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Thread: K Series [Rear] Brake Rotor?

  1. #1
    Out There Somewhere bmwrider88's Avatar
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    K Series [Rear] Brake Rotor?

    I have two K bikes- an 88 K100RS, and an 02 K1200 RS.
    Both have similar mileage- just over 50K. Last year, My K100 was found to have worn out completely its rear brake rotor. Now, my K12 is having ITS rear brake rotor replaced. It seems ludicrous to me that the rotors have worn to the point of having to be replaced after +/- 50K miles...

    Am I delusional?
    Naive?
    Is this planned obsolescence?
    Or cheap product placement to insure revenue for dealerships?
    If the front is where all the braking power is, am I over using my rear brakes, if the rotors are wearing out?

    Of course, my own opinions on my riding techniques, skills, etc. may not match realities but I don't feel like I spend too much time on my brakes, or that I brake too much, etc.

    What does everyone's experience tell them about brakes & rotors?
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  2. #2
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    I replaced the rr rotor on my '93 at 96,000 miles. I could of easily just put now pads on because it was still in spec. I just changed it because I had the wheel off.
    Jeff
    93 K1100LT
    03 K1200GT

  3. #3
    RK Ryder
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    My K100 has almost 88,000 miles on the original rotor and it still within spec.

    Correction; messed up converting from kilometres. Correct mileage is 150,000 miles.
    Last edited by Paul_F; 05-25-2013 at 12:08 AM.
    Paul
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Treasurer of the Forest City Motorrad Club #159
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  4. #4
    A bozo on the bus deilenberger's Avatar
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    Quote Originally Posted by bmwrider88 View Post
    I have two K bikes- an 88 K100RS, and an 02 K1200 RS.
    Both have similar mileage- just over 50K. Last year, My K100 was found to have worn out completely its rear brake rotor. Now, my K12 is having ITS rear brake rotor replaced. It seems ludicrous to me that the rotors have worn to the point of having to be replaced after +/- 50K miles...

    Am I delusional?
    I don't want to judge that..

    Naive?
    Or that..

    Is this planned obsolescence?
    Probably not.. just physics.

    Or cheap product placement to insure revenue for dealerships?
    Be hard to make brake rotors "cheap" - they're pretty much a lump of stainless steel, ground and finished.

    If the front is where all the braking power is, am I over using my rear brakes, if the rotors are wearing out?
    Not necessarily. We have to assume you're either using your rear brakes, or..

    Of course, my own opinions on my riding techniques, skills, etc. may not match realities but I don't feel like I spend too much time on my brakes, or that I brake too much, etc.

    What does everyone's experience tell them about brakes & rotors?
    Ah - I'm not everyone, but...

    I've rarely seen anyone wear out a K100 rear rotor at low miles. It's possible, but if it wore out in 50k miles, I'd be looking at:
    1. Dragging rear brake
    2. Too aggressive a pad
    3. Braking habits

    For the K1200RS - I believe it uses a floating caliper on the rear. These are known to bind up on the pins the piston assembly slides on, and that causes continual drag on the pads/rotor, with the resulting wear. A quick test is - after a brisk ride, without excessive braking. Stop, dismount, wet a finger carefully and apply the wet finger gently to the rotor surface. If it sizzles, stick the finger in your mouth to cool it off, and look for what's causing the hot rotor. (I'm just sorta kidding on this technique, I've been known to raise a blister when I forgot the wet part.. so do it with care. I take no responsibility for pain/injury you may experience doing this test..)

    Just replaced the rear rotor on my '07 R1200R (at about 64,000 miles,) where except for low speed cornering stuff, I almost never touch the rear pedal since it is a linked system that seems to give excellent balance without intervention on my part. I was using EBC HH pads - which are quite aggressive (and stop RIGHT NOW), and as is typical - there was a slight amount of dragging of the rear caliper. I got an EBC replacement rotor, and at their suggestion went with their new "V" pad (aka "Vee") - which is a semi-sintered pad, made for good braking with less wear than the HH pads. The EBC setup was less than 1/3rd the cost of a factory BMW pad/rotor replacement.

    While I had the system apart on the R12R - I separated the mount from the piston assembly on the caliper and cleaned and lubricated the pins they slide on. I used some high-temperature Wurth-3000 grease (good stuff IMHO.) I no longer get any heating at all of the rear rotor.

    On your K100 - make certain the pads aren't dragging when the brake is released. A very slight contact is normal, any drag is not. If it is dragging, I'd first do a fluid flush, if that didn't solve it, it may be time for a caliper rebuild and a master-cylinder rebuild (if the piston/seal assembly is available.) And perhaps brake line replacement (the bike is old enough to have children in kindergarten by now..) I would look for an organic (dirty, but very low wear of the rotor) or the VEE pad from EBC, HH is pretty much overkill for the rear brake.
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  5. #5
    Registered User 58058D's Avatar
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    Two rear rotors on sorta similar bikes at what would be considered extremely low mileage by most of us might indicate a rather heavy foot. how many sets of rear pads have you gone through? In all seriousness, I have only replaced my rear set once in 128,000 miles. They still have tons of life. I admit I rarely use my rear brake. Most K12 riders I know annecdotally smirk that our bikes seem to accelerate when we use the rear brake.....but, also in all seriousness, I am thinking it is a function of how you brake or a dragging piston. I go through a set of front brakes every 20-30,000 miles, but again, only one change for the rear. How does your front pad consumption compare with the rear?

    My '85 had sticking pistons in the front and I went through pads in 8,000 miles and both of those rotors in 22,000. I was new to motorcycling but fortunately had some good advice and got the problem corrected.

    Seeing that Don replied while I was typing, I am inclined to agree fully with his three items, with emphasis on #1 and #3 in that order...
    Jim Douglas '00 K1200RS >135,000 miles my primary bike again,
    Gone: '09 K1300S sold @ 22k mi, '93 K1100RS traded @ 78k mi, '85 K100RS sold @ 44k mi
    '06 Kaw 650R track bike sold
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  6. #6
    NC Piedmont Rider ncstephen's Avatar
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    My 03 K RS had the rotor go out of spec around 50k. In other conversations others have projected the wear rate to be out of spec on the rear by 40k. I seldom use just the rear brake and use down shifting to slow most of the time. I changed mine at 90 k when the wear lip would just about hid a penny on each side. My rear pads tend to need replacing about 15k so I usual do it at every other tire change.

    The front pads tend to start looking a little thin at 50k. Just had them replaced again at100k. The front rotors are still great.

    In checking on warmth as mentioned after running highway sppeds for 20 miles. Running up a steep off ramp and down shifting to slow and using front (both) brake lever from less than 10 mph, I find the front rotors cool and the rear warm.

    So i think your K12RS experience is normal

    Hope this helps.
    NCS
    03 K 1200RS (Black is Best)
    03 Honda RC51
    74 Honda CB750 K4

  7. #7
    Out There Somewhere bmwrider88's Avatar
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    Just thinking about this

    Last night, I was talking this over. In reality, I bought the bike last year, in May- so I have owned the 02 K12RS for a little over one year.

    Last June 2012, we rode it fully loaded, two-up about 3000 miles, and last month,, it went fully loaded, two-up another 1400 miles. Other than that, I've used it mainly just for "normal", or typical every day type use. I have several bikes, and mostly just putter about- with the occasional weekend outing, or commute- so under "normal"* conditions, my bikes don't see heavy mileage each year.

    Realistically, then,, perhaps my own riding habits had little to do with wearing out the rotor?


    *normal appiled subjectively, YMMV.
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  8. #8
    NC Piedmont Rider ncstephen's Avatar
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    Quote Originally Posted by bmwrider88 View Post

    Realistically, then,, perhaps my own riding habits had little to do with wearing out the rotor?


    *normal appiled subjectively, YMMV.
    Exactly. The pads and rotor wear out surprisingly quickly.

    NCS
    03 K 1200RS (Black is Best)
    03 Honda RC51
    74 Honda CB750 K4

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