Rear disc brake has been making a terrible racket when I use it recently. Took the pads out just now and one side has worn down to the metal plate! I’ve got some new pads at home.

Have I Knackered the disc?
If I ride home without the pads in the brake will ok won’t it?

you’ll be fine, just don’t brake. If the disc looks ok, it probably is!

If you ride without the pads in there, please don’t be tempted to pull the lever, or you’re likely to do quite a lot of harm.

The brake will be fine, although the rotor may be a little scarred, but you should be able to see any damage. Chuck a new set of pads in and it should be fine.

check the disc for grooves. Get angle grinder with abrasive disc and sand them out. You’ll be fine. Also check that both pistons are moving equally, one could be sticking if you say one pad had worn to the metal. What brakes are they?

Should be OK unless as above they are really scored. Just don’t brake, replace pads and see what the braking it like before you do anything else 🙂

Sand the grooves out? Why? No need at all!

Put those knackered pads back in for the journey home, then replace when you get back – as above you be tempted to use the brake on the way home and the pistons may pop out casuing you loads more hassle. Though it usually the case that if one pad is worn to nothing and the other isn’t, that the piston on the non-worn side is sticky or jammed, hense why it’s not pushing the pad out and getting worn as the same rate as the other side. You need to get it moving again, or the same will happen with the new pads, sometime just lubricating the piston, and pushing it back and forth is enough, other time a complete strip is required.

What Al said, should I perhaps ‘sand’ out all the holes in my rotor too?

Angle grinder? You’re joking right?

I threw the pads away 😳 I’ve written NO! On the back of my hand LOL.

Get angle grinder with abrasive disc and sand them out.

eh terrible advice.

if it scratched a bit leave it. if its deep groves replace it.

My mate who did his PHd in train brakes says grooves make brakes perform better, based on experimental results.

If one piston is sticking and not going in / out then remove wheel and old pads. Then push the working piston back into the caliper and hold it in place while pulling the brake lever. This will force the sticking piston to move. Once it has moved out a bit, push it back in and repeat a couple of times.

It should then be freed up and working fine.

z1ppy – Member
Put those knackered pads back in for the journey home, then replace when you get back – as above you be tempted to use the brake on the way home and the pistons may pop out casuing you loads more hassle. Though it usually the case that if one pad is worn to nothing and the other isn’t, that the piston on the non-worn side is sticky or jammed, hense why it’s not pushing the pad out and getting worn as the same rate as the other side. You need to get it moving again, or the same will happen with the new pads, sometime just lubricating the piston, and pushing it back and forth is enough, other time a complete strip is required.

This is 100% right. I popped a piston 3 hours into my first whw attempt by getting my juicy threes down to the metal. I wrecked the caliper and the disk. And my knee about 12 hours later as I couldnt stop.

Leave the pads in, dont brake, sort the sticky piston if you have one when you get home.

I’ve written NO! On the back of my hand LOL.

Proper laughed at that!

remember to leave your glove off!!!!

Made it home! Just took it easy really. Right, stuck new pads in but couldn’t get the wheel back in and noticed the disc wouldn’t fit in-between the pads, so stuck a big screwdriver in and wiggled them back into place and wheel dropped in fine all goes round and brakes work but the pads rub a bit. Is that normal?

Sorry for all the questions

you should really have forced the pads apart using the old ones before fitting the new ones.

Sounds like you need to realign your caliper – people do it different ways but easiest is loosen the caliper bolts so you can wiggle it a bit, then pull your lever and this should get it prettty close to central – tighten the caliper bolts 1/4 turn at a time (trying not to move the caliper) – then spin wheel, you may have to make small adjustents

Sounds normal to me! Pump the brake a couple times for the pistons to reset be cautious the first couple of times you use the brake as they’ll need to bed in… for me normally one long drag and they’re back to normal!

just align caliper as Yoshimi says it will be fine – you may ahave a stuck calipe rif only one side wore out. that is a right pain to fix.

Blimey that took an age to get lined up. It rubs a bit in one place as you spin the wheel is that ok? Done the front as well as they were looking low. Did what Yoshimi said about pushing the pads in and it worked a treat.

Yey me!

Yes, the disc may be ever-so slightly bent and causing it to rub just a tiny bit. It really doesn’t matter.

I hate getting brakes right but when they are it makes soooo much difference to my confidence, it’s worth it.

Rachel

Is now the time to tell you the easy why of aligning the caliper?

Just loosen the caliper bolts, then hold the brake on and do the bolts up whilst still holding on the brake.
Usually results in a perfectly aligned caliper.

Sorry for not telling you that 2 hours ago 🙂

Get angle grinder with abrasive disc and sand them out.

eh terrible advice.

if it scratched a bit leave it. if its deep groves replace it.

Nothing wrong with using an angle grinder if you know what your doing. Grooves will have no detriment to braking at all they will just wreck your new pads you’ve just put in.

@ziggy yeah you could sand your rotor holes out and fill the one in between your nose and chin.

Using an angle grinder on a disc is wrong. You will make the disc thinner thus weeker ( you do know there is a minimum thickness for a disc?), controlling how much material you remove will be difficult meaning you could end up with brake judder.

its a stupid thing to do.

The grooves in the disc will simply mean it takes longer to bed pads in and will have no detriment once they are bedded in

its not rocket science. I done this hundreds of times cars,bikes.some of those raced on tracks you just be careful and use a micrometer and straight edge. how do you think rotors are made

Not with an angle grinder

Most are cut from flat

they are ground, to make sure they are flat.