A 8

Hoping for some brake expert advice.

Just had all rotors and pads changed on my A8. Original fitted and broke in. The brakes were/are fine when cold but once heated vibrates heavily. I am thinking they are still even (as there are no vibrations when cold) but it seems the friction varies over the disc surface when hot.

Now I had the exact same problem when the car was new and had the Audi dealer change rotors 3 times in a row until they became acceptable.

I am thinking this can not be by chance and has to have an explanation...so if I change again I can make sure the problems can be avoided.

Anyone know?

Thx.

jazbo123

I had a problem with a certain brand of brake pads where they left a deposit on the rotor surface which resulted in pulsing. The problem did get worse when the brakes warmed up. I bought a second set of rotors (same pads) and had the same problem.

Finally, I bought a different kind of pad and resurfaced the rotors and the problem was fixed. The old pads were green (green line?). The new ones are Akibono.

PaulW

What type of rotors and pads? Jazbo could have a point.

Perpetual Novice

Remove rotors and pads, sand rotors with 80 grit pad in a cross-hatch pattern, sand pads as well, chamfer the edges.

Clean and relube everything, reinstall.

I keep seeing discussions of how this pad squeals for some, not for others, etc. While all pads are different, I've often found its a glazing issue. Of course YMMV

jfrahm

Most pads should transfer material to the rotor surface, the trick is to make sure that transfer happens evenly during break-in. Otherwise it'll build up unevenly and get worse over time, like washboard on a gravel road. Organic pads might be less inclined to do this, I'm not sure. It did seem to be less of a problem back in ye olde times before metallic pads became so common.

One thing I heard was that it is easier to break in rotors or pads than it is to break in rotors AND pads. So if you clean up these rotors you might have good results, provided you bed the pads in well this go-round.

Given what a pain it is to remove the rotors I would try deglazing the rotors on the car with a sanding disc (or on the car brake hone.) Allowing the rotor to turn slowly while it is sanded might clean it up evenly. You'd need some spacers to bolt the rotors on properly I suppose.

I just replaced my rotors due to pulsing and because the PO of my car indicated he'd had the rotors cut to minimum. That turned out not to be the case, the rotors I removed were only lightly worn but they did pulse like heck. Ah well.
I very carefully used the Pagid break-in procedure with my new Zimmerman rotors (and I cleaned the rotors very carefully before and after installing them.) The brakes are great, no pulsing hot or cold. Braking was very poor at first as the pads rebedded.

While bedding is important it is also important not to park the car with the rotors blazing hot as the rotors will cool unevenly. When I first came back from my bed-in runs I thought the brakes had cooled but when I got out of the car I could tell they were still very hot and so I drove around for another 10 minutes.

-Joel.

jazbo123

Right, I should have said uneven deposits :-) That's what I had.

KYNZ

which requires a few highway (60mph) to zero stops inorder to get them seated and properly fitted to the rotors. read the box that the pads came in or do a search for bedding brakes. its important.

A 8

Nothing visible

A 8

It audi originals, all marked with the audi logo.

Its not Brembo someone at audi said it was called Gurli something?

Thx/

A 8

I did the break-in procedure as described but still got this problem. I also did this when the car was new as well but still the same problem...

I noticed that the mechanic had not cleaned the discs fully (probably oil), could this be the reason I am getting uneven deposits?