Thread: Rotor wear on a 2011 D4

Originally Posted by niobe

So mechanic reckons he measured the rotors. I will now measure them myself. certainly the rotors have worn up to a millimetre, not more.

What is the original thickness and the legal minimum thickness? Some vehicles only have about a mm or two to play with.

From a mechanics perspective I always machine or replace rotors when doing pad replacement to customers cars. It is the only way I can guarantee no squealing from the brakes after the job is done.
Three times in the last 2.5 years I have not machined rotors (at the customers request), three times I have had customers come back complaining of brake noise. Coincidence?

The rear rotors don't wear evenly across the pad contact area, becoming dished due to the arrow-headed shape of the pads that causes the centre of the pad to outlast the edges with a corresponding uneven wear of the rotor. The pads fitted to the earliest D4 that were fitted with aluminium calipers are full width at each end but because they squealed in reverse if slightly dusty, LR reverted to the D3 caliper and pads. The square-ended pads fit the D3 & later D4 calipers and don't seem to squeal, which is what is currently fitted to my D4. I will be getting those same pads next time if I can.

Originally Posted by BigJon

From a mechanics perspective I always machine or replace rotors when doing pad replacement to customers cars. It is the only way I can guarantee no squealing from the brakes after the job is done.
Three times in the last 2.5 years I have not machined rotors (at the customers request), three times I have had customers come back complaining of brake noise. Coincidence?

Hrrm, so what are the implications if the brakes are already squeeling?

It is really surprising for rear pads / rotors to wear substantially faster than fronts. The majority of breaking force is borne by the front wheels.

My 2011 just had a service at 43000 km. both sets of pads. No mention of rotors. Seems like the wear patterns for most on the forum are pretty similar.

Pat

Originally Posted by Meken

It is really surprising for rear pads / rotors to wear substantially faster than fronts. The majority of breaking force is borne by the front wheels.

With modern electronic braking controls the fronts only do more work in hard braking, for which they have pads with greater contact area. For more gentler braking the rears do as much work so with their smaller contact area they wear faster.

Originally Posted by Meken

It is really surprising for rear pads / rotors to wear substantially faster than fronts. The majority of breaking force is borne by the front wheels.

The fronts will probably do two thirds of the braking, but they also have three times the contact area on the pads.

I have just had a service at 50,000km and the report is 60% wear on the brakes.
I think the difference is that I do a lot of country miles and very little short runs. These cars are certainly very heavy on brakes as we have all observed.