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Thread: Worn tires = heated brakes?

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    Default Worn tires = heated brakes?

    I ran two weekend ago at my local track. My tires were old (street tires).
    Brake fluid motul 600, SS brake lines, brembo 4 piston with hawk HPS.

    So besides the fact that I was driving faster that usual (getting better I guess), I noticed that I had to put the brakes more and more to stop, and eventually oveheaded the fluid and got some bad brake fade (nothing happened thankfully).
    I am wondering if the fact that my tires were worn, overworked the brakes and caused the fluid to fade.

    I want to add also that I was running on new pads and rotors. Fluid had been tracked 3 times by now.
    Thanks
    Last edited by FoxSTI; 06-28-2017 at 09:47 PM.

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    no, worn tires don't heat up brakes. most of the time, it is the opposite. as worn tire have less grip = less heat in brakes.

    few possibilities:
    1. you are a faster driver now.
    2. you are locking up brakes, ABS is kicking in more than usual. it could be your new brake pad setup.
    3. have you driven this track before (recently, assuming you were at same skill level). some tracks are a lot harder on brakes than others.
    4. were you on HPS in the past ? HPS is a street pad, I would only recommend it for complete track noob.
    5. It could be your style of driving have changed (more trail braking for example)
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    Quote Originally Posted by bellwilliam View Post
    no, worn tires don't heat up brakes. most of the time, it is the opposite. as worn tire have less grip = less heat in brakes.

    few possibilities:
    1. you are a faster driver now.
    2. you are locking up brakes, ABS is kicking in more than usual. it could be your new brake pad setup.
    3. have you driven this track before (recently, assuming you were at same skill level). some tracks are a lot harder on brakes than others.
    4. were you on HPS in the past ? HPS is a street pad, I would only recommend it for complete track noob.
    5. It could be your style of driving have changed (more trail braking for example)

    I am runing Motul 600. It was recommended I go to 650 now that I have to change the fluid.
    My fluid was also from 2012 (although never opened, but Motul confirmed it may be too old for track). However it worked


    Some answers for you:

    1. you are a faster driver now.
    yes, very possible overall (although still a newb)
    2. you are locking up brakes, ABS is kicking in more than usual. it could be your new brake pad setup.
    maybe, could be. I am trying to figure it out - why did I heat up the brakes.
    3. have you driven this track before (recently, assuming you were at same skill level). some tracks are a lot harder on brakes than others.
    Never driven this track before. First time.
    4. were you on HPS in the past ? HPS is a street pad, I would only recommend it for complete track noob.
    Do you have any better recommendations. Should I try the Motol 650 first next time?
    5. It could be your style of driving have changed (more trail braking for example)
    yes, I am braking a little bit later and harder than usually and yes some trail braking here and there. Too bad I don't have a brake sensor logged yet. Sounds like I need now.

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    Quote Originally Posted by FoxSTI View Post
    4. were you on HPS in the past ? HPS is a street pad, I would only recommend it for complete track noob.
    Do you have any better recommendations. Should I try the Motol 650 first next time?
    5. It could be your style of driving have changed (more trail braking for example)
    yes, I am braking a little bit later and harder than usually and yes some trail braking here and there. Too bad I don't have a brake sensor logged yet. Sounds like I need now.
    Hi Fox, A couple points aren't quite clear.

    4) William is saying you need a full track pad. He is not talking about fluid. Just look for a dedicated track pad if you want to reduce/eliminate fade. It would be helpful to know what car you are driving, but the basic point is true either way: a multipurpose pad will probably fade.
    5) Logging is great, but you don't need it to tell if you are trail braking. If you are releasing the brake fully before turning in, then you are not trail braking. If you are still partially on the brake at turn in, then you are trail braking.
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    Quote Originally Posted by ETK View Post
    Hi Fox, A couple points aren't quite clear.

    4) William is saying you need a full track pad. He is not talking about fluid. Just look for a dedicated track pad if you want to reduce/eliminate fade. It would be helpful to know what car you are driving, but the basic point is true either way: a multipurpose pad will probably fade.
    5) Logging is great, but you don't need it to tell if you are trail braking. If you are releasing the brake fully before turning in, then you are not trail braking. If you are still partially on the brake at turn in, then you are trail braking.
    Hi,

    4). Question, what causes brake fade? the pads overheating of fluid?
    What I experience was having to push the pedal more and more as if I had air in the system. If my fluid was boiling, I need to replace it don't it

    5) I am trail braking at times, but I try to minimize that.


    Car is a 2015 STI.
    I just want to log braking to see when I am starting to brake etc, maybe I was braking too late also and this pounding on the system.

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    You're right that it could be that you overheated the fluid. I don't know if I can tell pad fade from overheated fluid -- they both suck. I think you are correct that hot fluid means a long pedal, whereas pad fade means you stomp on a hard pedal with little result. Both mean you push down and not enough happens, so on track (especially when new), it can be hard to tell.

    Regarding trail braking: its a good thing. I havent tracked an STI, but I think trail braking will be key to getting it to rotate. It also lets you brake later. Proper trail braking means higher trap speeds, so yes, it will work the brakes harder. You shouldn't have to avoid trail braking to avoid fading the brakes. If that is the case, you need better fluid/pads/ducting/BBK, etc.
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    thanks everyone. I am going to try new fluid and connect my ducts in the front.
    haven't had to that in the past, but now may be the time. Specially it being summer.

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    When you installed the new pads and rotors did you bed them properly?

    From what your description I'd guess the pads are a bigger issue. STIs are relatively big, heavy but powerful track cars so you will likely need to upgrade your pads to something that can handle those conditions. If you don't want to swap pads and possibly rotors out for track days look at something like Carbotech XP10s or XP8s that can be used on the street and track. They will make noise on the streets but they still work well. That's what I used back when I drove my Miata on the street and track. If you go that route you'll need another set of rotors or have your new rotors turned for fresh surface.
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    brake pads:
    what Red_5 said. HPS is a street pad, I would not recommend anyone take it to track, unless it is their first time. or in a super super light car (sub 2,000LB).

    brake fluid:
    when you said your Motul 600 is from 2012, I sure hope you meant new sealed container from 2012. If that was an open container, you are lucky you survived one track lap. Motul 600 is a very good fluid, you don't need to go to Motul 650. that's not the issue here.

    trail brake:
    trail brake is a good thing, it is what you use to control turn in.

    brake duct:
    did you disconnect it ? and why would you ? brake duct is one of those thing with no negative.
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    Old brake fluid and worn pads (diminished heat capacity) are likely the issue.

    If you're driving it hard, you likely should be bleeding the brake fluid with Motul (or equiv) before every weekend on the track, perhaps after each day. I wouldn't bother with higher temp fluid; rather bleed more often.

    Slowing 3300lbs generates a tremendous amount of thermal energy. It's not a linear relationship. A little more speed, grip, ambient, worn pads, etc can easily push things over the edge.

    A few data points from my former STI:
    - Fluid after one day would typically take on a much darker amber. The darker amber usually correlated with a slightly softer pedal. I'd bleed until I see the light amber.
    - Street performance and organic based pads are not adequate and can create lots of problems (e.g. uneven pad transfer).
    - I ran a variety of race pads from every manufacture (Hawk, Raybestos, Porterfield, PF, etc etc). Hawk DTC-70s performed best in terms of torque/heat/longevity.
    - Rotor temps routinely came off track 850-1000F - after only a few laps of hard driving.
    - Vaned rotors can vent better than pillar design for this application. Two-piece can be worthwhile for other reasons
    - Do no run the pads too thin. The insulating qualities greatly diminish and that heat goes directly into the fluid. Thick pads are important.
    - Titanium backing plates can be worthwhile to help shield the fluid.
    - Take advantage of your cool down laps, that air flow is key to longevity of the brake components (some in unexpected ways like the stress to the threads where the caliper is bolted).
    - Motive Power Bleeder is worthwhile investment for easy/rapidly single-handed bleeding.

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    What did the pedal feel like when you had to "push the brakes more and more?"

    A hard pedal that does little is pad fade. Pad fade occurs when the overheated pads emit a gas that forms a boundary layer that prevents the pad's friction material from contacting the iron rotor. A mushy pedal that does little is air in the hydraulic system.

    You mentioned you have three track days on your brake fluid, but a relevant question is whether you've bled the system at anytime therein.

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    Good Morning guys, I have been wanting to reply the past day but I have been busy.
    Finally figured out how to multiquote. So below are some answers.

    Some of you have seen other thread regarding wheels. So yes I am planning to get new tires (which I need) and new lighter wheels to help the car go and stop a little more efficiently.

    Quote Originally Posted by Red_5 View Post
    When you installed the new pads and rotors did you bed them properly?

    From what your description I'd guess the pads are a bigger issue. STIs are relatively big, heavy but powerful track cars so you will likely need to upgrade your pads to something that can handle those conditions. If you don't want to swap pads and possibly rotors out for track days look at something like Carbotech XP10s or XP8s that can be used on the street and track. They will make noise on the streets but they still work well. That's what I used back when I drove my Miata on the street and track. If you go that route you'll need another set of rotors or have your new rotors turned for fresh surface.
    Pad and rotors where brand new for this event. I did drive on the highway a good 50 miles, and followed Hawks procedure the night before. I don't see why or how they would not have properly settled.
    I am wondering what people who replace pads at the track are doing to bed their new pads. Apparently it takes some time and heat cycles.

    Quote Originally Posted by bellwilliam View Post
    brake pads:
    what Red_5 said. HPS is a street pad, I would not recommend anyone take it to track, unless it is their first time. or in a super super light car (sub 2,000LB).

    brake fluid:
    when you said your Motul 600 is from 2012, I sure hope you meant new sealed container from 2012. If that was an open container, you are lucky you survived one track lap. Motul 600 is a very good fluid, you don't need to go to Motul 650. that's not the issue here.

    trail brake:
    trail brake is a good thing, it is what you use to control turn in.

    brake duct:
    did you disconnect it ? and why would you ? brake duct is one of those thing with no negative.
    Yes the bottles were close and sealed but slightly deformed. The fluid was very amber-ish. I contacted motul and they told me that it was just too old for track use being a 2012 bottle.
    Never bleed them after sessions. honestly did not know that was required. I did see a few people at the track with spare fluid. I am guessing it for just in case brake bleed.
    I have one of those pressurized bleeders, looking forward to using it this time.

    The brake ducts were disconnected out of silliness. Actually one of them I can't connect until I remove or relocate the windshield washer fluid bottle to the trunk. But I will def. have that done for next time.

    Quote Originally Posted by ucfbrett View Post
    What did the pedal feel like when you had to "push the brakes more and more?"

    A hard pedal that does little is pad fade. Pad fade occurs when the overheated pads emit a gas that forms a boundary layer that prevents the pad's friction material from contacting the iron rotor. A mushy pedal that does little is air in the hydraulic system.

    You mentioned you have three track days on your brake fluid, but a relevant question is whether you've bled the system at anytime therein.
    The pedal would travel a lot more than usual as it where there is air in the system. After a while of cooling off, driving back home, and even recently wen I drove to a local dunkin donuts down the street from my house and car stops fine. But I am going to replace all the fluid before the event. Same goes for oil. It has 2 track days with the same oil (I know... I know.. its more a time constraint than the 30 dollars of the oil)
    So back to your question, never bleed the system between sessions or track days.

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    Quote Originally Posted by FoxSTI View Post
    Pad and rotors where brand new for this event. I did drive on the highway a good 50 miles, and followed Hawks procedure the night before. I don't see why or how they would not have properly settled.
    I am wondering what people who replace pads at the track are doing to bed their new pads. Apparently it takes some time and heat cycles.
    I started buying pre-bedded pads so I didn't have to waste a session bedding new pads. Rotors on Miatas last forever.

    Aren't HPS street pads? It doesn't matter if they're brand new if the compound can't handle the heat your car's brakes are creating. You said you are getting faster, you've likely outpaced the ability level of using street pads on track.
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    pre-bedded.. nice. You learn something new everyday.

    So I have a question, yes I am using brand new HPS pads on what where brand new rotors.
    if I change pads to let's say EBC yellow pads or Blue. Do I need to get new rotors or get them resurfaced. They are brand new and where not cheap =(.

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    I talked to Andy Porterfield, of Porterfield Brake fame, and one of the races many years ago.

    I asked him, "What do I do when I am at the track and need to change pads and I can't bed them?" He scoffed a bit and said, "Just put them on and go race." I have done that a bunch of times now. In fact, I never even bed them in any longer. They stink a bit the first three laps and then all seems to be normal.
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    Quote Originally Posted by Olitho View Post
    I talked to Andy Porterfield, of Porterfield Brake fame, and one of the races many years ago.

    I asked him, "What do I do when I am at the track and need to change pads and I can't bed them?" He scoffed a bit and said, "Just put them on and go race." I have done that a bunch of times now. In fact, I never even bed them in any longer. They stink a bit the first three laps and then all seems to be normal.
    not sure why he told you that. but green fade (is that what they call it) is real. pads will fade few laps in (first time you get them hot), but it goes away after you let it cool down. I wouldn't race on a brand new set because of that initial fade.
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    Quote Originally Posted by FoxSTI View Post
    The pedal would travel a lot more than usual as it where there is air in the system. After a while of cooling off, driving back home, and even recently wen I drove to a local dunkin donuts down the street from my house and car stops fine. But I am going to replace all the fluid before the event. Same goes for oil. It has 2 track days with the same oil (I know... I know.. its more a time constraint than the 30 dollars of the oil)
    So back to your question, never bleed the system between sessions or track days.
    As the system cools, the air in the system contracts, which could be why it stops fine on the street and not on the track. Bed your pads, and make them more track-oriented pads and bleed your brakes after every event. Then report back.

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    Quote Originally Posted by ucfbrett View Post
    As the system cools, the air in the system contracts, which could be why it stops fine on the street and not on the track. Bed your pads, and make them more track-oriented pads and bleed your brakes after every event. Then report back.
    so much work .....................
    stuff we do for tracking a car
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    Quote Originally Posted by bellwilliam View Post
    not sure why he told you that. but green fade (is that what they call it) is real. pads will fade few laps in (first time you get them hot), but it goes away after you let it cool down. I wouldn't race on a brand new set because of that initial fade.

    Hmmm? I can't say I have experienced that green fade with the Hawk DTC-70 and Raybestos 47s I run.
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    Race pads like the Hawk DTC and Raybestos 43/47s (and some others) don't require any special bed-in (the manufacture does include procedures, these are not necessary with these pads).

    They're ready to go a few turns into the out lap. As Oli said, just put them on and race. I've run DTCs for nearly 10 years and I can't recall the last time I did a bed-in with these particular pads.

    Back to OP - HPS pads will not last _IF_ you're fully utilizing the braking potential of the STI while lapping (even fully stock). No street pad will (and the HPS is an excellent performance pad among them). You could be outside the maximum temperature of street pads, never mind operating range. If you have a sensitive foot you may actually feel street pads give way under heavy braking outside operating temp, peak braking event - subtly alternately grabby and pedal/torque relationship slightly changing - the pedal will overall feel less effective mid event (to some "longer") - pad wear tends to be horrific, chance of uneven + hardened rotor deposits that introduce subsequent judder, sometimes escalating.

    If you change compounds using the same rotors, you should sand the rotors with ~100-220 sand paper (electric sander even better). A minute or two a face is usually sufficient. This will remove any old bed-in pad material that could compromise initial effectiveness of the new pads. This is especially important with less aggressive pads. Race pads like the the DTC 70s/ST47s/Blues etc are sufficiently aggressive that they do an excellent job cleaning the rotors, but I'd still sand them if switching from a different compound.

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