2008 XT disk brake adjustment

[Weight Weenie]

Hey guys

 

Im struggling a bit with my rotors rubbing, so need some help adjusting them.

 

Problem is the pistons seem to not be retracting fully and thus there is not much space for the rotor to move about in.  Ive removed the brake pads and reset the pistons but as soon as I put the wheel back in and pull the brakes the pistons seem to 'self adjust' and go closer to the rotor so the problem is back.

 

Whats the remedy for this? Maybe some fluid needs to be removed from the reservoirs?

 

Thanks,

WW.

[Daniel XTR]

I had similar issues. Try to "flush" the brake out. By this i mean spray some cleaner benhind the pads, the pistons may be sticking and not fully retracting, if that makes sense.

 

Or else, i am Sure, JB will have the answer in a sec.

 

Oh and, i feel your pain, its the most irritiating thing.

 

PS: why do you even need brakes, you are WW

 

 

[trailrider]

Hey WW,

The first thing to do is to ensure that your calipers are properly centred on your rotors. The way to do it is to loosen the calipers from the frame/fork and then pull the respective brake lever hard. Keep pressure on the lever and tighten the caliper again without moving the position of the caliper in relation to the rotor. It helps if you have a third hand.

Hope it helps.

[Wernervdmerwe]

Yeah, also, fold a business card over the rotor before you put the caliper over it, then do the pulling-the-brake then fasten trick. I also have 2008 XT brakes, that works like a charm for me.

[Weight Weenie]

Yep trail have wanted to try that but its not a misalignment issue, there isn't really any space between the rotor and pad/piston on any side as they are not fully retracting, which if I was to believe the Servo Wave BS from shimano they are supposed to be doing exactly to stop the cause of my problems.

 

 

[trailrider]

The business card trick is a great idea, I used to slip a feeler gauge on either side if necessary. For that you need four hands though. Thanks Werner, business card it will be.

[trailrider]

I once had a recalcitrant (big word) piston up front on my LX's. I carefully pulled the lever to expose as much of the piston as I could which I then blasted with a citrus degreaser as it seemed as if just about microscopic bits of gunk had accumulated on the pistons. I then centred the calipers with feeler gauges, business card from now, to give a bit of space initially. That sorted my problem.

 

[Dirtbreath]

Take your time when tightening the bolts as well. This tightening can twist the caliper enough to mess up your setup. ALternate little by little. Drop a bit of mineral oil on the piston to help it rettract.

[Johan Bornman]

Get your expections right first.

Remember, disc brakes have no mechanism to retract the piston/s after applying pressure to the brake. So there is no setting you can fiddle with. The little bit they do retract is from the bit of elasticity in the system - fluid, seals and the like. It just so happens that these factors play in your favour a little bit. It is not by design.

 

The discs have to be absolutely true, otherwise you'll get a touch at the high spot once per cycle, like a front derailer touching the chain as you pedal. Fix any run-out before bothering with re-centrering the brakes.

 

Other than that, it is a matter of re-centering the caliper as described above and perhaps more effectively, learning to live with discs. They're a bit like cats - an acquired taste. You learn to put up with the allergies, fur balls and aloofness.

 

 

 

 

[Weight Weenie]

Haha thanks Johan, they have some problems but they still are the cats miaow

[MAMBABAAS]

Hi there

Unscrew your reach screws on your brake levers, then try to press your pistons out. If that doesn't work, unscrew your bleeding nipple half a turn and press your pistons out and screw bleeding nipple back again. This works excellent on most discbrakes.

 

Hope you manage!

Cheers!!

[Weight Weenie]

Thanks will try and let you know