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I recently installed 1521s all the way around. I didn't have an opportunity to bed them in initially but they were quiet. Finally got a chance to bed them in today (5 runs 60-30 per Carbotech instructions then 15 mins or so cruising with no stops). Now the car sounds like a Mack truck during low speed stops. Not just a squeal - it's embarrassingly loud. I read that Carbotech did not recommend using shims so I didn't. For those of you running these what is your setup?
Looks like I have found the source of the problem. There was quite a bit of discussion about this in some old posts back in 2010 so I assumed Carbotech had fixed this issue but my rear pads appear to be too wide for the rotors creating a groove from the rotor lip.
Here you can see the pad sticking out past the rotor edge when installed.
Looks like Mike hasn't fixed that issue with the rears yet, but I'd bet he's hardly sold any rear pads. They just don't wear out at all.
With the minimal wear that we see on the rear pads, and with most of the bias being up front, when going to a track (especially if you're inexperienced) would you recommend against sticking to regular street pads in the rear, while only switching the front for track specific pads?
I'd obviously change to some high temp brake fluid but I'm curious to see if it's worth even change the rear pad to a more track oriented pad. I'm just using regular stoptech street pads right now.
There's more to it than wear. The torque characteristics will also impact bias - RR Racing already mentioned this in one post, and I think he's spot on with getting more rear brake by using a pad with higher μ in the back. I haven't tried it yet, but it definitely stands to reason. So, you might be very unhappy with the Stoptech rears depending on which fronts you choose.
There's more to it than wear. The torque characteristics will also impact bias - RR Racing already mentioned this in one post, and I think he's spot on with getting more rear brake by using a pad with higher μ in the back. I haven't tried it yet, but it definitely stands to reason. So, you might be very unhappy with the Stoptech rears depending on which fronts you choose.
Appreciate the response. It makes sense, I was just wondering if it was something that was worth trying, but sounds like it wouldn't be. I'll continue researching this topic, thanks.
I couldn't take the noise so I went back to Bosch QuietCast ceramics in the rear (Carbotechs still on front). Brakes are nearly silent now but the overall braking performance feels off and I'm sure the front is even more biased with this combo.
I agree with Lobux and Rafi that higher Mu in the back might be the way to go to give more brake balance. I have XP10 rears for track days but daily driving will never get the heat they need to perform so back to drawing board on this...
I recently installed 1521s all the way around. I didn't have an opportunity to bed them in initially but they were quiet. Finally got a chance to bed them in today (5 runs 60-30 per Carbotech instructions then 15 mins or so cruising with no stops). Now the car sounds like a Mack truck during low speed stops. Not just a squeal - it's embarrassingly loud. I read that Carbotech did not recommend using shims so I didn't. For those of you running these what is your setup?
I also have the Carbotech Bobcats which are also loud when stopping, even after initially bedding them in. Had it for a few years and still the same problems whenever I brake at lower speeds.
Didn't realize these had that issue until you mentioned it. I'm not going to go with Carbotech pads again. Thanks for pointing this out!
09-05-15, 11:04 AM
Carbotech Bobcat (1521) - Use Factory Shims?
