Post Track Inspection - Thoughts?

[OldRanger]

Hey,
I wanted to get a second set of eyes on how things are going with my front wheels and brakes (E46). I have Ohlins R&T, Apex 18x9.5 ET35, Potenza RE-71RS. The OEM rotors and PFC-08 pads were new in May. The car has been to 8 track days at Summit at intermediate pace.

1) are the micro-cracks and other pad deposits typical?
2) do I need to put any effort into cleaning the brake dust out of the holes?
3) the pads are forming a groove in the rotor surface closest to the hub. Should I consider brass guide bushings?
4) I need to get the tire off the strut. The depth of the groove in the tire suggests only a few mm are needed. I’m not getting new wheels with a different offset, so is a 5mm spacer an acceptable, safe option for the front?
5) for track duty with spacers, (I have a 12mm in back already) should I be using studs instead of lug bolts?

Thanks for any ideas.

[foolio]

My two cents below:

Hey,
I wanted to get a second set of eyes on how things are going with my front wheels and brakes (E46). I have Ohlins R&T, Apex 18x9.5 ET35, Potenza RE-71RS. The OEM rotors and PFC-08 pads were new in May. The car has been to 8 track days at Summit at intermediate pace.

1) are the micro-cracks and other pad deposits typical? Yes. Typical rule of thumb is if you scrape your fingernail across the surface and it catches, time to replace rotors.
2) do I need to put any effort into cleaning the brake dust out of the holes? Won’t hurt but it’ll come back.
3) the pads are forming a groove in the rotor surface closest to the hub. Should I consider brass guide bushings? Yes, absolutely.
4) I need to get the tire off the strut. The depth of the groove in the tire suggests only a few mm are needed. I’m not getting new wheels with a different offset, so is a 5mm spacer an acceptable, safe option for the front? Yes, a 5mm spacer will be fine but check it after a session in case you need a slightly larger one.
5) for track duty with spacers, (I have a 12mm in back already) should I be using studs instead of lug bolts? I think that is primarily a personal decision. I don’t know if one is really better than the other other than convenience if you change wheels/rotate your tires. Studs make those jobs a lot easier.

Thanks for any ideas.

[OldRanger]

Thanks foolio - I appreciate your take.

I also want to add another element to the discussion on brake rotors, spacers and studs/lugs

One of my rear rotors (the end with 12mm spacer) was rotated on the hub a few degrees. The ID of the rotor bolt hole is larger than the OF of the bolt threads. So I dug in a bit. It appears the anti-corrosion coating wears off in a manner that can accumulate unevenly between the rotor and hub. This is on a wheel that I torque check upon arrival at track, and after every other session. The concern is that when rotating or removing tires for a brake bleed, etc., the shavings can end up in clumps prevent a proper install.

Recommendation: if you are using Zimmerman OEM rotors or any other with the coating on the rotor ‘hat’ - remove it.

the first two images are before, the third is after removing the material with a drill/wire wheel

[Wernd]

I would caution against running a coated rotor just for the simple fact that the coating will help hold heat in. It's the same exact reason I would tell you to clean the holes out of your rotor after each event.

Also, once you do a stud conversion you'll wonder why you didn't do it earlier. Make sure to buy quality studs and they're NOT a lifetime part! They should be replaced every couple of years (15 events or so) or if one breaks you should at a minimum replace every stud at that corner. Don't be the idiot that runs them forever has one break and just replaces that one and then doesn't understand why his wheel came off at turn 5 and blames studs

[bigjae46]

Thanks foolio - I appreciate your take.

I also want to add another element to the discussion on brake rotors, spacers and studs/lugs

One of my rear rotors (the end with 12mm spacer) was rotated on the hub a few degrees. The ID of the rotor bolt hole is larger than the OF of the bolt threads. So I dug in a bit. It appears the anti-corrosion coating wears off in a manner that can accumulate unevenly between the rotor and hub. This is on a wheel that I torque check upon arrival at track, and after every other session. The concern is that when rotating or removing tires for a brake bleed, etc., the shavings can end up in clumps prevent a proper install.

Recommendation: if you are using Zimmerman OEM rotors or any other with the coating on the rotor ‘hat’ - remove it.

the first two images are before, the third is after removing the material with a drill/wire wheel

That's odd because the head of the rotor hold down screw countersinks into the opening so the rotor shouldn't move unless the hold down screws were missing or fell out.

[OldRanger]

That's odd because the head of the rotor hold down screw countersinks into the opening so the rotor shouldn't move unless the hold down screws were missing or fell out.

I agree. I was a bit baffled. Note: the hold down screws are longer with the Future Classic 12mm spacer, and there is enough tolerance to let it happen on track. The threads from the lugs had actually worn marks into the rotor. Just goes to show even with proper torque, if there is anything between that rotor and the hub or rotor and wheel...it can cause trouble. And "anything" seems to include the coating.

P.S.: FCP Euro did/does not have an accurate photo of the Zimmerman rotor. The picture shows a rotor with no coating. I was a bit miffed when I opened the box.