Weird Brake Rotor Pattern & Wilwood First Impression
 

Anyone know whats up with the weird stripe pattern on the rotors? Seems to line up with the internal ribs. This was after one day of use with the new setup. I was also feeling some thumping in the pedal.

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So first impression with the spec race kit with wider Aero6 calipers (I tend to focus on negatives):
- Out of the box, one caliper was weeping brake fluid along the seam down the center of the caliper (WW replaced it)
- Fit with plenty of room on stock C5Z 18" wheels (no spacer required)
- Dislike the tiny bleed screws, seems like they'll strip very easily
- The pad pins should have been designed to insert the opposite direction, that would make it much easier to install / remove the retaining clip
- No issues at all with the pipe thread elbow or WW braided lines.
- Not a fan of the 12-point self-locking nuts. On / off three times and they now spin like a standard nut. Are people replacing these frequently or just using loctite?

The kit came with BP30 pads and I'm using Raybestos ST43 on the rear. The brakes felt consistent throughout the day but not as aggressive as my favorite PFC01's. May try the BP40 or H next time. Car was dancing when hard on the brakes but don't know if that was the alignment or a poor match between F/R compounds.

Other than the weird pattern in the photo, the rotors already have some very minor spider cracks (these are fixed hats). The inner pads show very little top / bottom taper (couple thousands) but the outer pads are tapered with more wear at the top by .01" to .02". You can see that in the photo, the inner half of the diameter looks completely different than the outer half diameter. The other face of both rotors looks evenly worn (as indicated by the pad wear). Don't know if this taper is part of the caliper assembly tolerance or flex. Not very large but will keep an eye on it to see if it grows with use. Still not thrilled with the way the rotor wear is uneven but maybe it will look more uniform as the pad wears.

Taper along the length of the pad is interesting. The inner pads have more wear at their leading end (.015" taper). The outer pads have more wear at their trailing end (about the same amount of taper). So maybe the caliper isn't sitting parallel to the rotor. This is small enough not to be concerned about.

Rob

To make a guess, looks like hard spots forming between the cooling vanes. Any brake pedal pulse? It also looks like the inner portion of the out pad is working more than the outer portion.

Yep, it was thumping. Just emailed the photo to WW to see what they say.

I've had a similar issue with my WW BBk and GT 72 Curved Vane rotors. My first set cycled in nicely and lasted nearly 3,000 track miles of advanced level driving, getting deep in the ABS several times a lap. I replaced them due to cracking and pedal pulsation, which was really bad during warm up and nearly nonexistant at track temps. I knew that was my last event on those rotors. . My replacement set showed the hard spots on the wear surface at the cooling vane placement after the first event, like yours. They have pulsated ever since, which I'm living with for now. It's not terrible. When they get worse I'll replace them again. BTW the uneven brake pad deposits should be addressed before the next event, which I think your already mentioned. .
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What I have learned is when you get closer to the limits of pad heat range, rotor for the job, and caliper for the job you get more pad taper, claiper rebuilding interval shortens, and increased rotor replacement. It looks like you have too much heat in those pads and the pad transfer is what you are seeing and feeling on the rotors. My 1st solution would be to got back to the pfc01 or something close like carbotech xp 12 or higher. Start from scratch and season the rotor by bedding the brake pads. Hopefully the harder and higher heat capacity pfc or carbotechs will scrape off the bad pad transfer you have now. For track use the pfcs or carbo should work and once properly bedded in should be fine. If the pad surface area of the pfc or the carbos is too small for the application you could overheat those too. If you can scrape off the old pad from rotor and lay down a new transfer layer of pfc or carbo you will have to have the rotors trued and then season the rotors properly.

If you have a stout brake system like the 4 caliper stoptech T1 kit you can just put new rotors on and new pads on and go beat on them because the heat capacity of that system is exceeds the needs of the C5Z in SCCA T1 trim. In general adding aero or more horsepower or weight means you need to increase your brakes to match.

My first guess is going to be pad smear from too much heat. Can't say I'm a huge fan of the BP30s from what little experience I've had with customers using them. By default I'd nearly always push the customer into the proven Poly H compound. It appears what I see from use of say B compound when a customer starts on that with street rubber and then moves to a higher Cf tire but fails to elevate the pad with it. Curious to hear what 'tech' says on it.

Anyone know whats up with the weird stripe pattern on the rotors? Seems to line up with the internal ribs. Uneven heating passing pad threshold. spiders normal. May try more even warm-up.

Not a fan of the 12-point self-locking nuts. On / off three times and they now spin like a standard nut. J nuts are single use if you want full locking strength.

The kit came with BP30 pads and I'm using Raybestos ST43 on the rear. The brakes felt consistent throughout the day but not as aggressive as my favorite PFC01's. PFC 01 are awesome, BP may not be enough pad.

Other than the weird pattern in the photo, the rotors already have some very minor spider cracks (these are fixed hats). Is it a standard size rotor where you can get a PFC or AP rotor?

Taper along the length of the pad is interesting. Differential sized pistons? You upgraded brakes and not hubs?

I agree with Todd those pads weren't meant for the way you were using them. Don't even bother with the BP40s as they aren't good track pads either, I went through a set of those in one day at Sebring running on street tires. I had decided to use them since I was driving from NY to Sebring and then on to Key West and then back home and thought the BP40s would hold up to a couple of easy days at Sebring. Boy was I wrong. Before the first day was over they had worn down to the backing plates and I though my trip to Key West was going to be shot until a fellow forum member donated a set of almost worn out H pads that I used to make the rest of my trip.

Go with the H pads. The Hs are great track pads. If you want a high torque on initial application the A pads will give you that.

The rotors will get some heat checking on the first day. Most will, the full floating AP rotors I have on my C7Z got heat checks on the first day. You should be able to get 13 to 15 days out of those Wilwood rotors with no issues.

Bill

DunlevysZ, interesting info. Which pads are you using?

FatBB / BKBD69, I'll have to see if PFC makes something in the 6620 pad shape. If they do, thats definitely the way I'll go.

Todd, if PFC a no-go, I'll give you a call for some of the H's. I'm on 315 NT01's. Funny, before even installing the kit, I emailed with someone relatively high up in WW asking why the kit came with 30's, when it was supposed to be 40's, and also asked about H. Said I'm looking to match the PFC01's. Of course, he said he had no knowledge about PFC compounds. He was pretty adamant that they were having ABS issues with 40's and 30's were the way to go.

Bill, thanks for confirmation on the H's and not to waste any $ on the 40's! I thought the 30's were quiet enough to use on the street.

I guess the next question is if the rotors can be reused (sand, turn, or just toss on new compound pads).

BKBD69:
- Typical one lap warm-up then on them full tilt.
- I screwed up and put red loctite on a worn J-nut. When I went to remove it, the stud unscrewed instead of the nut.
- Haven't looked into using other brand rotor rings on the WW hat. Todd explained in one of my other threads, the offset for these 14" rotors to fit the (wide) calipers is not the standard C6 offset.
- Total piston area is the same as OEM. The calipers do use different diameter pistons with the larger diameter at the exit end of the caliper.

Thanks everyone for their input!!

Meant to add the pad info.... I'm running WW H pads front, and ST 47's on the rears. Completely satisfied with the braking and the WW H compound was very long lasting as well. I'd be interested to know if changing to a different pad would clean up your rotors and stop the pulsing, which would only occur if that is due to friction material deposits and not heat. . Based on my experience I say it won't, but I'd love to be proven wrong. Also a shout out to Todd at TCE. Bought BBK and replacement parts from him and couldn't be happier with the service and prices. .

Few additional thoughts:

I don't care for the 12pt nuts, all my own work ships with 6pt Jetnuts which can be used a few times over. And remember to lube the stud and not use the Loctite...Available from me or Pegasus Autoracing Supplies

The tapering we are speaking of is related to the pad wear in my opinion.

Keep in mind these or the 40s, or the H pads etc are NOT a street pad. Ideally you'll need street pads as well.

That being said the choice to run the 20mm pads creates an issue for both street pads and alternative brands. The 17mm pads are far more common from other suppliers. And even Wilwood has no street compound in 20. The only alternative to that is to run the thin pads with the pistons hanging out....OR run pad wear plates to back space the gap. I have them in both 1/8 and 3/16 as well as Ti for that very reason.


Thanks for the kind words. Help when I can, if I don't have the answer; I'm ok with admitting that...Still interested in more official input on the rotors.

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If you go with the PFC 01 pads, my experience is that they need proper bedding to perform well. I tried a set at Mid-Ohio a couple years ago (stock pad shape) and didn't have a chance to bed the pads before going to the track. I heated them up pretty good going up and down the service drive and let them cool before my first session but didn't follow a good systematic bedding process. I really liked how the pads performed but by mid-morning I was getting the vibration you were mentioning and by lunch they were vibrating so bad I had to change them. The smearing on the rotors was worse than yours. I blame myself, not the pads, but I never tried re-bedding the PFC 01s and giving them another go.

At lunch break i put on a brand new set of my normal Cobalt Friction XR1 pads (with no bedding) and enjoyed the rest of the day. They removed the splotchy transfer material and worked great. I know they are more expensive but not having to go through an elaborate bedding process makes the expense worth it to me. They last noticeably longer with some bedding but it isn't required. I don't really have a good area to to properly bed pads near my house (third world Michigan roads) and the car being pretty loud draws unwanted attention.

Todd, For the street I'm using the 17mm BP10 with spacers (I made my own in several thicknesses). Guess I'll need to pickup a supply of the nuts. Do you sell them w/o the shims? I'll post in the thread when I hear back from WW.

YYZ, I've probably gone through eight sets of 01's in the stock calipers. Only did a proper bedding on the first set. All the rest were installed before driving to the track. Only one set thumped and I had to replace the rotors. I did a full bedding on both the BP10's and some bedding on the BP30's. Hard to get them "track hot" on the street.

These rotors may end up being my spares. I guess before doing that it would be worth attempting to turn them.

The transfer layer can be removed without turning the rotors. Scotchbrite, elbow grease and a mild solvent (alcohol, paint thinner, WD40) will remove the material without having to turn the rotors. I've even used plumbers tape to remove old transfer layers. Clean with brake cleaner before use and you'll be good to go. Unless you have a good shop to turn the rotors, I've found they remove way more rotor material than necessary to merely clean the surface.

Doesn't sound like it requires much of a solvent! Didn't realize it was that easy to remove. I also have MEK, acetone, and some old trichlorfluro. Scotchbrites don't like any of those.

I have ample supply. I'll do $3.00ea any qty vs the PARS price. Shoot me a message with your email and qty needed. I'll in turn send an invoice. $8 USPS. *maybe see if there's anything else you want to add to it for the shipping??

My WW setup has worked out great once I figured out I needed a good about of heat in the rotors before tackling brake zones. It may take a few laps of dragging the brakes through the entire brake zones. Also in doing this my rotor cracks are slower to develop. Rear brakes found putting a more worn set of pads on the rear helped a lot with rear brake grip, less likely to to lockup. I'm using the H pad all around, and they last 5x longer then any Carbo did. Rotors are a year old also, between the pads and rotors costing less and lasting much longer this setup will eventually pay for it self.
Wondering if there is a good replacement for that 12pt caliper nut
Thanks Todd TCE

The nuts can be replaced as noted above from Pegasus and others.

Considering the AERO6 upgrade, sounds like the H-Type pad is the way to go for track days

It's gonna be tough to get exact answers as everyone uses their car differently. I'll chime in as I have the exact setup you do and used them for 6 track days only so far. The pattern you see is normal and will go away somewhat after future use. The further away from center, the more rotor velocity. At 14", there's probably a 20% difference in speed from the inner most part of the pad to the outer most. If you're like me, you went with the Wilwood setup for bang for the buck. It's really one of the best you can get for the money. Anything measurably better costs a LOT more. I upgraded to the Thermloc pistons, although I'm not sure it was necessary. BP30's are fine for intermediate to advanced HPDE. Beyond that, you'll probably want more pad. They were fine for me. Saw some taper but it was minor and expected for the abuse. Some thumping was noted but nothing serious. The small cracks are completely normal and I have yet to find a rotor that's abused that doesn't have them. You're going to be pulling the nuts frequently. I bought extras but only in case I lose one. A little drop of PINK Loctite will add some security if you're worried. Unlike you, I like the bleeder screws. I like having upper and lower for draining and I like that the screw is not in the aluminum of the caliper. It gives you option to change in the future if needed. Also, the tiny screw also means you need less torque to seal it up.