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brake repair

artemery

New member
When checking the front brake pads on my K1300S,(48000KM) I found one of the four pads was worn down much more than the others.The wear indicator slots were down a bit on three of them, but non existant on the left outer pad. I was told this was caused by a build-up of brake dust and the piston was not returning properly. Could this be cleaned when the pads are removed without having to do a caliper rebuild ?
 
I would sure give it a go. But before I pulled the pads out, I would try to press the subject pad back into the caliper. If it doesn't go, I would remove the pads and clean things up really well and retest. If it does not go back in after cleaning the outside well, I would flush the lines properly and retest. If that does not solve it, there are other searches you can do for information on rebuilding the caliper.
 
Just finished brake pad replacement this morn. The right pistons would retreat with finger pressure. The left , not so easy. I left the master cylinder intact and used a 'C' clamp to push the pistons back. As one went in, the pressure would force another one to project. I then cleaned using brake cleaner and a toothbrush and coated with synthetic brake lube. By using a wood wedge ,I was able to force each one individually. In order to push them all back-in I removed the master cylinder cap. wraped it and finger pushed them all in. This caused some overflow brake fluid and had I not anticipated this, it would have caused a big mess. The service manual indicates the removal of the master cylinder foam ( the recall thing) and using a BMW tool that forces all the pistons back at the same time. But by doing it this way you do not have the opportunity to clean and lube the pistons.
 
Just finished brake pad replacement this morn. The right pistons would retreat with finger pressure. The left , not so easy. I left the master cylinder intact and used a 'C' clamp to push the pistons back. As one went in, the pressure would force another one to project. I then cleaned using brake cleaner and a toothbrush and coated with synthetic brake lube. By using a wood wedge ,I was able to force each one individually. In order to push them all back-in I removed the master cylinder cap. wraped it and finger pushed them all in. This caused some overflow brake fluid and had I not anticipated this, it would have caused a big mess. The service manual indicates the removal of the master cylinder foam ( the recall thing) and using a BMW tool that forces all the pistons back at the same time. But by doing it this way you do not have the opportunity to clean and lube the pistons.
It is quite likely you have solved the problem. Anything between the caliper piston bore and the disc could possibly impair retraction of a brake pad and produce asymetrical wear. Remember, there is no "active" force pushing the pad away from the disc. Therefore, you cannot actually "see" whether your work was successful until sufficient time/miles shows wear to be even or uneven. After a few hundred miles of riding and braking (to allow the new pads to "bed in" a bit), raise the front wheel and give it a spin. If you feel undue drag such that the wheel will not turn freely, there may still be a problem with the caliper. Let us know!
 
When checking the front brake pads on my K1300S,(48000KM) I found one of the four pads was worn down much more than the others.The wear indicator slots were down a bit on three of them, but non existant on the left outer pad.

I had this exact same problem on my K13S; discovered it at the 12k mile service when I was changing the brake fluid. I cleaned everything up, pushed all the pistons in (didn't seem like any one of them was harder to push in), and replaced the pads with some Carbone Lorraines from Beemer Boneyard. That was 6,000 miles ago. I got a very good look at the front pads when I took the calipers off to remove the front wheel for a tire change last week. They all look worn identically now.

I'm guessing it doesn't take much to cause a piston to stick slightly and not retract the same as its opposing mate. So you should be OK after cleaning and lubing as you described. :thumb

Rod
 
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