Brake disc life

[Denty]

Car is 2003 C220cdi.Bought from MBenz Direct with 18000 miles 2005. Needed new discs all round at B service carried out by main dealer at 25000 miles total cost £1000+. Then again needed new discs at 43000 miles recently when failed MOT due to excessive vibration when braking (this had not been evident to me and was only shown up on the rolling road during test). I think this is excessive - I drive very conservatively - but having referred to MBenz Customer Service they do not want to know because the MOT and 2nd disc replacement was carried out by my local garage (who I trust implicitly) and not by main dealer (having seen their prices you can guess why!)
Anybody else had this experience and is there anything I can do other than grimace and bear it? Many thanks

 

[television]

Hello Denty and welcome.

It is unusual to need 4 new disc as the rear outlive 2 or more front disc, are the rear disc worn after 18 k miles,I do not think so as they only have 28% on the braking force applied to them, someone here is not being honest I feel. My SL weighs in at 2 tons and still on the original rear disc at 36k miles, and thats a fast car

 

[SQ_W211]

I agree with Malcolm, the rear brakes should not wear at this rate. Did your local garage provide you with the worn parts after replacing or did he dispose them? It could be that he just tried to make little extra on the MOT. There is no chance of the discs of being at fault as they should all wear at standard rate and I have never heard of any defected brake discs EVER.

Someone has make some money from you. Not sure if it is MB or your local garage.

 

[Denty]

Hi television and Amo rahal
Many thanks for these comments. As I say I do trust my garage without question and they put the car on the rolling road so I could see the distortion on the gauge. The faults were much worse on the front nearside and the back offside but obviously they had to replace the discs as pairs. They did give me the old discs (they always offer to give replaced parts) and I was hoping to take these to the MBenz main dealer who fitted them at 25K but as I say they do not want to know! Is there anything else I can do?

 

[television]

Not really, disc can warp, and this should have been picked up at the time, did you not feel the bumping when you braked

 

[Birdman]

Puzzling. My W210 E55 has had its present discs for over 50k miles. The brake vibration problem I experienced was due to disc patching. This I cured by a series of fierce 10-60-10 mph braking sessions. Do you have patching on your discs? Not bedding in the pads correctly - which is done as above - and holding the car stationary on the footbrake after a particularly heavy stop can cause patching - ie uneven transfer of pad material onto the disc itself.

 

[Denty]

Thanks again for comments. As far as patching is concerned I assume I would be able to see this but there seems to be no evidence on the discs which were recently replaced. I appreciate the car is well out of warranty but with the general consensus being that you should never have to replace discs twice within the first 43000 miles on any car let alone a 'quality' Mercedes the thing which really annoys me is that MB are flatly refusing to get involved as the MOT and previous A service were not carried out by them. To answer another point I was not aware of any vibration and thought the garage was Joking when they said it had failed.

 

[television]

They would have to be a long way out to fail, cant recall hearing of this one, and I will check with the MOT guy in the morning

 

[Birdman]

What is the amount of wear on the replaced front discs, in millimetres? You can tell from the diference between the unworn outer rim, which will have a slight 'lip' to it, and the area worn by the pads.

The only cause I can think of is if the discs were not securely bolted to the mounting and you then raced or rallied the car. But even if you did (and I take it you did not) warping a front disc let alone a rear disc, is an improbable event. Have you checked them yourself for 'run out'?

Could be faulty manufacture I suppose...

 

[SQ_W211]

Yea it could be faulty/cheaper MB part. cnt think of anything else which could cause this

 

[wireman]

The disk is held sandwiched between the hub and wheel so no problems will occur if the little screws provided to hold the disk in place are not realy tight because its got five big 12mm bolts at a high torque holding it much more securely than the holding screw could ever do, if you over tighten the securing screw it can be a swine to remove when you need to change the disk. It is there only to hold the disk in place so no particles get between the hub and disk (thus causing disk wobble) during wheel off procedures.

Stopping from heavy braking with very hot brakes and holding the car on the brakes will distort or "patch" the disks since the pads will insulate their contact area of disk or soak heat from the disk at a rate different to the rest of the exposed disk, this is bad driving practice, the car has a parking brake for this purpose (and if you don't use it it can sieze up), vented disks seem (to me) to be a little more prone to distortion as a result of regular abuse.

The disks are usually made from a softish gray cast iron and respond well to a good rub (at each service interval) with abrasive papers to remove the glass hard surface spots which they accumulate at each hot stop and hold cycle. Make sure to get all the abrasive remains out or this may also reduce disk /pad life.

If the disks are "abused" so to speak regularly their life will be shortened, I seem to require new disks for each second pad change.

 

[britnordic]

Denty
Mine is a similar age, but C270cdi Estate, I bought it with 35k on the clock in 2007. To date its done 85k. Rear pads replaced at 51k. Front discs and pads replaced at 83k. All MB parts fitted by Jib.
I wonder what you had fitted?