Bicycle Mechanics - Oil on disc?

hi, my rear disc break has all of a sudden become very slow to react and "soft". could it be because some oil got onto the disc and has accumulated onto the pad, rendering it fairly useless? if this is the problem is it just neccessary to change the pad or can it be cleaned or tightened? i noticed it as i cycled through some tall wet grass, would that have possibly caused it? and if i do change the pad, should i clean the disc to ensure no oil residue is left??

I'm not sure about the pads, but apparently Lighter fluid works well for the rotors (discs)

If it is on the pads proper, you may have to replace them. If it is on the rotors, you can use a oil remover from the hardware store. A guy brought in a bike to where I work yesterday that he had used WD40 and Mobile 1 to clean his drivetrain and brakes. Needless to say pads were replaced.

hi, my rear disc break has all of a sudden become very slow to react and "soft". ...??

When you say "soft", do you mean your levers feel soft/mushy?

See if there's a piece of grass stuck in there.

ive had a good look and nothing stuck in the housing, like the brake works, but i dont come to a full stop as quick. ive wiped the discs thouroughly with just a dry rag, but ill try an oil remover and see if that helps. The lever itslef still feels good and solid, no change there, so its just the reaction at the other end of the cable! thanks guys, great help!

Go to you local autoparts store, of Wal-mart, and buy a can of brake cleaner. It will remove any oil, grease and dirt that is on your brakes.