Fixing Magura lazy pistons

From TrialsWiki

[b]Lazy Piston Definition[/b]: When one pad wont come as far back as the other, and usually rubs on the rim.

In most cases, lazy pistons happen because there is too must adjustment on the tpa. The tpa is the red dial on the leaver, as brake pads wear down the TPA needs to be wound in so that the leaver maintains the same bit point. However by doing this the tpa forces the pistons with the pads attached towards the rim, too much adjustment on the tpa will cause one pad to predominantly stick out, this can cause lots of alignment problems and may drag on the rim.

To stop this from happening you simply unwind the tpa so both brake pads retract fully. Then you need to unbolt the mounts that holds the brakes down and physically move the pads closer to the rim, then bolt them back down. You may need to give the tpa a couple of twists but now you should have a brake with a good bite point and no lazy pistons.

If you still have a problem, either with a lazy piston, or the leaver pulls too far down. You need to undo the clamps and move them ever closer to the rim, remembering to unwind the tpa right off befor setting the brake up again.

If you're still having problems follow the guide below.

[b]Tools required:[/b]

• A track pump - [url=]example[/url]
• 5mm allen key
• 3mm allen key
• 8mm Spanner
• 5mm/4mm allen key - Depending on mount bolts
• Bleed kit - especially the hosing and hose connector!
• Oil
• Mole grips/pliers.
• WD40/GT85

[b]Method:[/b]

1. Take the Magura off the bike. I'm sure you know how, take off bar-end, grip, slide off lever. Undo mounts, and cut off any cable ties or anything holding the hosing on your frame.

2. Take it apart. [i]Please note: Be sure you're confident with bleeding it once you're done![/i]

Undo the bleed bolts, and then the hosing.

[i]Make sure you don't make a mess with all the oil/water going everywhere![/i]

3. Now all that's off, you'll have the two pistons/slave cylinders on their own.

[img][/img]

4. Take one, and attach the bleed kit hose to it. And the other end of that hose, you attach to your pump. - As you would a shraeder (car type) valve.

[img][/img]

And pump the pump. This should blast out any crap in the piston. It's handy to get the mole grips and clamp the nipple, then turn it so it's against the prongs of the slave cylinder. - This will pull the piston out a bit.

[img][/img]

Also spray some WD40 all over it, in the hose holes, and on the piston. Even fill up the clear bleed kit hose with WD40, and pump it through. Do this like a mad man untill you're happy with it. Then do the same to the other one.

5. Now that's the slave cylinders sorted. Might aswell clean out the lever. Take it all apart. - Undo the lever bolt, and out it all comes.

[img][/img]

You can kinda see it, but there is a lot of oil and general crap around the bolt hole. Just rinse it with water, and scrub it all off.

6. Don't be thinking that's it with the lever! Remember what you just did to the slave cylinders? Do the same to this. Fill it up with oil through the bleed bolt hole, and pump it a bit. This will lube it all up. Then attach the hose and pump to it, and pump away! Once you're happy with that, put it back together.

7. Now you've got all that clean, you need to bleed it and refit to the bike.