[Zark]

My coworker has these brakes and is complaining of some pump up in the system. The lever engages farther from the bar as it heats up. I thought Magura went to an open system for all their brakes for '02, which it would seem wouldn't have that problem. Also he squeezed the lever with the wheel out Not smart I know. Magura's manual said spread the pads apart and thats it. Don't you have to bleed the brake after that happens?

 

[sub6]

I can't speak for the open/closed system thing, because I don't use or follow Maggie stuff.

But I can speak for the pad thing - WHY is that not a good thing? All you do is push the pads back! That's the whole point of self-adjustment. (Although if it's self-adjusting, it should be an open system.)

[Rant]
You don't have to bleed them after you do that! Bleeding is for when you get air in the lines. Nothing else. Everybody always thinks bleeding brakes is a cure-all for every possible problem, but in reality it's not. I couldn't count the number of times I've seen somebody on the DH/FR board on MTBR say "my hayes are weak, they feel fine but have no power" and some dumbass chimes in with "have u bled them yet? U should bleed them". Everybody needs to get a grip. You bleed your brakes when you get air in the lines. End of story. [/Rant]

Sorry, bro. That wasn't so much directed at you, as much as the general brake-bleeding public. This seemed like a good place to put it.

Anyway, fear not! You don't have to bleed them. Just push the pads all the way back, and pump the lever a few times to get 'em back into place.

One thing - my buddy used a flathead screwdriver to do that, which is fine, except that it had grease on it, and he ruined his pads. Use a clean screwdriver!

 

[Zark]

Claras are an open system. Since they are pumping up they do need to be rebled. I'll have Peter swing his bike by the shop Randolph. As for sub6, when many hydros are squeezed at the lever sufficiently without a rotor in place to stop them some systems DO need to be rebled because it can introduce air into your lines. I've seen this happen with Hayes, its not urban myth, its common knowledge. Also brake fluid DOES break down and needs to be changed periodically, not just when you get air in your lines. You'll see huge clods of black gunk in Hayes fluid after a year or so. Water collects in DOT fluid over time, even in a "sealed" system. Sorry to rant too, but I didn't feel that was the whole story.

 

[sub6]

Yeah, I thought about the issue of cooking your brake fluid or water contamination when I posted that, but that has more to do with replacing all the fluid than with just bleeding/getting air bubbles out, so I didn't throw that in there. (I've always considered bleeding to be reserved for air bubbles and nothing else, perhaps I've been misconstruing it all this time.)

I have never heard of air getting into lines that way (squeezing lever with no rotor), but if you say it can happen, I'll accept that.

It just makes no sense to me how it would do that, unless you had air in your reservoir or something? I mean, ideally, there isn't any air anywhere in a brake system, right? So unless overextending the pistons allows air to get into the lines down at the caliper, you shouldn't have that problem. Is that what happens?

I've got XTs and Grimeca Sys.8s, and they've never needed to be bled after pushing the pistons back when installing new pads or having the lever squeezed w/ no wheel.

And I still think people bleed their brakes too much!

 

[Zark]

Yeah Sub6, you got it. Overextending the pistons can allow air to enter the system. I know this to be true for Hayes and I think it can happen in some other systems. Yeah some people do bleed their brakes too much. I guess I generalized rebleeding with fluid replacement in my post, those are kinda distinct. Any time you open the system, you bleed the system. I didn't think about the reasons why (fluid replacement, or purging bubbles). Pad wear doesn't extend the pistons far enough to intoduce air (man that would suck!)