Hey all,
I put some used STi Brembos on my wagon (w/ SS lines and good fluid). The rotors I installed had ~7,000 mi. of use but looked to be in good shape. I did not get them turned before the install. During the install, I also put in a set of new Porterfiled R4S pads to replace the ~1/3-1/2 worn OEM pads. After ~1,500 miles (mostly highway) driving w/ one aggressive track day (over 100 miles on track that day) and occ. "romping" the rotors showed some serious looking circumferential scoring (like the rings of Saturn). I decided to pull them and have them turned.

Perhaps of note, the mechanic that did the install totally screwed up the front Goodridge SS lines and they were heavily kinked! Goodridge was kind enough to replace them free of charge (wow!) and I reinstalled the new lines myself (correctly) when I pulled the rotors. {actually a lot easier than I expected- also installed speed bleeders- excellent inexpensive mod}

Now, after ~30 miles, the same pattern of scoring is appearing. Have other PF pad (or high end street pad) users seen the same wear patterns?
here are a coup[le photos: http://www.threeringranch.org/norm/rotor.htm

What kinds of lifespan are others getting from OEM and/or aftermarket rotors. Assume normal city driving w/ occ. spirited backroads or specify otherwise.

I also noticed that the pads are very close to rotor- infact, I can't even slip a sheet of paper between the pad and the rotor (w/ engine off). Is this normal? Are the pads perhaps dragging on the rotor? It is apparent on one of the web photos.

thanks,
norm

 

I can't comment on your high-performance pads and rotor wear. I use the street-type Axxis Ultimate which does produce minor scoring. Braking performance seems unaffected. I think some additional wear from aftermarket pads is to be expected.

Disc brake pads remain in constant contact with the surface of the rotors. It should not be enough to prevent you from easily turning the rotor by hand but it won't rotate for very long if you were to give it a spin (without the wheel as an additional flywheel effect). Drag racers used to swap out factory front disc brakes for drums on '60s iron just to eliminate the slight drag.

You might want to keep to a minimum the amount of rotor material removed during turning. I consider rotors to be replaceable items, especially if you track your car. The amount of material removal that Subaru specifies as safe is just a few thousandths of an inch (don't know what that amount is, offhand). You need that metal to help absorb and dissipate the tremendous heat generated from the braking action. Does any company offer a two-piece rotor for your Brembos? You would only have to replace the disc section and not the re-useable center hat. DBA in Australia makes them for some cars but I don't know about factory-equipped Brembos.

--
0==WW==0
"…axles of evil…" - george w. bush

 

thanks for the info.
The place that turned the rotors has a spec book which lists tolerances. They use a micrometer to make sure there is enough material to safely machine rotor surface.

I agree that rotors can/should be replaced, but replacement rotors for STi Brembos run ~$360-400 (aftermarket vs. Brembo) to as much as $700 (2 piece). I wanted to try machining [$32] within spec, before replacement.

WWW.STOPTECH.COM has excellent tech section on every aspect of brakes, fluid, lines and pads including excellent of how/why to bed pads and brake bleeding. HOWEVER- do not follow their instructions for bleeding "order", instead, follow Subaru recommendation b/c of order that brake lines come off master cylinder [ http://www.scoobymods.com/forums/sho...=6623#post6623 ]

My concern is that rotor surface should appear smooth and these rotors still continue to wear w/ concentric grooves (though still very shallow- essentially just color variations on the rotor, but in same pattern that were deeper grooves pre-turning). There are some possible explainations (some not good) as to why this may be occuring. I was curious whether others w/ same pads had same issue (or if it was one of the "not good" reasons).

I did bed the pads correctly, but will try again when other suspension issues get resolved.

 

just a wild *** question, did you get new pads after you turned the rotors? if you did then disreguard, i thought i'd ask sence you didn't mention it.

that needs to be done after a fresh turn. likewise the other way around. but sometimes you don't NEED to turn rotors with new pads. i try to keep a good habit, and a guaranteed one time job, to get fresh surface to fresh surface.

 

No. I used new Porterfield pads on the used STi rotors. With proper pad bedding, that should not have been much of a problem. (see www.Stoptech.com for excellent explaination). Then, I had rotors turned and continued w/ same pads (now w/~1,500 miles on them).

It seems like it would probably be a pad problem, not rotor, since these new pads scored the used rotor and then the same pads continue to show similar wear patterns on the newly turned rotor. Perhaps this sort of "aggressive" wear is standard/common/expected from these somewhat aggressive pads.

It's possible I messed up the pads w/ bed in somehow, but the wear pattern is a bit odd. Again, it may be quite normal for these pads. In their defense, the Porterfield R4-S pads have been absolutely excellent performers (also $$$ but you usually get what you pay for). They work fine on the street, hot weather and snow w/ NO noise EVER (except in reverse, when they almost always squeak) and they performed great on the track (repeatedly hauling car from 100+ to 40 or 60 to 15) under heavy braking w/ no fade after 20 minutes at Thunderhill (a heavy braking track). Dust level is minimal (or at least acceptable and not much noticed on a car that's often kinda dirty, anyway).