|
Suspension | Chassis | Brakes -- Sponsored by 949 Racing Relating to suspension, chassis, and brakes. Sponsored by 949 Racing. |
|
Thread Tools | Search this Thread |
03-10-2015, 11:03 AM | #1 | |
Driving Coach
Join Date: Jun 2012
Drives: BRZ
Location: Atlanta
Posts: 3,666
Thanks: 3,723
Thanked 4,137 Times in 1,707 Posts
Mentioned: 90 Post(s)
Tagged: 6 Thread(s)
|
Uneven wear with AP Racing Sprint BBK
Quote:
My car is tracked heavily and my first set of rotors have 8 track days on them and I believe they need to be replaced as of yesterday at Road Atlanta. First set of CL RC6's that came with my kit lasted 5 full track days and the wear was uneven on the pads (driver's side more worn) and before the 5th track day I swapped the driver's side pads with the passenger's side and finished those off. My second set of pads were Carbotech XP12's and I wasn't happy with those. They lasted 2.5 track days and they felt softer on the pedal since they aren't sintered and contain kevlar. Bite was great and they never faded, I just didn't like the feel compared to the sintered RC6's. I removed the XP12's yesterday at Road Atlanta at lunch hour and installed fresh RC6's and finished my track day with much enjoyment aside from this perplexing uneven brake wear issue. Here are the pics of my XP12's off the car and the rotors on the car. First is my driver's side rotor. The J Hooks are fading away and I can see cracks forming between the gaps in the hat. Deep groove around the outer edge of the rotor. Driver's side XP12 pads. Note the bottom pad was on the inside. Passenger's side rotor. J hooks still look okay and the grooves are less significant. Passenger's side XP12 pads. They are worn significantly less and the slot in the middle is still visible. Disclosures: I do not do the pedal dance prior to tracking my car; I do hold the button down to turn "everything" off. I instruct at every track day and I simply do not have time to fully warm up my car or remember/look up the sequence to do it. I am typically jumping out of my student's car and immediately into mine and taking 20 minute breaks every hour to rehydrate, use the restroom, track talk, etc. I am also running 911 GT3 brake air guides strapped to my control arms to direct air in the wheel wheels at speed to the inside face of the rotors to help keep rotor temperatures under control. Help, advice and insight is much appreciated. I'm at my wits end. @CSG Mike / @JRitt / @Racecomp Engineering / @Reaper / @buddy32 Please help me by tagging anyone else with the AP Sprint BBK
__________________
Last edited by ATL BRZ; 05-17-2016 at 07:33 PM. |
|
03-10-2015, 11:12 AM | #2 |
Senior Member
Join Date: Sep 2013
Drives: 2022 WRB BRZ Sport-Tech
Location: Ottawa, Canada
Posts: 1,746
Thanks: 131
Thanked 1,411 Times in 715 Posts
Mentioned: 25 Post(s)
Tagged: 2 Thread(s)
|
Could it be as simple as a sticky pot on the driver side caliper?
|
03-10-2015, 11:22 AM | #3 |
Off Topic
Join Date: Feb 2014
Drives: 2014 Subaru BRZ Limited
Location: Vegas, baby!
Posts: 4,610
Thanks: 2,369
Thanked 4,243 Times in 2,170 Posts
Mentioned: 43 Post(s)
Tagged: 3 Thread(s)
|
What would cause more wear on the driver's side? Could it be something as simple as increased weight from the driver or braking into left corners more than right corners or something like that?
|
03-10-2015, 11:25 AM | #4 | |
Driving Coach
Join Date: Jun 2012
Drives: BRZ
Location: Atlanta
Posts: 3,666
Thanks: 3,723
Thanked 4,137 Times in 1,707 Posts
Mentioned: 90 Post(s)
Tagged: 6 Thread(s)
|
Quote:
I don't know. I've run both clockwise and counter-clockwise tracks with the BBK. I threshold brake in a straight line and rarely trail brake. I am not engaging ABS into every corner.
__________________
Last edited by ATL BRZ; 03-10-2015 at 11:36 AM. |
|
03-10-2015, 11:44 AM | #5 |
Senior Member
Join Date: Feb 2014
Drives: 2023 BRZ
Location: Denver, CO
Posts: 1,816
Thanks: 1,490
Thanked 1,264 Times in 683 Posts
Mentioned: 34 Post(s)
Tagged: 2 Thread(s)
|
This is a good post. Thanks for sharing the info. It seems to me like there could be several causes of this uneven wear. I also think the next step in diagnosing the issue is to turn off all of the nannies. Without doing that, you really don't know how much the brakes are being applied at each corner.
I appreciate what you say about being rushed while at the track. I am sometimes in a similar situation. That said, to do the pedal dance takes almost no time. Therefore, you'll have a tough time convincing me you can't do it easily. The car does have to be warm, of course, which can take some time. Do you have a helper that can start it up 15 minutes before your session? If not, could you just let the car idle between sessions? I know it's wasted gas, but it doesn't burn much if it's just idling. And when you consider the cost and/or complexity of other methods of diagnosis, it still seems like a pretty good option IMO. I'm looking forward to hearing what others have to say. |
03-10-2015, 12:06 PM | #6 |
Senior Member
Join Date: Jul 2012
Drives: 2013 Asphalt FR-S Manual
Location: Whitby, ON, Canada
Posts: 6,716
Thanks: 7,875
Thanked 3,353 Times in 2,134 Posts
Mentioned: 99 Post(s)
Tagged: 1 Thread(s)
|
I have a hard time believing this would be related to not doing the pedal dance. The chance of it always applying that much more force to the same wheel at every braking zone is essentially zero.
If the rears were wearing more than the fronts, I would blame VSC, but assymetrical wear left to right on the same axle sounds more like a hardware issue. It also looks like they're wearing significantly more at one end of the pad than the other which makes me think it might be a crossover tube? Are they more worn at the front or the rear? How does the fluid flow through these calipers, crossover at both ends, or only at one end? Which end is the brake line attached to compared to the more worn end of the pads? Another thought, could the caliper bracket be mis-aligned or bent at all? Can you feel more drag on that wheel with the car in the air
__________________
Light travels faster than sound, so people may appear to be bright until you hear them speak... flickr |
The Following User Says Thank You to wparsons For This Useful Post: | DAEMANO (03-10-2015) |
03-10-2015, 01:25 PM | #7 |
Senior Member
Join Date: Nov 2014
Drives: Fr-s
Location: MN
Posts: 760
Thanks: 133
Thanked 535 Times in 280 Posts
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
|
I would start by pulling the scoops off for an event or two, see if those are feeding uneven amounts of air.
|
03-10-2015, 01:46 PM | #8 |
NASA SpecE30 Racer
|
With uneven wear like that my guess is it is a caliper issue. I doubt the GT3 air guides or not doing the pedal dance are the primary causes. Have you only done two pad install/swaps on the calipers? I would pull the pistons out of the calipers and give them a good look. The uneven wear like that on a multi piston caliper is most likely caused by one of the pistons providing more pressure. Perhaps there is an issue with the anti-knock back spring behind one of the pistons as well.
__________________
- King Tut
Street/Track Car: 2006 Honda S2000 TT3 || Race Car: 1987 BMW 325is SpecE30 || Tow Vehicle: 2014 RAM 1500 EcoDiesel Sold Cars: 2012 BMW M3 || 2013 Subaru BRZ || 2012 Porsche Cayman R || 2009 Chevrolet Z06 || 2009 BMW M3 || 2004 BMW M3 || 2004 Nissan 350Z |
03-10-2015, 01:56 PM | #9 |
Off Topic
Join Date: Feb 2014
Drives: 2014 Subaru BRZ Limited
Location: Vegas, baby!
Posts: 4,610
Thanks: 2,369
Thanked 4,243 Times in 2,170 Posts
Mentioned: 43 Post(s)
Tagged: 3 Thread(s)
|
Both pads from the driver's side are worn significantly more than both pads on the passenger side though. Would one piston of a four piston caliper cause both pads to wear down that much more?
|
03-10-2015, 01:58 PM | #10 |
Driving Coach
Join Date: Jun 2012
Drives: BRZ
Location: Atlanta
Posts: 3,666
Thanks: 3,723
Thanked 4,137 Times in 1,707 Posts
Mentioned: 90 Post(s)
Tagged: 6 Thread(s)
|
IIRC.... Carbotech 1521 street pads > CL RC6 > Carbotech 1521 street pads > CL RC6 > Carbotech 1521 street pads > Carbotech XP12 > CL RC6 |
03-10-2015, 02:00 PM | #11 |
Join Date: Aug 2012
Drives: S2000 CR
Location: California
Posts: 2,109
Thanks: 537
Thanked 1,721 Times in 956 Posts
Mentioned: 173 Post(s)
Tagged: 3 Thread(s)
|
It is heat. What rear pads are you using? If you overwork the rear, it'll cause the front to work harder. The heat is also a function of how you use your brakes too.
This can be replicated on other brake kits as well. Wilwood is the worst. You'll end up just eating one pad up instead of a pair...lol. |
The Following User Says Thank You to CSG David For This Useful Post: | DAEMANO (03-10-2015) |
03-10-2015, 02:31 PM | #12 | |
Driving Coach
Join Date: Jun 2012
Drives: BRZ
Location: Atlanta
Posts: 3,666
Thanks: 3,723
Thanked 4,137 Times in 1,707 Posts
Mentioned: 90 Post(s)
Tagged: 6 Thread(s)
|
Quote:
__________________
Last edited by ATL BRZ; 03-10-2015 at 03:53 PM. |
|
03-10-2015, 02:41 PM | #13 |
Join Date: Jul 2012
Drives: 2013 BRZ, 2020 KTM Super Duke 1290R
Location: Denver
Posts: 1,788
Thanks: 714
Thanked 1,141 Times in 624 Posts
Mentioned: 49 Post(s)
Tagged: 1 Thread(s)
|
Curious, because the topic of VSC came up, I am under the impression that VSC would alter brake pressure by use of the ABS system, individually per wheel. So if VSC were a culprit you should feel the telltale vibration from ABS activation.
Or, does it have the ability to modulate brake pressure more finitely at each wheel transparently, to the point that the driver might not even know it's happening? Brakes are a dumb mechanism, they rely purely on physical force to do a thing. When brake pressure is applied, its in the same proportion, every time (unless VSC/ABS/etc). Braking in a straight line shouldn't cause any of these variables. If one side is getting hotter to the point that it's visibly expediting wear, I'd suspect something mechanical. Could be a stuck piston that's not retracting properly, causing the pad to drag excessively. In the DS pad pic, I assume the left side of the pad is the leading edge (points toward rear of vehicle)? That would make sense as the pad wants to be drug out of the caliper by the rotor, that the leading edge can wear more, but not when the opposing pad (and both on passenger side) looks so even. I wonder what the back side of the rotor loos like... I'd check piston movement. |
03-10-2015, 02:54 PM | #14 |
Senior Member
Join Date: Apr 2014
Drives: 2014 BRZ
Location: Redmond, WA
Posts: 639
Thanks: 299
Thanked 392 Times in 229 Posts
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
|
The driver side pads look like one piston is not working correctly. Notice that one pad is worn evenly while the other has a clear diagonal wear pattern.
__________________
|
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Will OEM STi (2004) 17x7.5 +53 fit a BBK (AP Racing sprint/Willwoods)? | dejxx | Wheels | Tires | Spacers | Hub -- Sponsored by The Tire Rack | 4 | 12-25-2014 02:28 PM |
No squeal pads for AP Racing Essex Sprint Kit | Hags86 | Suspension | Chassis | Brakes -- Sponsored by 949 Racing | 39 | 04-04-2014 03:53 PM |
AP Racing Sprint kit with OEM rims | dp1 | Suspension | Chassis | Brakes -- Sponsored by 949 Racing | 10 | 02-18-2014 07:47 AM |
SoCal Selling AP Racing Sprint Kit | evilconcarne999 | Brakes, Suspension, Chassis | 7 | 04-02-2013 07:06 PM |