How many brake pads should you get through before you need new discs?

coylemj

Is there a rule of thumb on this? I'm deliberately keeping this generic so am not going mention the make and model.

I bought the car from a main dealer when it was three years old with 32,000 kms on the clock so it had relatively low mileage. I know that the previous owner lived in D4 and worked in D6 so the car was mainly used for short journeys and I've no reason to think that he abused it as it was spotless inside and out.

It's now six years old and there's 66,000 kms on the clock. On a recent main dealer service where they just did the basics for a fixed price, the guy told me when I was paying that there was about 3,000 kms left on the pads which is fair enough but also that I needed new discs soon. This came as a complete shock to me as to my knowledge the car is still running on the original brake pads - I suggested that the discs should last longer than the pads and he just grunted so I left it. I'm very light with the pedals so tyres and pads last a very long time with me.

Is this an attempt to generate unnecessary business and am I right to expect that the discs should last for several change of pads and definitely should not need replacing when it's still on the original pads?

George Dalton

It's not just about mileage when it comes to discs. Time is a factor as well due to corrosion. So it is highly likely that they need to be changed along with the pads.

corkgsxr

Wouldn't surprise me at 66k to be changing discs.

It would suprise me to get 66k out of a set of pads.


I get about 20k

GarIT

It also depends on the condition of the pads. An hour's driving with fully worn pads could do as much wear to the discs as a couple of months driving with good pads.

coylemj

GarIT wrote: »

It also depends on the condition of the pads. An hour's driving with fully worn pads could do as much wear to the discs as a couple of months driving with good pads.

The pads are not fully worn - the garage said there's 3,000 kms left on them and anyway the particular car has wear sensors.

And there was no mention of corrosion, it was described as wear in that the thickness of the discs was getting close to the recommended minimum, how can that happen if I'm still on the original pads?

GarIT

coylemj wrote: »

The pads are not fully worn - the garage said there's 3,000 kms left on them and anyway the particular car has wear sensors.

And there was no mention of corrosion, it was described as wear in that the thickness of the discs was getting close to the recommended minimum, how can that happen if I'm still on the original pads?

I was just answering generally, if the previous owner had of let the brakes go, it could make a significant difference.

In the specific case mentioned I've no idea.

Toyotafanboi

post a picture of them, we'l soon tell you!

Chimaera

Every time the pads hit the disk, they wear off a little bit of each other. It's not impossible to think you'd need new disks at this point, particularly on the front since they do most of the work. An easy way to get a feel for this yourself is to check for a lip on the edge of the disk. It might be the case that even though you're not that close to the minimum thickness yet, you'd likely hit and exceed it during the lifetime of the second set of pads and the garage may not want to take the risk of that happening.

Another factor is that the disk might have worn unevenly: if there are a lot of grooves on the surface, it might take a few thousand km of driving before new pads would bed in enough to give full braking performance, whereas on a new disk, they'll bed in after a few hundred km. If the disk is getting close to minimum thickness, it won't be possible to skim them without making them too thin.

As an aside, minimum thickness is set to allow sufficient material for heat dissipation and mechanical strength at the end of the disk's life.

PaddyFagan

Hi,

So I'm guessing is a rear wheel drive german car I'm on my original pads at 78k km, the wear indicator says replacement is due at 100k km. But I know the main dealers tend to advise replacing the disks around the same time as the pads, I believe the guidance from the manufacturer has very strict limits on disk wear which triggers this. I'm sure a back street garage would a) replace the pads at a fraction of the cost and b) comment more reasonably about the state of the disks.

Paddy

gctest50

coylemj wrote: »

The pads are not fully worn - the garage said there's 3,000 kms left on them and anyway the particular car has wear sensors.

And there was no mention of corrosion, it was described as wear in that the thickness of the discs was getting close to the recommended minimum, how can that happen if I'm still on the original pads?

could be a bad batch of discs

after asbestos was removed from brake pad material disc wear seemed to increase too though

corkgsxr

Chimaera wrote: »

Every time the pads hit the disk, they wear off a little bit of each other. It's not impossible to think you'd need new disks at this point, particularly on the front since they do most of the work. An easy way to get a feel for this yourself is to check for a lip on the edge of the disk. It might be the case that even though you're not that close to the minimum thickness yet, you'd likely hit and exceed it during the lifetime of the second set of pads and the garage may not want to take the risk of that happening.

Another factor is that the disk might have worn unevenly: if there are a lot of grooves on the surface, it might take a few thousand km of driving before new pads would bed in enough to give full braking performance, whereas on a new disk, they'll bed in after a few hundred km. If the disk is getting close to minimum thickness, it won't be possible to skim them without making them too thin.

As an aside, minimum thickness is set to allow sufficient material for heat dissipation and mechanical strength at the end of the disk's life.

You'd want serious groves to take several thousand kms to bed in

coylemj

PaddyFagan wrote: »

Hi,

So I'm guessing is a rear wheel drive german car I'm on my original pads at 78k km, the wear indicator says replacement is due at 100k km. But I know the main dealers tend to advise replacing the disks around the same time as the pads, I believe the guidance from the manufacturer has very strict limits on disk wear which triggers this. I'm sure a back street garage would a) replace the pads at a fraction of the cost and b) comment more reasonably about the state of the disks.

Paddy

Spot on Paddy, thanks for that.