RS Revs Caliper mounting too close to disc?

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RS Revs Caliper mounting too close to disc?

18 posts & 8 voices | Started 2 years ago by V8_shin_print | Latest reply from V8_shin_print

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V8_shin_print - Member

My caliper mounting is now so close to the disc that it is at the limits of its adjustment but the mounting bolts are still 'ting'ing off the disc.

I have replaced the hub (axle was bent) and the disc (thought it might not be true anymore) but the problem still occurs. Plus the QR is as tight as i can get it.

Is it possible for the lowers of my forks to get twisted? What else could it be? Twisted mounting? Should I get the IS mount trued?

Any advice?

Details:
'07(?) Revs 426 (QR)
Avid Juicy 5
185 mounting and disc
XT hub

Posted 2 years ago #
b r - Member

Has the wheel been dished wrong?

Or the mounting bolts too long?

Posted 2 years ago #
bikewhisperer - Member

File the bolt ends down? Getting the mount faced is not important with Avids as they have the crazy annoying sperical washers. You could take the paint off behind the mount though.

Posted 2 years ago #
soma_rich - Member

I bet the bolts are too long.

Posted 2 years ago #
GeeWavetree - Blocked

br - how would the dishing affect the hub? the hub is static left to right int he dropouts

Posted 2 years ago #
skiprat - Member

I assume your talking about the bolts that hold the adaptor to the forks? Try shorter bolts or just put a washer under the allen key end to bring it out.

Are you using an original Avid adaptor? One side stands out more where the bolts go through. Look to see if theres an arrow on it, this points to the top. You could just have the adaptor the wrong way round.

I have a similar set up (08 Revs, Juicy 5's 185mm) but am using a Hope hub and have no problems.

Chris

Posted 2 years ago #
V8_shin_print - Member

I think i didn't explain that very well, it is the "crazy annoying sperical washers" which are touching the disc.

Posted 2 years ago #
cynic-al - Member

file them down.

Posted 2 years ago #
V8_shin_print - Member

That's not going to help when i put new pads in.

Posted 2 years ago #
bikewhisperer - Member

If that's the case then do get the IS mount faced. It should move the whole caboodle out by a mil or so, however you sometimes need to put washers back in to stop the mount being skewed by other parts of the fork..
Or otherwise there is some tolerance on the inside of the spherical washers. You could pull them over to one side as you tighten the bolts. That's a 3 handed job though!

Posted 2 years ago #
skiprat - Member

Look at the adaptor, if its the wrong way round it will move the whole caliper towards the disc. Is the adaptor like this

This is a Hayes mount but it shows the extra bit that sticks out where the bolts go through. This the wrong way round will position the caliper towards the disc.

Posted 2 years ago #
V8_shin_print - Member

I think facing will be the way to go, I just can't understand what has happened. I've either bent the mounting adapter or twisted the IS mount.

They are already pulled over as far as they will go (strap round lever)

Posted 2 years ago #
cynic-al - Member

That's not going to help when i put new pads in.

How? Pistons will retract?

Posted 2 years ago #
V8_shin_print - Member

From memory the avid mounting has a pretty clear arrow on it for the direction of rotation, i don't think i have that wrong.

Posted 2 years ago #
V8_shin_print - Member

Al: With new pads even when the piston are full retracted the disc must be fairly central in the caliper or one pad will bind. As the pads wear you can get away with the disc not being central as the pistons can compensate.

[Edited] for inexcusable where/wear spelling balls up.

Posted 2 years ago #
bikewhisperer - Member

Unlikely you've bent them. Imagine if the IS mount has slightly more material on the rear side of the bolt holes. (They're only a casting so can be really wonky!) That may only be a few degrees out from flat, but over the length of an adapter to the calliper that can add up to a couple of mil. So even if you face it and then pack it out to the original size with washers, it'll still work out different at the end the calliper bolts onto.

[Edit] but still scrape the paint off first.. This is the most likely culprit

Posted 2 years ago #
MrTall - Member

Some hubs just have a slightly different tollerance to others. I have Reba Maxles on my 29er using Sun Ringle wheels and the clearance is as tight as it can be. I can probably get a piece of paper between the disc rotor and the caliper mount but no more than that. I have a mate with the same forks but hope hoops and he has far more space than me? My other normal QR reba 29er fork has no problems either and that's with Bonty wheels.

Posted 2 years ago #
V8_shin_print - Member

Thanks guys. I guess I could put an extra washer in between the nut and cone of the hub, that would do the same. I think there would still be enough room to get the hub into the QR, it's not tight at the moment.

Posted 2 years ago #

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