Piernas Flacas Posted September 12, 2019 Posted September 12, 2019 Ok, so I'm busy upgrading my old Deore groupset (including brakes) to full 1 x 11 SLX. I transferred the old components to my wife's old bike which had Avid Juicy 3 and Deore 3 x 9 drive train. The Juicy's rear brake had developed an "on or off" kind of behaviour. No modulation and almost no lever travel, so good opportunity to replace them. However, now with the Deore's in place and for some strange reason the same brake lever feeling and behaviour also presents. What I've noticed is that the rear rotor on my bike is 1.5 mm thick as opposed to 2.mm on my wife's bike. Also, I haven't replaced the pads so in theory there should be a little bit of room there that should make up for the difference in rotor thickness, right? The front brake is good as it was previously with the Avids. The Avid rotor thickness is also 2mm but so is my front Shimano rotor. (??) When I had the Deore brakes on my bike I could feel the rear lever travel and proper modulation, but now they feel very different. What's your thoughts? Rotor compatibility? Glazing? Rotor position to the caliper?
Christofison Posted September 12, 2019 Posted September 12, 2019 I say reset(push back) the pistons on the rear caliper and that should sort the problem out. If the problem persists, buy a new(compatible) disk.
Jehosefat Posted September 12, 2019 Posted September 12, 2019 What I've noticed is that the rear rotor on my bike is 1.5 mm thick as opposed to 2.mm on my wife's bike. Also, I haven't replaced the pads so in theory there should be a little bit of room there that should make up for the difference in rotor thickness, right? What's your thoughts? Rotor compatibility? Glazing? Rotor position to the caliper? Hydraulic brakes are "self adjusting". As the pads and discs wear, the pistons in the calipers remain further out thus maintaining the distance between the disc and pad braking surfaces. If you have put the same caliper onto a new, unworn disc, the pistons are probably too far out leaving the pads too close to the disc. Suggestion is as per Christofison. Remove wheel from bike, remove pads from caliper, put bleed funnel on at brake lever and use a plastic tyre lever to push the pistons back into the caliper.
Piernas Flacas Posted September 12, 2019 Author Posted September 12, 2019 Thanks, guys, will try that.
dasilvarsa Posted September 12, 2019 Posted September 12, 2019 The Calipers must be centralized in relation to the disks.The disk must run in the center of the caliper.There is adjustment by loosening the mounting screws.
Piernas Flacas Posted September 13, 2019 Author Posted September 13, 2019 Thanks, guys. Just pushing the pistons back and re-assembling seem to have done the trick.
MORNE Posted September 13, 2019 Posted September 13, 2019 recently had an issue with the wife's brakes where it wouldn't matter how well you set the pads and gaps on the stand...as soon as you use them while riding they would rub. So last weekend I took the pads out, cleaned and worked the pistons in and out with some mineral oil until they came out equally on both sides. Both callipers had one side do all the work and the other side a bit sticky. cleaned with some brake cleaner afterwards. Reinstalled new pads sommer.No more rubbing and brakes as new. point is...servicing the calliper pistons is defo something that has to be done every now and then...especially if you had them real dirty, submerged or whatever.
thebob Posted September 13, 2019 Posted September 13, 2019 great video for those struggling to get the most out of their brakes:
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