Pitted Brake discs - oldcarwest
Following up the letter published in the may 31 edition I recently had a safety report on my Grand Scenic 1.9 dci first registered september 2004 with 29000 miles saying the discs were pitted. When I challenged such unwelcome news on a three year old car with less than 30K miles I was told it was because I used the bakes a lot on local journeys and discs lasted much better on cars doing high mileage on motorways. Is this problem a Scenic failing, a general Renault problem or are all makes now requiring new discs at such an early stage.
In addition to the disc problem this Spring the heater (which never performed well) reostat burned out and cost about £350 to replace -mainly labour- and the glow plugs had to be replaced after the meassge came up "check injection". I am told the plugs do wear out but Renault do not specify a time or service mileage replacement interval leaving owners to be confronted with a worring meassage at any time.
Pitted Brake discs - Collos25
Glow plugs under normal use should last around 5 years 80k ish miles because one is faulty you don't have to change them all they are quite cheap to buy and not all that difficult to fit, were the discs looked at by Renault or an independant if it was Renault it is part of the service teams script on a car outside 3 years old to say the discs want replacing go to an independant for a second opinion.
Pitted Brake discs - Bill Payer
Disks tend to pit on cars that aren't used much - they go rusty and then small amount of local use doesn't rub the rust off.

Having said that, it was noted on my car's MOT that the disks were pitted and might need replacing soon. It shortly after went in for service and the dealer was keen to change them. However on dicovering that the car was on a service contract they suddenly decided that the disks were fine!
Pitted Brake discs - Brit_in_Germany
Can anyone tell me why pitted brake discs need replacement? After all, high performance discs can be drilled. I would have thought the only criteria for replacement would be lack of material or lack of braking efficiency.

Pitted Brake discs - Group B
Where my girlfriend used to work they had a Celica as a pool car and the rear brakes on that were quite badly rusted, as it used to sit for a week at a time in the car park not being driven.

The discs were not pitted as in having holes in a flat disc surface, the disc surface was very uneven such that the pad contact area was much reduced. Even thought the front discs were in okay condition, when driving it you could feel the braking power was not what it should be.
Pitted Brake discs - Red Baron
You are quite right to speculate. Pitted discs do not, per se, require replacement.

If not pitted to severely (deeply) then skimming or grinding may resolve the problem. But you cannot know how far to grind until you reach bottom. By then you may have replaced the discs more cheaply.

Discs pit through lack of use. But unless the car suddenly get driven much much more requently then the pitting will only worsen.

Discs pit because of improper storage. After driving on salted/gritted roads, don't put the car in a garage and go on holiday for a week. Rust and pitting will set in especially where the pad is resting on the metal.

How inefficient does the braking have to get before the disc is replaced. If its a gradual thing it may never get noticed. Until it is too late. Severe pitting will cause premature failure of discs as they are now weakened.
Pitted Brake discs - yorkiebar
Mot test will fail a disc for the following reasons.

A brake disc or drum insecure, cracked or excessively scored, pitted or worn.

If in doubt about whther needed or not ask an mot station for an opinion!
Pitted Brake discs - doctorchris
My Panda 4x4 had worn its front disc pads by 25,000 miles. I measured the disc thickness and it was below the wear limit so I replaced pads and discs at the same time.
It is not unusual now, due to the materials used, for discs to wear as quickly as pads. The Panda 4x4 is not a fast car but it is heavy and I drive it quite hard so I saw nothing unusual in the replacements I had to make.
Pitted Brake discs - Armitage Shanks {p}
Last May I had an advisory on my car's first MOT, for pitted rear discs. This year it failed on that point and I took it in to have the discs and pads replaced; the garage rang me and said they could skim them and I said go ahead. When I went for the retest the tester was scathing about the job done; he passed it but gave me another advisory and said they hand't skimmed the discs - just cleaned them with a grinder. He said it was a waste of time to skim discs as they could be replaced for £15 each, on my car anyway.
Pitted Brake discs - spikeyhead {p}
You're right, non vented discs cost eht trade about £10 each. A set of pads will be £15, so you're looking at £35 an axle set to replace non vented discs and pads for a standard car. I'm well aware tht the cheapest I could get discs for a Porsche GT3 was over £100.

Labour, even I can change an axle set on most cars in half an hour. Any back street mechanic can do the job.

Rear discs will corrode more as the pressure on them is too low to clean the discs unless they've been deliberately spec'd to be a lot smaller than teh front ones and you regularly brake hard.

Pitted Brake discs - jbif
He said it was a waste of time to skim discs as they could be replaced for £15 each, on my car anyway.

Think of it as a service to mankind and the environment - they prevented a set of discs going to waste disposal.

p.s. I was charged £10 +vat environmental waste disposal fee for disposal of a 1 inch square piece of sill that had to be cut when it was welded.

Pitted Brake discs and MPH to KPH - Doug Sussex
I have a 2004 Scenic too, its done just over 31K and I've been told that front and rear discs are close to the minimum, even though the rear pads are only 50% worn. Is the rear status a feature of the parking brake? Certainly it's disappointing that the discs appear to have worn so quickly. By the way if anyone wants to know how to switch the digital speedo read out from mph to kph, you have to hold the top rocker switch down on the computer stalk, put the card in the ignition slot (but don't touch the brake or clutch) and press the on button. After 5 seconds the speedo will flash mph, keep the on button pressed, the speedo will then flash kph, keep the button pressed, the kph will then stop flashing - release the on button and the top rocker switch. The press the on button twice (as per the readout instructions) and hey presto you have kph for European driving. It will stay kph until you repeat the process.
Pitted Brake discs and MPH to KPH - DP
Our 2004 Grand Scenic will next month have its first front disc replacement (and 3rd pad replacement) at 54,000 miles. The discs are heavily lipped, but not scored or pitted, and the brakes feel fine.

The car does about 15k a year with a mix of motorway and town use. Most journeys are 20+ miles.

These are heavy cars (wrong side of 1500kg), and the diesel engine has precious little engine braking, so the brakes definitely work for a living

Good info on the mph/kph switch. I guessed it could do it, but didn't know how.


Edited by DP on 17/06/2008 at 00:08

Pitted Brake discs and MPH to KPH - Maurice Waite

I was just browsing about the life of brake discs on a Scenic (I've only had the car since 35,000 and just had replacements all round at 54,000, so I hope they were the first it's needed!), and I quite unexpectedly came across your method for changing to kph. Brilliant, worked first time, and I've tried to do it several times by following the driver's handbook, but that has never worked. We take this car abroad once or twice a year, so it'll be great having the right reading instead of having to remember the mph equivalent of each continental speed limit (as well as allowing for the fact that the speedo over-reads by 1-3 mph, going by the GPS). With a digital readout, you can't even stick a paper converter over the dial! Thanks so much!

Pitted Brake discs and MPH to KPH - jc2

Why not just change the GPS to kph?


Ask Honest John

Value my car