arnick'02-6spd

So. About 6K ago I put on a stop tech BBK. Look great, feel great, stop great. Note: I don't blame the product... yet. I was happy. Had my local shop do the install. My first concern was that the pad to rotor tolerances seemed pretty tight and for the first couple of days, the rotors seemed 'sticky'. As if there was zero run-out, and the pads were dragging with no brake pedal. Both AMS and Stoptech said what I described sounded normal. And it all loosened up a bit later.

Q1: is sticky tight tolerance normal with brand new rotors and pads? Or did I fry my rotors right off the bat?

I'm running Axxis Ultimate pads up front, Mintex red-box in the back. I've had no issues with the back pads and rotors. Rotors are very smooth, always have a good gun-metal color and have never squealed. The fronts are a different story...

I followed all the bed in procedures, and was very careful never to use the brakes aggressively and then come to a stop and sit on them. I was CAREFUL. Nevertheless, the brakes were always noisy, big squeals, and 3000 miles later, I noticed a vibration under braking at 80mph+ only. I did another bed in, and a canyon run, and the vib went away... Only to come back much worse at about 6000 miles. Before the rest of this story (it gets better) 2 more questions:

Q2: Has anyone had issues with the Axxis ULT pads? I always had the feeling that in 90% of my driving (city), I didn't get them up to temp - I'm a gentle driver - most of the time, I'm driving my dog around. Under these conditions, would they eat the rotor up? Stoptech and another shop said No, they generally don't have problems and both shops steered me away from buying a more OEM threshold pad.

Q3: Why would I feel the vibration only at high speeds? When my stock rotors went, I felt it at all speeds under light braking.

The story continues: So I've now got this bad vibe at only high speed. I call stoptech. The've been very helpful and willing to talk. They suggest I try to cool-scrub the rotors with rented Hawk Blue Pads. Then put in a new set of street pads.

If it had worked, I'd be posting a success story, but the results were far worse: I followed their directions closely and went through the process. Oddly enough, half way through the process, I was coasting and could hear the pads dragging on the rotors again - under no break. Steering left or right made the noise momentarily worse. When I stopped, I saw that the racing pads had not only not cleaned up the rotors - but rather had scored severe Saturn grooves all across the rotor face! I don't know how. When I put them in they looked ok. When I pulled them out, they had lines on them. And the high speed vibration is still there - albeit a little less. If the rotors weren't ruined before, they certainly are now. So...

Blue pads out, and will be sent back to Proparts (Nice guys). Old pads back in - not going to bed new pads into junk. Bed in old pads, and now I can see where they're bedding into the ridges on the rotor face and not making even contact. Braking distance is up. I need to get new rotors now.

Q4: What gives? Are stoptech bed in procedures too agressive because the allroad is just too hard on brakes?

Q5: Is the Axxis pad too aggressive for my style of driving or is it as gentle and moderate as Stoptech says?

Q6: Could something else be going on with my braking system, or the calipers themselves? And if so How On Earth, am I going to chase that down? Note: (the old pads rotate fine, no dragging because they have 6k on them.

Q7: Both Stoptech and DC performance (also nice guys) say recommend the Ultimates again on the new rotors. I really don't want to, and I'd easily sacrifice some performance for a softer pad. The last thing I want to do is stare at another rotor bill 6000 miles down the road. Because that would be b.a.d.bad.

Thoughts, Suggestsions? Sorry about how disjointed this post is.

TIA
NIck.

TorontoAllroad

I would say that the agressive pads dragging may have induced an increase in DTV (disk thickness variation) causing your brake judder problem (or brake vibration)

There are generally 2 types of brake judder but both are related to high DTV. 1)when the brake pad material is too agressive and wears away at the rotors unevenly or 2) high temps cause the friction material to transfer and stick to the rotors.

The term "warped" rotors is commonly used but in actuality, the rotors do not warp unless we are talking about extreme heat followed by extreme cooling.

Anyhow, I would recommend you try turning your rotors and trying again. Perhaps the pads were too thick? I'm not sure as I don't have too much experience with aftermarket pads on an allroad.

I do know that when I got my allroad, it had a very bad brake judder and I machined the rotors and all has been good since. I didn't measure the DTV but from the amount of material I had to remove wasn't much.

If you have a micrometer, it would be interesting to measure the rotor thickness all around the rotor (at least 25 equally spaced readings) to understand how sensitive the allroad is to DTV.

Most cars tend to be sensitive when the DTV is greater than 20 microns but some japanese vehicles are known to be sensitive to DTV's as low as 10 microns.

Not sure if this helps at all...

ar-Rings

ULT/Ultimate ceramic pads f/r. As I got ready to add some anti-squeal formula I noticed there was a piece of ? glued on the backsides of the pads. I did not apply anything and threw them on. I followed the descibed bedding proceedure (in a downpour). I am thinking I am into them for about 1000 miles. Never a squeek. I have only needed to brake very-very hard one time, no problems. I have however noticed that they do at time feel a bit grabby.

Nick,
I am sure all this blah blah blah, doesn't help you much. Just thought I would share my outcome.

Maybe a piston hanging up ??? Good luck.

Vacation this week, ar under cover (taking the camper) home on Friday. If next weekend is nice I am going for a day long mountain drive around Mt. Rainier. Will push it some, and will do a write up. Been thinking of doing a report on the kit anyway. Kind of late for you though.

Jon =)

ArchAudi

I have the PBR/Axxis metal master and I have horrible stopping when cold and great when hot.

allroad'Ed now

Yea the pads were a bit snug the first time I tried to install so I just took off a few thousanths material on my belt sander and all was fine.
In your case, is the interference both inner and outer pads or is one worse than the other? Before you go to the expense of all new rotors and pads, why not just try putting the Axxis pads back in on the old rotors. Even if they are grooved, that at least should eliminate the squeal. But before sticking the pads back in, try roughing up the surface to break any glazing that might be there. Woth a shot.

arnick'02-6spd

you had a snug fit as well. I assisted the mech. with the initial install, and then and with this weekend's pad changes, it seems the fit is equal on both sides of the rotors on both sides of the car. The rotors are also feel grooved front and back equally. This leads me to believe I probably don't have a caliper/piston problem. Do you think something could be wrong with my system above the lines? Something like not enough pressure release? I'm totally making this up but who knows...

i did put the old pads back in. Didn't see the point of putting in new ones on grooved rotors, and I have a lot of material left (1/2-3/4). Braking performance is down, though, and the judder never abated.

I'm going to talk to Matt at Stoptech on Monday, and see what he says. Maybe the fit was tight enough to cook 'em in the first thousand miles.

I'll post here what he says. If there's a bright side to this, it's that I'm no longer afraid to touch my brakes.

Thanks,
NIck.

allroad'Ed now

that you glazed the pads initially and that's what caused the degradation of braking performance. I would not in the least be concerned about the grooves in the rotor... grooves are bite and help bed a new pad in. Now, if the grooves are excessively deep that's a different story but I can't believe the other Hawk pads caused anything excessive. I've used Hawk Blues and Pagid Orange and Black in the past on other cars and they all caused rotor grooving but nothing abnormal.

arnick'02-6spd

The grooves are minor, so I'm going run these rotors a while longer. The high speed judder isn't as bad as it was before.

When it gets time for new rotors and pads, I'll make sure the next set of pads are taken down a bit to cut the risk of glazing them at the start.

I didn't talk to matt today, plan to tomorrow.

Thanks for all your help.

Nick.

allroad'Ed now

First, are your rotors drilled or slotted? Mine were slotted. I'm personally not a big fan of drilled rotors for the street but that's a separate topic. Anyway, you might just want to try scuffing the rotor surfaces with some 180 grit sandpaper before putting the pads back in. You mjight just have pad transfer material on the rotor in one spot causing a high spot that feels like a warped rotor. Classic problem with Porsches that use that pad.... the ST40 calipe uses a Porsche 944TS pad. One gets the pad really hot, expecially in your case where the fit might have been too tight and the pads really heated up from the friction.... then stop with the overheated pad stationary... instant transfer of pad material to the rotor. Imperceptible to the eye but it only takes a few thousandths of an inch. I suspect that's why they suggested you run the aggressive pad was to see if the abrasive nature of the pad might just scuff that off.

I've had really good luck with just putting the rotor on my bench, putting 180 or 240 grit paper in my hand held belt sander, and very lightly scuffing the rotor surfaces. Don't want to induce heat, but just take create a fresh rotor surface. By also scuffing the pad surfaces, you now have effectively fresh materials and you then re-bed everything. Hey, it's worth a try and doesn't cost anything but a hour or two of time. Old 9444Turbos were often afflicted with this malady and lots of folks remedied their "warped rotors" with a bit of sanding.

arnick'02-6spd

I've got to make the time, though. Probably should have tried this first. I don't have a belt sander (yet;-) but a 3M sanding sponge and some elbow grease might do the trick.

Wish I had a lift.