On Tuesday, 16 January 2018 18:16:00 UTC, Mad Roger wrote:
On Tue, 16 Jan 2018 08:52:07 -0800 (PST),
tabbypurr wrote:

not really. But cars generally seem to deal with it ok.
Ultimately it comes down to enough force to create enough
friction, and almost any friction material can do that.

I agree with your logical thought process in that the only scientific
summary that makes logical sense is that all pads work just fine in
passenger vehicles, with the main difference being the foot pounds of
torque applied to the brake pedal to obtain the desired deceleration rate..

Hence, any pad is fine, EE or FF or GG, for stopping the vehicle.

With respect we know that all pads or shoes don't work fine, and I've never claimed they do. If your unfamiliar with brake failure on modern cars due to the driver using them more & harder than design specs then maybe brake work is not for you. It's precisely why pursuit vehicles have better brakes.

Driving down a mountainside in one history piece I had, well aware of the tendency for brakes to fail in that scenario. Suffice it to say I had to stop when they were getting close to that point. Had I been Jo Average with no clue about brake fade there would have been a big mess. The first time I encountered this I discovered that the degree of fade was far worse than I'd expected, braking effect can go from 100% to nothing repeatedly. The only thing preventing carnage is the nut behind the wheel.


I certainly bought bad pads in about 2000.
I go though a set of front pads once every couple of years, never more than
two years on my own vehicle, but on this vehicle, it took 20 years to go
through one set of rear shoes.

The ones from the scrapyard OTOH I had no problem with.

The problem isn't the scrapyard per se.
The problem is getting the *right* pads at the scrapyard.
That can't be easy (see my other post on how that's done).

it's almost trivial

Those I got to see after they'd been used a bit, so I knew they
weren't disintegrating, let alone badly, or oily.

What does that even mean?

You criticised buying pads off scrap vehicles before, but truth
is every time you buy a used car you're getting used brake pads.
It's not a problem really.

I don't at all disagree with your apropos logic that every time you buy a
used car you get used pads, but, you can assume (logically) that the pads
fit.

One would hope so

I've been to junk yards where there literally are junked cars piled four
and five cars high outdoors, where you walk the yard looking for the fender
or mirror that you want.

To look for brake pads would be an order of magnitude harder because you
can't see the brake pad until you find a similar vehicle make model and
year, you climb up to the top car, you remove the wheels, you pull the
rusty drums or calipers off, and then, only then, do you get any chance to
see the condition of the brake pads and shoes.

Normally they're ok, and normally the owner has a pretty good idea which of his stock has had recent brake work on it, so will point you to those.

Or, if the scrapyard does all that for you, and has placed a ton of brake
shoes on the shelves, you can pick among them for the right size and shape,
but that process comes with the problem that you have to have a comparison
pad and shoe in your hands, which means your car is up on blocks and you're
borrowing someone else's car.

If you can read the AMECA edge code, you have a chance at getting the right
shoe or pad, but it sure does seem like a lot of effort when an FF pad or
shoe is about $20 a set of four at Rock Auto.

Did I surmise the scrap yard process incorrectly?
If so, how would you correct that process of *selecting* the right pads?

there were no markings or codes on them then. AFAIK all the available options were asbestos based.

$20 to get pads you don't know how they'll hold up in service versus $1.50 to get pads that you can see are doing good and have 90+% of life left. That's really the choice, at least for cars where you have both options, which of course you don't always.


NT