Disk maintenance question

[Bateleur1]

I have a Cube Hardtail with Shimano brakes on it.  Bike is 2,5 years old with about 4000km done on it.  A little while ago I noticed that the rear breaks are extremely noisy when I apply brakes and it is almost as if there is a loss in braking capability, although I do feel the there is quite a bit of pressure applied on the disks.  Almost as if there is something oily or wet on the disk.  Yet I don't see any obvious sign of abnormal dirt on the disks.  This morning I notice the same starting to happen with the front brakes.  And the noise is like a screaming bat out of hell noise that spreads panic among pedestrians and fellow commuter when I stop at a traffic light.  I have not yet gone into finding the fault but thought in the mean time to as for pointers where to start looking for the problem.

 

Would a simple cleaning or sanding or replacing of the pads be the first step?

 

Thanks in advance.

[PeterF]

The brake pads have probably become glazed over time. First step would be to try sanding them if that doesn't work then new pads.

[Letum911]

I have a Cube Hardtail with Shimano brakes on it.  Bike is 2,5 years old with about 4000km done on it.  A little while ago I noticed that the rear breaks are extremely noisy when I apply brakes and it is almost as if there is a loss in braking capability, although I do feel the there is quite a bit of pressure applied on the disks.  Almost as if there is something oily or wet on the disk.  Yet I don't see any obvious sign of abnormal dirt on the disks.  This morning I notice the same starting to happen with the front brakes.  And the noise is like a screaming bat out of hell noise that spreads panic among pedestrians and fellow commuter when I stop at a traffic light.  I have not yet gone into finding the fault but thought in the mean time to as for pointers where to start looking for the problem.

 

Would a simple cleaning or sanding or replacing of the pads be the first step?

 

Thanks in advance.

 

I would start by cleaning the disk with some rubbing alcohol and lightly sanding the pads. This should sort things out. 

[Pah Bear]

I would start by cleaning the disk with some rubbing alcohol and lightly sanding the pads. This should sort things out. 

Been here and done all that Let... suggest. Helped in the short term but condition came back soon after. Only went away once I replaced pads.

 

Avoid touching the rotors with your fingers. Easy way of landing finger oil on there.

 

Just as an afterthought, I heated up the old pads and saw oil droplets like sweat beads coming out of them. 

[Letum911]

Been here and done all that Let... suggest. Helped in the short term but condition came back soon after. Only went away once I replaced pads.

 

 

 

Sometimes this is the only true solution. But it is more costly than a bit of elbow grease. 

[Pah Bear]

Although I never tried this, I believe it is acceptable to use dish washing liquid and scrub the old pads, then dry and try. It removes any surface grease you cannot see and if not deeply embedded, it should work.

 

With screeching brakes, although you might not see oil contamination, once you apply brakes, the pads heat up bringing the oil to the surface.

[Bateleur1]

Thanks, will go the sanding route for the short term but need to order some parts again and will add that to the list thanks.

[Bateleur1]

Although I never tried this, I believe it is acceptable to use dish washing liquid and scrub the old pads, then dry and try. It removes any surface grease you cannot see and if not deeply embedded, it should work.

 

With screeching brakes, although you might not see oil contamination, once you apply brakes, the pads heat up bringing the oil to the surface.

 

Anyone tried putting the pads in the dishwasher? That will sure sort out any oil in no time.  Not sure if the rest of the pad would like the temperatures in the dishwasher though.

[Kalahari Vegmot]

Clean rotors with alohol or brake cleaner and fit new pads.

[Christofison]

I have read a report by a brake manufacturer that brake squeal is caused by the caliper not being properly lined up with the disc. Ie, the surface of the pistons are not parallel with the disc face, thus allowing the brake pad to vibrate slightly when the brakes are applied. This will also affect the braking power.

 

Remember, metalic compound pads are a lot more noisy than organic resin.

 

As mentioned above, if the pad surface is shiny/glazed, give a sand down.

If you think that the pads may have been contaminated by chain lube, brake fluid etc, then wash with sunlight, grill in the oven for a few minutes and wash again. If they are resin pads then keep a close eye on them in the oven, 5 minutes max.

Finally clean that brake disc with some brake cleaner, isopropyl alcohol or carb cleaner.

[Rocket-Boy]

Alignment of the rotor and caliper is nice and easy to do. Just loosen the bolts a bit then lock the brake and keeping the level in tighten them back it, it will have aligned itself.

In the end when I had a similar problem I needed to clean the rotors and replace the pads to get rid of it.

[Bateleur1]

Thanks all for some good tips.  Will get busy this weekend.

[Eugene]

Jeez, so much effort with disc brakes.

 

Why on earth have they put them on road bikes?

[Bateleur1]

Jeez, so much effort with disc brakes.

 

Why on earth have they put them on road bikes?

 

To be honest I don't see myself changing to disk brakes on the road bike soon.  My MTB is my wet weather bike.

[Eugene]

To be honest I don't see myself changing to disk brakes on the road bike soon. My MTB is my wet weather bike.

I feel the same, but one of these days you won't have a choice.

[dev null]

To get oil out of a pad, heat it on the gas stove's flame. Worked for me when some fork oil ended up on the front caliper's pads.