Disc rotor fouling brake post mount....

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Rolf F
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Disc rotor fouling brake post mount....

Postby Rolf F » Wed Dec 26, 2012 11:27 am

Hello folks

Building up a new frame (Orange Crush - parts swap from a P7). On fitting the rear wheel (Deore hub), I found that the brake disc (Shimano XT) fouls the post mount - not a lot but even not a lot isn't right!

This seems to mean that I need a deeper retaining nut for the cones on the non drive side (and vice versa) or an extra washer and a tighter fit for the wheel in the dropouts. This seems a bit odd though - I'd assume that the placement of the post mounts would always allow clearance for the discs as these are surely fixed standards. Is this just something that occasionally happens (and if so, how is it normally dealt with?) or is it a frame problem. I can't see that it is a problem with the wheel. The P7 used an adaptor on the rear and it worked perfectly well.

Advice appreciated!
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The Rookie
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Re: Disc rotor fouling brake post mount....

Postby The Rookie » Wed Dec 26, 2012 16:36 pm

First measure where the wheel rim sits between seat and chain stays, if it's in the middle as I expect then it sounds like you need to look for a thinner PM mount, some can be a bit fat!

Dirtydog11
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Re: Disc rotor fouling brake post mount....

Postby Dirtydog11 » Wed Dec 26, 2012 19:26 pm

It may have been serviced and put back together incorrectly, Id have a look at the exploded view on the Shimano site and check washers/spacers against yours.


iirc the spacers/washers are drive side and non drive side specific (different thickness to each other) and may have been fitted the wrong way around, I can vaguely remember having a similar issue.

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stubs
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Re: Disc rotor fouling brake post mount....

Postby stubs » Wed Dec 26, 2012 21:03 pm

If they are the new Shimano discs with the steel rotor riveted to an aluminium spider they can catch post mounts. Both the post mounts front and rear on my Canyon have lost the paint, the clearance is minimal and the rivets catch slightly when cornering. Clearances are tight with the post mount standard but I would check with Orange the tolerances might be out.
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BigStu2
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Re: Disc rotor fouling brake post mount....

Postby BigStu2 » Thu Dec 27, 2012 20:45 pm

I had a similar problem with my Avids, I just used a thicker cone washer fom a set of V brakes to space the caliper further out.
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The Rookie
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Re: Disc rotor fouling brake post mount....

Postby The Rookie » Thu Dec 27, 2012 22:40 pm

Erm....it's fouling the adaptor, moving the caliper aint't goint to do much!

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stubs
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Re: Disc rotor fouling brake post mount....

Postby stubs » Thu Dec 27, 2012 23:02 pm

The Beginner wrote:Erm....it's fouling the adaptor, moving the caliper aint't goint to do much!


If its a post mount frame and an XT caliper there wont be an adaptor will there.
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The Rookie
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Re: Disc rotor fouling brake post mount....

Postby The Rookie » Fri Dec 28, 2012 20:33 pm

stubs wrote:If its a post mount frame

It's an Orange crush, check the Orange website, all are IS mount.....

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stubs
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Re: Disc rotor fouling brake post mount....

Postby stubs » Fri Dec 28, 2012 21:42 pm

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stubs
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Re: Disc rotor fouling brake post mount....

Postby stubs » Fri Dec 28, 2012 23:06 pm

He says its a new frame and thats a 2 year old frame you have linked to.
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The Rookie
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Re: Disc rotor fouling brake post mount....

Postby The Rookie » Sat Dec 29, 2012 08:11 am

Indeed, until he comes back, we won't know, the orange website doesn't show that frame and the photo of the 2012 is inconclusive.

Chunkers1980
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Re: Disc rotor fouling brake post mount....

Postby Chunkers1980 » Sat Dec 29, 2012 12:27 pm

Pretty sure the op say rear brake and fouling the post mount.

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stubs
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Re: Disc rotor fouling brake post mount....

Postby stubs » Sat Dec 29, 2012 13:51 pm

The photo I posted is the 2013 Orange Crush frame it has post mounts as did the 2012 frame. The 2011 frame has IS mounts till we know what the OP has we are just going round in circles.
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Rolf F
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Re: Disc rotor fouling brake post mount....

Postby Rolf F » Sat Dec 29, 2012 19:38 pm

Apologies - I think I got my terms confused - I thought they were post mounts because they look like posts. I should know better given other confusing terms like clipless pedals etc..... :oops:

And just to make sure I don't get them wrong again, rather than say what it isn't, I will say that the frame is as per the pic Stubs posted. I can post a pic of the actual frame when I get back to it in a couple of days but it probably isn't needed. On the pic, it is the upper of the two mounts which the disc rubs on.

The caliper is the sort with the separate spider.

I promise to try to go back to the Road Forums where I'm hopefully less of a liability when I've got this bike back on the road :lol:
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stubs
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Re: Disc rotor fouling brake post mount....

Postby stubs » Sat Dec 29, 2012 19:46 pm

Hi Rolf it can be confusing the pic here shows the 2 standards. It shows fork legs but frames are the same
Image

Post a pic of your bike showing the damage then we might be able to shed some light on the problem.
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Rolf F
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Re: Disc rotor fouling brake post mount....

Postby Rolf F » Sat Dec 29, 2012 20:05 pm

Keeping it tech...... it's the one on the right! :lol:

Tuesday hopefully for a pic but at the moment it might not show much - it's only scraped a sliver of paint off as I've only had the wheel briefly mounted with the frame on the stand. I could probably let it finish scraping the paint off but even then I'd worry at what might happen if the disc developed a slight warp. The clearance just seems stupidly non existent.
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Rolf F
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Re: Disc rotor fouling brake post mount....

Postby Rolf F » Sun Dec 30, 2012 18:07 pm

A couple of pics. You can see in the first a sort of step in the metal of the post which, if it wasn't there, would give a bit more clearance. The second shows more clearly how tight it is there. I think I need to ring Orange again....

Image

Image[list=][/list]
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stubs
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Re: Disc rotor fouling brake post mount....

Postby stubs » Sun Dec 30, 2012 19:58 pm

That is very tight clearance. Have you got access to another disc brake wheel to try and see if it is the wheel.
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allthegearnoidea
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Re: Disc rotor fouling brake post mount....

Postby allthegearnoidea » Sun Dec 30, 2012 20:55 pm

i'd certainly go for trying another disc as it looks like the disc spider is moving the over tight to the mount, i'd pop a 'normal disc' on there and check with that.
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