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  1. #1
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    When to Bleed vs. when to change pads

    Noob question here.

    How do I know if I need to bleed my brakes vs simply changing the pads. I bought a used set of xt brakes and the front is fine and the rear seemed fine initially but now I find myself pulling the lever almost all the way to the bar. The stopping power is definately there once it's pulled that far which leads me to believe it's simply a need to change the pads but I want to be sure.

  2. #2
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    Typically you'll need to bleed the brakes once you open the system. Other than that if they are leaking or some type of damage has occurred to them. Also if someone has opened them up in the past and did not do a correct bleed, air could have been trapped in the system resulting in the rear having that type of problem. IMO I would change the pads first to see if this helps. If I'm wrong, someone else will let you and myself know.

    How often do you bleed your brakes?

    How to know when your brakes need to be bled?
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  3. #3
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    Quote Originally Posted by Hutch3637 View Post
    Typically you'll need to bleed the brakes once you open the system. Other than that if they are leaking or some type of damage has occurred to them. Also if someone has opened them up in the past and did not do a correct bleed, air could have been trapped in the system resulting in the rear having that type of problem. IMO I would change the pads first to see if this helps. If I'm wrong, someone else will let you and myself know.

    How often do you bleed your brakes?

    How to know when your brakes need to be bled?
    ditto. Look at the rear pads and compare them to some new ones if you can. I would take this next suggestion witha grain of salt as i dont know the pad thickness when new so i may be way off. but i would replace them if them if the pad material is anything less than 1.5mm ~. again, i could be way off... lol

    the fact that they were fine when you got them has me worried though. the lever going to mush in a short period of time would make me think something is leaking or an improper bleed was done.

  4. #4
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    They weren fine, i def had to pull them more than the front, but they were better than they are now. Im a newbie so ive got a ton of bruises on me from dumping the bike so its possible i messed them up but they are working consistently. I think a pad swap is def in order first

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  5. #5
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    Remove the pads and check to see how much pad material is left. If they're worn almost to the backing plates (or if you have no pad material at all), then you need to replace them. Try this before bleeding.

    If there's still plenty of braking material left, try bleeding the system first.
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    If you crash a lot it could have done something to the caliper itself but then again unless we actually ride your bike then we would be able to tell exactly whats going on. Also you said they where used *how old* and I don't know if there's a actual mileage number you should replace your fluid.

    Hopefully someone can help with that but say you change your car brake fluid every 50,000 miles. Wouldn't that translate to 5,000-10,000 on a bike or how hard you are on brakes IE racing? Someone correct me if I'm wrong or they have more input on a time frame to change the fluid. It could possibly be that they do need a fluid change. Still think you should do the pad change first.
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  7. #7
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    Quote Originally Posted by kcvpr View Post
    .snip... way off. but i would replace them if them if the pad material is anything less than 1.5mm ~. again, i could be way off... lol

    .snip....
    Nope some even say less than 1mm
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  8. #8
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    UPDATE: Just threw some new pads in and problem appears to be solved (at least here in my living room) took the pads out and compared them to the new ones and it didn't seem like they were that worn down but I guess thats why they make precision measuring tools!

  9. #9
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    Some brakes are very sensitive to pad thickness. I've never used the XT brakes you're running, so I can't speak specifically to your situation.

    Before I upgraded my Formula R1 set with the FCS (pad contact point adjusters), I had to replace my pads way before all the material is gone. Now I can adjust the contact point as the pads wear down, so I don't replace them until they're almost completely worn away.


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  10. #10
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    Quote Originally Posted by splatworldwide View Post
    Some brakes are very sensitive to pad thickness. I've never used the XT brakes you're running, so I can't speak specifically to your situation.

    Before I upgraded my Formula R1 set with the FCS (pad contact point adjusters), I had to replace my pads way before all the material is gone. Now I can adjust the contact point as the pads wear down, so I don't replace them until they're almost completely worn away.


    fortunately, I bought these brakes used and the seller told me that the front pads were new and the rear would need changing. he included 2 sets of pads so it all worked out great for me. I suspect what your saying is correct, there was plenty of material on the pads, I guess the pistons just don't auto adjust close enough to the rotor.

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