Disc Brake Pads

For discussions about bikes and equipment.
PH
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Re: Disc Brake Pads

Postby PH » 14 Sep 2020, 10:43pm

EDIT - Irrelevant post now the above has been corrected.
Last edited by PH on 15 Sep 2020, 11:38am, edited 1 time in total.

Brucey
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Re: Disc Brake Pads

Postby Brucey » 15 Sep 2020, 12:07am

those are EBC's measurements and the 35mm dimension includes the tab with the hole in it. The 30.68mm dimension is the 'width' of the pad (in the dimension swept by the disc)

cheers
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thelawnet
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Re: Disc Brake Pads

Postby thelawnet » 15 Sep 2020, 8:31am

Brucey wrote:BR-M6000 uses the same pattern of pad as;

Shimano BR-M475/M515/M525
Nexave C500/C600
TRP Spyre /Spyke/Hy-RD
Tektro Augila/Auriga

amongst others.

In EBC brakes this is pad type CFA327, and has backings that have principal dimensions 35mm x 30.68mm.

cheers


No, it most definitely does not.

I have the M6000 brakes and they use Shimano's M985 pad design. These pads don't fit in the older brakes and I know this as someone just tried to pinch my pads and they wouldn't fit (as I told him before hand)

Shimano calls the pad you refer to B, and it's widely compatible with other brake brands, as you note. The newer pad design is intended to be proprietary.

https://docs.google.com/spreadsheets/u/ ... c/htmlview

PH
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Re: Disc Brake Pads

Postby PH » 15 Sep 2020, 8:36am

Brucey wrote:those are EBC's measurements and the 35mm dimension includes the tab with the hole in it. The 30.68mm dimension is the 'width' of the pad (in the dimension swept by the disc)

cheers

Well what I know comes from the products rather than the documentation - The pads that Shimano supply with Deore M6000 calipers are not the same as those TRP supply with Spyre brakes. Whether they're interchangeable, I wouldn't know, as they're both readily available why would I bother finding out.
The like for like replacement for M6000 from Discobrakes is the one I linked to before your post.

PH
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Re: Disc Brake Pads

Postby PH » 15 Sep 2020, 8:46am

thelawnet wrote:Shimano calls the pad you refer to B, and it's widely compatible with other brake brands, as you note. The newer pad design is intended to be proprietary.

https://docs.google.com/spreadsheets/u/ ... c/htmlview

Might the answer to this be in in your attached spreadsheet:
B - calipers using this are 'wide', and may interfere with two-piece 'narrow' rotors (this probably depends on the design of the rotor, see rotors tab for more detail). Most wide rotors are recommended for resin pad use only. If you use a 'narrow' rotor with a 'wide' caliper, you may find your pads wear quicker. OTOH there's no issue using a 'wide' rotor with a 'narrow' caliper, excepting obviously that they may be cheaper

Would the B type fit if you're using a wide rotor?

thelawnet
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Re: Disc Brake Pads

Postby thelawnet » 15 Sep 2020, 9:04am

PH wrote:
thelawnet wrote:Shimano calls the pad you refer to B, and it's widely compatible with other brake brands, as you note. The newer pad design is intended to be proprietary.

https://docs.google.com/spreadsheets/u/ ... c/htmlview

Might the answer to this be in in your attached spreadsheet:
B - calipers using this are 'wide', and may interfere with two-piece 'narrow' rotors (this probably depends on the design of the rotor, see rotors tab for more detail). Most wide rotors are recommended for resin pad use only. If you use a 'narrow' rotor with a 'wide' caliper, you may find your pads wear quicker. OTOH there's no issue using a 'wide' rotor with a 'narrow' caliper, excepting obviously that they may be cheaper

Would the B type fit if you're using a wide rotor?


The pads have to fit the caliper, so if you have a narrow type caliper (i.e. not old/low-end) you need narrow pads, and if you have a low-end aka wide caliper you need the wide aka B type (the one Brucey references).
IMG_20200915_145304.jpg

IMG_20200915_145350.jpg

IMG_20200915_145413.jpg


The dimensions aren't very different (the lighter coloured one is a new third party 'narrow' pad), but the narrow type spans a bigger arc, while the wide type is both a bit deeper towards the hub in terms of braking surface and the mounting hole is a bit further into the caliper, so the pad won't fit the other type of caliper.

The idea is wide = cheaper = heavier, while the narrow often uses plastic arms to reduce weight.

Cheap Shimano disc
497058_4174024.jpg


More expensive one

Shimano-RT99-Ice-Tech-FREEZA-CL-Disc-Rotor-Internal-Silver-NotSet-SMRT99L-0.jpg


I think the idea is that the B/wide type caliper/pad goes further into the disc and thus may interfere with the plastic /cooling bits on certain of Shimano's rotors. But this is not totally clear.

chris_suffolk
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Re: Disc Brake Pads

Postby chris_suffolk » 15 Sep 2020, 9:41am

Duplicate post
Last edited by chris_suffolk on 15 Sep 2020, 10:10am, edited 1 time in total.

chris_suffolk
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Re: Disc Brake Pads

Postby chris_suffolk » 15 Sep 2020, 9:52am

On a related, but slightly seperate note, the spring is marked R and L, so has an orientaion. Now, I don't doubt that it should be the right way round, but try as I might I can see no difference between the two ways round - the spring is completely symmetrical so far as I can tell and so are the pads.

Anybody??

Brucey
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Re: Disc Brake Pads

Postby Brucey » 15 Sep 2020, 10:18am

thelawnet wrote:
Brucey wrote:BR-M6000 uses....

In EBC brakes this is pad type CFA327, and has backings that have principal dimensions 35mm x 30.68mm.

cheers


No, it most definitely does not.


agreed; apologies for passing on duff info; EBC's listing (by brake model) is wrong (I have just contacted them so that they might correct this). However they do (unlike many brake pad manufacturers/suppliers) at least show the exact dimensions and shape for each pad backing.

This means that any error would soon become apparent by checking the measurements of the pad backings; the BR-M8000 (etc) pads (CFA614 from EBC) have a backing (29.7 x 32.2mm) which is wider than the other one, and they are fairly obviously different.

In general terms for a pad to fit and be suitable the following apply (in roughly this order):

a) that the backings are the exact correct dimension, and have the correct pad retention features etc (eg some come with springs, others don't)
b) that the friction material (by position, shape and size) is a match for the disc track width and the caliper
c) that the friction material is compatible with the disc (so don't go using sintered pads with 'resin only' discs for example)
d) that the secondary properties of the pad/friction material are unlikely to cause operational problems (noise, heat transfer) and especially won't cause a non-benign failure mode.
e) that the more obvious properties of the brake pad (friction coefficient, wear life etc) are what is required.

All too often e) is the reason for changing pad type (note, PH) but a-d can trip you up en route; EBC's faulty listing is a good case in point.

b) can be a real stinker; for example the same pad backing is used by some manufacturers in more than one model, with different friction material placement. In other cases the same pad backing and approximate friction material placement is used between makes/models but they are still not the same; for example genuine BB5 pads use a tapered puck of friction material (so the pads are handed), but other pads which are otherwise similar don't; the usual effect of this is that the other pads wear unevenly when used in BB5 calipers. At least they can be turned I suppose.

You can of course grind excess friction material from a pad backing to make it better match for the discs etc.

Some aspects of d) are subtle; for example I might use a sintered pad in a closed hydraulic system but not in an 'open' one; the risk is heat transfer into the hydraulics, but the failure mode in each case is quite different; with a closed system the brake comes on by itself and stays on until the brake cools off (which is annoying but fairly benign), but with an open system the brake can transition from being 'just fine' to 'nothing whatsoever' with no warning (which is potentially about as dangerous as it gets).

So if you want to 'play it safe' then stick to what the manufacturers recommend. However if you want a different performance/life characteristic, this usually means dealing with a third party supplier who may have faulty information (as above) or might tend to exaggerate the range of compatibility of their products. Caveat emptor and all that....

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

PH
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Re: Disc Brake Pads

Postby PH » 15 Sep 2020, 11:19am

Brucey wrote:agreed; apologies for passing on duff info;

cheers

You might edit that information in case anyone stops reading at that point and buys the wrong pads.

Brucey
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Re: Disc Brake Pads

Postby Brucey » 15 Sep 2020, 11:26am

yes indeed (and I shall do so), thanks for reminding me, but I can't edit other people's quoting of it...? So the problem is reduced but not eliminated thusly.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Brucey
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Re: Disc Brake Pads

Postby Brucey » 15 Sep 2020, 11:55am

chris_suffolk wrote:On a related, but slightly seperate note, the spring is marked R and L, so has an orientaion. Now, I don't doubt that it should be the right way round, but try as I might I can see no difference between the two ways round - the spring is completely symmetrical so far as I can tell and so are the pads.

Anybody??


some springs are definitely handed, with others it is less obvious that this might be the case (which in fact it might not). But there is no harm in installing them 'correctly' is there...?

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~