Track Cars & Brake Issues

[Savanna7]

Looking for those that track their Emiras frequently…..

I’m having brake issues that aren’t fully making sense to me. This happened with the factory pads for the initial shake down, and now the EBC RP-1s. I’ve read every brake thread I can find with no definitive answers.

Essentially, I can get about 3 great laps where everything feels exactly as expected. By the 4th lap, the brakes go from consistent and smooth to, inconsistent and “chunky” almost as if they are pulsing, or the pad material themselves are experiencing degradation and build up, but I would say it’s definitively not an ABS issue.

I’m currently running the factory Cup2s and have Motul 660 fluid already installed as well.

1. Due to it consistently happening within 4 laps, it sounds like a heat soak issue, but the brakes never get soft or mushy.

2. Based on number 1, it then leads me to think about heat based warping of the rotors and/or I read a thread about the parking brake getting involved once hot. If that were the case you would feel this all of the time after that initial saturation I think.

3. If it were air in the line, this would create a similar outcome to number 1 with a feeling of inconsistent pressure or mushy pedal, not the feeling I’m experiencing.

4. I could install brake ducting (and probably will), but I still think I would experience a brake “fade” issue rather than the feeling I’m getting when hot.

I was hoping I had a few loose lug nuts or caliper bolts that were allowing too much “flex” and a simple bolt check would solve the problem, but that has not proven to be the case.

Multiple people drove my car and felt the same sensation regardless of their pace. It was always on the 3rd or 4th lap. Each driver is very experienced in tracking and racing. One even owns a shop.

Is anyone else experiencing this? If so, how did you fix it? My next steps are trying a different set of pads and rotors while adding ducting, but that seems like an expensive game of chase, and I believe I read that at least two others had similar issues. Any help you can provide before I go down the economic rabbit hole would be helpful.

Thank you!

 

[kitkat]

You’re sure your pads have been properly bedded? You can definitely overheat the stock pads and smear them to get pulsing, but it sounds to me like the EBCs should be capable of handling track heat and this seems to go away after they’ve cooled down right which indicates it isn’t friction material smearing. I also agree with all the other things you’ve ruled out.

 

[Savanna7]

They were definitely bedded properly. I even sanded the rotors to remove previous material (which I don’t typically do). There are no signs of glazing or hot pad material on the rotors themselves. I’ll have to pull the pads this weekend to see what they look like though.

 

[Ft.S]

I am not sure I understand the sensation of "chunky." I only have 2K mi. on the car and attended four track days thus far. I cannot say the brakes are great on the Emira, adequate probably is a better way of describing it for me. I have Jubu cooling vanes, Pagid RSL29 pads and RBF 660.

The way I would normally brake did not work for me on the Emira. Going from ~130 mph to 45, for example, I normally would apply the brakes pretty hard initially, then gradually taper off into the corner and transition to throttle. This worked well with my Porsches and BMWs, not so in the Emira. I had to gradually build up the brake pressure, then start to tapper off into the corner. This gradual build up is still quite rapid, but not as before, it takes about 0.5-0.7 secs. With the former method on the Emira I felt the pedal felt very hard, essentially like ICE mode. I believe the ABS was kicking in. With the later method, braking has been very consistent for more than 10 laps each session. I have confidence in braking, but necessarily the performance of my previous cars.

The downside is that the maximum negative g I could generate with the Emira is about 1.1-1.2, whereas with the others cars, I could consistently get -1.4-1.6. I do not know if any of this helps you, but I hope you find the issue and the fix.

Cheers.

 

[Kaz]

My stock rotors warped when very hot, took about 15 min of full threshold braking in the canyons but they definitely would warp. They would also lose grip pretty quickly, the Jubu cooling ducts did help in this regard. After about 3k miles my stock rotors looked trashed - replaced with Girodiscs and have had no issues. I use Tarox Corsa pads, they are in between street and race but more aggressive than stock.

 

[seriously]

Maybe sanding your rotors has something to do with it. Normally I would think hard braking pretty much cleans up your rotors. It’s conceivable that a slight sanding issue could basically enable faster feeing of warped rotors after heat soaking.

 

[OppositeLock]

I track mine pretty hard on RP-1's, and never experienced what you describe. Over the course of a session, the brake modulation does change, though. They feel a little less grabby and require more brake pressure. Girodisc rotors do have a better feel than the OEM.

 

[OppositeLock]

I am not sure I understand the sensation of "chunky." I only have 2K mi. on the car and attended four track days thus far. I cannot say the brakes are great on the Emira, adequate probably is a better way of describing it for me. I have Jubu cooling vanes, Pagid RSL29 pads and RBF 660.

The way I would normally brake did not work for me on the Emira. Going from ~130 mph to 45, for example, I normally would apply the brakes pretty hard initially, then gradually taper off into the corner and transition to throttle. This worked well with my Porsches and BMWs, not so in the Emira. I had to gradually build up the brake pressure, then start to tapper off into the corner. This gradual build up is still quite rapid, but not as before, it takes about 0.5-0.7 secs. With the former method on the Emira I felt the pedal felt very hard, essentially like ICE mode. I believe the ABS was kicking in. With the later method, braking has been very consistent for more than 10 laps each session. I have confidence in braking, but necessarily the performance of my previous cars.

The downside is that the maximum negative g I could generate with the Emira is about 1.1-1.2, whereas with the others cars, I could consistently get -1.4-1.6. I do not know if any of this helps you, but I hope you find the issue and the fix.

Cheers.

Yes! I feel this too. If you brake too hard initially, there's not enough weight transfer forward, and the brakes overwhelm the front tires. When you do it progressively, you gain grip as you increase braking, so the tires can hold. The initial bite on the pads here is very important. When I first tried EBC-SR11, I couldn't for the life of me brake properly, since the initial bite was too strong.

 

[kitkat]

No issues so far on track with the Rsl29 on girodisc

 

[F1 SML8R]

GiroDiscs make a big diff. I've run them on essentially every car I've owned. I'd upgrade the rotors, fresh fluid and pads and I'm thinking your problems will go away.

 

[lynchy73]

The brakes for me are also not too impressive. I skimmed my factory disks and fitted endless pads/fluid after the factory discs were trashed with pad residue. They are better, but still not great.

I’ve gotten “no ABS warnings” and “traction control not working” but that clears after they cool down. The front wheel speed sensors stop working when things get hot. Front yellow calipers have changed colour from the heat.

 

[David s]

You’re sure your pads have been properly bedded? You can definitely overheat the stock pads and smear them to get pulsing, but it sounds to me like the EBCs should be capable of handling track heat and this seems to go away after they’ve cooled down right which indicates it isn’t friction material smearing. I also agree with all the other things you’ve ruled out.

Yes. Don't underestimate this simple step. It cost me a big off on an early v6 exige I had. Very expensive. On the upside, it resulted in me upgrading to a 410 exige. I've always said, your lap times are often determined by how you paid for your car ,and how much that matters to you compared to how much a lap time is worth.
Good advice by Kit Kat as usual.

 

[bshads]

Am going to bet that your rotors are warped, or at least warp at temp. I had a similar issue happening with the stock pads, where they pulsed once hot, then when cool felt normal again. I think the rotors have a design or manufacture issue where they don't expand properly when heated. Would highly recommend a performance set of rotors. It fixed that issue for me.

 

[lynchy73]

For a track focused setup, do people think the factory callipers with uprated discs/pads is sufficient? Or just swap to a new front (plus maybe rear) brake setup entirely?

Any brake cooling options outside of the JUBU ducts? Could go with them, it’s just pains me getting some big/bulky bits of expensive 3D printed plastic shipped half way across the world.

 

[OppositeLock]

I've pushed my car damn hard on sticky rubber. The limit is the tires, not the rotors or calipers or pads. It's fine as it is. The Elise had the opposite problem, where it was hard to get enough braking force with that tiny little pad.

 

[Savanna7]

I am not sure I understand the sensation of "chunky." I only have 2K mi. on the car and attended four track days thus far. I cannot say the brakes are great on the Emira, adequate probably is a better way of describing it for me. I have Jubu cooling vanes, Pagid RSL29 pads and RBF 660.

The way I would normally brake did not work for me on the Emira. Going from ~130 mph to 45, for example, I normally would apply the brakes pretty hard initially, then gradually taper off into the corner and transition to throttle. This worked well with my Porsches and BMWs, not so in the Emira. I had to gradually build up the brake pressure, then start to tapper off into the corner. This gradual build up is still quite rapid, but not as before, it takes about 0.5-0.7 secs. With the former method on the Emira I felt the pedal felt very hard, essentially like ICE mode. I believe the ABS was kicking in. With the later method, braking has been very consistent for more than 10 laps each session. I have confidence in braking, but necessarily the performance of my previous cars.

The downside is that the maximum negative g I could generate with the Emira is about 1.1-1.2, whereas with the others cars, I could consistently get -1.4-1.6. I do not know if any of this helps you, but I hope you find the issue and the fix.

Cheers.

I am not sure I understand the sensation of "chunky." I only have 2K mi. on the car and attended four track days thus far. I cannot say the brakes are great on the Emira, adequate probably is a better way of describing it for me. I have Jubu cooling vanes, Pagid RSL29 pads and RBF 660.

The way I would normally brake did not work for me on the Emira. Going from ~130 mph to 45, for example, I normally would apply the brakes pretty hard initially, then gradually taper off into the corner and transition to throttle. This worked well with my Porsches and BMWs, not so in the Emira. I had to gradually build up the brake pressure, then start to tapper off into the corner. This gradual build up is still quite rapid, but not as before, it takes about 0.5-0.7 secs. With the former method on the Emira I felt the pedal felt very hard, essentially like ICE mode. I believe the ABS was kicking in. With the later method, braking has been very consistent for more than 10 laps each session. I have confidence in braking, but necessarily the performance of my previous cars.

The downside is that the maximum negative g I could generate with the Emira is about 1.1-1.2, whereas with the others cars, I could consistently get -1.4-1.6. I do not know if any of this helps you, but I hope you find the issue and the fix.

Cheers.

Maybe you’re on to something here as the way you previously braked is exactly how I handle it today. Heavy pressure followed by easing off toward trail braking.

It’s possible it could be the ABS, but it certainly didn’t feel that way to me. I’ll try easing on/easing off Mr Miyagi style next day out.

 

[Savanna7]

Maybe sanding your rotors has something to do with it. Normally I would think hard braking pretty much cleans up your rotors. It’s conceivable that a slight sanding issue could basically enable faster feeing of warped rotors after heat soaking.

Maybe, but I don’t think 120 grit is going to distort the rotor surface in a manner that you’ll feel under braking. To some degree it’s meant to create imperfections that the new pad material is meant to fill. It’s supposedly the proper way of switching pad material (according to EBB and some other manufacturers)

As for the warping, I would have expected to feel the warping even after they cooled. If something that thick gauge warps, it rarely cools to normal.

 

[Savanna7]

Yes! I feel this too. If you brake too hard initially, there's not enough weight transfer forward, and the brakes overwhelm the front tires. When you do it progressively, you gain grip as you increase braking, so the tires can hold. The initial bite on the pads here is very important. When I first tried EBC-SR11, I couldn't for the life of me brake properly, since the initial bite was too strong.

Reading your thread was ultimately the reason I chose these pads. It’s good to hear you’re not experiencing this. Have you done anything else to your system? (Ducting, rotors etc?)

 

[Savanna7]

Am going to bet that your rotors are warped, or at least warp at temp. I had a similar issue happening with the stock pads, where they pulsed once hot, then when cool felt normal again. I think the rotors have a design or manufacture issue where they don't expand properly when heated. Would highly recommend a performance set of rotors. It fixed that issue for me.

Maybe you’re right. I still struggle to believe I wouldn’t feel the warping once they cool, but ultimately rotors will be next on the mod list with the cooling ducts.

 

[scv]

Using dial gauge check rotor runout cold and hot; will address warping concern based on results.