Rear caliper slide pin boots(burp them)

[Acpantera]

I know it sounds silly, but when I put on another set of rear pads (left pad shot, right pad still 40%) I noticed that the slide pin boots act like air springs that keeps the left pad pushed tight on the rotor. So after lubing the pins and resealing the boots I burped the air from the boots so that minimal preasure is on the left pad. After several hundred miles I have noticed very little brake dust on the wheel(thats always been a gripe of mine with this bike) and the brake lever feel is much improved...more solid at the first application. Try it

[ka5ysy]

Photos?

[bobw]

It's not uncommon to have one side wear a bit faster, but it's interesting that you have no more dusting and a firmer pedal from this simple procedure. You used OEM pads? I will give mine a burp and see how she responds. Thanks for the tip.

Cheers

Bob

[deilenberger]

I'll certainly give it a try - one thing though - the LEFT PAD starts life THINNER than the RIGHT PAD. It's that way right out of the box - which is why the left one wears out first. If you measure the difference I suspect you'll find like I did - the wear was even.. the remaining pad material on the right (outside) pad was equal to the additional thickness of it when new.

[Acpantera]

I used carbone metalic from the beemer boneyard, and the differance from left to right when new was not noticable but after 9k miles the inner pad was half the outer pad. Same wear was noted from the oem pads except I replaed those at 7k miles. This set of pads are DP but I have a feeling that the air preasure pushing on the caliper has caused excess wear and heat wich caused a slightly spongy handle after some miles. Burb the boots ,clean your wheel and observe.

[bobw]

Thanks for the additional parts info.

Cheers

Bob

[deilenberger]

I used carbone metalic from the beemer boneyard, and the differance from left to right when new was not noticable

Actually - it's very noticeable on brand new Carbone Leone pads - lay them down on a flat surface side by side. The inside pad is at least 2mm, mebbe 3mm thinner than the outer pad. I have a brand new set in the garage.

but after 9k miles the inner pad was half the outer pad.

When I replaced my factory pads - the new factory ones also exhibited the same difference in thickness, and the ones I took off - with the worn out inside pad - exhibited the same thickness difference. Those pads are sitting in the garage (Dog knows why..) right next to the new Carbone Leone pads. If you want pics - I can provide them..

Same wear was noted from the oem pads except I replaed those at 7k miles. This set of pads are DP but I have a feeling that the air preasure pushing on the caliper has caused excess wear and heat wich caused a slightly spongy handle after some miles. Burb the boots ,clean your wheel and observe.

I don't understand what's generating the air pressure in the bellows. Once compressed it doesn't seem as if they'll build up air pressure, and I can't imagine they seal well enough to retain it for very long, at least not enough to cause excess wear or dusting. (I'm asking why?)

{If you're wondering why I have all these pads laying around - I bought the BeemerBoneyard ones, installed them, didn't like what the rotor looked like after a few hundred miles, and decided to put in new factory pads so BMW wouldn't have an excuse to not warranty my rotor if it gave me problems. It hasn't - and it appears to not be wearing quite as fast with the factory pads, but that could be my imagination.. I'm saving the Carbone ones for when I'm out of warranty..}

[Acpantera]

Well let me say that I did not measure the worn pads but I can tell you that it was WAY more than 2mm. The air preasure isn't "generated" it's trapped when you reassemble the slide pins/boot. When have the caliper off and compress the caliper frame to the caliper the air trapped in the boots(it's a hellava seal) pushes the frame and caliper away from each other, that would mean that the left pad always has some residual force pressing it twards the rotor causing undo wear,friction and heat. I'm just stating an observation.