[kenwood72]

OK so I was buying a new bike and thought I will try something new and go with the new XTR kit. I was even on here defending the XTR brakes and i think i was trying hard to convince myself I had not made a huge error.

So yesterday I am going do the trail and front brake has almost zero power, i can grab the brake 100% and push the front wheel and it will move. I am coming off about 2 months off the bike due to a knee surgery and sadly this isnt the first time i have had similar issues with Shimano. Last time though the shop blamed me but whatever....

anyhow any else in the same boat, are the caliper leaking fluid?? This is ridiculous, and to top it off I decided to go down the fire road back and kind of heat the brake up, at the bottom i had more power so it makes me think there is an issue with the caliper. I had also ridden the bike earlier that week and it did the same thing but not to the same degree.

I have 2 bikes one all SRAM and on all XTR, i can honeslty say that everything about eagle and SRAM is better. I may not like how the CODEs feel in the parking lot but that disappears on the trail.

 

[compengr]

Pretty much every set of Shimano brakes I've ever used has done this. They work great if you use them regularly, but if allowed to sit for a while (usually over winter) they act as if they have been contaminated.

I heat up the pads to burn off contaminants, give them a quick sand and they are good as new. Until next time....

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[Dagonger]

Have never had an issue with Shimano brakes. 7 sets, currently on XT 4pot and Xtr m9020 trails.. just typical bleeds, and cleaning of pistons..

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[rideit]

Absolutely loving my new 4pot XTR, flawless with around 100,000 ft of descending so far.
Keep tinkering.

 

[Cleared2land]

So yesterday I am going do the trail and front brake has almost zero power, i can grab the brake 100% and push the front wheel and it will move.

whatever.... anyhow any else in the same boat, are the caliper leaking fluid?? This is ridiculous, and to top it off...

Leaking brake piston/puck seal? Prolly not... I'm thinking that you need to answer this question yourself.

Let's clarify some of your issues first. You pull the lever and almost zero power. Did you feel like this was an issue with the brake pads (firm brake lever, but reduced stopping power) or the function of the master cylinder or perhaps some air in the system that created a mushy brake lever or, you could pull the brake lever much closer to the handle bar?

 

[huckleberry hound]

How are you storing the bike when not in use?

 

[kenwood72]

funny how the responses are so different from yes all of them do it to it cant be right! I know it isnt a bleed as it has power at the lever, pads are just not grabbing. Bikes are stored in a rack standing upright. I do believe this is a known issue and it happened with a pair of saints before, i had two bikes and two sets of saints and one of them did this, same maintenance and such. Anyhow I was hoping shimano has fixed this, rode my SRAM brakes yesterday and came out of the garage with full power. I will take out the pads tonight and see if I can burn off whatever the cause is.

 

[fmendes]

funny how the responses are so different from yes all of them do it to it cant be right! I know it isnt a bleed as it has power at the lever, pads are just not grabbing. Bikes are stored in a rack standing upright. I do believe this is a known issue and it happened with a pair of saints before, i had two bikes and two sets of saints and one of them did this, same maintenance and such. Anyhow I was hoping shimano has fixed this, rode my SRAM brakes yesterday and came out of the garage with full power. I will take out the pads tonight and see if I can burn off whatever the cause is.

You may want to look closer, as this is not common, although happened to you twice. I've been running Shimano brakes forever (I think it's the only brand I ever used), and never had such problem.

You can try to use softer material (wood, plastic, etc) to verify the force of the bite. You should have a pretty good mark from the pads on soft material.

If the bite is good, then I'd check the pads themselves. Put them on the oven, clean the rotors and try again. If this improves but does not solve, get new pads. And clean the rotor before installing them.

 

[Cleared2land]

If you elect to cook'em, I would clean the rotors and start over in bedding the pads in as if they were a new set of pads.

 

[Schulze]

I have a similar issue - it's just so easy to contaminate pads and then they either squeal or don't grip the rotor. I have two bags of J02 and G02 in my brake box and a jar of acetone - yeah I spent like $120 on pads one time. One bag is cleaned, other bag is contaminated. If I catch a whiff of my pads doing this, I swap them out with a fresh set, rub the rotor with alcohol, and go ride. It seems once you bed a new set, you can clean them in acetone and put them back on and there's no more bedding process. After I build up a few sets of contaminated pads, I'll put them in the acetone. Take them out, rub them together, dip back in until no more black stuff falls off. Then into the clean bag of pads for next time. Haven't had to bake yet.

 

[kenwood72]

You may want to look closer, as this is not common, although happened to you twice. I've been running Shimano brakes forever (I think it's the only brand I ever used), and never had such problem.

You can try to use softer material (wood, plastic, etc) to verify the force of the bite. You should have a pretty good mark from the pads on soft material.

If the bite is good, then I'd check the pads themselves. Put them on the oven, clean the rotors and try again. If this improves but does not solve, get new pads. And clean the rotor before installing them.

it is common i believe that but bottom line is that it is easy to fix. my daughter is in pastry school so ironically i realized last night we had a small blow torch in the kitchen. heated up the pads with the torch, lightly on the rotors and used some rubbing alcohol then hit the pads with sand paper and holy crap stupid power. easy enough to do but i do believe there is a problem with the brakes

 

[lemke]

I think your caliper piston seals have hardened up. And I still think you should bleed the brakes. A little lube around the piston seals (mineral oil) at the caliper might bring them back to life. You don't need syringes to bleed the brakes, just the fluid cup for the lever. Set the bike up at about a 45 degree angle (front wheel up), disconnect the calipers, remove the pads, insert your bleed blocks, and open up the bleed port. Watch the fluid level in the cup, and reinstall the bleed screws when you don't see any more bubbles. Flick the lever a few times, and lightly tap the M/C and lines to get any more bubbles up and out. Remove the fluid cup, install the MC screw, remove the bleed blocks, clean the calipers, reinstall your pads, clean the rotor, reinstall your calipers, and go ride.

 

[Miker J]

I've had a similar issue with Shimi brakes after a long sit. Pads went bad. Like they got contaminated.

 

[bigdrunk]

Nice! I am going to give acetone a try.

Also, my 9120's are behaving great so far (metal pads).

I have a similar issue - it's just so easy to contaminate pads and then they either squeal or don't grip the rotor. I have two bags of J02 and G02 in my brake box and a jar of acetone - yeah I spent like $120 on pads one time. One bag is cleaned, other bag is contaminated. If I catch a whiff of my pads doing this, I swap them out with a fresh set, rub the rotor with alcohol, and go ride. It seems once you bed a new set, you can clean them in acetone and put them back on and there's no more bedding process. After I build up a few sets of contaminated pads, I'll put them in the acetone. Take them out, rub them together, dip back in until no more black stuff falls off. Then into the clean bag of pads for next time. Haven't had to bake yet.

 

[lemke]

Shimano calipers are notorious for leaking... just bleed your brakes.