Bicycle Mechanics - Shimano Deore LX Disc trouble
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01-01-07, 07:17 PM
hi, my shimano deore LX disc brakes, seem to be rubbing a little against the pads. when i spin the wheel, it odesn't seem to be getting that many rotations, maybe like 4-5. also i hear a little rubbing when i spin them. in addition, in the front, while riding... i seem to hear a little small clicking noise, probably comming from the brakes, i don't believe this is something major, because the brakes are fairly new. however i'm wondering if something might have gotten inside.
how should i approach this, can i fix it myself, what do you think is wrong?
Either you have a bent rotor or they just need to be recentered. You should be able to find a manual on Shimano's website to cover this. Otherwise, bring it to a shop if you don't feel confident. Being as they are hydraulic, make sure the brake lever doesn't get depressed with the wheel out of the bike--the pads will not return without some tools and adjustment.
01-02-07, 07:14 PM
kay, thx. just wondering, what do you guys use as your disc brake pad spacers, where can i find some...what do they look like?
01-03-07, 04:37 AM
like Seely says probably the brake calipers just need centering-just a case of loosening the bolts holding the brake calipers to the frame- getting the brake calipers correctly centered and retightening the bolts. I seem to remember that last time I did this with my LX brakes following the shimano service instructions I couldn´t seem to get the adjustment right. When I retightened the bolts the caliper wasn´t correctly adjusted for some reason. Probably due to my amateur mechanics skills. But when I adjusted the brake calipers using more of a trial and error approach (moving the caliper a bit where the pad was rubbing then tightening the bolts and rechecking I eventually managed to solve the problem.
On the inside there should be a knob,put a feeler gauge between the pad and the disk and turn that knob in or out until the feeler gauge is snug. You can also use a business care or two. On the outside loosen the two allen bolts just a little,with the feeler guage between the pad and disk. I don't know about the clicking,but I think it could be the maginet for your computer. Good luck.
01-03-07, 05:48 PM
yea, no computer on my bike. whats a feeler gauge? and by loosening them, what does it do?
but i guess i could just use credit cards instead.
now, am i recentering the rotors? or just moving the caliper body(the silver mechanism) until the rotor is not touching either side?
A credit card is to thick.You can buy feeler gauges at Home Depot.You can start by using a business card or something as thick. I used .015 on the feeler gauge,that's a little thinner than a business card and it worked pretty good. On the outside your moving the caliper when you loosen the 2 allen screws that are holding it. All they have to be is loosened enough to slid it in or out. You have to reach through the spokes to get at the inside adjustment.If it's a knob just turn it clockwise or counter clockwise. Some bikes have a allen head there, but do the same thing as you would turning the knob.The feeler gauge will go between the disk and the rotor. After your done try spinning the wheel and then you can make your adjustment. As for the clicking noise,pull the front wheel off and then spin it. If you still have the noise try lubing the bearing or hub.
01-03-07, 06:35 PM
yea, i figured it out... but even with a business card. theres not enough room to go on both sides of the rotor, to fit a card. ie. [ | ! | ]
[ ] being the caliper/pads, | | being the paper and ! being the rotor.
but i fixed my rear, by ear. i just spun it, and adjusted the caliper until it didn't make any noise at all. :]
gotta tend to the front one now.
i know the clicking is comming from the rotor being too close to the pads.
and i meant, using a credit card as a momentary disc brake slot thingy, to prevent u from depressing the pads. :)
01-03-07, 09:42 PM
i actually have one more question, since i wasn't able to fit a business cards width between the rotor and the pads, on both sides, is there a way to increase the distance between pads?
so that i can fit the rotor, and a business card on each side of it?
You don't want or need all that much clearance on any disc brake system. It is the inherent nature of any hydraulic disc brake system for there to be near zero clearance between the caliper and the rotor in the released state.
While I'm not explicitly familar with this specific system, the TSM at Shimano seems to indicate that these are double action calipers, wherein both pads are pushed towards the rotor by the pistons when the brakes are applied. What happens in this instance is that the caliper seals flex outward slightly as the brakes are applied, and then tend to retract the piston ever so slightly when the brakes are released. However, some negligible fricton between the pads and rotors is normal when in the released state.
My guess is that this is either a situation of T.M.D.T. (This Model Does That) or you have some dirt or other forign material on the pads, least likely, barring an abuse situation, would be a rotor problem.
Links to TSM's at Shimano
Front Brake Exploded view, with parts list (http://bike.shimano.com/media/cycling/techdocs/en/bikecomponents/BR/EV-deore_lx-fdiscbr_v1_m56577569830538685.pdf)
Rear Brake Exploded View, with parts list (http://bike.shimano.com/media/cycling/techdocs/en/bikecomponents/BR/EV-deore_lx-rdiscbr_v1_m56577569830538687.pdf)
Shimano TSM for Disc Brakes (http://bike.shimano.com/media/cycling/techdocs/en/bikecomponents/DiscBrakeSystem/SI-8DB0A_v1_m56577569830538239.pdf)
If, after reviewing the documents you don't feel you have the skills necessary to perform a diagnosis or repair, I strongly recommend you take your bike to a qualified mechanic. After all, you life depends on proper brake function. Good luck with this.
Do one side at a time. Your trying to do both sides at once. The business card is a quick fix. If you look at .015 you will see it's much thinner. Feeler guages cost about $5.
01-04-07, 04:22 PM
oh guys... i already fixed the problem... thanks for your ideas. props to royalflash, cuz all i did was mostly use trial and error, i tried to look straight down the rotor, and make sure i could see a tiny bit of light coming from both sides, then i would spin the tire to make sure the caliper was in the right spot. so no more clicking, or friction!
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