RibEye
Senior Member
My front brakes are not spongy. Once the lever gets to the active point, the function is nice and hard. The problem is that it takes over half of the lever travel before compression is detected. I have rebuilt my master cylinder, and fully replaced all fluid during bleeding. Some improvement, but I did not see much wear on the MC seals. Before the rebuild, ineffective lever travel was around 2/3.
I'm told that accumulation on the caliper pistons can cause this. I can't for the life of me figure how that could be. Being an engineer, I need to know the failure mechanism. It seems that if the pistons were dirty, the pads would not retract, causing drag, but I can't see how that would account for the ineffective brake lever travel.
Last unrelated repair operation, the tech at the dealer did something I did not get charged for, that made the brake operation almost immediate in lever travel, but I did not get charged, nor did it get put on the invoice. I did seem to get quite a bit of brake drag in that state, until the lever travel worked its way back down a bit, over a few hundred miles.
I need a mental model of the failure mode, and its correction. Can anybody help?
Enjoy,
Rich P
I'm told that accumulation on the caliper pistons can cause this. I can't for the life of me figure how that could be. Being an engineer, I need to know the failure mechanism. It seems that if the pistons were dirty, the pads would not retract, causing drag, but I can't see how that would account for the ineffective brake lever travel.
Last unrelated repair operation, the tech at the dealer did something I did not get charged for, that made the brake operation almost immediate in lever travel, but I did not get charged, nor did it get put on the invoice. I did seem to get quite a bit of brake drag in that state, until the lever travel worked its way back down a bit, over a few hundred miles.
I need a mental model of the failure mode, and its correction. Can anybody help?
Enjoy,
Rich P