Hydraulic Disc Brakes

Gorill8

Help please, went out for a spin last night, pretty wet and dirty road, and on the way back the rear disc brake was making a horrible grinding sound. I cleaned the bike down and tried to figure out what the problem was but can't seem to find it.
When I turn the wheel the grinding sound is still there, like metal on metal. Could the disc be bent? It doesn't look it, or is it some grit stuck in it, and if so how do I get it out
cheers

Greyspoke

A grinding noise would usually be one of two things - either grit caught between pads and rotor but that often just works its way out or grinds away and the noise goes.
Just drop the wheel out to check.
Often though its because your pads have worn down to the metal backing and the sound is very much metal on metal which means you're causing damage to the rotor (not too serious if you sort it soon). Often new bikes come with softer resin pads and while these are great for braking they do wear quickly (very quickly sometimes), especially when it's wet and mucky. This seems to be a particular problem on the Ballyhoura trails when they're wet as the sandy soil becomes very effective grinding paste. If the pads are worn out, it'd be best to replace them with harder wearing metal sintered ones.

Home:Ballyhoura

Hey there! My new bike came with hydraulic disc brakes and the same thing happened after about a month. Whenever I turned it used to rub, turns out the pads were completely worn down already! The mechanic also showed me why they might rub for other reasons. If you removed and replace the wheel, it may not be sitting in exactly the same position as before. To solve this problem, loosen the bolts attaching the caliper to the fork (slightly). While spinning the wheel, give it a few taps to make minor adjustments to its position. You will eventually find the sweet spot where no rubbing will occur. It cost me €24 to replace pads front and rear, however I saw pad on eBay for less than half this price but I'm not 100% sure how to replace pads. If anyone could offer advice on this procedure it would be great! Cheers

Gavin

Another way to get the caliper lined up properly is to loosen the bolts as above and squeeze the brakes. Re-tighten the bolts and let go of the brake. Caliper should be lined up properly

Home:Ballyhoura

I hope you do know that don't press on the lever (i.e. use the brakes) when the wheel is removed. You will have fun replacing the wheel if you do, I found out the hard way!

Gavin

Yeah good point, I didn't make that very clear. The rotor needs to be in the caliper when closing the brake and this pushes the caliper into the right position. I'm paranoid about squeezing the brake with no rotor, so stick in the little plastic plugs whenever the wheel is out

Home:Ballyhoura

Gavin wrote: »

stick in the little plastic plugs whenever the wheel is out

You have plugs? Very nice, did they come with you bike or purchase them separately. I'd love some of those, very handy indeed. Have you got a link to a picture or where I could buy them. Cheers

Greyspoke

Try www.superstarcomponents.com for very good prices on brake pads - he appears to be a one man operation in the UK and seems to be a sound guy.
Replacing pads is usually simple enough but because the old ones are worn right down the pistons will need to be carefully pushed back into the caliper body - you can generally work them back in with a thin spanner or screwdriver. When the new pads are in you will need to pump the brake lever a few times to reset the pistons/pads to their correct position in relation to the rotor.

Home:Ballyhoura

He was the guy I was talking about earlier! Are the pads from him any good? I can get them for less than half the price of my LBS

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150306795793

Greyspoke

The pads seem fine if a little wooden feeling - that's the sintered ones and since I had the resin ones before, I guess that's to be expected. It might be worth trying the resin ones because at his prices you wouldn't mind going through them fairly quickly if it meant better feel. I would certainly buy from him again.