Noisy brakes again

[OldBull]

Hi all.

 

I know this topic was dealt with repeatedly, but I still have a question.

 

My MTB have very noisy rear brakes. went to several LBS and it is still noisy and does not perform at all. Currently using metal pads.

 

Somebody suggested using organic pads. Apparently not noisy at all and performs well.

 

What is your take on these organic pads?

[Pulse]

Organic pads are usually a lot less noisy than metalic or sintered.

They do ware faster, and some people say they loose a bit of top end braking. Organic pads may also glaze over with hard use, so you may need to roughen tge surface every now and then.

 

I havd them on my HT commuter (for no specific reason), and can’t say they feel different. But it is a commuter bike, so don’t get much abuse.

 

Try them, and see

[droo]

Pads are either contaminated or glazed.

 

1. Don't get oil on your pads or rotors. This goes as far as not touching them, the oils on your skin can be enough to cause squeal and loss of performance.

 

2. When fitting new pads, perform a few hard stops from s decent speed to bed the pads in. Failure to do this will cause pads to glaze, causing similar issues. You'll notice that performance improves with each stop - repeat until no further improvement is felt.

 

3. Don't drag your brakes - brake when you need to, then let go.

[RobertWhitehead]

Like droo said - contaminated pads or rotors. Some things you can try prior to getting a new set of pads: 

Take the finest sanding paper you can find - I think it's like a P8000 or some big number and clean the contact area of the rotors. You'll notice a discoloration on the rotor before you start (dark grey / black). Clean that off and then inspect the pad surface. If its glazed (Shiny) then it got contaminated, you can try to sand the surface (not advised - more a last ditched effort). 

 

If you know that you got some oil on them then you can try to bake them in the oven to get the oil to evaporate (It does sound like a Dowwe Dolla suggestion but it actually does work  )

[ZeroPlay]

Preheat oven to 200C, bake the pads (on a tray) for 20min.  Clean rotors with spirits.  Try that before anything more drastic (like sanding).

 

Like droo said - contaminated pads or rotors. Some things you can try prior to getting a new set of pads: 

Take the finest sanding paper you can find - I think it's like a P8000 or some big number and clean the contact area of the rotors. You'll notice a discoloration on the rotor before you start (dark grey / black). Clean that off and then inspect the pad surface. If its glazed (Shiny) then it got contaminated, you can try to sand the surface (not advised - more a last ditched effort). 

 

If you know that you got some oil on them then you can try to bake them in the oven to get the oil to evaporate (It does sound like a Dowwe Dolla suggestion but it actually does work  )

[Jacoo]

I have bought many used bikes and ive almost never bought one thats brakes weren't contaminated. Not so much squealing (although sometimes that too), but generally just not nearly as bitey as they should be. The method that i always use works very well. First take the pads out and remember which position they were in and dont mix them up. Then use a 600 grit sandpaper and sand both the pads and also the rotor. Sand the pads just enough to get the shiny layer off. Then hit the pads and the rotor with a little blowtorch, i use one of those little blowtorch type lighters. You will see the contaminants boil off quickly. Then put the pads back in their original places and bed them in again. Cycle fast and break as hard as possible. Repeat. Much easier on front brake since the back skids easily. They will bite harder than ever after all this, and they wont squeal.

[OldBull]

Thanx all for your advice. Going to play around with the brakes this evening and will give feedback.

[Jacoo]

Like droo said - contaminated pads or rotors. Some things you can try prior to getting a new set of pads:

 

Take the finest sanding paper you can find - I think it's like a P8000 or some big number and clean the contact area of the rotors. You'll notice a discoloration on the rotor before you start (dark grey / black). Clean that off and then inspect the pad surface. If its glazed (Shiny) then it got contaminated, you can try to sand the surface (not advised - more a last ditched effort).

 

If you know that you got some oil on them then you can try to bake them in the oven to get the oil to evaporate (It does sound like a Dowwe Dolla suggestion but it actually does work )

8000?? Is that the grit? Finest grit is aware of is 2000, which is meant for smoothing down a new paint job without sanding too deep. After which you would use a buffing compound to achieve a shine. 2000 is super smooth. No need for a very high grit, even a 600 is quite fine. You don't want to be sanding for ages to get the glaze off the pads, its a quick and easy job, and the life youll take off the pads is basically negligible.

[OldBull]

Right, I baked my pads, sanded to rotor, cleaned everything with spirits, but still very noisy and still only about 15% of my braking power. So no real difference.

 

I saw on the rotor that the minimum thickness is 1,5mm, and it measured 2,2mm. So the thickness is not the cause.

 

What I have noticed is a black dust like substance on the pads. Cleaned that off before I baked it. 

 

Also when I baked it the one pad was smoking a lot. And no, it was not silly grass!

 

I also switched front and back pads and the back was still noisy and not braking. So I suspect it is not the pads.

 

I did notice an oily feel to the brake housing.

 

Could it be that the pistons are leaking? If so, can I get a service kitt for my braking unit.

 

Deore brakes

 

Thanx

Edited March 19, 2019 by OldBull

[BaGearA]

Right, I baked my pads, sanded to rotor, cleaned everything with spirits, but still very noisy and still only about 15% of my braking power. So no real difference.

 

I saw on the rotor that the minimum thickness is 1,5mm, and it measured 2,2mm. So the thickness is not the cause.

 

What I have noticed is a black dust like substance on the pads. Cleaned that off before I baked it. 

 

Also when I baked it the one pad was smoking a lot. And no, it was not silly grass!

 

I also switched front and back pads and the back was still noisy and not braking. So I suspect it is not the pads.

 

I did notice an oily feel to the brake housing.

 

Could it be that the pistons are leaking? If so, can I get a service kitt for my braking unit.

 

Deore brakes

 

Thanx

IF and this is A big IF ...they are metal pads , soak them over night in acetone then burn off the excss ( not the whole bowl just the left over after taking the pads out ) 

 

then put A drop of water on one of the pads and put the pads together ( braking surface on braking surface and run them together you should suddenly feel its almost impoosble to slide them over eachother 

 

now refit and check for noise , if its still there you have to start the proccess of elimination 

 

new pads , then new rotor , then new pads and new rotor , then new brakeset , then new bike 

 

by now your noisy brakes should be fixed

[Abdul]

A few years ago I went through a similar experience as you with squealing brakes. Tried all the usual remedies like sanding, cleaning with alcohol, etc.

Eventually I discovered that the caliper had developed a fine hairline crack causing a tiny bit of mineral oil to leak onto the pad.

Replaced the caliper, and it's still working perfectly.

The Deore caliper was surprisingly not expensive. The shop I bought it from still has it in stock. Here's the link :

https://www.cyclosport.co.za/index.php/buy-now/parts/disc-brake-set/shimano-deore-hydraulic-brake-caliper-f-r-post

Edited March 19, 2019 by madmak

[GaryP]

Hi OB. 

 

If all else fails do try organic brake pads as various manufacturers do also confirm that organic pads are less prone to noise than metal ones.

 

Ciao.

[Jacoo]

Baking them in the oven will not burn the contaminants off. Blowtorch like i said.

[HuckNorris]

My pads drove me insane a few months ago , squealing when used , otherwise just chirping with every rotation of the wheel.

 

I eventually took them off and poured a teaspoon full of surgical spirits on them and set it alight . You cannot see it burn , just leave for 20 -30 seconds and it burns out.

 

Have had silent pads ever since    

Edited March 20, 2019 by HuckNorris

[OldBull]

Hi all.

 

It seems like my caliper had a crack. Replaced with a new one and now my brakes are working 100% again.

 

Thanx for all your help.

[Bateleur1]

Glad to hear Old Bull.  I was following this thead with interreset as my rear brakes are noisy as they get.  The cracked caliper is one thing I have not checked.  Will be doing that soon.