Help please (before I get the big file out!)

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Al
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Help please (before I get the big file out!)

Post by Al » Thu May 28, 2020 8:09 am

Hoping someone has an inspired bit of advice before I resort to a big file.

Recently swapped over to some new (to me) forks have been unable to centre the brake over the rotor.
Fork is a prong, calliper is a hope x2 and hub is a Stans 3.30.
You can see in the photo the calliper is at the limit of movement but still way off centre.
Tried a bit of careful filing of the calliper with a jewellers file but daren’t go too far and still way off.
Put in the wheel off my spearfish and that looks ok(will post pic) so it looks like the hub is the issue. Have tried a different rotor on the stans hub - no difference.
So over to the great bb hive-mind; any ideas? Can you face rotor mounts on hub? Is it stupid to try filing them down?
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Al
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Re: Help please (before I get the big file out!)

Post by Al » Thu May 28, 2020 8:10 am

Hope hub from different bike (so not the fork):
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Bearbonesnorm
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Re: Help please (before I get the big file out!)

Post by Bearbonesnorm » Thu May 28, 2020 8:16 am

Is it stupid to try filing them down?
Very. However, getting someone to machine them down wouldn't be an issue :wink:

Given the changing of parts, it would indeed appear that the hub is at fault. If you think you've a bit more room in the caliper slots then extending those further would likely be my first stop. Otherwise it does appear that machining the hub or changing it could be your only course of action Al.
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redefined_cycles
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Re: Help please (before I get the big file out!)

Post by redefined_cycles » Thu May 28, 2020 8:26 am

https://forums.mtbr.com/brake-time/hope ... 28073.html

Looks like a commonly occuring problem. What rotor (splined shimano or standard 6 bolt?)... I'd not shave much more material inside your IS mount. Can you maybe add some washers between the disc and hub to move that out slightly...?

I don't know the exact answer btw...

[Edit: just realised why the washer ideas wouldn't work aftrr looking at the gap/problem again and unddrstand why Stu mentions the lathe... ignore me :smile: ]
Last edited by redefined_cycles on Thu May 28, 2020 8:46 am, edited 1 time in total.

Gummikuh
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Re: Help please (before I get the big file out!)

Post by Gummikuh » Thu May 28, 2020 8:29 am

Could you not simply add a washer between hub and fork?

I had a similar issue with my Genesis longitude and I thought about filing down the adaptor before realising I could add a washer, biggest issue I had was finding a washer to fit as it is an odd size hole.

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Mariner
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Re: Help please (before I get the big file out!)

Post by Mariner » Thu May 28, 2020 8:37 am

Would a larger rotor and mount for the caliper solve it?

Al
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Re: Help please (before I get the big file out!)

Post by Al » Thu May 28, 2020 8:40 am

Bearbonesnorm wrote:
Thu May 28, 2020 8:16 am
Is it stupid to try filing them down?
Very. However, getting someone to machine them down wouldn't be an issue :wink:

Given the changing of parts, it would indeed appear that the hub is at fault. If you think you've a bit more room in the caliper slots then extending those further would likely be my first stop. Otherwise it does appear that machining the hub or changing it could be your only course of action Al.
Wouldn’t you need to take the wheel apart to get it in a lathe? Or have you got something else in mind stu?

Washer is not a bad shout - but like you said finding one The right size is tricky with shops shut at the moment.

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Bearbonesnorm
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Re: Help please (before I get the big file out!)

Post by Bearbonesnorm » Thu May 28, 2020 8:47 am

Wouldn’t you need to take the wheel apart to get it in a lathe? Or have you got something else in mind stu?
You might be able to get the full wheel on a mill Al. There are lathes big enough but they're few and far.
Would a larger rotor and mount for the caliper solve it?
This ^ might actually buy you some additional wiggle room Al.
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ScotRoutes
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Re: Help please (before I get the big file out!)

Post by ScotRoutes » Thu May 28, 2020 8:49 am

I'm not familiar with the hub, but is it possible the end caps are fitted incorrectly, like on the wrong side?

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Re: Help please (before I get the big file out!)

Post by Al » Thu May 28, 2020 8:52 am

ScotRoutes wrote:
Thu May 28, 2020 8:49 am
I'm not familiar with the hub, but is it possible the end caps are fitted incorrectly, like on the wrong side?
Measured them - exactly same both sides. Then swapped them anyway just in case :lol: no difference unfortunately.

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ScotRoutes
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Re: Help please (before I get the big file out!)

Post by ScotRoutes » Thu May 28, 2020 8:54 am

Ha. It was just a thought.

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Re: Help please (before I get the big file out!)

Post by slarge » Thu May 28, 2020 9:21 am

You could (not recommended though) bend the rotor. The chances of getting an equal bend all the way round are slim, so you would most likely end up with a warped rotor, but with some perseverance it could work.

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Bearbonesnorm
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Re: Help please (before I get the big file out!)

Post by Bearbonesnorm » Thu May 28, 2020 9:25 am

You could (not recommended though) bend the rotor. The chances of getting an equal bend all the way round are slim, so you would most likely end up with a warped rotor, but with some perseverance it could work.
Would you not end up with the working face of the disc at an angle to the pads though Steve?
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BigdummySteve
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Re: Help please (before I get the big file out!)

Post by BigdummySteve » Thu May 28, 2020 9:31 am

Perhaps you just need to shim to rotor outboard a little, if you think that would work let me know as I have a 1mm shim kicking about.
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Bearbonesnorm
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Re: Help please (before I get the big file out!)

Post by Bearbonesnorm » Thu May 28, 2020 9:33 am

Perhaps you just need to shim to rotor outboard a little, if you think that would work let me know as I have a 1mm shim kicking about.
Disc needs to go in towards the hub Steve.
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slarge
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Re: Help please (before I get the big file out!)

Post by slarge » Thu May 28, 2020 9:49 am

Bearbonesnorm wrote:
Thu May 28, 2020 9:25 am
You could (not recommended though) bend the rotor. The chances of getting an equal bend all the way round are slim, so you would most likely end up with a warped rotor, but with some perseverance it could work.
Would you not end up with the working face of the disc at an angle to the pads though Steve?
Yes, a tiny angle, or if an adjustable spanner is used then it could just be offset, however my method would only ever be a bodge until a proper solution could be found.

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Re: Help please (before I get the big file out!)

Post by Bearbonesnorm » Thu May 28, 2020 9:53 am

Remind me never to buy a Jaguar :wink:
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Re: Help please (before I get the big file out!)

Post by faustus » Thu May 28, 2020 10:10 am

Had a very similar thing recently and it was an incorrect end cap on the disc side. Luckily I had a spare that did the job perfectly but it was obviously a different cap. If it's not the fork , and the other wheel fits, then maybe it has the wrong end caps on both sides? Maybe it fitted another fork because of more leeway with a rotor adaptor...? Good luck!

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Re: Help please (before I get the big file out!)

Post by slarge » Thu May 28, 2020 10:19 am

Are the forks QR or bolt through?

Just thinking - with the skewer / bolt loose is the disk centred? If it is, then the incorrect end cap idea might be the problem.

(I don't do brakes Stu - nothing to fear buying a Jag!)

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Re: Help please (before I get the big file out!)

Post by FLV » Thu May 28, 2020 10:33 am

How does the stans hub look on the other bike/forks?
Perhaps it works and you can play swapsies with your wheelsets?
If we take it that the parts and end caps are right...

My first step would be to try a different adaptor (it looks like there is one fitted?)
Second I'd get said other adaptor and slot the holes in a bit,, looks like you'd only need to open the holes up by up to 1mm tops with a round file? You'd have to make a judgement on the amount of material left and not go too far, its all in compression though so.. you know... (also, if it has a counter bore, you'll have to fettle that too)

Worst case you could knock up a 'custom' or modified caliper adaptor from a bit of aluminium with a bit of good old fashioned bench fitting.

As someone said, I'd try caliper adaptor / up a disc size first, this should allow a fit of flexibility into the stack up.

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Re: Help please (before I get the big file out!)

Post by Gummikuh » Thu May 28, 2020 12:08 pm

I still say put a washer on the disc side of the axle. You may need to dish the rim a little if it bothers you, but a quarter turn on each nipple on that side should do it.

You can always make a washer fit, by drilling out the centre to the diameter of the axle. Just don't do it whilst holding it with your fingers!

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Re: Help please (before I get the big file out!)

Post by FLV » Thu May 28, 2020 12:20 pm

Gummikuh wrote:
Thu May 28, 2020 12:08 pm
I still say put a washer on the disc side of the axle. You may need to dish the rim a little if it bothers you, but a quarter turn on each nipple on that side should do it.

You can always make a washer fit, by drilling out the centre to the diameter of the axle. Just don't do it whilst holding it with your fingers!
I'd personally only shim in a fork if I was going to skim some off the other side to keep as flat a face as poss. I wouldnt want a wonky contact face. (I know it wont be cock on anyway, but wouldnt want it worse)

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Re: Help please (before I get the big file out!)

Post by Wotsits » Thu May 28, 2020 1:28 pm

Are the brake mount & disc also Hope? Sometimes different makes don't play well together.

Worth checking the adapter isn't a rear one, some (e.g. shimano) can be front/rear specific.

Had a similar problem with a rear brake a few years ago, someone had butchered a front adapter to make it fit.

Al
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Re: Help please (before I get the big file out!)

Post by Al » Thu May 28, 2020 4:51 pm

Thanks for everyone’s input.

Having cursed the crap tolerances of stans hubs (and their toffee freehub bodies while we’re on the subject...) I thought I best try one more hub. And it turns out a superstar switch is also way off centre. So feck knows what is going on at this point. The calliper and hub were fine on my old Reba it’s only the new fork that swap that seems to have caused problems.
So in defiance of all good engineering sense and the absence of a massive lathe, I hunted round in the dusty corners of the shed an found an old penny washer. I set about it with a file and have made a 1mm shim washer to sit on the axle. The fork legs spread pretty wide when you’re putting the wheel in ( :shock: )so it was fairly straight forward and I can now centre the brake. Going to go for a ride later and hopefully I won’t die.

Pretty chuffed with the forks too thanks Allen...
...think I deserve a beer after all that :-bd
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Re: Help please (before I get the big file out!)

Post by ScotRoutes » Thu May 28, 2020 5:21 pm

So, it's the disk mount on the fork that is on the piss?

If you're not swapping the wheels around then taking a sliver off the non-disk side end cap would relieve any stress on the forks. A perfectionist would re-dish the wheel too 😉

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