New brake rotor needed? Only 50k km??

Discussion in 'Technical' started by CBR250, Feb 14, 2013.

  1. CBR250

    CBR250 Ol'Timer

    Hey guys,

    My 2010 CBR250 had some drag coming from the front. Changed the pads and it was cured 80%, but not fully.

    The Thai Honda delearship says I need a new front brake rotor... the bike only has 50k km over 2 years?

    Sounds a bit iffy to me.

    Unless it is warped (the drag wasn't pulsing so don't think it is) isn't there a way to just clean them with a special cleaner and toothbrush?

    Does needing a new rotor sound odd?
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  3. TonyBKK

    TonyBKK Ol'Timer

    You don't replace a brake rotor because it's dirty, you replace it because it's worn below minimum thickness.

    While 50k km seems short for the life of a brake rotor, if you were suffering brake drag that would certainly wear the rotor faster than normal.

    I imagine a new rotor for your bike must be very very cheap, no? It's not like the dealer is going to make much money selling you a new one, right?

    If you still think your dealer is pulling your leg why don't you measure the thickness of your rotor yourself to see if it is within spec? Most rotors have the minimum thickness stamped right on them.
  4. CBR250

    CBR250 Ol'Timer

    ^ I wouldn't think it is anything to do about money, I would think it is about laziness.

    I have instructed them to do the following before anything else:

    I presumed they did it with every change of pads as they also coincide with my full-services. They obviously don't. 50,000km and four sets of pads is probably long enough.

    Will check out the thickness, cheers.... though the logic of thinner brake rotors making the brakes be jammed-on causing enough drag to lug the engine, doesn't really seem too strong.
  5. TonyBKK

    TonyBKK Ol'Timer

    If you "presumed" that honda rebuilds your brake calipers every time you change your pads you would be presuming wrong. Rebuilding brake calipers is not something thats called for on a regular basis, rather as needed and should not be needed on a nearly new vehicle, be it car or bike.

    I am curious to know why you were getting brake drag on a nearly new bike. Brake calipers are pretty maintenance free and should not require rebuilding for several years. I recently rebuilt the calipers on my 7 year old GSXR and that's the first time I've ever felt a need to rebuild brake calipers.

    Did your dealer tell you WHY they want to replace your rotor? The only reasons to replace a brake rotor are because it's worn or damaged or has worn below minimum thickness.
  6. TonyBKK

    TonyBKK Ol'Timer

    One more thing to mention- I reckon your model is so new that your dealer has never rebuilt a set of CBR250 calipers. It's not a difficult thing to do but it must be done right! Make sure they know what they are doing before they split and rebuild your calipers! Your brakes are not something you want to leave to chance!

    If for any reason you don't trust your dealer to get it right I recommend you get a service manual and do it yourself.

    Does your bike have linked brakes? If so, they usually need to be bled in a specific sequence to make sure all the air is out if the lines.

    Best of luck!
  7. CBR250

    CBR250 Ol'Timer

    That's exactly what I want to know.

    I booked in with them notified about the problem.

    They just changed the pads, then sent me away.

    Problem still there, took it back, they just said 'Needs new rotor. 2,300b'. The English manager wasn't there so that's all the info I have.

    Bike isn't exactly new. 50,000+km bought in 2010.

    Will be popping around there tomorrow.
  8. TonyBKK

    TonyBKK Ol'Timer

    Hydraulic brakes don't drag because of the pads, per se, they drag because the pistons are not retracting into the calipers the way they should, which keeps the pads in contact with the rotor.

    Possible causes include a damaged or defective master cylinder, too much pressure in the lines (usually caused by a pinched or kinked line), or damaged or binding caliper pistons.

    Regardless of the cause, it's an easy fix once you identify what's causing the drag.
  9. CBR250

    CBR250 Ol'Timer


    I just C+P'd that to the English manager with a note of make sure all of these are checked as I want to know exactly what the problem is/was.
  10. CBR250

    CBR250 Ol'Timer

    Got a message back saying:

    "The min thickness stamped on the rotor is 3.5 mm. I just checked your bike and was getting different thicknesses between 4.39 and 4.43 around the rotor. I also checked a new bike and got 4.45 all the way around. So you haven't gone down to the minimum thickness yet, but it appears as if the rotor surface itself is not even.

    ....I'll have them clean out the piston and caliper on the front when they change rotor."

    Sounds like plenty of life left in the rotor, but just slightly uneven. For the sake of 2,300b I'll just have it changed anyway.
  11. monsterman

    monsterman Ol'Timer

    Brake rotors can warp at much lower mileages brembo rotors are notorious i have seen them warped at 10k
    Honda 250 has 50k aand rotor is cheap its not a big deal.
  12. CB400F2

    CB400F2 New Member

    If it's been draging, it's probably being generating excess heat. Not much point in renewing the rotor unless you renew the caliper piston seals / dust seal at the same time I would suggest.
  13. crowster69

    crowster69 Active Member

    yeh that would be my guess a warped rotor.Ive had a couple over the years and yes they were brembos.excessive heat is the cause.

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