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Wanted to share my experience of the Urge spec AP racing front 299x32 big brake kit.
I went with this kit due to the generally positive reviews on s2ki and the reputation of Urge for making high quality products. Unfortunately this has not been my experience with the brake kit.
Quality:
The workmanship of the kit is fantastic, as many people have said in the past the quality of the components is fantastic. Everything bolted into place perfectly, the caliper places the pad in the perfect position relative to the disk. The AP racing CP8350 caliper is of superb quality. The fasteners are all extremely high quality NAS bolts and jet nuts.
Brake bias & pedal feel:
The brake bias is reasonable though I would prefer a bit more front torque output to hold up better to my 255 RE71R front tires. Pedal feel is improved dramatically with the very stiff AP calipers.
Rotors:
This is where the kit really falls flat for me. Though Urge claims that these rotors are sufficient because they are found on 500hp race cars that weigh more than an s2000. This is misleading in my opinion. These rotors are found in the AP racing super late modified catalogue to be used on dirt oval super late modified cars. Yes these cars are heavier than an s2000 and are in fact 500hp, but they run on dirt ovals. They have 2 short braking zones in a lap and do not see the kind of abuse that s2000s put into their brakes. My car is NA with standard bolt ons and stock ECU, while running 2:04 laps at Thunderhill recently, I thoroughly faded a set of hawk DTC-30 pads to the point where I was only about to manage about 12 minutes sessions before I no longer had any confidence in my brakes. After inspection I had significant pad deposits and tons of micro cracks in the rotors.
Although these disks have significantly more cooling than the factory disk, at only 10.5lbs of thermal mass they have the same or less heat capacity than the OEM disks. The extra cooling provides a benefit to the heat dispassion throughout a lap but the thermal mass is what provides the ability to absorb heat within a single braking zone. I was getting near total pad fade on braking into turn 14 at Thunderhill. This points to a lack of thermal mass as there are 2 high speed braking zones in a row (10 & 14). Braking into turn 1 was fine as there was enough time for the rotors to cool on the front straight. Noise:
I get a significant clicking noise from the rotors at anything above ~0.6G cornering. I have confirm that the noise is coming from the floating rotor by applying a light coat of wd-40 to each button which cause the noise to go away. I believe the issue is due to the float in hat disk, every other Essex AP racing kit uses a float in disk system which puts the bearing surface on the hard iron disk. Due to late model disk being used, Urge had to switch to a float in hat system. Float in hat is common on Brembo rotors but they use 7075 aluminum (easy to identify due to the telltale bronze anodizing) which is significantly harder and stronger than the 6061 aluminum urge used.
Overall:
The biggest reason I upgraded to this BBK was to provide increase confidence in my brakes and reduce running costs. I have done 4 track days on my current rotors and they are already near replacement levels of micro cracks (this was the around typical lifespan of stock discs) . Pad life is improved but pad performance has not. I previously used hawk DTC-60s with girodisc rotors. I was hoping to be able to use a less aggressive compound with a proper BBK but this has not been the case. If I were to continue using the urge spec kit, I would be forced to switch back to a DTC-60/70 pad but I’m hoping to find a better solution.
Looking at the discs, it appears that the pad compound you are using just isn't up to scratch. Try the Pagid RS29 compound, I can PROMISE you you will notice a significant reduction in pad deposits and fade (if you get any at all). I appreciate they are likely to be considerably more expensive, but you won't have the issues you are experiencing now. I run these on the standard discs (after trying some "lesser" pads) and the difference is night and day, being able to leave braking to the absolute last minute with zero fade (I am using Castrol SRF though):
Those rotors look fine to me. Get some DTC-60s and street drive them a bit and they'll clean up. I'd probably say you haven't used even half the life of that disc. If you're really wailing on the brakes with a higher temp pad, ALL rotors are going to form those thermal stress crack within the first few days of track usage. It's ok to keep running them. Rule of thumb is to replace the disc when the cracks can catch your thumbnail.
Also, the 11.75" x 1.25" discs are good, but as you found out, they're not very high mass, so they do experience some pretty big temp swings and can struggle to shed a lot of heat. I personally think the 12.19" x 1.25" disc is well worth the ~1-1.5 lb weight penalty. It keeps peak temps down, and due to its larger surface area and slightly higher outer vane speed, provides quite a bit more cooling.
To run more mild pads you're going to need a MUCH heavier rotor to keep peak temps in braking zones down, and one that can shed heat much quicker, so it'll need to be larger. The big Stoptech kits can sometimes get this done with their heavy and large rotors, or maybe the 13.1" Wilwood kit - but the replacement rotor cost makes it a false economy of scale.
BTW - click in a floating rotor setup might mean your wheel bearings and/or spindle is flexing under lateral load. The clicking is the rotor being pulled/pushed in and out of the hat. But as with anything, your spindle/bearing/hub assembly is not infinitely rigid, so there will be SOME flexing.
That said, some minor noises are normal in a floating rotor setup, that's the nature of the beast, and why I think they're of limited usefulness for brake rotors of this size and usage (over a typical bolt/jet nut arrangement), but they're a cool marketing point. I just never see anybody educate buyers on the negatives of floating hat systems, and always tout them as the most awesome whiz-bang solution to brakes ever. They help prevent rotor "coning" if you have that, but I've never seen it in these smaller rotors used on track myself when using a bolt/nut.
Please swap to an appropriate pad compound and provide an update when available. DTC-30 are well outside of their operating range here even with a BBK up front.
Regarding DTC-30s, I feel they don't have very good street manners - generally loud, cold response doesn't really seem any better than DTC-60s, maybe they're slightly less rotor aggressive when cold, and can't take much heat on the high end.
They don't seem a good dual duty street pad. I'd rather try a Stoptech Sport pad for that honestly. They don't seem to give many negatives (pad deposits etc.) if slightly overheated, and are great street pads minus the dust (which is easy to deal with).
But DTC-60s on the street aren't that bad, just rotor aggressive and you've got to watch the dust, as it can stick around forever if not cleaned regularly.
Please swap to an appropriate pad compound and provide an update when available. DTC-30 are well outside of their operating range here even with a BBK up front.
My main point is that I ran DTC-60 with my oem rotor and then giro disk rotor, this was supposed to provide and upgrade and run cooler. Thermally this kit is no better than stock.
BTW - click in a floating rotor setup might mean your wheel bearings and/or spindle is flexing under lateral load. The clicking is the rotor being pulled/pushed in and out of the hat. But as with anything, your spindle/bearing/hub assembly is not infinitely rigid, so there will be SOME flexing.
That said, some minor noises are normal in a floating rotor setup, that's the nature of the beast, and why I think they're of limited usefulness for brake rotors of this size and usage (over a typical bolt/jet nut arrangement), but they're a cool marketing point. I just never see anybody educate buyers on the negatives of floating hat systems, and always tout them as the most awesome whiz-bang solution to brakes ever. They help prevent rotor "coning" if you have that, but I've never seen it in these smaller rotors used on track myself when using a bolt/nut.
I replaced my wheel bearings and hubs with OEM parts just a few months ago for what it's worth.
Those rotors look fine to me. Get some DTC-60s and street drive them a bit and they'll clean up. I'd probably say you haven't used even half the life of that disc. If you're really wailing on the brakes with a higher temp pad, ALL rotors are going to form those thermal stress crack within the first few days of track usage. It's ok to keep running them. Rule of thumb is to replace the disc when the cracks can catch your thumbnail.
Also, the 11.75" x 1.25" discs are good, but as you found out, they're not very high mass, so they do experience some pretty big temp swings and can struggle to shed a lot of heat. I personally think the 12.19" x 1.25" disc is well worth the ~1-1.5 lb weight penalty. It keeps peak temps down, and due to its larger surface area and slightly higher outer vane speed, provides quite a bit more cooling.
To run more mild pads you're going to need a MUCH heavier rotor to keep peak temps in braking zones down, and one that can shed heat much quicker, so it'll need to be larger. The big Stoptech kits can sometimes get this done with their heavy and large rotors, or maybe the 13.1" Wilwood kit - but the replacement rotor cost makes it a false economy of scale.
I haven't taken pictures after driving to remove the pad deposits but the cracks are much much worse when not being covered up by pad deposits. In the top right of the first picture there is about an inch long crack that definitely catches a finger nail. The rotors are toast.
I have had this same issue with any hawk I've ever used, get yourself a quality pad like carbotech or gloc and go from there. Also do you have brake ducts??
03-23-2017, 11:56 PM
Urge Spec 299x32 Brakes Issues After 4 Events
