Corey Posted July 31, 2017 Share Posted July 31, 2017 Just got some new tires mounted on the wheels and upon putting the wheels back on the bike I noticed a slight scraping sound from the front left rotor which I believe to be the disc contacting the brake pad. This sound was there before I took the wheels off, but I always thought it wasn't right. When looking at page 97 in the manual it talks about proper clearance between the brake disc and caliper holder. The clearance does look very close. That combined with the sound makes me feel it is in need of an adjustment. The problem is, I can't figure out how to increase the clearance. Any suggestions? Link to comment Share on other sites More sharing options...
Member Contributer thtanner Posted July 31, 2017 Member Contributer Share Posted July 31, 2017 The pads will often lightly touch the rotor with no pressure applied. Link to comment Share on other sites More sharing options...
Member Contributer Marooncobra Posted July 31, 2017 Member Contributer Share Posted July 31, 2017 May be a binding brake piston that is holding the pad against the disc once you release the brake lever. The pad should always be in contact with the disc but with no pressure against it, hence the binding piston issue. Normally a quick clean up will resolve it but if not you may need to strip the caliber and clean the pistons with a real fine emery cloth to dislodge all of the crud. I normally do this once a year on all of the calipers. It really helps to give you sweet brakes Link to comment Share on other sites More sharing options...
Auspanglish Posted July 31, 2017 Share Posted July 31, 2017 Have you actually checked with the feeler gauge that comes in the tool kit usually it is found in a small slot in the back of the kit, it is 0.7 mm gauge and that is exactly the gap that there should be between the brake disc and the edge of the caliper and it should be that distance around the entire circumference of the disc unless the disc is warped in which case you need to change the disc but it is common especially with new pads to hear a sound of the pad rubbing on the disc. When you change your pads you should use the brake lever and pedal to displace the pistons outward so you can give them a good clean but be careful not to pop them all the way out or you'll have to re bleed the system with hydraulic fluid and then when they are nice and clean and shiny and smooth work them in and out with the long plastic or wooden lever not some hard metal that will scratch and nick the surface of the pistons. If you are having trouble getting the pistons fully retracted into the caliper body it may be that you have too much hydraulic fluid in the reservoirs so get a syringe open up the reservoirs and remove just enough so that when the pistons are fully retracted the level is at the maximum mark, don't overdo it and end up with air in your lines. Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted July 31, 2017 Member Contributer Share Posted July 31, 2017 It is easy enough to push the ends of the forks together when inserting the axle and that would lead to the disc to caliper clearance being too small. Loosen the axle clamp off and give the forks a good bounce then retighten. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted July 31, 2017 Member Contributer Share Posted July 31, 2017 Loosen the LEFT fork bottom axle clamp only ! The right side is the reference one that the axle is clamped to & thus the wheel retained at the correct clearance from the right fork leg. Remember the correct tightening sequence for the front wheel replacement, once all parts are in place, lightly thighten the right fork clamp bolts, to the point you can still just rotate the axle with soem friction in the fork bottom by turning the axle using the cross drilled holes in the left side. Now tighten the axle end bolt to the specified torque. Next tighten the right fork bottom clamp bolts to the correct torque. Lightly tighten the left fork clamp bolts then bounce the suspension to centre the forks & axle, on the last bounce release the load on the fork slowly to full extension & then torque up the left fork clamp bolts. That should leave everything as squre as possible, assuming the yokes are/were correctly alligned. If the bike has ever been dropped even lightly, it may be worth alligning the yokes, but that's another procedure. The problem with sliding calipers is two fold, 1. Only having one set of pistons to pull the back, means the pads have 50% the clearance of opposed piston units. 2. The sliding mechanism can get dirty or corroded & thus fail to self centre the pads on the disc. Remember that 0.7mm is NOT disc to pad clearance, its disc to caliper body ! Normal clearance is less than 0.5mm per side of disc to pad. Link to comment Share on other sites More sharing options...
Corey Posted August 8, 2017 Author Share Posted August 8, 2017 Thanks for the input. I appreciate all of the information. I think everything is OK and safe. I do think I probably should rebuild my calipers at some point in the near future and closely inspect the disc for warping. I put about 100 miles on the bike and everything felt fine. I do have one additional question.... When freely rotating (spinning) a tire, how many rotations should it typically go before stopping? Link to comment Share on other sites More sharing options...
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