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- #21
I could actually see the pad and piston moving in and out while someone was pressing and releasing the pedal. Dont think its sticking, just not staying in position.
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Is the pad in the problem side/area tapered?How should this be corrected, if the pistons are sliding back in/retracting, should the caliper be replaced?
Check the pads to see if the backing plates are still flat, it sounds like you had a lot of pickup on that side. If the pads do not move freely in the calipers that can give you a problem. When the pad and calipers get warm they grow so if you have a pad that is slightly tight in the caliper body, it can get stuck, pad taper is normal for non racing brake systems, rotating pads side to side can help even out wear. Make sure the pins are not worn, the locating pads inside the caliper are smooth (where the pad fits into) We do recommend using the anti-rattle clip so the pads always have tension on them, one hard curb jump and knock the pad out of position and in the next braking zone lock that pad up in the caliper or even bend the pad. Depending on the track one side can also run cooler or hotter depending on braking demands, left vs right turns. Remember the outside tire will always carry more speed, so if a track puts a lot on one side vs a balance of left and rights, pads will see more wear and heat on the busier side. Typically the inside pad will wear faster than the outside, some of this is due to trapped heat in the wheel well, ducted cooling works but the outside rotor surface will tend to run cooler because its in open air. The other reason the inner pad can wear more is due to the leverage of the caliper mounting. The inner pad is closer to the mounting point, under heavy braking the caliper will deflect, the outer pad will do less work because it is further away and sees the most deflection. Race brake systems have stiff calipers that are radial mounted for this very reason, this is why the GT350 brakes are so good, the upright was designed for radial mounting it deflects very little. Even on motorsport brake systems the adapter bracket needs to be very stiff to maintain the caliper position, but it is only as strong as the upright.On problem side, both pads are tapered. both are thiner on the outside area, looks like they may have been binding. They were hard to slide out and there was alot of tire rubber stuck in there. Suspect that the brake cooling ducts picked up some trash a dumped it in there. I'm going to get everything disassembled and cleaned up. Also install inlet screens on the ducts.
Thinner on the outside area - do you mean at the rotor OD here as opposed to near the rotor hat diameter? If so, that sounds like the caliper may be spreading under heavy braking. Low-mu pads would tend to exaggerate this (you need greater caliper piston force to achieve the same amount of braking torque). Tall tires would also cause greater piston forces for the same amount of deceleration. Sticky tires would allow you to demand higher braking torques and pad to rotor / caliper-spreading forces.On problem side, both pads are tapered. both are thiner on the outside area, looks like they may have been binding. They were hard to slide out and there was alot of tire rubber stuck in there. Suspect that the brake cooling ducts picked up some trash a dumped it in there. I'm going to get everything disassembled and cleaned up. Also install inlet screens on the ducts.