Hi Guys,
Something that's been bugging me, I've got a front brake disc that appears to be wearing unevenly - braking isn't noticeably lumpy or wobbly. I started noticing this about 500 miles after I got my front tyre changed... and I'm not sure that they balanced the wheel when they changed the tyre. Could this be the cause? And will getting the wheel balanced sort it or am I looking at shelling out for a new disc and pads?

Cheers in advance... this has me stumped!

~D

  It's a bit hard to diagnose without seeing what the "wear" looks like Dafydd   But I'd hazzard a guess that the "unbalanced" wheel isn't the culprit   An unbalanced wheel is more likely to show an odd wear pattern on the tyre   Check that the wheel is in correctly and not missing any spacers or shims   But I'm afraid whatever the "cause" of your disc wear, you'll have to replace it & the pads once you've found out what it is    But you should be able to find a serviceable disc from a breaker, either in person, or on ebay at a sensible price    Pads are not very expensive these days unless you "want" to spend a fortune   As you said in your other post that you don't ride hard, you wont need "racing" quality pads which tend to be more expensive    No point replacing them yet as they will probably only suffer the same fate   Firstly get the wheel balanced   Most tyre fitting places will balance a "loose" wheel for a fiver while you wait   If you cant see anything "obviously" wrong with the way the wheel is fitted when you come to take it out for balancing then fit another disc & new pads & "monitor" the wear   It could be that the disc is getting through it's hard skin and is now into the softer part of the disc   Is it close to, or past, it's "wear limit"   You can find out what the "minimum" thickness is from a Haynes (or other workshop manual )   Post some pictures of the wheel/disc in your profile then we can have a look and might be able to help you further   Which bike is it happening to                                                                                                                                                                                

Thanks for the advice Emzed, I'll get the wheel balanced before the weekend anyway. It could be that its just the thickness gone thin... the material of the disc isn't rusty or anything, its just a different colour. Also its only doing it on one side of the disc. Either way, I'll probably take the wheel off on Thursday and get it balanced while I'm in town for my tattoo appointment. Either way i.ll let you know what happens. Thanks for the hints!

Ohh and the bike is the honda cbf250... my kwak has never had any problems with the brakes and will stop on a sixpence despite its weight!

Looking at a workshop manual for the Honda CBF250 brake caliper it only has pistons on one side and so is dependant on the sliding part of the caliper to move freely in order to allow both sets of pads to make contact with the disc equally. If the caliper sliding mechanism has seized then it could cause uneven wear as only the pads on the piston side of the caliper will be making effective contact.

Scorpio54, thanks so much for the information! It makes sense as when I had the wheel balanced the wear on the disc started to even up - probably because both sides of the caliper were wiggled when the wheel was re-fitted. I shall take the caliper off tomorrow and clean/lubricate etc.

Out of interest, where'd you find a workshop manual for it? I've never seen one as it's not a very common bike in this country!

Thanks for the help guys,

~D

Scorpio54, thanks so much for the information! It makes sense as when I had the wheel balanced the wear on the disc started to even up - probably because both sides of the caliper were wiggled when the wheel was re-fitted. I shall take the caliper off tomorrow and clean/lubricate etc.

Out of interest, where'd you find a workshop manual for it? I've never seen one as it's not a very common bike in this country!

Thanks for the help guys,

~D

  Your probably quite right Ken   Tis a most likely cause   Can't think why it never occurred to me   All that waffle   It's me advancing years I think   I keep forgetting about single sided sliding calipers       Try this D       http://www.pdfmotomanual.com/index.php?r=site/page&...p;lang=ENG     Or this     http://www.carlsalter.com/motorcycle-manuals.html                                                                                                                                                                                 

you mean single sided non sliding calliper MZ  lol   They work ok when new but sooner or later succumb to the rigours of our climate, whilst you there I would strip the piston out too...clean it up, hook the seal out and carefully scrape out the corrosion you will find under the seal. Ensure the sliding part of the calliper is carfully freed off and the surfaces cleaned to a smooth finish if possible, lub up with copperslip (only a little) and replace any suspect dust boots or seals. Replace the pads if the disc measures within its wear limit which is probobaly stamped on the disc somewhere. Any garage will measure it for you if you ask nicely. All this will take you a few hrs but its the only way.  Oh have fun bleeding the brake afterwards...many methods but that's another story.                                                                                                                                                                             

I'd wondered if they had bent the brake disc a little when fitting the tyre, so it was not running true, those tyre changing machines look a bit fierce. Sounds like you've found the culprit though.