XTR 985 Brake Problems

Discuss light weight issues concerning mountain bikes & parts.

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Sworksxtc
Posts: 86
Joined: Mon Jun 25, 2007 12:31 am
Location: Calgary, Alberta, Canada

by Sworksxtc

Dudes,

Can any one send me a link for a video on how to bleed these brakes. Every time I get it done the brakes squeal really bad and they rotors glaze over and I am pretty tired of it.

Also do you bleed the brakes with the big blocks in the calliper ? I find if I do I end up with no power once I squeeze them after I take the blocks out and have the pads in. The lever goes or almost to the bar.


too add to all this, I brought the bike to mexico and I might have to use motorex mineral oil.... will it work with shimano ? I am tempted to buy a pre bleed deore brake set and rock and roll with that.

Regards,
Thats how I ROLL!

by Weenie


TheRookie
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Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

You must bleed with the blocks in, they will take a while to settle the levers, try advancing the pads (google it) overfilling (bleeding without the blocks) is what is causing the squeal and binding, so STOP IT.
Impoverished weight weenie wanna-be!
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Elrey
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by Elrey

Mineral works for Shimano.
Don't go from XTR to deore. Nono. And yes! Keep the pads in.
You do both suck and press when you bleed, right? Sorry, but Don't know how skilled you are.

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Sworksxtc
Posts: 86
Joined: Mon Jun 25, 2007 12:31 am
Location: Calgary, Alberta, Canada

by Sworksxtc

Oh okay so you do suck and pull! I wasn't doing that. I was just putting the reservoir cut on the lever and filling it with oil then pumping the lever and then opening the nut on the calliper and squirting the oil out into a tube!

So you use a sringe on both ends and push and pull?
Thats how I ROLL!

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Sworksxtc
Posts: 86
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Location: Calgary, Alberta, Canada

by Sworksxtc

I ended up buying new brake pads and new rotors. One of the problems is the brake pads and rotors had oil on them and the mechanic said you can never get rid of that
Thats how I ROLL!

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Elrey
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by Elrey

True. Oil on rotors and they are done.
I used to run Hope Pro Evo, Saint or Avid on my SS 26'er an 29'er.
Avid are easy to bleed and last long.

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Sworksxtc
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Location: Calgary, Alberta, Canada

by Sworksxtc

I might have to try them. I don't really want to be buying new rotors all the time....
Thats how I ROLL!

TheRookie
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Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

Shimano are dead easy to bleed, much easier than avids, just try following instructions instead of going out into left field and inventing your own 'process'. Funnily enough Shimano put a wedge of money into finding the best way to bleed their brakes, ignore it at your peril.

Rotors can be cleaned with IPA no need to renew whoever says bin them is either an idiot or a con artist! I rescue contaminated pads as well, but most don't like the idea!

You have a bleed bottle and drain don't you?
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

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Elrey
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by Elrey

You should visit Denmark. Would like to see how you safe oild up Rotors.
Nice friendly post btw.

TheRookie
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Location: Midlands, United Kingdom

by TheRookie

IPA - iso-propyl alcohol will clean oil off a disc perfectly well, it doesn't soak into steel after all!

It's unfriendly because frankly your being rather daft suggesting buying new brakes rather than trying to bleed what are considered much better brakes than the avids just using the Shimano process, all available in their technical documentation, easy to follow. It's like complaining your tyres are draggy without actually putting any air in them!
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socratease
Posts: 169
Joined: Thu Oct 13, 2011 5:25 pm

by socratease

Sounds like OP just had contaminated pads--an issue already resolved.

I do find that with mineral oil based brakes, it's much easier to contaminate the pads. I always remove the pads on shimano brakes. Adds like, 1 minute to the process, and the only reason I wouldn't do it is stubbornness.

As far as replacing the rotors--typically not necessary, however, if there's a significant amount of discoloration, shimano will tell you to replace them. Really, soaking them in isopropyl and using some scotch-brite will do a very good job of cleaning anything simple contamination would cause.

Bringing back pads: really, I find its a matter of how much they were contaminated in the first place. Soaking in isopropyl, sanding, resoaking, sanding, then braking into them until they are very hot, then flushing with water seems to be the best method. I find power never really gets back to 100 percent with mineral oil based brakes, but I've had good luck with dot contamination.

Last 2 cents: unless you're obsessed down to the last gram (in which case, theres MT8s and formula R1s), xtr brakes are the best on the market in terms of power, modulation, ease of service. I've had 10 times the headache from Sram's brakes than Shmano's. The new style are better, but XX brakes have a very solid history of feeling like crap and requiring constant attention. However, there are some problems you want to watch out for. The main ones I've seen have been the banjo crimp-on leaking, and some of the ceramic pistons not holding a seal (probably imperfection in the way they were cast), and over time weep mineral oil out behind and onto the pads. If your brakes have a tendency of getting contaminated, take the pads out, clean the pistons really well, then check back in a couple of days to see if there is any residual mineral oil. If so, that would be a warranty issue.

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Elrey
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by Elrey

I told him to stay with XTR. Do you read the posts or just write random accusations?
Sorry for OT here.

As I sayd. Stay with your Shimano, should you want to try other brands. The ones I wrote served me well.

TheRookie
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by TheRookie

I succesfully decontaminate pads (even mineral oil) by spoaking in petrol (gasoline) for a day and then baking in the oven on max (250C) for 30minutes, I also roughen the surface with some coarse sand paper to get them to bed back in, it's not for everyone but it works for me.
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1spd
Posts: 175
Joined: Fri Jun 15, 2012 2:27 pm
Location: Gaithersburg, Maryland

by 1spd

Had issues with my front M985 last week. I bled the hell out of it to no avail. I mean it would fork for a few minutes booking up and down the street but then go right back to a horrible squeal and no stopping. As a test, swapped the pads from front to rear and instantly the squealing was on the rear. Ordered new pads from Disco Brakes for $20 and replaced both front and rear. Rebled as per Shimano directions and now work great! Love my M985's but if I had the money when making the original purchase would have gone with Hopes or R1's (got my XTR's new in box from a friend for $300 for the set so I jumped on it and couldn't be happier).
Cannondale Synapse (alu)...it works

Dirk
Posts: 118
Joined: Fri Sep 08, 2006 2:08 pm

by Dirk

First used the gravity method as shimano advises.
Bleed wasn't perfect.
With 2 syringes everything went fine.
Took the pads out and used the yellow block though.

by Weenie


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