When to replace brake pads?

glider3560

My car is on 23,000 miles and just over 3 years old. I assume it still has the original brake pads.

They're now down to 50% worn. Mechanic advised to have them changed "soon but no rush" after my last service.

When do other people have theirs changed?

Also, should the discs be done at the same time as the pads, even if they are ok? My previous cars have all been old bangers so I've never really had this issue before (as both pads and discs have needed changing).

Joe_Horner

When they're worn out.

"Percent worn" is meaningless for this sort of thing but a great sales tactic. Your car will have a brake wear warning system that'll let you know when they're down to around 2 - 3 mm. Once that light comes on get them changed as soon as convenient. Obviously, if the warning fails and you start to hear grinding noises then they need looking at pronto!

Unless you know (for example) that you're off on a 5k grand tour and want them done before you go, changing before that is throwing money away and creating waste unnecessarily.

To give you an idea, the warning on our 5 series came on in November but it wasn't convenient at the time. Finally changed them in about Feb, by which time it'd done another 3 - 4k miles and the pads still had enough on them to pass an MOT (1.5mm limit).

As for disks, if they're ok then no need to change - again, you'll be wasting money AND making needless waste. Incidentally, a little bit of a lip or minor scoring doesn't make a brake disk unservicable. If anything they marginally improve cooling by increasing the surface area

liltzero

I have lifetime brake pads so I change them whenever but usually every 5000 miles.
Brake pad compounds wear down over time and distance - better be safe than sorry. No way would I wait 23k miles before replacing mines.

AndyMc.....

liltzero wrote: »

I have lifetime brake pads so I change them whenever but usually every 5000 miles.
Brake pad compounds wear down over time and distance - better be safe than sorry. No way would I wait 23k miles before replacing mines.

Why not? If they're not worn why replace?

angrycrow

Not all cars have an electronic brake wear warning. Some use a metal stud in the friction material or a metal finger on the edge of the pad that squeal when the pads wear to a certain point and the metal stud or finger hits the disc on braking. Some cars don't have any warning.

Discs are normally good for a couple of sets of pads before they get too low. Inside of the disc often deteriorates quicker than the outside because they are exposed to more muck off the road and tend to rust more. Oem discs normally have a cut out on the inside of the disc when the discs wears down to the cut out they need changing.

If you have alloy wheels you should be able to see the pads through the cut out in the wheel. The backing will be about 5 to 6mm and you want a couple of mm of friction material.

Ignore the ridiculous suggestion of changing brakes every 5000 miles, I would expect about 20000 to 25000 out of a set of pads in average driving but I look and plan ahead rather than screeching to a halt. However if your rear breaks were to be missing I suppose you might wear the fronts out in 5000��

BeenThroughItAll

liltzero wrote: »

I have lifetime brake pads so I change them whenever but usually every 5000 miles.
Brake pad compounds wear down over time and distance - better be safe than sorry. No way would I wait 23k miles before replacing mines.

You have lifetime brake pads? Please explain.

angrycrow

BeenThroughItAll wrote: »

You have lifetime brake pads? Please explain.

I suspect he is referring to the Halfords lifetime replacement of brake pads. Halfords are not going to replace them if they are not worn out. The other catch is that to keep the lifetime replacement you have to agree to any other brake work at the time of the pad replacement. I suspect every time you tried to claim you would be hit for new discs or a new caliper. Clever money making scheme.

Joe_Horner

angrycrow wrote: »

However if your rear breaks were to be missing I suppose you might wear the fronts out in 5000��

Very good point

Surprised that any modern cars aren't fitted with sensors - I'd assumed such a simple and useful feature would be standard by now.

liltzero

angrycrow wrote: »

I suspect he is referring to the Halfords lifetime replacement of brake pads. Halfords are not going to replace them if they are not worn out. The other catch is that to keep the lifetime replacement you have to agree to any other brake work at the time of the pad replacement. I suspect every time you tried to claim you would be hit for new discs or a new caliper. Clever money making scheme.

Not halfords. And I get new Brembo pads fitted with no questions asked.
You get what you pay for with my mechanic.

takman

liltzero wrote: »

I have lifetime brake pads so I change them whenever but usually every 5000 miles.
Brake pad compounds wear down over time and distance - better be safe than sorry. No way would I wait 23k miles before replacing mines.

Every 5000 miles???, you must be braking far to much!. My brake pads usually last over 50,000 miles but I don't brake for every corner like most people do.

If I did mine every 5000 miles I would have to change them every 3 months which would be ridiculous.

AndyMc.....

takman wrote: »

Every 5000 miles???, you must be braking far to much!. My brake pads usually last over 50,000 miles but I don't brake for every corner like most people do.

If I did mine every 5000 miles I would have to change them every 3 months which would be ridiculous.

I'm onto 79000 and only recently replaced the front discs and pads.