[bentom2]

I’m curious how long the 372mm rotor rings that come in the front AP/Essex kit are lasting for others and whether the life I experienced on the first set is typical. Please share your experiences. For those looking for more info, read on… 😊

I just discovered a crack that radiates out to the edge and runs the full depth of the rotor face, so I’m calling them done, despite having only lost 0.5mm of material after roughly 22 hours over 11 days on them. That was 2 sets of DS3.12 pads. Does that sound typical?

I was able to get roughly 50% more life from a set of OEM rotors and blue calipers with DS29 pads and admittedly some less sticky tires (mostly Hankook RS4).

Anticipating questions, here’s most of the variables I can think of.
Pads: Ferodo DS3.12
Tires: mix of 200TW tires- A052, Falken RT660, RE71, GY SC3
Driver: aggressive and fairly quick pace
DSC: Probably 50% on vs balance in Traction Mode
Event format: Mostly 5 or 6 20 minute sessions per day, but also several open lapping days where I would run closer to double that at 40-50 minutes until the fuel light would come on.
Mods: suspension only, no power or aero
Tracks: Pacific, Ridge, ORP.

Seems like this is heat related. Any thoughts or experience with different pads having a positive impact on rotor heat?

Unfortunately, I didn’t put any temp sensitive paint on the rotors.

Thanks all!

[OG Shark]

Seems a bit fast although the 3.12 does wear on the disc more than their other pads. DSC is probably not doing you any favors either. Have you reached out to Essex to get their input?

[bentom2]

Originally Posted by OG Shark

Seems a bit fast although the 3.12 does wear on the disc more than their other pads. DSC is probably not doing you any favors either. Have you reached out to Essex to get their input?

Haven’t yet. Will do so when I have some time to.

DSC use was roughly 50% of those track miles, maybe less. I was certainly running DSC a higher percentage of the time when I was on OEM rotors, and getting quite a bit more life from them- replacing based on thickness rather than excessive cracking.

Maybe it’s just a fluke, and that one rotor had a small defect/impurity in the iron. Caught me by surprise that they were done so fast and had to overnight a new set of rings in. Probably a good idea to keep a spare set on hand. I do with brake pads, so makes sense to do the same with rotor rings.

Photos attached. This was after driving 30 miles home.

[ZM2]

I’ve run 20-25 track days on mine before wearing down the J-hooks with no rotor cracks.

Do you have any kind of brake duct cooling in place that would fluctuate temps rapidly?

PS. Mine are a custom 378x36mm 72-vane setup (9660 calipers), so slightly different.

[bentom2]

Originally Posted by ZM2

I’ve run 20-25 track days on mine before wearing down the J-hooks with no rotor cracks.

Do you have any kind of brake duct cooling in place that would fluctuate temps rapidly?

PS. Mine are a custom 378x36mm 72-vane setup (9660 calipers), so slightly different.

No cooling. I just removed the dust shields as recommended by Essex.

I had ducting on with the OEM brakes, but removed it after finding some giant chunks of tire rubber inside my rotors since I didn’t have a screen on the duct inlet and didn’t feel like futzing with it.

20-25 days would be fantastic. What pads are you running?

[ZM2]

Originally Posted by bentom2

No cooling. I just removed the dust shields as recommended by Essex.

I had ducting on with the OEM brakes, but removed it after finding some giant chunks of tire rubber inside my rotors since I didn’t have a screen on the duct inlet and didn’t feel like futzing with it.

20-25 days would be fantastic. What pads are you running?

DS3.12. Sounds odd, I’d definitely talk to Essex about it.

[bentom2]

Originally Posted by ZM2

DS3.12. Sounds odd, I’d definitely talk to Essex about it.

Thanks.

One more question- what are you running for rear brakes?

I’m still running the blue 2 piston calipers and OEM rotors, also with 3.12.

[ZM2]

Originally Posted by bentom2

Thanks.

One more question- what are you running for rear brakes?

I’m still running the blue 2 piston calipers and OEM rotors, also with 3.12.

Yup, same thing.

BTW, I don’t think DSC would play a factor here unless you’re completely way overdriving the front end which would also show up with completely demolished tires with shorter than expected life. DSC on usually eats up the rear brakes more than the front. Are you constantly relying on the ABS going into hard braking zones?

I also don’t think it’s the DS3.12. I think the DS.UNO is kind of a crappy pad compound with too much bite, short life, and hard on rotors, but I found the DS1.11 and DS3.12 pretty easy on rotors with the 3.12 providing better heat resistance and only slightly shorter life.

Please let us know how your investigation goes!

[OG Shark]

Originally Posted by bentom2

Haven’t yet. Will do so when I have some time to.

DSC use was roughly 50% of those track miles, maybe less. I was certainly running DSC a higher percentage of the time when I was on OEM rotors, and getting quite a bit more life from them- replacing based on thickness rather than excessive cracking.

Maybe it’s just a fluke, and that one rotor had a small defect/impurity in the iron. Caught me by surprise that they were done so fast and had to overnight a new set of rings in. Probably a good idea to keep a spare set on hand. I do with brake pads, so makes sense to do the same with rotor rings.

Photos attached. This was after driving 30 miles home.

Likely a decent jump in wear with those "stickier" 200TW over the Hankooks - but that does seem fast. I could still see that even at a lower percentage of DSC use than before - running 50% of the time with a tire like the RE71 could really accelerate it over a less sticky tire with oem brakes. And the 3.12 is a pretty aggressive pad. I think that much DSC time at a hard pace with these pads is having an effect. Still think it's too fast though & would definitely get with Essex to get their thoughts.

One thing might try moving forward (if you haven't already) are the 1.11 pads. Longer wear, easier on the rotors - excellent performance but noticeably less initial bite. I like to run these in my longer races and/or in the wet. I run the 3.12 on short sprints when I want everything to heat up as fast as possible on the typical one out lap we get before the checkered flag. I do not run vents either.

Also have you taken a look at your braking technique? Not implying you have bad technique - but always something good for us to look at when seeing issues with something on the car (I always assume first that it is something I'm doing wrong). Late, hard braking in as short of a distance as possible and not prolonging the time on brakes? Might be something worth reviewing just to rule it out as well.

[bentom2]

Originally Posted by OG Shark

Likely a decent jump in wear with those "stickier" 200TW over the Hankooks - but that does seem fast. I could still see that even at a lower percentage of DSC use than before - running 50% of the time with a tire like the RE71 could really accelerate it over a less sticky tire with oem brakes. And the 3.12 is a pretty aggressive pad. I think that much DSC time at a hard pace with these pads is having an effect. Still think it's too fast though & would definitely get with Essex to get their thoughts.

One thing might try moving forward (if you haven't already) are the 1.11 pads. Longer wear, easier on the rotors - excellent performance but noticeably less initial bite. I like to run these in my longer races and/or in the wet. I run the 3.12 on short sprints when I want everything to heat up as fast as possible on the typical one out lap we get before the checkered flag. I do not run vents either.

Also have you taken a look at your braking technique? Not implying you have bad technique - but always something good for us to look at when seeing issues with something on the car (I always assume first that it is something I'm doing wrong). Late, hard braking in as short of a distance as possible and not prolonging the time on brakes? Might be something worth reviewing just to rule it out as well.

Appreciate the continued thoughts. I haven’t tried 1.11 yet, but will likely give a set a go. They sound like they might be a better match for my needs as well. I wouldn’t mind a bit less bite as I’m used to a heavier pedal in my other car.

I think I’m generally using later braking and minimizing time on the brakes, but open to feedback. I made this video to look at intake temps, but the throttle and braking inputs show through as well. This is DSC off at a track I know well.

To ZM2’s question, I do have a tendency to over-drive the front tires a bit, and occasionally to carry too much speed at corner entry that I have to shed with heavy trail braking and some slip angle. So I’m sure I’m a contributing factor. ��

This is straight out of grid into my warmup lap, so probably best to skip ahead 1:30 or so.

Unfortunately, brake data is just on/off from OBD, but should give an idea of timing and duration.

This is on 265/275 35r18 RE71’s. Also, DSC is coded to M4 GTS.

[kpaso]

That is definitely too fast, but what is your brake cooldown process? I do a full lap cooldown before coming into the pits and driving around for around 5 min trying to cool the brakes down before pitting. If you don't, you can definitely run into issues with the AP rotors.

[bentom2]

Originally Posted by kpaso

That is definitely too fast, but what is your brake cooldown process? I do a full lap cooldown before coming into the pits and driving around for around 5 min trying to cool the brakes down before pitting. If you don't, you can definitely run into issues with the AP rotors.

I do a full lap, but rarely drive around after coming off unless I had to cut the cool down short, or to run out for fuel.

An extra 5 minutes of cool down time isn’t something I’m likely to do after each session. If that’s really what is necessary, I guess I’ll just have to deal with short rotor life. Hope not though.

[DRLane]

@jritt@essex

Any insight or best practices here?

[kpaso]

Originally Posted by bentom2

I do a full lap, but rarely drive around after coming off unless I had to cut the cool down short, or to run out for fuel.

An extra 5 minutes of cool down time isn’t something I’m likely to do after each session. If that’s really what is necessary, I guess I’ll just have to deal with short rotor life. Hope not though.

You don't have to do 5 min, but maybe even 1 lap around the paddock might help. A min or two.

[OG Shark]

Originally Posted by bentom2

Appreciate the continued thoughts. I haven’t tried 1.11 yet, but will likely give a set a go. They sound like they might be a better match for my needs as well. I wouldn’t mind a bit less bite as I’m used to a heavier pedal in my other car.

I think I’m generally using later braking and minimizing time on the brakes, but open to feedback. I made this video to look at intake temps, but the throttle and braking inputs show through as well. This is DSC off at a track I know well.

To ZM2’s question, I do have a tendency to over-drive the front tires a bit, and occasionally to carry too much speed at corner entry that I have to shed with heavy trail braking and some slip angle. So I’m sure I’m a contributing factor. ��

This is straight out of grid into my warmup lap, so probably best to skip ahead 1:30 or so.

Unfortunately, brake data is just on/off from OBD, but should give an idea of timing and duration.

This is on 265/275 35r18 RE71’s. Also, DSC is coded to M4 GTS.

Beautiful track - looks awesome out there! Definitely wouldn't want to have an off though yikes.

To me hard to tell with the on/off indicator on the braking. Without it showing the pressure level it makes it tough to see how the braking is being applied. Again not saying this is the culprit but for me user input/error is typically my first go to if there is a problem. DSC also has a significant effect on the fronts, not just the rears. One thing I have always noticed with BMW dsc is that it does affect heavy braking. My cars have never felt as planted under threshold braking with any form of dsc on - full on, mdm, euro mdm, GTS - all have an effect in the stability of the car compared to threshold braking with no dsc. With 3.12s, stickier tires this might be the culprit plus if you feel like you are carrying too much speed into entry.

Still might be something else going on with that ring (especially if the other is ok) and worth talking with them about. Would recommend trying a set of 1.11 if you feel like the 3.12 are a bit too aggressive - I'm with you on there. I feel like the 3.12 are just a bit too much - but do prefer them on the shorter runs (30 min or so) when the start is so much more important. 1.11 ought to give you better rotor life as well.

Originally Posted by bentom2

I do a full lap, but rarely drive around after coming off unless I had to cut the cool down short, or to run out for fuel.

An extra 5 minutes of cool down time isn’t something I’m likely to do after each session. If that’s really what is necessary, I guess I’ll just have to deal with short rotor life. Hope not though.

We rarely get the opportunity to do some extended cooling driving as well. To me the main focus is to try to be as easy on the brakes as possible during the cool down lap and that is really the best we can hope for.

[bentom2]

Originally Posted by OG Shark

Beautiful track - looks awesome out there! Definitely wouldn't want to have an off though yikes.

To me hard to tell with the on/off indicator on the braking. Without it showing the pressure level it makes it tough to see how the braking is being applied. Again not saying this is the culprit but for me user input/error is typically my first go to if there is a problem. DSC also has a significant effect on the fronts, not just the rears. One thing I have always noticed with BMW dsc is that it does affect heavy braking. My cars have never felt as planted under threshold braking with any form of dsc on - full on, mdm, euro mdm, GTS - all have an effect in the stability of the car compared to threshold braking with no dsc. With 3.12s, stickier tires this might be the culprit plus if you feel like you are carrying too much speed into entry.

Still might be something else going on with that ring (especially if the other is ok) and worth talking with them about. Would recommend trying a set of 1.11 if you feel like the 3.12 are a bit too aggressive - I'm with you on there. I feel like the 3.12 are just a bit too much - but do prefer them on the shorter runs (30 min or so) when the start is so much more important. 1.11 ought to give you better rotor life as well.




We rarely get the opportunity to do some extended cooling driving as well. To me the main focus is to try to be as easy on the brakes as possible during the cool down lap and that is really the best we can hope for.

Long winded response follows, but trying to be thorough…

It is a bit hairy when offs happen there. Can’t see on video, but the gravel along the edge of the track can be 8-12” below the track surface in places, so even two off can do bad things. But it’s a classic NW track close to the city, and as a result sees a lot of event use.

Thanks for taking a look at the video. I could probably redo with lateral acceleration/decel so you can see brake force represented in g-force form.

I’m certainly open to critique of my driving, especially if it’s contributing to the faster wear. No feelings will be hurt.

I was just at the same track in the video again yesterday for a two run group event with 7-30 minute sessions. I drove roughly 20-25 minutes of the first 6 sessions, first session fairly mellow to finish bedding the new pads/rotors and warm up the driver, and with one later in the afternoon at a slower pace so I could get video of another driver’s line for them to reference later. Last session was just 10 minutes until I ran out of fuel. In all, roughly 200 track miles, which is close to two regular days for me.

DSC off the entire day.

I used 3mm of the new front 3.12 by the end of the day, so on pace for 5-6 days total, which seems about right for these pads.

One thing occurred to me; I’ve been driving this particular track a lot this season, and I’ve altered my approach to the section following the main straight.

I used to stay full throttle down the straight to the fast right hander, back off to maintenance or slightly positive throttle for the fast right hander, then maybe wide open again for a moment before the big hairpin, where I’d take a conventional single apex line from track right through the hairpin. Max speed was maybe 137-140 with this approach.

Now, I’m staying at 100% throttle through the fast right hander, into a double apex of the big hairpin. Max speed is 143-147. A lot is going on here, so I could well be in ABS here. Need to pay more attention to that next time.

To make this section worse on either line, the straight after the hairpin is a fairly steep downhill to a slow turn. I’ve also started moving to slightly right of center at entry, rather than the school line that is to brake far track left. I’m closing up the turn, but get to take advantage of some banking on the inside, and save several 10ths by doing so. However, it means I’m braking from 110 to 30, instead of 40 to make that line work.

So more time at this track, that has a very demanding braking section an I’m making more challenging with a very aggressive line.

Oh, and 1.11 are on order. Will see how they do. I wouldn’t mind a bit heavier pedal at braking threshold. I’ve adjusted to the 3.12 and can drive very smoothly with them now, but they’re a bit much as you said. Will update later this month or early next month after I get some time on them.

Will also try to contact Jeff next week for advice.

[ZM2]

110 to 30 is a pretty major braking zone! Dipping into ABS there will def chew up some rotors, but I’d still expect longer life.

I’ve gotten pad fade with the DS1.11 after 20min of hard driving, and is why I stick with the DS3.12. It’ll go away after a few corners of easy braking, but just something to be aware of.

[bentom2]

Originally Posted by ZM2

110 to 30 is a pretty major braking zone! Dipping into ABS there will def chew up some rotors, but I’d still expect longer life.

I’ve gotten pad fade with the DS1.11 after 20min of hard driving, and is why I stick with the DS3.12. It’ll go away after a few corners of easy braking, but just something to be aware of.

Thanks for the heads up! First track I’m likely to run them on will be one that’s less demanding of the brakes, so will be a good place to start. Will definitely take note of any changes in pedal feel.

To clarify the above, there are two back to back braking events. 140+ to 60, then a few seconds later is the 110 to 3 that also happens to be downhill.

To the 3.12’s credit, they take it all in stride and pedal feel never changes. I really do like them overall and will just budget for the faster wear rather than look outside the Ferodo pad family. But the 1.11 seems worth a try.

[kpaso]

Originally Posted by bentom2

Thanks for the heads up! First track I’m likely to run them on will be one that’s less demanding of the brakes, so will be a good place to start. Will definitely take note of any changes in pedal feel.

To clarify the above, there are two back to back braking events. 140+ to 60, then a few seconds later is the 110 to 3 that also happens to be downhill.

To the 3.12’s credit, they take it all in stride and pedal feel never changes. I really do like them overall and will just budget for the faster wear rather than look outside the Ferodo pad family. But the 1.11 seems worth a try.

FWIW I've done many sessions at Laguna Seca which has very similar braking zones, several 120-35mph corners, and haven't had that issues with mine. And I bought mine used as well. But I run 1.11s and also am extra careful with cooling afterwards.

Let me know what Essex says, I'm sure they'll have some good info!

[NISFAN]

Not building heat gradually enough is usually the reason for rotor cracks. Thermal shock.

[bentom2]

Originally Posted by NISFAN

Not building heat gradually enough is usually the reason for rotor cracks. Thermal shock.

That makes sense but hadn’t occurred to me. All the tracks I drive locally put you onto the main straight from grid. While I tend to take the first few corners slower to warm the tires up, I tend to just charge into the first braking zone from cold, and likely put a tone of heat into them in one shot. Sounds like I should also give the brakes the same consideration.

Too late for Thursday and today, but will adjust for the next few events and see what happens.

Thanks!

[ZM2]

Are you sure you didn’t have Brake Magic turned on?