this type of feedback in this thread. One person says they burned through a set of pads in half the time that another person does on the same car. Everyone is using their brakes under a different set of conditions. Different tracks, tires, brake calipers/discs, pads, driving style...the list of variables goes on. Dialing in the proper pad choice is going to take some time and experimentation for each individual based on their car, their track, their tires, and their driving style. That won't necessarily be the same as their friend with the same car, which makes things tricky.

As a pad supplier, we try to ask our customers questions so we can help choose the right pad for them. In the case of our brake kits, the DS1.11 is our default starting point. As noted above, they work for many people under a wide range of conditions. They are a great point of departure, and the majority of our customers keep coming back for more because they are a sweet spot in tradeoffs...they don't eat discs, they last a reasonable amount of time, they work well in varying condition, they aren't silly expensive. That said, some people want lower mu, some want better wear, some want less noise...every situation is different.

Another problem we face is that we're typically flying somewhat blind. On our brake dyno we have a very controlled set of variables and an incredible amount of data. We can manually adjust pressure, length of stop, time between stops, etc. With race teams, we also have data. We have caliper, pad, and disc temps, sometimes real-time from a car. Having data makes it much easier to adjust our recommendation. Most retail customers can't give us any usable data. They have pyrometers that only go to 999F, they lose 300F by the time they pull into the pits and collect a temp, etc. That means we're many times trying to make recos with very little actual data. It's all based on past experience, what we've seen with other customers, etc. We do a very good job of it, but it's not perfect.

New Endurance Compound= Ferodo DS3.12

Yah, yah, that's all good...now help the author of this post!

We are just getting ready to launch a new endurance racing compound from Ferodo called the DS3.12. This compound didn't even have a name until last week! Under identical conditions on our dyno, we're seeing considerable increases in wear rates. I don't want to attach a number to it, but it is significant. Ferodo had tremendous success with this compound in European GT3 racing in 2018. We've had about a number of customers running this pad compound for the pads year on various platforms ranging from BRZ, Civic Type R, M3, Corvette ZR1, etc. The results have been extremely encouraging, and we're getting ready to launch this pad commercially. The DS3.12 has an insanely flat torque curve up to temperatures that exceed what the DS1.11 can handle. It does have a slightly higher mu though, so it won't require as much pedal pressure to get the same response. All our beta testers have said it remains completely controllable.

rm21,
You seem to potentially be the perfect candidate for this new pad compound. Please shoot me a PM and I'll get you set up with a set of these to test (at no charge). I'm going to be asking a few others to try them as well. I plan to make a separate post in this forum on that topic later this week.

Thanks for listening everyone. Time for more Sunday morning coffee!

CDinSing

mdrums

MaxLTV

Ok, what am I doing wrong that I have this happen with Ferodo DS1.11 at about 50% or more of material left? I run tracks that are easy on brakes, and pads last a very long time with very little wear and then just turn into dust. I thought one set was defective, but it happened again and again. The material on the photo looks a little less than 50% but that's because I did half a session while it was already crumbling and wearing at high rate, and pulled in because it felt wrong. But before that session it was definitely at over 50%. That's just not safe - check before a session, and there is plenty of material, go out and lose brakes right after a warm-up lap...