Hello everyone, long-time lurker, first time requesting assistance from the collective hive.
I'm having some very odd issues with my rear brakes and would appreciate your insight.
I drive a '15 Sonic RS with the 6-speed manual and rear disc brakes. I replaced the rear pads & rotors at about 75K miles, but now in less than 10K miles one of my rear rotors is absolutely destroyed. Some kind of braking system malfunction is causing one of the rear brakes to grab and hold that corner outside of normal operation, and the excess wear completely demolished the new pads and destroyed the rotor. I'd like to understand the underlying system malfunction before i just toss on another new rotor and pad set, then have those ruined.
The rotor seems to be grabbing in situations where I'm rolling forward in neutral, such as when I'm approaching a traffic signal or making a slow turn at an intersection but haven't yet touched the brake pedal. It won't completely lock up the wheel, but it is definitely forcing the pads to compress firmly against the rotor and slowing the entire vehicle drastically. Often, that corner won't release until I've accelerated away from the intersection, the vehicle thus pulling against that compressed rotor for 10-15 seconds. At some point there's an audible 'kunk' sound, the caliper releases, and things work pretty normally.
For illustration, I was driving about 45 mph on a straight, flat road and anticipating slowing for a light aways ahead. I shifted into neutral to simply coast for a bit. The RH rear brake suddenly clamped down fairly hard without my foot touching the brake pedal at all, and that one brake slowed the car to a full stop before i even reached the intersection. The car stayed straight in the lane, and the braking was smooth yet firm. I had to accelerate against that clamped brake just to reach the intersection. The brake remained clamped even though I rested at the intersection with the car in neutral and no foot on the brake. I cycled the e-brake handle a couple times while stationary, and the caliper remained compressed. As described above, I had to accelerate pretty hard against that clamped brake for about 10 seconds, reaching about 25 mph before the caliper released with an audible clunk sound.
Have any of you experienced something like this? This is obviously something far in excess of the Hill Start Assist system - or perhaps a malfunction of that system. Is this a brake-proportioning problem perhaps? I see no leaks or even significant corrosion on my rear brake lines, so I'm a bit at a loss. Is it worth trying to disable the HSA (and if so, how do I go about doing that)?
I'm having some very odd issues with my rear brakes and would appreciate your insight.
I drive a '15 Sonic RS with the 6-speed manual and rear disc brakes. I replaced the rear pads & rotors at about 75K miles, but now in less than 10K miles one of my rear rotors is absolutely destroyed. Some kind of braking system malfunction is causing one of the rear brakes to grab and hold that corner outside of normal operation, and the excess wear completely demolished the new pads and destroyed the rotor. I'd like to understand the underlying system malfunction before i just toss on another new rotor and pad set, then have those ruined.
The rotor seems to be grabbing in situations where I'm rolling forward in neutral, such as when I'm approaching a traffic signal or making a slow turn at an intersection but haven't yet touched the brake pedal. It won't completely lock up the wheel, but it is definitely forcing the pads to compress firmly against the rotor and slowing the entire vehicle drastically. Often, that corner won't release until I've accelerated away from the intersection, the vehicle thus pulling against that compressed rotor for 10-15 seconds. At some point there's an audible 'kunk' sound, the caliper releases, and things work pretty normally.
For illustration, I was driving about 45 mph on a straight, flat road and anticipating slowing for a light aways ahead. I shifted into neutral to simply coast for a bit. The RH rear brake suddenly clamped down fairly hard without my foot touching the brake pedal at all, and that one brake slowed the car to a full stop before i even reached the intersection. The car stayed straight in the lane, and the braking was smooth yet firm. I had to accelerate against that clamped brake just to reach the intersection. The brake remained clamped even though I rested at the intersection with the car in neutral and no foot on the brake. I cycled the e-brake handle a couple times while stationary, and the caliper remained compressed. As described above, I had to accelerate pretty hard against that clamped brake for about 10 seconds, reaching about 25 mph before the caliper released with an audible clunk sound.
Have any of you experienced something like this? This is obviously something far in excess of the Hill Start Assist system - or perhaps a malfunction of that system. Is this a brake-proportioning problem perhaps? I see no leaks or even significant corrosion on my rear brake lines, so I'm a bit at a loss. Is it worth trying to disable the HSA (and if so, how do I go about doing that)?
