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  1. #1
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    486 brake change out

    My new Jamis came with an odd combo of a M486 brake up front, and the M485 in the back. While I wouldn't consider either of these strong stoppers, they've had good modulation which is all thats needed for most trails. Problem is, the rear brakes power is as good as the front....and its in the rear. No bueno. I've cleaned rotors and pads with alcohol swaps, thinking that perhaps when I was putting air in the negative chamber of my reba, some oil sprayed onto the rotor making it slick. After several cleanings, no change. So I'm thinking it's something with the 486 brake itself. I want better power. I'm on a super tight budget and as such was considering replacing just the caliper with an XT, keeping the 486 lever and hose. Will this boost the power, or do I need to get a full front brake setup to make a difference. Or could the problem be just with the 486 lever? I'd think not, but then again, ya never know!

  2. #2
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    I've cleaned the pads and rotors. I've even sanded the pads a bit to try to remove any debris that could be making things slick.I've made sure the pads are engaging properly. This 486 brake is NOT working properly. I have NO power with it. It's actually been a bit dangerous a couple of times. My rear brake literally has more stopping power going downhill than my front brake. The sensation reminds of riding with vbrakes that are packed with snow.(Reach back in your memory) You squeeze, you feel it engage slightly, but not much happens really. Anyone have any suggestions for this? Or is buying a new brake my best bet for proper braking? The only thing I haven't tried is riding down a long downhill to heat up the brake. Maybe burn the pads and rotors in a bit? The back brake works great though and has had the same riding as the front. I'm getting frustrated dodging trees and overshooting lines cause my brake won't work.

  3. #3
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    Take a look, there is a recall on those brakes. Get your receipt and knock the shop you bought the bike.
    Shimano BR-M485 Disc Brakes - Recall of sorts...

  4. #4
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    I'll give shimano a call about it tomorrow. My rear is the 485 and it has worked just fine. Decent power and good modulation. It's the 486 up front that is the issue. But being that it's a sibling brake, maybe it's covered as well. I've checked for oil leaks, Nothing. Thanks for the heads up though. Hopefully Shimano can shed some light on this.

  5. #5
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    And try opening the reservoir cap to check the mineral oil level? Trapped air can make your disk spongy since air compresses so much easier than oil. Follow Shimano instruction that came with your bike to check. Or take it off the handle bar, clamp it on a vertical tube of some kind (higher than the caliper) to so oil wonít spill out when you open the cap. If oil is low, thatís the cause. Tap caliper and line from the bottom to top to encourage air to move up. Pump the level a few times to see if you see bubble comes out. Itís easier than you think.

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