Grand C4 Picasso 2014Pads and discs
Posted 20 September 2018 - 12:29 PM
Posted 20 September 2018 - 01:40 PM
Welcome to the forum.
40k miles is good for a set of pads and discs to last but it depends on how many times the brakes have been used rather than the distance covered. Cars used for mainly long trips will do more miles before they need replacing. On a C3 we bought I had to replace them at about 16k miles and 4 years, a year after getting the car. The previous owner must have done a lot of round town driving and worn them out. Usually by the time the pads are worn down the discs will also have worn down to their minimum thickness so it is normal to replace both at the same time.
Now it is impossible to say how worn the pads/discs were a year ago and your driving may not be the same as the previous owner. You might be using the brakes more often per mile than before so the wear rate could have increased. However, you could look at the service records to see how the brakes were at the previous services, our dealers give a print out which lists the items checked and includes pad wear.
You do not need to have the pads/discs replaced just because the dealer advises it, they might just be wanting some extra work. They will give a recommendation on whether they think they will last to the next service at the service interval mileage (could be 12 to 20k miles depending on the engine). You can always measure the parts yourself but a micrometer will be needed to check the disc thickness. New discs have a thickness of 26 or 24 or 22 mm (depends on the model/engine) with a minimum of 2 mm less, measured away from the outer wear ridge. New pads have a friction material thickness of about 12 mm with a minimum of about 3 mm - if the garage is saying 90% worn that will mean the friction material may be down to 1 or 2 mm - you can get a quick idea using a torch to look at the pads through a wheel and seeing how far away from the disc is from the inner edge of the pad metal backing. The metal backing is about 6 mm thick if you want to measure from the outside of a pad to the disc - at 90% worn the garage must be suggesting about 7 or 8 mm from the outer edge of a pad to the disc.. You would also need to check the inner pads as well as the outer ones in case they have worn more.
Something to bear in mind. Servicing of brakes is not part of the normal service so at 4 years old your brakes have probably never been serviced and could be a bit seized up with brake dust. On our cars, I remove the pads every year or 2 depending on mileage and give everything a good clean.
Posted 21 September 2018 - 08:50 AM
Thanks for your reply.
What I am trying to get across is that my driving style is "economic." I work fro home and avoid rush hour driving where there would be a lot of stop start. And even if my usage was the same as the previous owner, I would still only account for 25% of the wear on the pads and discs.
Posted 21 September 2018 - 12:06 PM
Maybe there was 6 mm of friction material on the pads when you bought the car and at the same wear rate you would expect there to now be 4 mm which could still be ok for some time. However, the build up of brake dust could have made the pads a bit seized so the wear rate is now higher than before, even though you hardly use the brakes. I would still do the measurement checks yourself, just to see if the garage is trying for a bit of work. At 44k miles though many cars will be on replacement pads/discs, they are not difficult to diy replace either and a garage might do them in an hour.
Looking at my records, our 2007 C4 at 46k miles the front discs were down to mimimum, our 2011 C4 the front discs/pads were replaced at 44k miles, our 2003 C3 front discs/pads were replaced at 36k miles, our 2010 C3 the front discs/pads were replaced at 16k miles. All replacements were since the discs were down to the minimum thickness, rather than the pads being down to their min. Discs seem to wear a lot quicker now asbestos is not used in the brake pads.
You could still go back to the supplying dealer and see if they will replace them or give you a discount since you were not expecting them to need replacing so soon.
Posted 21 September 2018 - 01:53 PM
Dealer that supplied the car has a policy of replacing parts more than 50% worn on a previously owned vehicle
That sounds like an unusual policy from your dealer. Certainly when I tried for a new set of tyres on a C5 which I was buying from a Citroen dealer, he wouldn't agree because they were not near the limits, although they were worn beyond the 50% level.
You could probably get away with just the pad change. My C5 is at 61K now with the front pads about 1/2 worn but the discs will also need changing next time around, so my guess is that it's on its second pair of pads.
A Xsara which my daughter bought from new needed new front pads at 36K although the discs didn't need changing.