Rear brake pad wear on a RWD - any technical explanation?

[freeforall]

Hi all

I did my 2 years service a few weeks back and my car has a mileage of 25k km. They obviously checked the brakes and they told me that my rear brake pads are almost completely worn whereas the front ones have very minimal wear.

This was a big surprise for me. This is my understanding from a technical perspective: since I have a RWD model, regenerative braking can only be used for the rear wheels only and front wheels will always use physical braking. So I expect the front wheels brake pads to wear way more faster than the rear ones.

Why the complete opposite is happening? Am I missing something here? ?

FYI I do a lot of city driving.

It feels like an engineering problem to me. Probably the car is trying to always brake through the rear wheels brakes on a RWD even when the regenerative braking cannot be triggered. And since it is a pretty heavy car only rear brake pads are taking the hit. I would have expected the braking happening on all wheels to load balance the wear when regenerative braking is not available. (In my case, probably very often to low speed braking in the city.)

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[daveo4EV]

Porsche will use the rears for torque vectoring and dynamic stability control…depends on how hard you've driven it…given that the fronts are not worn - this would most likely be automated systems using the brakes to stabilize the cars - it would be hard to imagine brake pedal application wearing the rears because under normal braking the front brakes would carry most of the load…

when tracking my 911 GT3 w/computers enabled (not turned off) the rears wear pretty quickly…

that being said brake pads are meant to be worn - they are a consumable - and easily replaced - it's a big heavy vehicle.

 

[freeforall]

Porsche will use the rears for torque vectoring and dynamic stability control…depends on how hard you've driven it…given that the fronts are not worn - this would most likely be automated systems using the brakes to stabilize the cars - it would be hard to imagine brake pedal application wearing the rears because under normal braking the front brakes would carry most of the load…

when tracking my 911 GT3 w/computers enabled (not turned off) the rears wear pretty quickly…

that being said brake pads are meant to be worn - they are a consumable - and easily replaced - it's a big heavy vehicle.

Thanks for the reply. I don’t know whether that applies to my case. I don’t keep accelerating hard and kicking off the stability control. If I am not mistaken, each time the stability control gets involved the correspondant yellow icon in the dash starts blinking. It did happen but rarely and only when the tires are still cold.
As of torque vectoring I believe I don’t have that on my car. I did not option it when I ordered.

Note: also my front tires were worn at 18k kms whereas my rear tires are still ok at 25k kms. My understanding if you drive a RWD car hard, rear tires should wear faster. So tires wear behavior are not matching brake pad wear behavior.

Agree about the brake pads being a consumable I was just surprised and it didn’t make sense to me the garage didn’t push BTW to get them changed right away. He told me to do it when the light for the brakes will turn on

 

[SergeyIndy]

This does not make sense to your point @freeforall. My best advice would be to compare your experience with other RWD owners with the same mileage and what does your maintenance journal state regarding brake pads.

I am not a RWD and can only say that my front tires are wearing out much faster than the rears and my maintenance journal states that brake pads are due to be replaced only at 6 years for age and not wear and assume it is specific to my brake setup type: PSCBs.

 

[freeforall]

This does not make sense to your point @freeforall. My best advice would be to compare your experience with other RWD owners with the same mileage

I hope some of them will be reading this thread and share their experience

 

[Gru]

same car, 2yrs (and a half) service after 77k km scheduled for this wednesday. I'll let you know.

I moved from 20" to 21" after 55k km with the original Michelin: I could have keep them a bit more.

 

[Gru]

Note: also my front tires were worn at 18k kms whereas my rear tires are still ok at 25k kms. My understanding if you drive a RWD car hard, rear tires should wear faster. So tires wear behavior are not matching brake pad wear behavior.

I see only one reasonable explanation: lot of drifting around rd pt des Champs Elysees.
Front tires take all the weight while rear brake pads control the trajectory...

 

[freeforall]

I see only one reasonable explanation: lot of drifting around rd pt des Champs Elysees.

Actually I take that rond point very often.
You may be right then. The car is almost drifting and PSM works so well that I don’t even feel it ?

Only one solution to find out: disable PSM

=> I will let you know if I hit a wall

 

[Gru]

back from service : all fine, no sign of worn brake pads (rear or front).
Actually that service was cheaper than the 1st one : 696€

 

[freeforall]

back from service : all fine, no sign of worn brake pads (rear or front).
Actually that service was cheaper than the 1st one : 696€

Ok thanks for the feedback. It is my car then, not a general issue/behavior

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