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Facing Misaligned Brake Tab

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Facing Misaligned Brake Tab

Old 02-01-18, 01:00 PM
  #1  
RocThrower
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Facing Misaligned Brake Tab

I completed a brand new bike build, but when I try centering the front caliper, it and the brake pads sit at an angle to the rotor, instead of parallel. This makes alignment nearly impossible, and introduces rotor flex when applying the brake (Shimano hydros). When I remove the caliper and adapter, it appears that the IS mount is sitting at a slight angle to the rotor. I have ensured that the wheel is fully seated in the dropout, and the rotor is true and flush with the hub. I know that facing helps ensure the caliper sits square to the rotor, but would that be enough to correct this issue? I'm also concerned that the outside of the tab would still sit at an angle, and could possibly put stress on the adapter mounting bolt.

It was hard to get a picture of this, but this is the best I could capture:


I do have an email out the manufacturer about this, and will wait to hear from them before I do any facing. I just want to see what the experts here have to say. Thanks!
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Old 02-01-18, 02:10 PM
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fietsbob
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NB;There is a shop tool set, for that grinding-facing https://www.parktool.com/product/dis...ing-set-dt-5-2


Bene Sugg: go thru a bike shop rather than skip over them .. for better service.

IDK where you got the bike in question.


Disc Brake 101, loosen the mounting bolts grab the brake, hold it on while you re tighten those bolts





....

Last edited by fietsbob; 02-02-18 at 01:36 PM.
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Old 02-01-18, 04:13 PM
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So are you saying facing it would fix the issue? Surprisingly, out of the last 4 shops I called this afternoon, none of them offer this service, and only one of them even knew what I was talking about. I should have access to an IS tab facing tool next week, but I just wasn't sure if these were too far out of alignment or not.
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Old 02-01-18, 07:03 PM
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Has that brake tab been properly welded on?


Screen Shot 2018-02-02 at 11.58.18 am.png

Last edited by cobba; 02-01-18 at 07:07 PM.
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Old 02-01-18, 08:00 PM
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That seems pretty bad for IS tabs, not sure many would want to take off that much material with a disc tab facer.

For what's it's worth any Avid brake would probably work with no modification of the tabs. They have hardware to allow the calipers/mounts to align to the disc regardless of the frame or fork tab alignment.

I'd probably try and get that thing replaced/warrantied though.
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Old 02-02-18, 02:15 AM
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Looks like that's pretty far off. Facing that one would need to remove more material than I'd personally be comfortable with.

how's the rest of the fork, are the legs bent or twisted to be contributing to that?

and most shops don't know about brake mount facing because it's an expensive specialized toolset, and nowadays when things go wrong the reaction is to warranty replace stuff instead of fix it... no more skilled labor
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Old 02-02-18, 03:10 AM
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Originally Posted by xenologer View Post
and most shops don't know about brake mount facing because it's an expensive specialized toolset, and nowadays when things go wrong the reaction is to warranty replace stuff instead of fix it... no more skilled labor
A decent shop should know about it, but why do it? for an issue like this, it's poor/defective manufacturing, and is a warranty issue for the manufacture, their problem, not the shops.

For anything, if it has a warranty, why wouldn't you use it????, fixing items is for after the warranty expires, not if the item has one.
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Old 02-02-18, 06:17 AM
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Originally Posted by jimc101 View Post
For anything, if it has a warranty, why wouldn't you use it????, fixing items is for after the warranty expires, not if the item has one.
This is going off on a tangent... but 'for anything'

time and convenience
last month I had some electronics fail due to dry solder joints (manufacturing defect)
definitely warrantyable, but instead I just resoldered by hand
10mins to fix instead of waiting a week sending back and getting a replacement.
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Old 02-02-18, 07:16 AM
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As someone who has used the facing tool for disc brakes, you would be inviting trouble trying to face that parallel with the disc. Simply too much material needs to be removed, and while it could be done, it wouldn't fix the other side (whose screw head is now cocked at a severe angle, stressing further an already stressed screw).

IF you were to get it faced, it would need to be roughly shaped with a file on both sides, first. That said, an incomplete weld+brake tab is a recipe for disaster. Get a replacement.
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Old 02-02-18, 08:01 AM
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Thanks for all the replies. The rest of the fork looks fine, and the dropouts are aligned. I think the problem is the tab isn't set properly. This does have me concerned and I appreciate the feedback/confirmation. I'm in talks with the manufacturer and shop about getting this replaced. It was purchased new and is still under warranty.

Last edited by RocThrower; 02-02-18 at 08:47 AM.
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Old 02-02-18, 09:25 AM
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Post more photos showing the welds in that brake tab.
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Old 02-02-18, 12:52 PM
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Originally Posted by cobba View Post
Post more photos showing the welds in that brake tab.
I had time to snap a few over lunch, but didn't get any from the other side. I put the adapter on last night, and it doesn't look as drastic of an angle to the rotor.









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Old 02-02-18, 01:41 PM
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Originally Posted by RocThrower View Post
So are you saying facing it would fix the issue? Surprisingly, out of the last 4 shops I called this afternoon, none of them offer this service, and only one of them even knew what I was talking about. I should have access to an IS tab facing tool next week, but I just wasn't sure if these were too far out of alignment or not.

I'm just a stranger on a forum, dealing with some pictures from your phone..

You get better answers, by presenting it in person to an actual bicycle shop.


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Old 02-02-18, 01:44 PM
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Originally Posted by xenologer View Post
This is going off on a tangent... but 'for anything'

time and convenience
last month I had some electronics fail due to dry solder joints (manufacturing defect)
definitely warrantyable, but instead I just resoldered by hand
10mins to fix instead of waiting a week sending back and getting a replacement.
And you voided the warranty for the product, there is a reason to use a warranty if available, rather than do the work yourself (and this applies to bikes as well), once you have taken it apart, you the manufacture doesn't know what was wrong from the factory, and what damage you caused, so has good cause to reject any future claim.
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Old 02-02-18, 04:32 PM
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If you get the inside faces aligned you can (and perhaps should) use spherical washers (as on the posts for v-brake pads) on the outside to keep the bolt heads from sitting at an angle.
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Old 02-02-18, 05:02 PM
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I suspect Avid's post mount ears are assuming v brake washer pairs are used on both aides .. they are abundant in My LBS

Every pad replacement has more with the new ones..
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Old 02-02-18, 09:48 PM
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Originally Posted by jimc101 View Post
And you voided the warranty for the product, there is a reason to use a warranty if available, rather than do the work yourself (and this applies to bikes as well), once you have taken it apart, you the manufacture doesn't know what was wrong from the factory, and what damage you caused, so has good cause to reject any future claim.

I'm not concerned
because I have more confidence in my own repair than simply receiving another copy with the same defect.
Same goes for my bikes. Though admittedly I get an extra safety net there: I work in an LBS, so the first stage of any warranty goes through me anyway. Warranty Repair, is the first step to consider before Warranty Replace.
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