02-18-2020, 12:40 PM | #23 |
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I will be tracking my car this year and wondered if you guys could help with the following?
If running dedicated front track pads (for example; RS29’s) could you still run the rear OEM pads and be OK? (bearing in mind rear braking accounts for approx. 25% of your total braking force).Ankit Mishra |
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02-18-2020, 01:42 PM | #24 | |
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02-19-2020, 08:56 PM | #25 | |
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I've heard the other brakes are indeed a very big shortcoming. |
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02-24-2020, 10:31 AM | #26 |
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Some input on the Ferodo DS compounds with regards to front/rear, and some overall notes on mixed mu pad setups.
Our recommendation on this chassis (and just about all chassis for which we develop brake systems) is to the run the same pad compound front and rear for superior performance and longevity. We design, run calculations, run simulations, conduct testing, etc. with the assumption of the same brake pad compound front and rear. Any deviation from that is going to impact brake bias. Any time you run a higher mu pad on one end of the car, you're shifting some amount of brake work to that end of the car. In the case of this thread, the DS1.11 is a higher mu pad than the DS2500, so you're shifting bias towards the front when you run 1.11 front/2500 rear. The relevant question here is, "Is that bias difference enough to be problematic?" We have quite a few customers across different platforms running the DS1.11 up front and DS2500 in the rear. As noted by others, this is mostly born out of the convenience of only having to swap one axle of pads. For the casual HPDE enthusiast, our experience tells us that leaving the DS2500 in the rear tends to NOT be problematic on BMW M cars. It's not ideal, but it doesn't create any major issues. Just keep in mind though, that when you're running DS1.11 front and DS2500 rear, you're shifting a little bit of brake bias to the front of the car. That is going to put more strain and wear and tear on the front brakes. Having the same pad compound at both ends of the car will use the brakes at both ends of the car most efficiently. To some people, the convenience factor is worth the trade-off in performance and wear. Some things below to watch out for however:
In some cases we've actually had people tune their brakes in the opposite manner via a higher mu rear pad compound. For example, we had one Subaru STI time attack gent run a slightly higher mu pad in the rear to try and get the car to rotate more under trail-braking. However, that would be much more of a problem on a nose-heavy pig, excuse me platform, such as the STI than it would on a beautifully balanced M2. Also of note, if you are running a more aggressive Ferodo compound like the new DS3.12 on the front, we definitely would NOT suggest running the DS2500 on the rear. Running the DS3.12 front and DS1.11 rear would likely be okay, as the difference in mu between those is not as great. The gap in mu between the DS3.12 and DS1.11 is considerable however, and more than we'd suggest running. That setup isn't going to give you the results you want. Below is a mu graph from Ferodo that shows the relative difference in mu curves across their pad compounds. Don't worry about the specific mu numbers. Trying to compare mu values on this chart with numbers provided by other pad brands is no different than trying to compare horsepower numbers from a Dynojet vs. a Mustang Dyno. This graph is really only useful for comparing mu curves within the Ferodo pad lineup. You'll see that the DS1.11 and DS2500 have fairly similar shapes to their mu curves up to about 900 degrees F (500C). At that point, you'll see a steady drop-off in the DS2500's mu, whereas the DS1.11 declines more slowly. The hotter you get 'em, the greater the difference you'll see in the ability of the DS1.11 and DS2500 to generate friction. In other words, if you're running your brakes super hot on a tough braking track, the spread between how much friction the pads are generating at the front vs. the rear of the car is going to widen. Hopefully the above is helpful and makes sense. |
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02-25-2020, 12:09 PM | #27 | |
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03-30-2020, 03:00 PM | #29 | |
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03-30-2020, 03:04 PM | #30 | |
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https://www.apcautotech.com/getmedia...e-8-2018_1.pdf All I do is find a road with little to no traffic on it. With the car going 55-65 MPH Left foot brake while keeping your right foot down on the gas. DO this with heavy brake pedal effort for 5 seconds at a time. Use the throttle to try to maintain steady speeds...Do this 3xs quickly then drive around and let them cool off. Repeat above a 2nd series of 5-7 sec applications. If you do this correctly your pads and rotors will get stinking hot and they will be bedded. I've been bedding pads like this for 30 years. Works awesome...
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03-31-2020, 05:42 PM | #31 |
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03-31-2020, 05:44 PM | #32 | |
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Link explained it super quickly, much appreciated man! |
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04-01-2020, 07:18 AM | #33 |
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Thanks gents. Here's another video on swapping between street and track pads. This one can save you some serious headaches:
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04-01-2020, 10:57 AM | #34 |
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Any tips when you don't have time to do this and you kind of have to do it in the track ?
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Fun/HPDE: 2023 M3 6MT Individual Malachite
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06-07-2020, 07:57 AM | #35 |
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Hey all, thanks for a very useful thread
I've actually killed my stock pads and rotors on a track and am looking for a proper setup now (front and back). Pads I'm thinking of Ferodo DS2500 vs 1.11 (Pagid's not easily available in Poland). I'd go with 1.11 but am a bit worried about the sound - car is 80/20 street/track. I'm not that keen on changing pads every time I go in for a track. Is the sound ok to live with or maybe 2500 will do the job? If it helps, car's tracked on semislick tires. Rotors Info I got is that I need OEM rotors as there aren't any good aftermarket ones. Is that true? Any recommendations on your end? Thanks! |
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06-09-2020, 09:25 AM | #36 | |
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If you have solid track awareness, you can do the bed-in during your first track session of the day. You just have to be extremely careful and aware of who and what is going on around you. If possible, you'd likely want to be first or last out in your run group so you (would depend on how many people are in the session). You want as much space away from other people as possible, and you have to be watching your mirrors. During your warm up lap(s) you can drag your left foot on the brake to introduce more heat to the pads and discs. That would be one of the best ways to rapidly build heat in your brakes. If you've never left-foot braked, then this would NOT be a good time to try it for the first time! The goal is to quickly get the pads and discs up to the temperature at which they will stick to the disc face. Driving down a long straight with cool air blasting the brakes and your foot off the brake is counterproductive. You could even tape off your brake duct openings if your car has any. That will compress the time required to get heat into the brakes. As you go into each turn, deliberately stay on the brakes a bit longer than you normally would. As heat builds you'll start smelling the brake pads burning. It usually takes a few more stops after that point to get the material transferring to the discs. You should be able to feel a change through the brake pedal when that starts to happen. After that, try to stay off the brakes as much as possible through the next lap to cool them down. After a cool-down lap, gradually increase your speed and feel the brakes out on the next couple laps. They should now feel 'grabbier' than they did on your first out lap. Gradually ramp up to your normal lap speed over the next couple laps. Did I mention being careful and aware of what's going on around you? |
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