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Rear brakes

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by G2teg, Dec 29, 2007.

  1. Hey guys.
    Just need a little help with the rear brakes. I found that the brakes were dragging on the rear ... so I just replaced the pads, and there still seems to be some drag.
    The brake fluid is right up to the max line, and I am unsure if this could cause a problem ... like there isn't anywhere to put excess fluid.
    When I changed the pads, the piston was quite easy to push in, so I figure it can't be the master cylinder.
    Any ideas?


     
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  2. Can you hear or feel drag?
    Pads will always just touch the disks put put no pressure on them.
    If you can actually feel drag start with a calliper inspection.
     
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  3. Yes, a little drag after new pads is no big deal. You could pull the caliper off and use a bit of copper grease on the pad retention pins, to help the pads back off when you release the lever. Immediately after you get off the bike, touch the disc: as long as it isn't hot (just warm's alright and it should normalise in 100km or so), it's all okay.
     
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  4. Ok ... it's a bit of a wierd situation.
    I rode from the city to home, not using the rear brake even once. With the bike in the garage, I touched the all the discs. The front was reasonably warm, but the rear was hot. This was done before replacing the pads.
    With the caliper dismounted, and the pads removed, I was able to push the piston back in with almost no pressure, just using my finger. I replaced the pads, and remounted the caliper.
    As soon as I press on the rear brake, the pads contract, but when I release, the pads stay touching the disc. If I release some pressure using the bleed valve, the pads open up.
    A friend of mine suggested that it may be the master cylinder, but it's sunday and I can't get parts.
     
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  5. I recently had the same issue with my bike. I stripped the rear caliper and found one of the seals had become lodged between the piston and the caliper body. A good clean of the caliper and a new seal kit solved the problem. I also smeared the pistons with silicon grease before installing them. But considering the pistons on yours seem to be fairly free perhaps it is the master cylinder. Quite often these can be pulled apart for inspection (usually just need circlip pliers). I reckon bleed a bit of the fluid out of the reservior (so maybe its only half full) and give that a shot. Hey its free and if it works you'll love it. A new MC is gonna cost a fair chunk of money :cry: (tho a lot cheaper if you get it from bikebandit.com)
     
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  6. If you strip and reassemble any of the brake parts, don't grease them. Use only brake fluid to lubricate them when you reassemble.
     
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  7. I just took the bike into Ducati in the city (the only bike store open today) and spoke with the mechanic there. He told me thats its not actually the brakes at all, but more likely the wheel bearing.
    Does anyone know how much it's going to cost to get a new bearing put in ... or should I just keep riding it as it is?
     
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  8. Bearing shouldn't be too expensive to replace, not really all that difficult a job. Of course what a Ducati dealer may charge is a different matter. Make sure you get it done now though - if you leave it then it'll only get worse and can destroy the rear wheel (just ask Loz).
     
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  9. Cost of a set of wheel bearings: $20-100
    Cost of fitting: $40-80??

    or

    Cost of failed wheel bearing: all of the above, plus maybe new wheel, plus repair any crash damage, plus tow truck to get to the workshop, plus taxi home, etc... Hey, you KNOW something is wrong with your bike. You KNOW there are maybe a total of 5 parts on your bike that can break
    without killing you, and wheels-brakes is NOT one of them.


    If you are mechanically knowledgeable enough to remove and refit your
    rear wheel correctly, then pull it out and turn the centre of the
    bearings with your finger to feel how much friction is in them.
    Should be no friction that you can feel.
    Should Not feel like it 'clicks' from one position
    to another as you turn it, instead should turn smoothly.

    If you are not mechanically knowledgeable, or not sure, get a professional
    to check it out for you.
     
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  10. Biggest problem I have is that I can't get the rear wheel up ... unless you want to come and hold it for me ... I don't have a stand for it yet.
    I have had the bike for three weeks or so, and am still learning about it ... but wednesday, the shops are open again, and I should be able to get it done somewhere.
    Hotcam ... you said the bearing shouldn't feel like it 'clicks' from one position ... when I ride the bike, I have a constant clicking sound. Could this be the source?
     
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  11. There's ways around that, car jacks work well or the other trick is to lean a piece of wood against a suitable support point then lean the bike against the sidestand and slightly forward. Done right this will lift the rear wheel off the ground slightly and at the same time the lump of wood will fall into place and keep it elevated. Of course easier if you can borrow someone to place the wood or tilt the bike for you.
    Edit: I accept no responsibility though if you stuff up and drop the bike ;).
     
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