Brake Rotor Cracks

[mbuskuhl]

Is it normal to get cracks in the rotors often? Car is a 2nd Gen with Mazdacomp ducts, Hawk blues. I put new rotors on 3-4 weekends ago (Brembo front, house brand rear) with 2 weekend old Hawk blues. I just noticed there are lots of small surface cracks on both front rotors, rear rotors are fine. Calipers are new and bled every other weekend.

What causes this - overheating? I was going to replace the front rotors but was curious why this happens. Also, I should run my Hawk blues down to the line in the center of the pad, correct? I've seen people lightly file down the pad surface when changing rotors, yea or nay? Thanks!

[Xian]

Is it normal to get cracks in the rotors often? Car is a 2nd Gen with Mazdacomp ducts, Hawk blues. I put new rotors on 3-4 weekends ago (Brembo front, house brand rear) with 2 weekend old Hawk blues. I just noticed there are lots of small surface cracks on both front rotors, rear rotors are fine. Calipers are new and bled every other weekend. [/b]

In my experience, Blues do this. You end up with visible but small, radial cracks all the way around the rotor. When they get larger, I go ahead and toss the rotors.

What causes this - overheating? I was going to replace the front rotors but was curious why this happens. Also, I should run my Hawk blues down to the line in the center of the pad, correct? I've seen people lightly file down the pad surface when changing rotors, yea or nay? Thanks!
[/b]

I suspect it is caused by the temp range and aggressive compound of the Blues. I've never bothered filing the pad when changing rotors. The blues have an aggressive enough compound that they seem to bed very easily.

YMMV

Christian

[Knestis]

We run Blues on the Golf, swapping on new pads and rotors at the same time, then throwing both away when the pads get really thing. Like 3/16" thin. We have very parallel wear and the rotors are typically full of little cracks at about the same time as the pad poop out.

BTW, we ran the entire Longest Day 24 without changing pads. But then, Nelson isn't terribly hard on brakes.

K

[JLawton]

Yup, use Hawk Blues, get cracks in the rotors, toss them after 3-4 weekends. I try not to go thin on the pads although the last weekend I ran them down to almost nothing (not on purpose). The pedal got long and I seemed to have some modulation problems.

[joeg]

with Blues, I just keep the rotors fresh.

I rotate used Blue pads all around to wear them all down at roughly the same rate. They are all well used and heat checked, but still function.

[77ITA]

Regardless of what pads I am using, I generally get no more than three weekends from a set of front rotors. One of the <strike>many</strike> only advantages to racing a Neon is that rotors cost me about $20/each for the "premium / made in USA" carquest brand.

[PDoane]

If the small cracks in your rotors don&#39;t go out to the very edge, they are most probably just cracks in the boundary layer of pad compound on the rotors, not in the metal itself.

I learned this after a long discussion with the Performance Friction rep at a GA race. We showed him the cracks. He told us about the cracks being in the boundary layer and said just change the pads. The cracks went away (at first, unitl the new boundary layer formed/grew again).

If the crack does go all the way out to the outer edge of the rotor, change them.