Stock sports pads at auto-x
Anyone else tried to use the stock pads at autocross? They seem to start off okay but turn to crap by the end of the run. Braking into the stop box the ABS was going into a kind of ice mode where the pedal was still firm but the ABS was pulsing and the car was barely slowing down. I slid through the stop box one time because the car just didn't want to stop, a rather disconcerting feeling!
Just from putting my hands over the brakes there was a big temperature difference front to rear. Do you think that the ABS system would get confused in this scenario and start activating prematurely? I've ordered some Hawk HP+ pads so we'll see how those do compared to stock. |
Man, I'd expect that from an OE session, but I'm surprised autox even got the stock pads to fade. How fast was the course?
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The course was long at over 2 minutes, and probably about 1.5 miles. There were 2 heavy braking sections where you had to brake from about 60 to 20, everything else was just moderate braking.
Seems weird to me as I never had this problem in my G35 and it had the wimpy sized stock brakes which seemed to love the heat. Now this car is lighter and has bigger brakes, doesn't make sense. |
Weird. Well I'll be curious how the Hawk's do. I was going to follow the Carbotech advice myself, but that would be for OT, not autox... and I have to get my car first ;)
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Carbotech has an auto-cross compound as well but I don't have any experience with it.
For track it's hard to beat carbotech, lots of brake tuning capacity with the various compounds. I think DD went with XP10's front and XP8's rear on his setup. |
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But I don't think surface is the issue as the problem is repeatable on a clean piece of asphalt on the street. You can make several stops 60-10 were it will be perfect and then as things heat up it gets progressively worse. It could just be my imagination but appeared as though everything was fine until heat soak reached the calipers and brake fluid. I.e. you could make repeated stops and get the rotors hot and everything is fine, then just cruise and let the heat soak in and then things start to go bad. I took it to the dealer this morning and they couldn't find anything yet. But this isn't surprising as you have to drive it pretty hard on the street to reproduce the conditions. Here's a link to another thread on the issue after I realized that pads were not an issue. Braking problem, malfunctioning ABS |
Okay, I think I know where the problem is. And you may be right initially, that the PADS are the problem.
The pulsing sensation you feel in the pedal wasn't from the ABS system. It's from the pads skipping across the surface of the rotor due to over-heating between the pads and the rotors. The pads "glazed," meaning heat near the melting temperature of the pad material allowed the brake dust to fill all the little surface imperfections and made it mirror like, and the result is instead of grabbing onto the rotor surface and providing friction to slow the car down, it just glides over the rotor and sort of just bounces, like trying to slide two pieces of mirror together. The result is you'll feel an odd, almost ABS like vibration when the pads knock back into the caliper from the surface imperfections of the rotor, pedal is firm but car's not slowing down. Once the pads cool off and the brake dust that fill the nooks and crannies can no longer stick to the little nooks and crannies the brake works again. Heat soaking into the fluid would result in a soft pedal, so I'm not sure if it's the cause here. At least that's what I think happened. A more aggressive, track oriented pad will likely cure the issue. |
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I never had anything like this problem with my G35 and it was a heavier car with smaller brakes (single piston caliper). It stopped like a champ and the pads seemed to love the heat. |
Odd. I'm at wits end. I thought I had gone through all the possible brake problems on my 350Z (I even manage to burn through an entire set of rear pads in a single day). Maybe there's something else going on here I can't explain.
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Thanks, I do appreciate the ideas.
No one else with a 370 has reported this problem yet so I'm thinking it has to be something unusual. |
Yeah, I'm starting to wonder if it's an ABS sensor or logic problem, somehow triggered by high heat...
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I feel like you've got to get the dealer to handle this. Maybe you could heat up the pads first, then immediately take them out for a drive with you...? It's just feels dumb for you to have to troubleshoot a car for them that you *just* bought. That's their job.
In fact, with brakes, I'm thinking that I'd actually write them formally notifying them that you have a serious brake issue, and that you need it to be fixed. Brakes are a massive liability to your safety and to the safety of others. I think that formally making them understand their liability might help them get their act together. After all, you are driving the car as designed, and the brakes are failing in some anomalous way - that should concern them. I would send the letter via certified mail, just so they realize how seriously you take this. I'm definitely curious what the final issue turns out to be... |
As the problem essentially only exist under racing type conditions I am hesitant to do that at this point. I'm sure they would be more than happy to void my warranty to solve the problem (from their perspective).
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I'm tired of this. If "racing of any sort whatsoever" is "improper use" of the vehicle, then Nissan shouldn't be handing the cars out to reviewers at the MF'ing track, or even be letting reviewers drive them anywhere near a clock. It's this sickness as a society that we write up contracts that are completely the opposite of what is realistic, just so people aren't liable. I really hate lawyers... :mad: Actually, though, the word "track" is not mentioned anywhere in the warranty - it just says you can't be "racing". I'd be tempted to say, "I was at the track, but I wasn't racing anyone". Turn their own legal crap against them :p |
By definition racing is either head to head (i.e. wheel to wheel) or a timed event. So yes technically you should be ok doing a HPDE drive where there is no timing available, which is that way for their own insurance. But I'm sure that they could still attempt to screw you saying that it was used in a racing application.
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