"Pre-bedded" sounds like an oxymoron to me. Part of bedding is about heat cycling, and part is about getting the pad worn in to the (minor, benign) curvature and grooving of your discs. Some manufacturers have a thin layer of a different material on the face of the pad to speed up the bedding process, but that's not "pre-bedded."
GameboyRMH said:"Pre-bedded" sounds like an oxymoron to me. Part of bedding is about heat cycling, and part is about getting the pad worn in to the (minor, benign) curvature and grooving of your discs. Some manufacturers have a thin layer of a different material on the face of the pad to speed up the bedding process, but that's not "pre-bedded."
Pre-bedding the pads means putting a heat cycle through them.
Bedding the rotors means getting a transfer layer going.
I'm really surprised you are glazing the ST43s. We run those on our Civic Lemons car which is about the same weight, but has more power and only slightly larger brakes. We get no fade at all, and the pads last 3+ entire endurance races including testing. Do you have your brake backing plates still in place? How about running some ducting?
Sonic said:I'm really surprised you are glazing the ST43s. We run those on our Civic Lemons car which is about the same weight, but has more power and only slightly larger brakes. We get no fade at all, and the pads last 3+ entire endurance races including testing. Do you have your brake backing plates still in place? How about running some ducting?
SM guys cant run ducts, so that can't be it. They felt SO good for those 2 sessions man, I couldn't believe it.
Tonight I'm going to start swapping parts between my street and track car.
First just pads and rotors. If the problem doesn't move, I'll swap calipers... and go from there. I will solve this.
I. WILL. SOLVE THIS.
Really dumb question, and I'm sorry for suggesting it if it isn't the case, but is there any chance you're riding your brake pedal whenever you're not on the gas?
The only time I ever experienced brake fade in my Rx-8, I realized the solution was (as dumb as this sounds) not use them as much. Pretty much exactly what Huckleberry said.. I was tapping my brakes a lot (I dunno why, maybe to "settle the car" when it wasn't needed?) so I wasn't ever letting the pads cool down enough.
WonkoTheSane said:Really dumb question, and I'm sorry for suggesting it if it isn't the case, but is there any chance you're riding your brake pedal whenever you're not on the gas?
The only time I ever experienced brake fade in my Rx-8, I realized the solution was (as dumb as this sounds) not use them as much. Pretty much exactly what Huckleberry said.. I was tapping my brakes a lot (I dunno why, maybe to "settle the car" when it wasn't needed?) so I wasn't ever letting the pads cool down enough.
No need to apologize. I really appreciate people taking the time to comment.
I rarely left foot brake and I'm not *that* slow of a driver. I only brake where I need to:
Thunderbolt: T1 (duh), nothing until T5. Wide Fn open. Slight lift into 6 (no brakes) and then braking hard into 7 and a little bit of left foot before 8.
Lightning: T1 (duh), a tiny bit into T2 while going back to 3rd, a little before 4, obviously hard into 5, then a little right before the bowl.
Summit: T1 (duh), a little into T3, T5 (duh), and then 10.
Do you have any video? Do you remember your brake marker at T1 at Summit Point?
WonkoTheSane said:Really dumb question, and I'm sorry for suggesting it if it isn't the case, but is there any chance you're riding your brake pedal whenever you're not on the gas?
The only time I ever experienced brake fade in my Rx-8, I realized the solution was (as dumb as this sounds) not use them as much. Pretty much exactly what Huckleberry said.. I was tapping my brakes a lot (I dunno why, maybe to "settle the car" when it wasn't needed?) so I wasn't ever letting the pads cool down enough.
I like this line of reasoning. Perhaps if it's not an operator issue, could it be a hydraulic/MC issue? Maybe pressure isn't being relieved properly causing the pads to bind up between braking zones? Is there a failure mode that could cause this?
Another possibility: what wheels are you running? Your competitors? It's been discussed before that different wheel designs promote better/worse airflow through the brakes and you aren't running ducts.
Keith Tanner said:Blaise said:Keith Tanner said:I want to know more about your pad bedding technique. I don't know anything about GLOC pads, but whenever I've had a glazing issue (rare) it's come down to insufficient bedding.
I'm following these instructions:
https://forum.miata.net/vb/showpost.php?p=2756334&postcount=58
Bed them harder? Softer? I had Dan @ 949 look at my most recent pics and he said they looked fine. I'm tearing my hair out over here. How is shiny and smooth not glazed?
I'm mostly interested in the first three steps, not the rotor bedding.
Basically, to bed pads, you have to get them up to full temp and hold them there for a little while. Pads intended for race use obviously need higher temperatures. I prefer bedding in a controlled environment where you have more control over your braking speeds, tracks obviously put some requirements/limits depending on how they're designed. In other words, I bed on straight roads. A couple of warmup stops (not a full stop to zero, but releasing the brakes at around 5 mph), then a series of progressively harder stops. You should smell the pads, but keep going even if they go hard. Street compounds take stops from about 45-50, race compounds need to stop from 60-65 to generate more heat. Then let them cool.
This.
I never had a problem with Carbotech's, and I see many people complain about the. I would basically go to an empty back road, and do repeated 75-10 stops until the brakes get stinky and the pedal starts going a touch soft. Drive home slowly barely using and allow to cool.
Bang good to go.
Any chance when you replaced everything you ended up with a drum brakes residual pressure valve in there somewhere? I've seen it a couple times on cars with swapped master cylinders, a master designed for drum/drum or disk/drum has the valve built into what looks like the line fitting adapter and hangs up the calipers.
I also suspect that there's something causing the brakes not to release all the way. I've run R12s, ST43s AND DTC-60s on my 160hp / 2600 lb Prelude and I can tell you that your brake pads should NOT look like any of the photos you posted. That crumbling around the edges of the R12s and ST43s are an indicator of severe overheating. You might be able to overheat the R12s on a track day Miata, but you shouldn't be able to reach those kind of temps on the ST-43s or the DTC-60s.
Have you checked the adjustment on the push rod that connects the brake booster to the brake pedal? It is possible to put in just enough preload that the car moves freely when the brakes are cold but the front brakes drag as soon as they get any semblance of heat in them.
You mention having multiple sets of rotors. Are you buying multiple sets of the same brand rotor, or swapping brands like you are pads?
steronz said:Do you have any video? Do you remember your brake marker at T1 at Summit Point?
No video. NASA was being kinda strict on any data for HPDE guys actually.
I was braking as close to 3 as I could get myself to. Straightaway speeds were 108-109, so ~5mph off SM speeds from what I can tell.
Blaise said:steronz said:Do you have any video? Do you remember your brake marker at T1 at Summit Point?
No video. NASA was being kinda strict on any data for HPDE guys actually.
I was braking as close to 3 as I could get myself to. Straightaway speeds were 108-109, so ~5mph off SM speeds from what I can tell.
Well that all sounds reasonable. Maybe it is mechanical after all....
Blaise said:No video. NASA was being kinda strict on any data for HPDE guys actually.
I was wondering when track day organizers would start to clamp down on data logging for insurance reasons...oh well, gonna enjoy it while I can!
So last night I swapped the front brakes from my street car onto my track car and vice versa.
https://i.imgur.com/Om2X8kK.jpg
The R10s on the front of the yellow car actually look TONS better than the initial pics I showed. Wonder why:
https://i.imgur.com/sNnaNHM.jpg
https://i.imgur.com/D5E3FqT.jpg
To recap:
-The red car used to have really hard pedal feel but not much friction on the brakes.
-The yellow car used to have pretty squishy pedal but lots of brake (except when I had my issues on track).
Now the cars are totally flipped. The yellow car feels like you're standing on a 2x4 but you can't stop very fast, and the red car has lots of squish but tons of stopping power.
That is, the feel of brakes totally moved with just the pads/rotors being swapped over. I think I'm ready to rule out simple mechanical issues on either car now and am ready to investigate whether the issue is that I don't know how to drive the car or I'm having some sort of pad/rotor friction issue.
If its the former: I've arranged for an instructor to ride and drive my car.
If its the latter: I have DTC-60s arriving tomorrow and will bring the R12s and ST43s as well.
Here's to hoping...
Do you have the same brand and type rotor on both cars?
I had this happen once on a Lotus Elan + 2. The adjustment screw from the pedal to the master cylinder was out too far not allowing the master cylinder to return all the way. The problem got worse as the fluid warmed.
On my mustang when switching to a four wheel disc master I was real careful to properly adjust the push rod.
In reply to Blaise :
Your comment about the R10's being "squishy pedal but lots of brake" is how they are supposed to feel. One of the characteristics of the Carbotech/G-LOC pads is modulation. They require more pedal travel for the same brake force, but that allows you to modulate the brakes, find the threshold point, and trail brake easier. I used to run Hawk HP+ on my RX-8, and they were like an On/Off switch. They felt the same whether you were slowing down for a stop sign or threshold braking. Some people like the modulation, others like a firmer on/off brake pedal.
Have you called G-LOC about the issue? I know a lot of spec miatas run Carbotech XP10 front and XP8 rear, which are similar to the G-LOC R10/R8. I wonder if the R12's are too much pad for this application.
Yep, GLOC president and I have been discussing. Still gonna check the MC rod length!
I run the Hp+ with a slightly smaller master diameter to get a little more travel.
I didn't see this addressed anywhere: what brand rotors are you running? Have you tried a different rotor brand?
Just one additional data point - I serviced a NASA miata in a previous life. Owner was complaining of no brakes yet was standing on the pedal. Turns out the pads were glazed (after much trouble shooting / MC swaps / etc - "the pads are new, look at everything else 1st" ). Found this out at the track (glazing) and filed them down and sent him back out - brakes worked great and then re-glazed.
At that point I had serviced dozens of race miatas and never seen any glazing issues. Turns out he bedded in this set in the rain during a full race. I dont recall the brand but once they glazed we could never get them back. Swapping to a new set of pads / rotors and bedding them in properly fixed all issues.
Just curious, can race pads be overkill on a "slow" car ? When I was running track days with my ZX2SR which performance wise is close to a Miata,I ran Hawk HP+ pads most of the time, even ran HPS at times. I ran a couple different cars on oem pads. How is the brake cooling ?
In reply to iceracer :
I think they can be. With aggressive pads on the Jeep driving on the street, I have to periodically remind myself to brake harder than I naturally tend to, otherwise the pads / rotors get polished and don't work well until they get used more aggressively again.
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