rotor catching on fork mount?

my mates hope floating rotor (the inner floating bit) seems to be catching on the fox fork, no matter how i try to align them for him….brakes are xt on pro2 hubs, im baffled, as the pistons are fine and running equal…is this a know problem and if so is there a cure?

its on every rotation you can hear it, it doesnt sound great and its DEFINITELY causing drag it catches that much?

I dont know if this is your exact problem but with my SLX mounts (IS mounts on fork) and Hope 180 floating rotors the rivet thingy* hits the mount adapter. I filed / dremelled a smidgen* off the mount to let the thingy pass with a margin. I just needed to do the lower part of the adapter.

* Proper technical terms!

yep 180 rotor but with a postmount adaptor as his forks are 09 fox….it is the exact same thing, the rivet (inner piece of the rotor) hits the mount adaptor, and i think it was just on the lower one too!

silly question but did you just use a standard file to get rid of it? its only catching by a bit, no more than 1mm it still spins freely enough but its the noise of it catching that winds him and me up more haha!

good to know i can cure it at least!

hope floaters and xt brakes don’t play nice. switch to none float or space it out if possible (someone mentioned using spacers under the post mount caliper but dunno if it’ll work in this case) or dremel the caliper if you really want

I used something like this:
http://www.screwfix.com/prods/60320/Hand-Tools/Files-Rasps/Bahco-Homeowners-Dual-Cut-Metal-File-8

You dont need to file the caliper – just the adapter.

Double post!

It’s a hub problem. Hope hubs have the rotor mount further inboard to make sure that the carrier on their two-piece rotors can clear the fork. Fox forks users have the fewest options and are prohibited from using floaters with CK or Industry 9 hubs without having to resort to filing the fork’s brake mounts.

The only solutions are a new hub, file the fork mounts or use a standard rotor.

I have a hope floating rotor on a hope pro II with an 09 Fox float RLC and it still catches on the fork. I put a washer on the QR to act as a spacer. Didn’t require any surgery then.

so is it defintely the adaptor thats catching then? not the mount sticky-out bits on the forks them selves? i know technically they should be the same as one fits on to the other, but if its the mount itself that needs filing im not so sure he’ll want to be rubbing that down???

i have combatted this before for him, by trying to align the pads over slightly to the other side – downsides were only uneven pad wear, but there was not much in it at all…however after several attempts last night i couldnt get it to play ball at all, it was rubbing severly, and more importantly annoything the hell out of us 😆

If the rotor is hitting the fork, it’s nothing to do with the pads. You could remove the caliper completely and the rotor would still hit the fork.

What exactly is hitting what?

from what i remember when i did it in the light last year for him, its either the post mount the inner rivet is catching or the adaptor…

last night it was pitch black and i couldnt honestly see what it was hitting, but it was the same catching noise as when i did it in the day before…

as i said hes had no issues for 6 months as his pads didnt need changing and its a bolt thru, so no need to worry about how many mm’s the QR is out…..i aligned the pads over to the opposite side last time and it cured it, its just given him uneven brake wear minor though and he had no catching for those 6 months, so the inner rivet was over to the other side more, not catching on the post adaptor/mount

my floating rotors on CK hubs with fox forks always just grind the fork leg.
i actually have a rotor that i now use just to do this as it’s scorched too.

interestingly, BETD do an axle for CK / Hope rotors that spaces this away [as such]..

so let it carry on rubbing and it eventually will wear away the “excess”…..

The rivet can’t move, or at least shouldn’t be able to. The rivet is fixed to the rotor carrier, which is fixed to the hub. It doesn’t matter what pads/pistons/calipers do, the rotor (and rivets) will always be in exactly the same position relative to the fork/mount adaptor. If the rotor/rivets have just started hitting the fork/mount, then it might be suggestive of hub bearing problems.

If you take it to a shop or show it to somebody who has a degree of mechanical sympathy, they should be able to identify the problem in a matter of seconds.

hmmm perhaps it just needs aligning slightly better then? as said above though the chap says that he had to file down the adaptor on his to get clearance, so will have a look in day light at it….seems strange that it didnt do it at all for 6 months, so perhaps it just needs finer tuning with the alignment etc

will have a look into it and report back!

whats this axle thing that BETD do then? i cant see anything on the site? is a QR or 15mm one?

hmmm perhaps it just needs aligning slightly better then?

Have you read anything I said?

well yes sir i have, im merely stating that perhaps there is a fraction of movement in the rotor somewhere that allowed it to move away ever so slightly…its no coincendence he had no rubbing for 6 months, then suddenly new pads in (no free movement) and its there again….perhaps it does have a minor minor bit of movement in the rotor/carrier, after all the the rubbing is only going to be a mm max if that, if its just catching…..so yes sorry i have read your point, i know what you are saying, im just stating it doesnt make sense how i managed to fix the noise before…its definitely catching on either the mount or the adaptor, playing with the alignment last time cured it (albeit, i have no idea how!) 🙂

The phrase “never argue with a fool: they’ll only drag you down to their level and beat you with experience every time” never seemed so appropriate. Just take the bike to a mechanic and ask them to explain to you what they’re doing and what is wrong; or start from scratch yourself without your preconceived notions of what is wrong. Forget what you think you know and learn how to learn.

Missing washer in the axle perhaps?

I’ve had this with floating rotor on Marzocchi fork with Hope brakes. I just rubbed the fork lower down a bit where it was hitting as it was only very slightly contact.

You should check whether it clips it when there’s now caliper on (or no pads in). If the pads rub a bit they could be flexing the rotor enough to make it make contact. In turn this could have led to uneven pad wear so that they didn’t push the rotor – then put new pads in and it might be flexing it enough to make contact again. Obviously all conjecture 😉

Three_Fish – Member

The phrase “never argue with a fool: they’ll only drag you down to their level and beat you with experience every time” never seemed so appropriate. Just take the bike to a mechanic and ask them to explain to you what they’re doing and what is wrong; or start from scratch yourself without your preconceived notions of what is wrong. Forget what you think you know and learn how to learn.

now thats not verrrrry nice is it, play nicely! 🙂

im just saying what has happened, going off what i did in the past to alleviate the catching/rubbing, perhaps it was luck perhaps it was nothing to do with me aligning – though when you alighn the calipers on the mount on the fork itself there is a bit of movement either side of where you screw in the bolts, hence it may be pushing the rotor slightly offset with a tiny tiny tiny amount of movement once the bolts are secured/tigthened in place, far fetched i know and i can see your point at not seeing past the rotor doesnt move but its stumped me…i know it doesnt sound possible/plausable and you may call me a fool again, but it worked….

again if its just a case of filing down the adaptor slightly then that should be fine and dandy, still doesnt explain why its not happened for the 6 months previous…..

i had this problem with a second-hand set of revelations. The end of hub had compressed the material on the inside of the fork so it effectively moved the brake mount further in than it should have been.
To fix it i filed down the inside of the brake mount to bring it back into line with where the hub made contact and then rebuilt the hub with an extra washer so the fork wasn’t being squeezed as much.
It’s been fine since.

EDIT: You will see an indent on the fork plate which touches the hub if you have the same problem, mine was probably 0.5 – 1 mm deep.