Losing my damn mind: Miata Track Pads Glazing nonstop

Kendall_Jones said:

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.  

I'm commenting mostly so it's easier for me to follow this thread, because some of the symptoms are similar... but not the same as I experienced with my TL running R10/R8 front/back (also pre-bed)... so it'll be interesting to see if "how you bed 'em" is the answer...  that'll be interesting 'cause there aren't "back roads you can do 60 and brake" around me without getting in an accident/ticket 

In reply to sleepyhead :

Bed them on the highway late at night with no traffic? 

Blaise said:

^ Also, I'm not really bedding them. The rotors have a transfer layer on them, I just need to get the surface of the pad to match the rotor after scuffing off the glaze. If they're even glazed... 

This just does not sound right. So from reading this you are not actually bedding the pads.  Bedding is much more about the heat cycling of the pad compound than the actual contact between the pad and rotor. 

I suspect that you are not actually bedding the pads in from you description above and that is causing them to glaze over. 

rslifkin said:

In reply to sleepyhead :

Bed them on the highway late at night with no traffic? 

I live outside DC... there is no such thing 

(most of the highways here are 50/55mph... and cops waiting around to nail someone for "driving erratically")

This sounds suspiciously like a master cylinder that's sticking and or not properly adjusted so it won't fully release. I am curious as to why you changed everything; parts were trashed out or just being proactive?

As for bedding the pads; if can't you do it on the road just go out in one of the slow groups to bed in the pads.

What rotors are you using?  I wonder if it is not a pad problem but a rotor problem as they seem to be the constant on the car. 

I found after years of racing that good old OE rotors were the best. Followed by standard grade (not the really cheep) Centric or Wagner rotors. I would run Porterfield or metal masters Or cool carbons. Never had a brake problem ever.  Bedding in was always done off the car using an old toaster oven that I would put the pads in cold and then bring it up to max temp and let the cook for an hour.  I then would just turn off the oven and let it cool slowly on its own. I would do this to all new sets of pads we were going to be using in a race.  We were endurance racing 12 and 24 hour races so we would have as many as three pad changes depending on the car and the track. 

dean1484 said:

Blaise said:

^ Also, I'm not really bedding them. The rotors have a transfer layer on them, I just need to get the surface of the pad to match the rotor after scuffing off the glaze. If they're even glazed... 

This just does not sound right. So from reading this you are not actually bedding the pads.  Bedding is much more about the heat cycling of the pad compound than the actual contact between the pad and rotor. 

I suspect that you are not actually bedding the pads in from you description above and that is causing them to glaze over. 

Appreciate the input but GLOC sent me a set of pre-bedded pads for this exact reason. Same problems.

dean1484 said:

Bedding in was always done off the car using an old toaster oven that I would put the pads in cold and then bring it up to max temp and let the cook for an hour.  I then would just turn off the oven and let it cool slowly on its own. I would do this to all new sets of pads we were going to be using in a race.  We were endurance racing 12 and 24 hour races so we would have as many as three pad changes depending on the car and the track. 

My understanding is that the above description (minus the toaster size) is what Carbotech & G-Loc call "pre-bedding"

Another dumb question:  Are the rear brakes working?  Is it possible they are not for some reason like stuck calipers, stuck valve, line pinched off, etc.,  in the system somewhere? 

My thought train on this is no rear brakes mean the fronts do a lot more work and therefore overheat.

jharry3 said:

Another dumb question:  Are the rear brakes working?  Is it possible they are not for some reason like stuck calipers, stuck valve, line pinched off, etc.,  in the system somewhere? 

My thought train on this is no rear brakes mean the fronts do a lot more work and therefore overheat.

 

Yep, they work. As I started to have issues up front it became very clear they were working as the tail would wag while braking for T1 as I had to increase pressure more and more.

Keep in mind that both far-forward and far-rearward brake bias will cause oversteer under braking, the only difference is that when it's far-rearward you'll hear the rear tires chirping while it happens.

Certainly sounds frustrating, I'd also suspect something is building pressure in the system and causing your brakes to drag and overheat.

That said, doing track days in my CSPish 97 answer on a completely stock braking system (literally factory rotors, calipers, MC, fresh fluid, and Hawk HPS/HP+ pads) filled me with confidence in Miata brakes.  Even in hard/hot lapping in which the cars around me were suffering bad fade, my brakes worked perfectly the entire time.  The car still has those same pads and rotors on it today two years later.

KyAllroad said:

Certainly sounds frustrating, I'd also suspect something is building pressure in the system and causing your brakes to drag and overheat.

I don't see it that way. I think something is slowing the return of fluid FROM the calipers back to the MC. It would not take much to glaze the pads, an extra second or two of touching too hot a rotor with the pads without enough pressure to scrape off the outer layer will glaze them.

Going out on a limb to ask. New Rubber lines?

KyAllroad said:

Certainly sounds frustrating, I'd also suspect something is building pressure in the system and causing your brakes to drag and overheat.

That said, doing track days in my CSPish 97 answer on a completely stock braking system (literally factory rotors, calipers, MC, fresh fluid, and Hawk HPS/HP+ pads) filled me with confidence in Miata brakes.  Even in hard/hot lapping in which the cars around me were suffering bad fade, my brakes worked perfectly the entire time.  The car still has those same pads and rotors on it today two years later.

That is exactly what I had on my ZX2SR.  As I noted earlier.

mad_machine wrote:

KyAllroad said:

Certainly sounds frustrating, I'd also suspect something is building pressure in the system and causing your brakes to drag and overheat.

I don't see it that way. I think something is slowing the return of fluid FROM the calipers back to the MC. It would not take much to glaze the pads, an extra second or two of touching too hot a rotor with the pads without enough pressure to scrape off the outer layer will glaze them.

Going out on a limb to ask. New Rubber lines?

 Exactly what I was thinking. A collapse line or something is not right in the proportioning valve.  The safety valve in the stock one could be acting up. I had that issue and a mustang and it caused a similar issue with the frount brakes not releasing well and the bias was way to far to the frount. 

If you know a shop that has a brake testing rack I would consider having them test the brakes to see the balance. 

Back at the beginning of the thread, you mentioned that the car has a ton of new parts on it. Is there any chance that the front and rear brake lines are swapped at the master cylinder?

tester said:

Back at the beginning of the thread, you mentioned that the car has a ton of new parts on it. Is there any chance that the front and rear brake lines are swapped at the master cylinder?

Nope. No chance.

In the meantime, I bought a 4th set of brakes for it last night and bedded them. Nobody told me DTC-60s would throw sparks like they do at night...  pretty sure I gave the oncoming minivan driver a heart attack the first time I did a stop.

Headed to Watkins Glen tomorrow with:

GLOC (carbotechish) R10 + R12 plus rotors

Raybestos ST-43 with their rotors

Hawk DTC-60 with rotors

Space MC, spare calipers

4 qts brake fluid

I am ready.

I have been using DTC-60s for years and they are the cat's meow. I have never heard of them throwing sparks though!

gl/hf

Even if your brakes suck you are at the Glen and that is a great place this time of year.  Have fun!!!

The "rubber" lines never got crimped did they?  I had a jackleg mechanic once replace my calipers and when he did, he folded over and clamped off the lines to "keep the fluid from running out" (seriously, so stupid).  In just a few miles of driving I about cooked the new pads because the fluid couldn't get back out of the calipers after each push on the brakes. 

Apply the brakes once. Take a slow lap without applying the brakes,  yes it can be done.   See if any of the brakes are hot.

Don't forget to check and make sure the master cylinder is fully releasing after the first session.