Gilera st 200 brake pad worn again!!!

Noticed the scraping sound again so my pad is gone. This is the 3rd time in 9 months it has worn out. There has to be something wrong. Are there any main offenders for this happening? I always had a funny feeling it was wheel alignment. My assume it is because when I spin the rear wheel the scraping noise only happens for about 1/4 of the rotation. Is this possible and how can it be diagnosed and fixed?

 

Wheel may need balancing if its scraping only a quarter of the way round?
May be bent? Id wait for someone like scubabiker or stevep or MARSH to come along... i may be wrong.

 

Well whatever it is, it ain't right. Unfortunately in Ireland we don't have many 'dedicated' mechanics to choose from. Most of the time you book in, do basic job and spit your bike back out. Sometimes it isn't even fixed or the fuck up something else. There is one place that Does bike diagnostics but need opinions before I bother them. They are always busy and take time to reply

 

is it just one side wearing down? or are both pads wearing equal? but does sound a bit like your disk is warped.

 

Well the pad width seems worn equally. Can a disk be warped or the wheel be off allignment? Just have to figure out how to proceed

 

could be wheel bearing, warped disk, or buckled wheel

 

Fit new pads, take scoot for a run without using rear brake, feel if the disc is hot to touch, if it is then it's binding and the caliper will need to be stripped/cleaned. If it's cool then you maybe using more rear brake than front whilst riding?

 

Agree with Scuba's comments and Marsh's comments.
Plus, if I remember rightly, the disc is mounted on a separate hub to the wheel, the same set-up as the vx's. And the caliper is fixed and not floating.
You need to check if the disc is warped, but at the moment I can't find the run-out limit of the disc, plus you would need an engineers clock and stand to measure it properly.
You could try going slowly along the road (10mph max) and just tickling the rear brake, just barely applying the brake and see if the bike feels like it brakes and then releases as the pads pass over the part where you think it rubs and then releases.
I have known the rear hub, the part where the disc bolts to, be twisted as well in the past.