Can I ask a quick disc brake question please?

[Grarea]

My disc brakes started rubbing suddenly.
Couldn't think of anything that made them do it.
Blamed it on temperature change and differential expansion (cheap brakes).

Any way, I adjusted the rear fine.
Straightened them up.

The front however, seems odd. I had to loosen them off a bit.
When I use them, they sound like I am using them on a cheesegrater.

So, I have checked the wheel is in straight, I can see no warp to the disc and there is no give as in it isn't loose.
I have adjusted the caliper to the least worst scenario, but it still sounds so weird when I pull the brakes on.

So I had a look at the pads and one looks like this.

IMGP2110 by chuffedas, on Flickr

I am a bit confused by it.
Is it showing that the caliper is twisted in comparison to the disc?
Is the fact that it it is now megubered meaning that it will make that noise now even if the caliper is straight?

[hamster]

Looks to me that the pad is worn out and down to the backing. One edge always wears a bit faster, even on big solid car discs.

[Brucey]

you don't say what kind of brake you have. It is difficult to help you if you don't mention this.

But I agree with the above; that pad looks worn out to me; if the brake is the sort that uses a spring to hold the pads apart, when the pads are worn so that the friction material is less than 1.5mm thickness (approx. total thickness of 2.5mm) the spring may touch the disc or wear through then break. Foul noises accompanying this process are almost inevitable.

Note that the life of the brake pads is such that you get to wear a little over 1mm (from the original total thickness of ~4mm) away and then the pads are done. Some pad types don't last long at all; a weekend's muddy riding is enough to see them off in some cases.

cheers

[Grarea]

you don't say what kind of brake you have. It is difficult to help you if you don't mention this.

Oh, ok, sorry.
They are Tektro cable disc brakes.
I can't find a model number on them.

But I agree with the above; that pad looks worn out to me; if the brake is the sort that uses a spring to hold the pads apart,

Like this, right?
IMGP2113 by chuffedas, on Flickr

when the pads are worn so that the friction material is less than 1.5mm thickness (approx. total thickness of 2.5mm) the spring may touch the disc or wear through then break. Foul noises accompanying this process are almost inevitable.

Note that the life of the brake pads is such that you get to wear a little over 1mm (from the original total thickness of ~4mm) away and then the pads are done. Some pad types don't last long at all; a weekend's muddy riding is enough to see them off in some cases.
cheers

Oh, really?
So, just to be clear, you are saying that if the thickness of the material on my pad is less than 2.5mm (which mine is) that is a worn out pad?
So, the construction of the pad material is 1mm braking material, the remainder is just a backing material is it?

But it looks like there is so much more to use.
Can't complain too much, it has a done a year of daily use.

Thanks for that.

[Brucey]

typical new pads are ~4mm total thickness, being ~1.5mm steel backing and ~2.5mm of friction material.

Because the spring does not lie perfectly flat you need at least 1mm, preferably 1.5mm thickness of friction material if you are to be sure that the disc isn't going to (noisily) contact the springs.

Even if the springs were not present, disc pads often become unreliable when the friction material is less than 1mm; the bonding can fail and the remaining friction material can just delaminate, leaving you with no brakes.

Thus any time you notice that the pads are worn more than 1mm, it is a good idea to change them for new ones.

cheers

[hemo]

I use the same pads B01S shimano type, the only time I have had an issue is on the South downs.
A new pair were mullered in less then 30 miles riding due to the wet chalk/clay mix.
To me it appears a small bit of grit or other debris has got in between disc and pad face to cause the wear, though once the material gets thin they do break up a bit.

[Grarea]

typical new pads are ~4mm total thickness, being ~1.5mm steel backing and ~2.5mm of friction material.

Because the spring does not lie perfectly flat you need at least 1mm, preferably 1.5mm thickness of friction material if you are to be sure that the disc isn't going to (noisily) contact the springs.

Even if the springs were not present, disc pads often become unreliable when the friction material is less than 1mm; the bonding can fail and the remaining friction material can just delaminate, leaving you with no brakes.

Thus any time you notice that the pads are worn more than 1mm, it is a good idea to change them for new ones.

cheers

Ah, ok. Thanks. I did misunderstand.

Ignoring the groove, there is still 1.9mm of friction material remaining.
So, they would still be good then. (If not for the damage).

Seems like hemo might be right about some debris getting between and making the groove.
That makes sense, looking at the damage etc.

This is all good info, I appreciate the knowledge.

Don't know why they were rubbing though.

However, I have just worked out why the weird cheesegrater noise.
The groove in the pad will have an edge and the holes in the actual rotor are at an angle and so will catch on the edge of the groove as they go past.

[Grarea]

Oh, so there isn't just one type of pad

OK, so types of pads.
There is nothing about the rotors that affects the choice of pads is there?

These ones are tektro bp618 5k98???
Which are the appropriate words and numbers so I can look these up please?

You say they are B01S shimano type?

[Airsporter1st]

Oh, so there isn't just one type of pad

OK, so types of pads.
There is nothing about the rotors that affects the choice of pads is there?

These ones are tektro bp618 5k98???
Which are the appropriate words and numbers so I can look these up please?

You say they are B01S shimano type?

You might find laser etching on your discs which says "Resin Pads Only", in which case (if you follow that instruction) you are limited in your choice of pad material.

The one you have photographed does look like a BO1S type. They are not only made by Shimano.

[Grarea]

Cheers.
I can't find anything etched on the rotors.
So that means I can use any type, right?

I am a bit confused by the B10S bit.
That is the shape isn't it?
I see that shimano make a B10S.

But Tektro don't seem to call that shape B10S, they call it Aquila or Draco, is that right???
http://www.wiggle.co.uk/tektro-disc-brake-pads-pair/

Brand X call it 811 Shimano 815

http://www.wiggle.co.uk/brand-x-organic ... 2146017739

Tektro also call it AQ/AUC/Draco/AUP/HDC300
https://www.evanscycles.com/tektro-aq-a ... s-EV199835

Ah, Clarks call them vrx811 so similar to the Brand X.

So, I just have to go by the picture for the shape do I?
Are there any that look the same but are different in any way? Like for a different rotor size? Or a different calliper type or anything? Different thicknesses?

So you can't do a search for this particular shape of pad because everyone calls it different things or am I missing something?

[Brucey]

Ignoring the groove, there is still 1.9mm of friction material remaining.
So, they would still be good then. (If not for the damage)....

that would make the total pad thickness ~1.5mm (backing) + 1.9mm(friction material) = 3.4mm.

It is difficult to be sure but I have to say that your first photo does not look like a pad that is only worn ~0.6mm from new.

For pads try

https://www.discobrakes.com/?s=0&t=0&c=16&p=483

these appear to be the correct sort for your brake.

There are minor differences in backing plate size and friction material thickness/placement depending on the manufacturer, but these only rarely result in a fitment that is so bad that the brake cannot be made to work.

cheers

[Grarea]

Thanks for that.

Yes, it was that sort of thickness.
If I remember rightly, the backing plate was 1.6mm.

I think perhaps that the darker part of the groove looked like it was all gone?

I have sanded it down to remove the groove and popped it back in for use tomorrow. So it is a bit thinner now.

I am surprised that each shape doesn't have something to search it by.
Anyway, I assume different manufacturers make varying quality of brake pads of differing types.
Be they sintered, semi-metallic or organic (which looks like they are called ceramic in that link?)

I am keen to get a half decent set as I like to try and keep under 30mph on the way into town be it wet, dry, warm or cold.
The difference in cost between the sets doesn't seem to vary hugely.
Plus they get a bit of mud occasionally.

I have been trying to find what my existing ones were to try and compare.
I shall have to have another go tomorrow.

[Brucey]

sintered pads seem to work best in wet conditions (and also seem to last longest) but they do wear the discs a bit faster than most, and they are often a bit noisier too.

cheers