Pad Rotor Problem AP Disks
 

Background:

Last year we installed the Sprint AP kit. After installing the DS2500 pads they were bedded properly and then tracked, super quiet great stopping.

However after a few weeks as the bedded layer wore off, attempts to re-bed never worked and brakes were like Freddy Krueger clawing at metal. Tried switching to different pads, nothing worked all noisy.

Then at the end of the year switched to Carbotech 1521s which were quiet until they got heat in them.

As it turns out seems like the rotors were warped/wavy.
https://lh5.googleusercontent.com/-4...o/IMAG2279.jpg




Question:

So got new rotors, I nstalling today, however the 1521 pads that I am re-using are not perfectly smooth and took on the wavyness of the old rotors. I tried to sand them smooth, but still a bit wavy to the touch.

Can I install the 1521s re-bed and will they smooth out or will they damage the new rotors?


Cleaned Up and Drying
On drying rack. New Rotors, cleaned hats, calipers. Re-using 1521s.

https://lh6.googleusercontent.com/-m...o/IMAG2277.jpg

I have only used DS2500 since having Sprint Kit fitted and I'm now on my 2nd set of front pads. My front discs are quite wavy as well and squeal like a stuck pig if I haven't tracked for a while. That is, after a week or so of being quite after a track day they start to squeal again. Other people have mentioned the same set up without squeal.

It must be rotor shock from the pads on the street?

Where is @JRitt when you need him? I am planning on fitting AP racing front and rear BBKs this coming weekend to my car, so would like to know his comments / advice

Edit - I love you brake kit washer!

He is over on m3post now selling the new kit for the E92/E90 M3s. :lol:

I talked to him Monday about it, just ordered new Rotors and got his recommended Hawk HPS pads for street.

I think what it boils down to if you are in a colder climate where you can't heat these things up, you have to always run a street pad no matter what then swap at the track. I mean it's common sense of course.

But the rotors seem to not be very tolerant of heating and cooling cycles.

It sucks that the rotors are trashed and my 1521 Carbotechs are all wavy from bad rotors.

But this season going to start with new rotors and street pads and see how they hold up. This is a competition brake kit, so running them for street duty as well may not work in the long run. (Despite trying)

I'm jealous, My wife would murder me if I ever use the dishwasher for that.

Let her go "shopping" for the day. Problem solved. ;)

Mine sound like a pig all the time regardless of pads.

The PMU 999's from @CSG Mike were quiet for about 15 minutes though after bedding. That's a record for my car.

I daily the Hawk HPS+ and haven't noticed any issues in rotor warpage. I switched to the DS2500 for the track day and once hot they squealed like crazy but never faded. Swapped the HPS+ back in after the track day, and they bed just fine.

I will say you need to watch out when the HPS pads are cold and wet. They are like wood. Cold they are ok at best, wet they are ok at best, cold and wet? That combination is like rubbing 2x4's together trying to start a fire.

I second all of that, I am on my second set of rotors running only the HPS after running the C300 AP pads with the original Sprint kit rotors. while they were wonderful on track, the street driving simply destroyed the rotors running those pads. As you said, the HPS are virtually useless cold, but they are near silent on my setup on a new set of friction surfaces. As I will not be tracking the car anymore I am content with it the way it is and just take it easy on the brakes when they cold. While swapping pads would be cheaper then purchasing a Miata or something else at a similar price point for track use, I think long term it is still a better option for me. Also a good excuse to buy another toy. :D

Grooves that run radially are normal...

Do the AP Racing S100 pads work well and not make noise? Any one know their temperature range?

I'll get a picture of the 1521s they were not groves more totally uneven accross the entire surface. You can feel it with our fingers too. Very wavy.

THat's HIGHLY unusual for the 1521. I'd speculate that the grooves on the rotors were there from a race pad, and the 1521 molded to that shape...

The 1521 isn't abrasive enough to do that unless you cook em badly.

Work fine. Make noise.

I'm still here! But yes, I am trying to sell M3 kits too! You guys can't hoard all the good sh*t!:paddle:;)

Stay away from my M3!

:moneyburn:

:)

In my case, depth/shape-wise, I had a single radial dimple, with the low spot on the rotor and the high spot on the pad. I experienced no reduction in performance from this anomaly, as described here:
http://www.essexpartsblog.com/news/c...acing-comp-bbk

I was not, however, swapping pads nor pad compounds on the same rotor. I wouldn't have had a problem putting on a fresh pad, but would not have put the used pad on a fresh rotor.

In the case of this thread, what is a street pad/track pad you can run without ruining the rotors. Meaning, without changing rotors what pad can I run on the street and when I get to the track swap to a different pad, and before going home from track put the street pad in. All that on same rotor. Basically 1 set of rotors, different set of street and track pads. This on AP racing sprint kit.

Thanks :D

Guys...sorry I didn't have time to write a full response earlier. Here's the scoop:
The issue is the J Hook discs, and what you’re seeing is normal. If you look at that pic above, every concentric ring being worn on the disc is at the end of a J Hook. The spent pad debris collects in the J Hook, and then exits the J Hook at its termination and causes the grooves. Other than a cosmetic issue, there shouldn’t be any performance issues. This happens more when the brakes are cold, since they’re working in an abrasive mode…they’re scraping the discs rather than sticking to them. When you heat pads up on the track, they’re scraping AND sticking to the discs (and you get a pad transfer layer). You will find that some pads do this more than others because some pads have more material break loose from the pads, or the material that breaks away from the pad is more abrasive than materials from other pads. To anyone who does not know what is happening, I can definitely see how this would be a concern, and I probably need to get something up on our website about it. Again, this is normal and nothing to be alarmed about though.

If you don’t like the grooves or are worried about them, we sell a plain-face version of the exact same disc, and they are $155 per disc.

Right hand side= part# 19 01 720
Left hand side= part# 19 01 721

Finally, J Hook slots can cause a little more whirring and scraping noises, similar to drilled discs because there are more leading edges for the pad to catch on.

Forgot to say...at $155 each, the plain face discs are $10 cheaper per disc than the J Hooks.

I want my bling http://www.ft86club.com/forums/image...ies/paddle.gif

I swear I asked if you had those before!!

Damn.. I might buy a set.. I still have spare rotors (burnished too) sitting around.. hmph.

So anyone want to buy some brand new burnished J Hook rotors? :)

I might need to test me some plain face discs ;)

Nice. I prefer plain rotors. They probably make less noise as well.

Can the sprint kit be bought with the plain rotor instead of the j-hook rotor

PM sent.

i may be retard

but it isn't showing up on the site when i look

Interesting, thanks for sharing, Jeff. I expect I'll be getting the Sprint kit a year from now. The grooves do concern me, as I'll be running separate street and track pads. I expect HPS and DTC-60, but am open to hearing others' experiences. I would prefer to stay with Hawk as I get them at a discount.
If someone is using multiple sets of pads, wouldn't it make sense to want to minimize the grooves and go with plain rotors? I am not racing, just HPDE 4 and maybe TT down the road.

Hopefully the blanks stop reverse clunk, and the "cricket" sounds you get when driving with the windows down.

If someone gets the plain rotors it would be nice if they could give a comparison between the two :)

I'm keen to see how you go with the new rotors and street pads, and whether you've managed to get rid of the squealing brakes. I'd love to get my hands of the Essex kit but I worry about the noise

Plain rotors will work just fine for you. Another option, which you've probably already considered, is to buy two sets of rotors and hats; that way, you get to skip the re-bedding process when switching pads.

@JRitt

Thanks for the response Jeff, I think a majority of our issue has been temperature. We need to absolutely run the mildest pad on the street because like this week Saturday was 75 and today its 34 with flurries.

Last season we swapped around pads trying to find a middle ground and nothing would maintain a transfer layer for more than a few days which is probably why our disks were so bad they were always scraping.

The Hawk HPS you sent suck, fade out after 6 stops but honestly that's exactly what we need for the street because they heat up super fast and always keep a good transfer layer, so that seems to be a good option for those running this kit in colder settings who don't want to constantly re-bed.

I agree if you are running this kit, the Jhook makes much more sense for performance reasons. But I should not comment until someone tries the flat face disks and see how they compare.

Since my BRZed is mostly a street car now I'm very tempted.. however I also rarely ever drive the stupid thing anymore...

I think we can test a set of plain rotors... although I suspect we'll be sticking to J-hooks for our car.;)

If I keep the BRZ I'd just bite the bullet and buy another set of hats if the plain discs eliminated the squeal. I don't even know why I care, it doesn't bother me, I'm just sick of "hey, get your brakes checked" comments all the time lol

I'm guessing the cricket sounds will go away but not the reverse clunk. I think the reverse clunk comes from the brake pads having some movement going back and forth.