Brake wear

Submitted by upgreyhound.844 on Fri, 17/02/2012 - 20:27

Hi everybody,

i need your opinion ; the in-dash computer is telling me that it's time to visit the work shop because my brakes are wearing out. My G 500 ( 2003 ) has 89000 kms. Should i only change the pads or the rotors also. Of course the dealer wants to change the whole thing but i have some doubts since they look quite good unless you know something that i don't !

Thank you

Comments

M2dxb's picture

Re: Brake wear

Submitted by M2dxb on Fri, 17/02/2012 - 21:14.

Hi and welcome.
I did the brakes & discs (all 4) on our 2000 G500 at 176k kms, but this was not driven by mileage, rather by observation.
Generally your discs will need changing if they are below/at the minimum thickness or are badly scored or have large variations in the disc surface (like radial peaks and troughs) assuming everything else is okay with them. Some of the variations can be sorted out by machining/turning but only if you have enough thickness left. Did you have any problems with the brakes previously?

You can check the thickness yourself and compare with the minimum, on ours the minimum was printed on the hub of the disk, approximately 27.4mm (new is 30mm):
http://seekpart24.com/mercedes/g-class-w463-89/g-500-463-247-463-248-463...

So don't take their word for it. A lot of times they will recommend a change if they think they will go below the minimum by the next service in x 1000 miles, but beware that new discs require new pads generally so as not to score the new discs with the shape of the old pads.

upgreyhound.844's picture

Re: Brake wear

Submitted by upgreyhound.844 on Fri, 17/02/2012 - 22:48.

Thank you M2dxb,
but what do you mean by " was not driven by mileage, rather by observation " ?
To answer your question : No, i never had any problems with the brakes and i can't feel any variation when i touch the disc with my fingers .

Thank you

M2dxb's picture

Re: Brake wear

Submitted by M2dxb on Sat, 18/02/2012 - 16:42.

Sorry I should say, we didn't change them based on "the car has done X miles" but rather, by measuring their thickness with a micrometer.

Pistonhead's picture

Re: Brake wear

Submitted by Pistonhead on Sat, 18/02/2012 - 19:29.

Brake pads and disc or rotors tend to wear with use and how you use your brakes, depends upon the time for wear.  In general, the pads wear out between, at around 30 - 36,000 miles with adequate wear on the discs to take on another set of pads.

I mentioned, that the pad and disc wear is conditional upon braking habits; if you brake heavily, almost at the last moments to stop in time, this pattern of braking diminishes braking life.  If, however, you gently brake over a longer distance, then the pad and disc life is extended.

You may expect disc life to be around 70 - 80,000 miles between renewal.  A tell-tale sign of excessive disc wear is to visually gauge the build up of lip around the disc.  Given the new disc is 16mm thick, and the minimum is 14mm, you can allow a 1mm lip either side of the disc.  To accurately measure, you need to do this with a micro-meter.

A good dealer should give you the measurements of the discs wear at a "B" - service, Mercedes Benz service schedule requires the Technician to record this.

Cheers,