Shimano Rotor touching brake (not touching fork) during compression

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Shimano Rotor touching brake (not touching fork) during compression
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flag one10
Posted: Feb 20, 2018 at 9:18 Quote
My front rotor seems to be lightly contacting my fork when the forks are under heavy compression. [edit: the rotor was not touching fork. It was touching the brake] The bike is a 2014 Trace 1 27.5 which comes with SLX brakes and a Fox 32 Talas CTD Evolution fork. The fork was rebuilt by Fox but has the same lowers.

Normally I ride trails but have recently taken the bike to the Steve Smith pump track several times and found that during compressions on the pump track, the rotor will contact the fork making a sort of vibrating/ringing noise. Standing still, if I "pluck" the rotor, I can get a similar noise and if I slide a 5er in between the rotor and the fork, the noise is deadened. The space between the rotor and the fork is very minimal. I will measure later but I'm guessing like 1.5mm. Maybe less.

The bike is still factory and I haven't had any hub issues at the front. The pads have been replaced a couple times but the caliper is nicely centered on the rotor. I recently replaced the front rotor with what I believe is the exact same part as factory however, since I did not take the bike to the park prior to the replacement I cannot say if there is a correlation.

Any thoughts on how to get rid of this? Is this "normal"?

S.
flag brianl
Posted: Feb 20, 2018 at 13:23 Quote
Are you sure the rotor isn't rubbing the caliper or adapter? check the clearance.
flag one10
Posted: Feb 21, 2018 at 7:56 Quote
Thank you Brian for asking me to check my assumptions.

I removed the brake caliper and could not get the noise. So it wasn't touching the fork. [title edited]

I then reinstalled the caliper following the procedure I have followed in the past and the noise came back.
1.snug up mounting bolts and back off a small amount so caliper can move
2.pump brake several times then apply and hold
3.gradually tighten mounting bolts evenly while holding brake.
4.by eye, check the brake pad retraction and caliper centring on the rotor

Visually the caliper looked centred and the pads seemed to retract evenly with an equal sliver of space between the each pad and the rotor. But even after repeating several times, the noise was less but still definitely there.

I then messed around with a feeler gauge to centre the caliper a bit better and the noise did reduce quite a bit but not completely gone if I plucked the rotor hard. This was allot of messing around and cannot be normal.

Any thoughts on what I might be doing wrong?
flag brianl
Posted: Feb 21, 2018 at 10:09 Quote
If I understand, you've spent some time centering the caliper, but it's still rubbing the rotor a bit?
Can you tell which is rubbing, the caliper body, or one of the pads?
Sometimes you can never completely stop a pad from rubbing, but if there's a metallic "clinging" sound from hitting the caliper body, like you said that's not something to leave alone. Find which side is hitting and slightly move the caliper the other way.
flag one10
Posted: Feb 22, 2018 at 8:43 Quote
Never had a pad rubbing, only the clinging sound under heavy fork compression.

It took a fair amount of tweaking and extra effort with a feeler gauge to get the caliper centred but I think my problem is probably solved. I still get a slight "clinging" if I give the rotor a very hard "pluck " to the side.

Since we have snow this week, I have not been back to the pump track for testing. With the extra effort put into centering the caliper I'm guessing the noise is gone.
flag gotohe11carolina
FL
Posted: Feb 22, 2018 at 12:53 Quote
Check to see if there is a raw metal spot where the outer edge of the rotor comes close to the caliper body. If your rotor has weird fins or other such its diameter might be slightly bigger than what's posted on it. You can just shim the caliper up with washers.
flag markg1150
Posted: Feb 23, 2018 at 1:12 Quote
Worn wheel bearings could cause miss alignment of disc and caliper under load. Or even just a loose axle
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