Brakes glazing over and over and over and over
 

Been having braking issues all season on track. Nobody seems to be able to have any idea what the problem could be.

Car setup info (relevant and not):

Chassis:
'92 NA 1.6 - 2450lb weight with driver
No Aero work, using hardtop
V8Roadsters frame rails
Blackbird SD rollbar

Drivetrain
Stock 1.6 - 104whp
Torsen 4.3 from '99

Brakes
NA8 Calipers/Brackets
GLOC pads: 10 Front, 8 Rear (more on this in a minute)
New lines (not stainless) - SS lines on order
no ABS

Suspension
Polyurethane bushings
FM Springs (gen1). No sag or bumpstop-slamming issues that I've noticed.
FM Rear Shock Mounts with included bump stops
FM "Improved" 10mm front bump stops
Tokico Illuminas Set to 4 (of 5) all around
Pinch Weld Height: 5" front 4.75" rear
RB #54107 sway bar on softer setting, RB Brace kit
Stock rear sway bar
Front: -3.0 Front Camber 5.0 Front Caster Zero Toe
Rear: -2.5° Camber 0.06° Toe

Wheels/Tires
15x8 6UL +36mm offset
Yokohama AD08 205/50/15
Had to bend/mold fender liners due to rubbing under heavy cornering

Safety:
Blackbird bar, 6pt harness, halo seat

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

I'm an intermediate-level driver running DE2 with NASA. I'd say I'm one of the faster drivers in my group but I'm anywhere from 5-8 seconds off of SM race pace. Point is, I'm an OK driver in a slow/lightweight car with not much power.

My issue is that I am glazing pads nonstop. This past weekend at Summit went like this:

Thursday: Bolt on G12 pads (pre-bedded) with new rotors, perform bedding procedure for rotors per 949 instructions

Saturday: Arrive at Summit. Brakes feel amazing for first session, 2nd session I start to get some fade so I pulled the wheels to bleed the brakes... and look at the pads. SHINY.

I showed the pads to a race shop who was on-site and does build SM cars but was running vettes that weekend. He said they were DEFINITELY glazed. We discussed for a bit and decided to try an ST43 pad. I didn't have a fresh set of untouched rotors so I ran them on the rotors which I had bedded with the GLOC 12s. The brakes were PHENOMENAL. I was pushing markers and having a blast for my 3rd and 4th sessions.

Sunday: First session was pretty slow as track was around 50 degrees and tires weren't gripping. Second session was repeat from previous day.. started to get fade and pulled the pads:

I scuffed the pads on the pavement and put them back on. Went out, took a few laps for the brakes to really grip, then they were back to being great... until the end of the session when they were fading again. Pull em apart, glazed again.

Put the XP12s back on, tried again, same thing. GAH :mad: :mad: :mad: :mad: :mad: :mad:

Monday: Bought another set of new rotors and bedded them with the ST43s. Also cleaned off the 12s and took them for a spin too.

Tuesday: Back on track, this time at NJMP Lightning. Ruined the ST43s in no time.

Put the XP10s on just because... same thing.

I'm totally stumped guys. To recap:

-New Calipers
-New Lines (SS lines arriving tomorrow)
-3 diff sets of pads (G10, G12, ST43)
-Multiple set of rotors
-New MC
-Sliders move as they should
-Pistons are not seized
-Adding spreaders to the pads did not help

I'm at Watkins Glen weekend after this one and I NEED to have this sorted. I'm beyond frustrated and I've run 10 events already this year with bad brakes. Any ideas? I'm ready for some off-the-wall suggestions.

XP12:

https://i.imgur.com/xJvwiGM.jpg
https://i.imgur.com/OUJszex.jpg

ST43:

https://i.imgur.com/mXlcFGg.jpg

Rotors for ST43:

https://i.imgur.com/3ViJ1qB.jpg

The rotors for the ST43 look "ok" (not great but OK). The XP12 rotors were clearly overheated. Not surprised things weren't working right once you started mix-matching the pads and rotors because Carbo/G-Loc pads are very particular about the transfer layer. None of those pads look particularly "glazed" to me... they just look like they've been running really hot. You may just be exceeding the temperature ceilings of your parts. The factory rotor size can heat soak pretty bad. Do you have brake ducts? If not, I'd recommend them. May or may not be the solution but you ought to have them anyways.

Side-note... sometimes intermediate drivers put more heat into the brakes than advanced drivers. Braking HARD is one of the last things a lot of folks focus on getting better at, but when they do get around to working on that they shorten their stopping distance and thus time on the brake pedal and avg operating temp of the brakes can actually come down. Sometimes a beginner or intermediate guy will have the same brake setup as an advanced driver and can't figure out why his is overheating when it's working fine for the advanced guy. This may or may not have any relevance to you.

I appreciate the input. The vendor who sold me the ST43s had the same advice: Don't extend your brake zones. I spent several years on motorcycles and was taught to pick a brake marker, brake as hard as possible, then move the marker if you find yourself to be coasting after you're done on the brakes. That's how I've been treating the miata as well, so I don't think the issue is that.

Please note: Yes, I did mismatch pads/rotors but only once. Yesterday I ran ST43s with brand new rotors. Same with Saturday with the pre-bedded 12s. Only Sat Afternoon/Sun Morning had mismatched stuff, and it actually worked the best and lasted the longest.

SM guys can't run ducts. They seem to do fine and are running faster into the turns and with more aggressive tires. I'm happy to add it through if you think it will help - after all this is just DE.

At this point I've tried 3 diff sets of pads, and the R12s are rated to 1850*F. I'm struggling to think the issue is needing a 4th set of pads.

Are you still using the rotor splash shields or have they been removed?

They're bent back/cut as I have NA8 brakes on an NA6 car.

Suggesting I remove them?

Two things I thought of last night: There's a thread from there where a guy was dealing with the same issue and it ended up being a bad booster. I've PMed him. Other thing was that I didn't adjust the rod length when I put in my new MC. So there's a possibility I could be preloading the MC?

Present plan for attack:

1) Remove MC and check rod length on booster.
2) Use IR gun to check whether the brake temps climb on a normal drive without application of brakes.
3) Possibly replace booster?

You need to eliminate the splash shields and let the rotors breathe.

+1 on removing splash shields, but I ran a whole season with them on my TTE car with R7s/XP8s on a 2400lbs car, no issues.

Do you have any pad sticking issues? Maybe you're MC rod length is too long or your pedal adjustment is way off causing the pads to drag excessively?

This has to be the issue. Emilio/949 is convinced there's pad retraction issues, but I'm running spreaders and the pistons and sliders both work as they should.

I'm planning on driving my street and track car back to back in the same exact conditions (no brakes used) and comparing rotor temps to see if I can verify that I have drag. IR sensor arrives today.

Different car, but I recently had major pad sticking issues on my Z with Brembos. Car would be fine from start-up until about ~10min of regular city driving and then the pads(DTC60s) would stick/drag enough to stop the car on level ground. The calipers functioned fine, even rebuilt them with new seals. Went through half a dozen bleeds, a bunch of grease on the sliders, even bleed the master. Turns out adjusting the brake pedal fixed it. So in the same theory, modifying the rod engagement length into the MC could be the fix....maybe.

Fresh calipers mentioned in the first post is why I didn't suggest pad retraction or stuck caliper but that was my first thought.

Recommendations for street car? Same, or leave shields? Begs the question, what is the OEM purpose?

I don't have a problem on the street. Those shields are designed for stock rotors getting hot and then you driving through a puddle and splashing cold water on them, possibly warping the rotors. I've had the shields off since 2010 and haven't warped stock or Corrado or 11.75 V8R and have done an incredibly wet track day or two.

I've witnessed a VW at the track with a failed return spring on the brake pedal causing excessive dragging. It confused their team, because out on track it was bad enough to cause excessive smoke from the pads, but by them they limped it to their paddock the pedal would return and they couldn't narrow down the issue. They eventually found out that if they used their toe to pull back on the pedal on the straights it was fine, until they got a new return spring.

I don't think your experiences are typical, so I don't think it's just undersized rotors, underspecced pads, etc. I would guess it's something unexpected going on, like a master that's sticking, pedal sticking, caliper not returning, etc. Unfortunately I don't have much help to give on narrowing it down.

Are you running the stock brake pad shims/backing plates?

I run G-Loc R10's in the front with NB Sport brakes and a new set of pads will not fully release with the shims installed.
I've found the R10's overkill and had to block off my Singular brake ducts to keep the temps up. Never had a single issue with my setup and a regular RBF600 flush before an event. My NB1 is similar weight (2475lbs w/ driver) and is making an extra 25hp. I can get a whole season of NASA HPDE on a set of pads.

Also what do you mean by fade? Does the pedal get mushy or does the car just not want to stop?

Something is definitely amiss, sticking pads or otherwise. I run XP8's/Centric blanks (NA8) all around on RC1's at ~2400lbs/124whp and splash shields still in place. Typically about 1 second off NASA SM pole for reference and haven't managed to get a hint of fade from that setup all season. Removing splash shields might help, but that's clearly not the root cause.

^ Agreed.

SS lines and IR gauge showed up last night. I work tomorrow but on Sunday the plan is as follows:

1. Drive street NA8 and track car back to back in same conditions with minimal brake use and compare rotor temps. I'm expecting this to show a significant difference and the track car rotor temps to climb without brake usage.
2. Remove MC and check for booster rod/MC length match.
3. Install SS lines all around, bleed entire system (obviously). Adjust rears. I can cut the splash shields up front too.
4. Drive car around again, use IR gauge to compare setup again.
5. If no help there, install new brake booster.
6. If that doesn't help, light car on fire.

Sound good? I guess at that point I'll also consider swapping spindles too.

You left out ducts. Brake ducts should be near the top of your list.

Why? Nobody else at my power/weight/tire level needs them. Spec Miata guys certainly seem to do fine....there's another problem to solve here.

Not trying to bandaid a bigger problem.

Spec Miatas don't use splash shields.

And I will remove them. But the splash shields aren't the cause for me overheating pad after pad with my slow lap times.

Lap times would maybe be faster if you used the brakes less?

: p

Please don't take this offensively, but have you had another driver in the car be able to repeat this phenomena? Just trying to eliminate all possible factors.

Zero offense taken. I care way more about solving this issue than my ego.

I wasn't willing to let anybody else drive my car due to the braking issues. Too much liability (not necessarily legal, I just won't let a friend drive the car if I'm concerned with something as critical as the brakes).

The vendor who sold me the ST43s is convinced the issue is with my driving. That being said, I'm new to HPDE but NOT new to the track or solving mechanical issues. My day job is chasing down problems on military aircraft... and this has been ongoing with both street and track driving. I haven't even pulled the wheels on my NA8 street car and it has better pedal feel than my NA6 track car. So there's gotta be something I'm missing.

If it's my driving, I'm not sure what to change. When the brakes were working, I was braking at the same marker as the SM guys. Granted this is only possible due to lower straightaway speeds but the point is I'm braking at 3 HARD not at 5 or earlier at 50%.

Have you ridden with a pro/semi-pro? I thought I was braking hard on the track, then I had this woman as an instructor. http://kristintreagerracing.com/

I realized I was braking like a geriatric in a Buick.

Bent spindles
 

Probably bent spindles. Pads glazing/ overheating when they shouldn't means they are dragging. If the driver does not left foot brake with foot on pedal the whole lap, then the only other cause is a bent spindle(s). This is actually pretty common, Difficult to measure and determine outside of simply replacing the spindle. In Supermiata, it is rare for a spindle to last more than two seasons before brake drag crops up.

One simple check is to raise the car immediately after exiting track and spin the front wheels. If you get 3 or so rotations, you are good. If you can not get more than one rotation even with a strong spin by hand, start checking stuff.

More common culprit is dirty caliper piston bores or worn out (hardened) seals but the OP has covered that.

Looking back to my truly noob days I recall struggling with pad life and glazing on another car I own. Turns out I was not stepping on the brakes hard enough. I was on em lighter and longer causing them to glaze up.

I think we can all agree it's heat glazing the pads. Why not start by adding some ducting? That maybe all you need. Won't hurt anyway. The spindle idea is interesting too.

That's the thing. I'm on them as hard as I can without locking up the tires. the AD08s make some noise before locking. I fully understand that I'm a noob but if I brake any harder I'm locking up the tires. Happens sometimes too.

Thanks Emilio. I tried to update the thread title but had no luck (still shows as overheating which may not be the case)....

I did my best to take very good notes today.

First, I drove my street NA8 and checked the rotor temps with my IR gun (no brake usage). Both fronts were ~90-100F from smallest to largest diameter.

Then I drove the track car around on the street for a bit(still has plates). Same deal, no brakes... 90-100F. So I'm not sure it's dragging at all. Certainly doesn't seem like it at street speeds...

I took the track car apart and installed the SS lines that arrived on Friday. Bled the system (Motive Powerbleeder, TYP200 fluid). Checked the adjustment in the rears as well. Also found my new MC has some moisture on the O rings at the base of the resevoir. Concern?

Took the pads off on all four corners. Surprisingly, the rears were also glazed. I think at this point we can ignore the spindle as the culprit as I'm seeing the same issue all around. Of course unless I glazed these from having to brake harder and harder when the fronts overheated... seems unlikely.

Pics of rear pads before and after scuffing:

(edited out, I linked the wrong pic, will fix)

I used 80 grit sandpaper. With the G10/8 pads on the car, I went for a quick drive to bed/seat/break them in. Once the pads were warm I did some harder and harder stops, nothing too crazy and never coming to a full stop. Treated this like a bedding process like it was new. Pulled into driveway and checked rotor temps, which were 600F+ and 400F+ for front and rear respectively.

Then I pulled the pads to find this:


https://imgur.com/5kh3j9I
https://imgur.com/dFmKXtP

The rears both looked like this. Difference in photo is just wiping away the dust. Possibly high spots from sanding????

https://imgur.com/a/9lbCb

Any input? I'm really blown away that I could have glazed the pads this badly just from a few minute drive. Of course everybody I've asked has suggested I swap to Hawk DTC60s... hard to justify a 3rd set of pads in as many weeks.

I don't actually know if any of these are likely to relate to the issue, but a couple random thoughts:

- What rotors do you use? Cheap rockauto ones? A brand name? Are they all the same, or have you tried different brands? Is it possible it's related to the rotor metallurgy?

- You are hosing it all down with brake cleaner after installing new rotors, right?

--Ian

I appreciate the random thoughts.

I've tried 3 diff brands of rotor. The issue doesn't appear to be metallurgy...

Yes, rotors are cleaned with the good BrakLeen stuff. Red can.

I can't believe I'm considering buying a set of Hawk DTCs for this weekend. Every bone in my logical body is screaming that this is either a different mechanical issue that I haven't been able to solve through replacing every part or I'm just incapable of driving on track pads.

Just ordered a set of DTC-60s.

Words cannot express how upset I am going to be when I show up to Watkins glen with FOUR sets of brakes and still spend every minute trying to figure out why they don't work.

Also Dan @ 949 says my pads don't even look glazed. I don't even know what direction is up anymore.

Hey now. The photos from today look fairly consistent with the various pads that I've had on my car. The pad on the left here is pretty normal looking in terms of shine in my experience: https://imgur.com/dFmKXtP It does have lots of blue-ing that i've not seen before. The deposits on the right hand pad and the rear pads are worse and really bad, respectively. Almost like they are picking the transfer layer up off the rotor as they cool? Dunno.

I am a recent convert to GLoc, having used DTC60s the previous season and Carbotechs before that on a different car. The carbon/kevlar stuff, Carbo, GLoc, certain PFC compounds among others, are all really sensitive to contamination and transfer layer.

I would defer to Danny@Gloc or _____ @ Raybestos at this point.

No hate for you Dan :) Hope you didn't take it that way, it's just frustration combined with a lack of sleep. Yes this is keeping me up at night... it matters that much to me.

Danny just called from GLOC so I'm talking to him about it. Thanks again for all your help.

Good luck, hope the problem just goes away leaving a mystery but no problem!

OK, so tonight I swapped the front brakes from my street car onto my track car and vice versa.

Attachment 229741

Don't worry, the sawzall is only for having removed the splash guards.

Interestingly, the R10s that were on the front of the track car look WAY better than they did before. I wouldn't have been worrying as much if I had seen this:

Attachment 229742

Attachment 229743

Anyway, swapped the $10 pads to my track car and the R10s to my street car. Bizarre.

-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.

I'm exhausted and I think I'm only feeling better because I'm so tired of thinking about this 24/7 that I'm ready to give it a break. Sigh.

nice work. these type of issues can be extremely frustrating but they are part of the game. swapping the pads was a smart idea and now you have a plan. In MY experience Hawk pads may not be the new hotness but the dtc-60 is a very good pad that can be purchased for many applications for, in some cases, around $100 . they are not super friendly on the wheels, and you may not care at this point but I suggest cleaning the wheels and spraying them with a anti dust wax product. basically wheel wax in an aerosol can. if you don't and don't clean the wheels asap you'll get deposits that are nearly impossible to remove. this is not unique to hawk but some of the fancy new pad may have ave less issue with this problem but they are costly and very particular about temps and rotors.

consider taking a step back and drive hard but use the brakes as little as possible. hit your points but let the tires do some of the braking. this does 2 things assuming you hit apexes and use all of the track and put the hurt on tires. it highlights how to carry speed and how to use all of the track. you will need to feel the tires scrub speed so a little faith is involved. Not trying to tell you about how to drive but I see students who buy good brakes and it holds them back because the cant seem to force themselves to carry more speed ( move your eyes up, look farther forward and don't hyper focus on brake markers, your car follows your hands and the hands follow the eyes.

its easy to drive a fast car fast, but you will never drive a fast car fast until you learn to drive a slow car fast. taking the time to figure out how to drive a slow car fast is critical and often overlooked. when you can chase down everyone in the group with a bone stock Mazda 6 rental car you've accomplished something. might be a little outdated, cars have gotten much faster in the last 18 years but point still valid. put shit pads on and tell the instructor about your issue. if he is any good he will show you how to make the tires howl from turn in to track out. just a suggestion if all else fails. the glen may not be the best venue for this exercise but it still applies. or you could get bigger brakes but that may not solve the problem, only introduce a new problem. one must be very aggressive when trying to get people to not over brake. then again I not the most aggressive breaker. flat spotting a tire sucks when you gotta drive home a few hours and buy new rubber.

get something set up and let a instructor with a miata drive your car. or check out qualifying times for spec miata races, a good mark to reach for. best of luck, you will get it figured out

Thanks for the kind words. You're right, this is really frustrating but clearly just part of the learning process that I was not anticipating.

It's also funny what you said about not using brakes, on late Sunday at Summit I was super frustrated because the brakes weren't working right so I did a few laps with using very little brake, just looking ahead and staying off of them. Bam... best lap time of weekend. Didn't even feel fast... standard 'slow is fast' feedback loop.

Was that Summit Point main? I have 4 days at that track and had no brake issues, granted I am running ducts but I'm also ~250 whp on stock rotors and gloc 10/8 pads. I was diving into turn 1 at 125 to 130mph and braking just short of the 500' mark. If you want to see a video or even my Harry's lap timer data I can share so you can compare to your driving style to see if there are any glaring differences. With that said I suck, but it's a data point none the less.

Thats great! take some satisfaction from the small victories, even if they come to you accidentally. you've learned a great deal from this, so try not to get frustrated when the car does not handle the way you want it to. This sport is alot about enjoying the process, and the quest for more speed. those who don't learn to appreciate the challenges often burn out and choose to spend their time elsewhere.

Well, spent another 2 days on track, this time at Watkins Glen. DTC-60 fronts with the G-LOC8s on the back.

First day was such a whirlwind as the track is so big and difficult to learn, so I wasn't quite up to pace until midway through Day 2.

I did again... get bad brake feel once I was really moving and was braking hard. However, I didn't lose braking force, just feel, so I kept driving.

Came into pits, let car cool and found pedal feel to still be very bad. Bled fronts - no change. Bled rears - BAM pedal feel was back. Looked at the rear pads and they're nice and shiny... fronts look perfect. I'm guessing they glazed over and boiled the fluid.

Hate to say it but I think I'm having a pad issue. I'm going to order matching hawk rear pads and I think that will solve it all. I really wonder why I've been having issues as I know lots of folks run GLOC pads with very good results.

Just very happy to have had such a good weekend!