Question about brake wear
 

I just recently purchased the Carbotech XP10/XP8 combo for my 1990 NA with the 02 Sport brakes, and installed them on the current rotors I had on the car, which were fairly new and in great shape.

As I did with my previous track-car, I have been street driving on these pads for the past week to scrub the previous pad material off the face of the rotors, and will be bedding them in at my upcoming DE at Sebring this weekend.

One thing I have noticed is the front rotors seem to have cleaned off all the previous material from the face of the rotor, it is a clean, silver metal tinge (previous color was blue-ish), but on the rear, only the outer 40% of the rotor has the clean, silver color, and the inner area is still blue-ish. Based on how the pad is "cleaning" the rotor, it seems like the pad contacts the rotor with more pressure on the outer-edge of the rotor? Is this normal for a single piston, "clamp-style" caliper?

My previous track-car had 4 piston calipers all around, and the wear was completely even, so I have nothing to compare this to.

Thanks all,

-Scott

Not sure about rear sport brakes exactly, but we don't use the full rotor surface in the rear for braking. At least the pad doesn't contact on the full surface.

There is also the common confused sport rotors with the regular NB rotors, so make sure you are using the correct rotors in the rear.

Posting up pictures might help. are you experiencing uneven wear on your pads (silly question considering you just put them on, but what about the old pads?)

Ah okay that makes sense then; I didnt know they dont use the full rotor surface.

I'll post up pics tonight, but when measuring the rotor thickness, as well as where the pad was contacting the rotor, it appears the rotors are for the correct application.

The pads that came off had perfectly even wear, each pad was level, and each side was wearing evenly. Not having any problems with any one corner locking up under heavy braking, it's not pulling to one side, etc.

I'm also figuring that the rears will take longer to clean the old pad compound off b/c it is a less aggressive pad and the brake bias is more towards the front anyways.

The rotor surface is not flat, but it will be after you track it a little bit.

check out the rotors in this picture:

Rears:
https://www.miataturbo.net/attachmen...ine=1320250521

Fronts:
https://www.miataturbo.net/attachmen...ine=1320250521

Is that what you are experiencing pretty much (with the rust)?

Yep, thats it; i had no idea the rears only used a portion of the rotor. wild.

Also, the rear rotor on the left side in that pic, you can see the two different color bands (outside blue-ish, inside silver-ish), thats exactly what mine looks like right now, expect the inside is blue-ish and the outer area is silver.

yea, I see what you are talking about. Not sure exactly about the different colors. I know mine have some slight color gradienting due to heat. thats what I would blame it on, but that's probably not accurate. I can see the pad material having an effect on that, but if you like I can take pictures of my rear rotors (xp8s on 1.8 brakes) and you can compare them to yours. mine have had quite a bit of track time on them and are daily'd between events.

all else fails, take a flapper disk to the rotors and use a micrometer/dial indicator to get things worked out. Cheap man's resurface.

Huge mistake. Take the rotors off and have an auto shop resurface them, or replace all 4 rotors all together. You CANNOT install Carbotechs on used rotors - you will blue the rotors from excess heat and wear through the pads much, much faster than you otherwise would.

Carbotechs are ---- about break-in procedure - you have to follow it down to the letter.

^I won't argue against that Savington, as thats what I would do (and have done). but I have heard of many people using carbotechs on rotors with old material. took a while, but it worked it self out after a month or two. What have you seen happen when you don't do that, just curiosity on my part.

but yea, Carbotechs are quite ----, but well worth the trouble.

You can use carbotechs on old carbotech used rotors but not with any other pad compound. If your in a pinch you can us a DA and sand them clean. After you bed them in the rotor will be all kinds of rainbow blue weird colors.

I got this article from a tech at Performance Friction, and this is why I decided to re-use my old rotors and "clean" the surface of them with the abrasive Carbotech pads....

It worked great with my PFC 01 pads on my previous car, so that's why I figured I could do it with the Carbotechs, I can't imagine it works fine for all of these other brands EXCEPT Carbotech.... I shot an email to Danny at Carbotech to see what he thinks.




http://www.essexparts.com/learning-center/swapping_pads


My Daily Driven Brake Lathe

If you read my piece on choosing brake pads, you know that most race or track pads are very abrasive when driven cold. In other words, rather than transferring to the rotor face when cold, they primarily generate friction by scraping the rotor face. We're going to use that trait to our advantage, and scrape the old pad material off of our disc faces. We'll do so by performing a series of stops, without ever allowing the race pad to get hot enough to transfer to the rotor. Some compounds are obviously more abrasive than others, but generally speaking, most race compounds with a high coefficient of friction will work for this procedure. I've always used Hawk's Blue compound, which is a safe bet at a fairly affordable price, and comes in a wide range of applications. When going to the track, I usually keep a set on hand in my toolbox in case I need to clean up my rotors.

The easiest way to clean up your rotors with race pads is to simply drive them around as your daily driver for a few days. Let's go back to our earlier street-to-track example. You did your bed-in with your Hawk HPS street pads. You have a track day coming up in a week. You plan on using Ferodo DS1.11 for that event. The easiest way to prep your rotors prior to bedding in your DS1.11's is to simply swap in the DS1.11's the weekend before the event and drive them around on the street. In normal daily driving, you'll never get the race pads hot enough to begin transferring onto the rotors. During that time they'll be operating in an abrasive manner, scraping the HPS material off of your discs. By the time your event weekend rolls around, you should be back down to bare, shiny metal on your discs. Sure they won't be quite as clean as if you were using brand new rotors, but you should be able to get just about all of the old pad material off of the rotors, providing the perfect canvas for laying down a layer of race compound through a proper bed-in.

Looks like an extremely ghetto way of cleaning rotors. In my experience, carbotechs don't eat rotors when cold so I wonder how 'clean' you get your rotors by using them as daily driven sandpaper. I don't know if you can ruin fresh XP10/XP8s like that, but I wouldn't take the chance.

Seems more logical to have a dedicated set of track pads and rotors along with a dedicated set of street pads and rotors. For the most part, rotors are less expensive than pads.

Doing the above procedure compromises you in two way -- obviously at the track ("won't be quite as clean . . ." -- I love the precise lingo) + while you're running around on the street doing lathing operations, you can't stop as well as you might need to.

Doesn't seem worth it to me.

ghetto AND efficient. worked great for me with my PFC pads in the past.

again, like i said, i'll see what Danny has to say. if he says that process wont work with their pads, i'll gladly have mine resurfaced or throw on new rotors. just dont want to spend money on it if i dont have to.

these pads actually have better cold bite than my mazdaspeed miata pads do.

After running through a couple sets of the XP10/8 combo I am growing weary of dealing with them. No problems with heat or fade on track (stock power), but the transfer layer with these pads will give you shit if you look at it cross-eyed. I installed mine on fresh rotors (Carbotech's instructions are explicit in this regard, some of you should try reading them) so there would be no issues from incompatible pad material, bedded them properly, etc. Even with a transfer layer that is initially even, over the course of a track weekend I've had it either build up or wear down (or combination of both) in an uneven manner to the point of being visually obvious on the rotor face, and causing annoying pedal pulsations. I generally like the pads except for the transfer layer BS, but that's kind of like saying the federal budget is generally in good shape except for all the debt.

I haven't really experienced this to that degree. occasionally when I daily them, I can hear the noise changing as different parts of the rotor and pads are touching. This tells me the transfer layer isn't even, but I have zero pulsing on track and off track.

Perhaps you have an issue otherwise? I don't really know, this is my first set that I am wearing out completely.

I don't know exactly what causes it, but it's happened on multiple (but not all) track weekends. I can't really explain it, but I'm moving on and will be running dedicated (separate) pad sets for street and track once the Wilwoods go on.

Also keep in mind that wearing out "completely" with Carbotechs does not mean "down to the backing plate." When you get down to a certain amount the rivets will start to contact the rotors and eat grooves into them. When you get to this point it will appear at a casual glance that you still have good pad material left. Try to milk too much life out of them and you'll be replacing rotors too. If you keep out of the rivets you can get 2 or 3 sets of pads to a set of rotors. The friction material is friendly in that regard.

good to know, I will be replacing mine pretty soon, about how soon do the rivets show up? I think I have about 3/16th left on the fronts.

It's actually really easy to imagine - Carbotechs are not a metallic-based compound like every other race pad, so you can't break them in like every other race pad.

Between my brother and I we went through 3 sets of Carbotechs. Same thing you describe, horrific break-in (even when done to-the-letter!), and crazy transfer over the course of a weekend. As a bonus, the pads wore 1/2-way down on my Civic and were completely trashed on his 240SX after ONE weekend. We said "FUCK THAT" and moved on. Cobalt gets my vote these days.

I had two sets of Carbotech pads, $150 each per axle, and I don't think I've ever been more pissed off. I wasted the first session bedding the brakes, then on the 3rd session they basically stopped working, it turns out the backing plate bent and the XP12 compound wore away. For the next day, I started fresh, those pads lasted another 3 sessions. I called to complain and of course they told me I didn't know how to bed pads. I know the procedure, checked to make sure there was a transfer layer on the rotor, and tried again.

The end result is clear, if the bedding process is so complex that conventional bedding methodologies don't apply, then I'm no longer going to take a $150 chance on a set of pads. I've been much happier with Hawk DTC-60s. I can run them on any used rotor and they work, I can beat the piss out of them, I can overheat them, the never taper, they last a very long time, they're $60 for the Wilwood shape, and you can ever store them in the same room as another pad compound.

:bowrofl:

Which is why I dislike using Carbotech.

Seriously, Try using Cobalt Friction.

Put them on any rotor that is not cracked and don't bother with bedding them pretty much no matter what other pad has left residue behind on your rotor. They still work smoother and better than a perfectly handled bed in procedure with Carbotech on their own dedicated rotors. They last longer and feel better with more consistency and smoothness to the bite.

Bob

Yep. Why bother with something so finicky and expensive when there are plenty of other options that do the job just as well (or better) for the same price or less and with none of the hassle?

Wow, if i would have known Carbotechs were so finicky I would have gone with the Cobalts or Hawks!

I wanted to go with the Performance Friction pads which I absolutely loved on my CTS-V, but they dont make them for the 02 Miata w/ sport brakes...

I'll try either the Cobalts or Hawks after these XPs are trashed.

For those running the Cobalts, what compound are you running on the front/rear?

Bob which Cobalt friction compound do you run? Do you street your car to events, or is it track only? Is the dust corrosive or friendly to wheels? Do they eat rotors? I may switch after my current carbotech set is done if they're non-corrosive and reasonably rotor-friendly.

Did you not read any of their instructions re: bedding, or did you simply ignore them? I'm honestly curious here. They explicitly state several times what needs to be done and that the rotors need to be absolutely free of any compound from any non-carbotech pad.

Yeah I'd like to hear more about the Cobalt Frictions as well. Definitely interested in them for my next set. Plus they make them for the 01-05 Sport brakes, PFC doesnt have anything for them and Hawk has limited compounds (Blues, HT-10s, HT-14s only).

Regarding the bedding instructions... I ignored them, just like I did with my last set of PFC pad "bedding" instructions, which worked great for those pads, and that info on street driving to clean the old material off the rotors was given to me by a PFC employee. Yes the rotor surface needs to be free of any compound of another manufacturer, but they also dont tell you that you can use the abrasive properties of the pad when it is cold to scrub off the old material for liability reasons. I understand that the Carbotech pad material is different from all the other metallic pads on the market, but when you are using the pad under it's temperature range, there isn't any transfer of material from the pad to the rotor surface, so the abrasive properties are the same as any other pad when cold. Them telling you to drive around the street for two weeks on track only pads is a liability for them.

Anyways, not really the point of this thread, it was more about the rear brakes of the Miata and if they use the entire rotor surface, which was answered for me on the first page. Not really worried about what people think about my "rotor cleaning" technique; it works fine for me.

Plus, doesnt seem like following the bedding instructions matters anyways based on peoples reports of the pads extremely short lifetime and finicky material transfer, lol.

I don't know, my carbotechs have lasted 5 events, or about 23 hours total on track, I am sure they would take me through my next event too, but it would be cutting it close, thats a total of 27 hours. can't ask for much more.

technically, I didn't follow the bedding to the T, but whatever. I am planning to experiment with pads half way through the next year, so we shall see!

Maybe not following their bedding instructions is the way to go then? lol.

Im sure I'll get more life out of mine than most b/c these sport brakes are OVERKILL for my little stock 1.6L.

I use Cobalt Friction XR2 front and rear. Spec Miata typically runs combinations of XR3's, 4's and 5's. But I’m going about 30 mph faster at the end of typical long straits. When I drive a Spec Miata it feels like I don’t need to use the brakes much at all.

They are not very friendly to rotors if you use them on the street much and the dust is corrosive. On the track though they are significantly less damaging to rotors than say Hawk Blue and actually have very low wear rate compared to anything else I have tried including Carbotech and nothing has compared to the feel smoothness and consistency. I don’t use them on the street I swap pads at the track while I’m putting on track tires might add 2 to 3 minutes. I run Wilwood BP10/Axxis Ultimates for street and autocross I tried Carbotech AX compound on the street but even those were finicky about bed in and they cost a lot more.

The thing is the bed in procedure with the Cobalts is just be careful for the first couple turns to make sure they make reasonable contact with the rotors and your good to go. Doesn’t seem to matter whether they are new out of the package or what other pad residue was left on your rotor. They are a sintered carbon ceramic compound and they have no binding material so they don’t even stink when they get hot. When I’m done with a track day they leave behind a nice clean and smooth rotor surface that the street pads really seem to like as well.

I take no compromises in brakes for street atocross and track use.

Bob

Ditto...

I got those things baked (smelt like a train) then waited half an hour before beating on them again. Rotors were 2nd hand and only treatment was a thorough Scotch-Brite session. :giggle:

I still sell the cobalts by the way, no complaints about performance from anyone who bought them.

Where are you getting your DTC-60s for $60? I paid $105 for DTC-30s in the stock shape, and I thought the 60s were more...

Wilwood Dynalite pads are cheaper than factory pads in every compound.

With your cheap brackets using cheap Corrado rotors, it's a bit of an expensive initial cost at $480, but then rotors are just as cheap as stock, and pads last twice as long and are cheaper. Win win in my book.

edit: that's assuming $250 for calipers, $80 for lines, and $150 for a used set of 11" brackets from someone upgrading to 11.75".

Radial DynaPro Pads are the same price as Dynalite and have 50% more usable pad thickness to wear through before you need a new set.
Bob

20% more expensive for a DTC60 ($70 vs $88). And the caliper is more expensive. By my math, you'd need to use 17 sets of pads through a DP4R before you break even on the additional investment.