Dimples in rear brake disks

[DrooPG]

Hi All,
Just noticed 3 small (~5mm) dimples in the rear brake discs on my W205 C200.
Googling suggests they are either wear indicators or some sort of brake performance improvement feature.

Any suggestions?

DrooPG

 

[W1ghty]

Hi All,
Just noticed 3 small (~5mm) dimples in the rear brake discs on my W205 C200.
Googling suggests they are either wear indicators or some sort of brake performance improvement feature.

Any suggestions?

DrooPG

Picture ?

 

[SamW]

I understood a random dimple (kinda looks like it’s a small drill hole that hasn’t gone through) is for balancing purposes.

 

[Gazwould]

Wear indicators ?

 

[carat 3.6]

Hi All,
Just noticed 3 small (~5mm) dimples in the rear brake discs on my W205 C200.
Googling suggests they are either wear indicators or some sort of brake performance improvement feature.

Any suggestions?

DrooPG

Some discs have sets of 3 dimples spaced around the friction surface as "pad scrubbers", they work in the same way as grooved discs.

 

[Petrol Pete]

Some disc manufactures put a few dimples on the swept surface of a solid disc to allegedly allow the pad to 'gas/scrub out' , you don't see many of them around and almost all (normal) MB cars have non drilled/slotted rear discs as standard.

IMHO the vast majority of road cars could quite happily get along with plain discs all round that would probably improve both day to day performance and vastly improve pad life.

That was almost always the case OEM . until.......the disc could be seen through the (now common) alloy wheels , so holes and/or slots are now a 'must have' ....

Nothing wrong with the discs you have on , just not OEM spec.

 

[DrooPG]

Nothing wrong with the discs you have on , just not OEM spec.

Thanks for the suggestions. My discs are OEM, in fact, they are the original discs from new. Turns out the 3 dimples are wear indicators, as Gazwould suggested. When the dimples aren't visible any more, the disc should be considered to be at minimum thickness and require replacement. Cheers.

 

[Petrol Pete]

Thanks for the suggestions. My discs are OEM, in fact, they are the original discs from new. Turns out the 3 dimples are wear indicators, as Gazwould suggested. When the dimples aren't visible any more, the disc should be considered to be at minimum thickness and require replacement. Cheers.

You have had this car from new ?

 

[DrooPG]

One previous who I know.

 

[Petrol Pete]

Fair enough , but just about every run of the mill MB car in recent history has been delivered from the factory with plain rear discs , including AMG models like mine . But , as we all know MB quite often have a 'new' idea that they try out on any model at any time in an effort to 'improve' their product.

The list is endless , anything from deleting drain plugs from TC units to having some models with larger disc brakes on the rear than are fitted to the front.

It's what keeps us coming back to this platform

 

[DrooPG]

Not sure if the so called dimples have become over stated. The discs are completely plain apart from the 3 very small dimples spaced at 120deg to each other.
See pictures in link below.

Pardon our interruption...