Quick replies appreciated - how much for brake pads / discs?

[nu11eaf]

Originally Posted by scw

My original discs/pads have over 40k miles on them and still have enough meat on the pads for at least another 10k. Most of that has been commuting 140 miles a day between home and Cambridge with adaptive cruise enabled. Anyone who's used the A14 between the A1 and M11 over the last couple of years will understand how much of a workout the adaptive cruise gets on that stretch.

So I don't think the blame can be laid solely on the cruise control.

Steve

A lot of the pad wear is down to using auto hold and auto parking brake, each time you set off after stopping the pads are on the discs until the rear brakes disengage which does not happen until discs rotate slightly.

[Clan]

Originally Posted by nu11eaf

A lot of the pad wear is down to using auto hold and auto parking brake, each time you set off after stopping the pads are on the discs until the rear brakes disengage which does not happen until discs rotate slightly.

A lot of people think that but how can it possibly wear material off the pads , there is very little pressure in the caliper when the wheels start to rotate . and it will only be a fraction of a full rotation . No , thats a myth and negligible i'm afraid .
When i go to work in the morning there is a 1 mile straight heading down hill all the way to the motorway roundabout , 2 lanes going down . People hammer down there at 70 + mph in their 2 ton cars ( when they should be doing 50 ) and then the braking starts , it carries on and on and on , for over 30 seconds , before they get to the roundabout , i've counted it . That is what wears brake pads and discs out ... remember it is not compulsory to ever press that middle pedal , you have full control of that pedal that is when the wear occurs .
with the auto brake the handbrake prepares to release long before the wheels move..... the clutch , brake pedal and throttle pedal sensors give the early warning signals that you want to move . 👍🏻

[nu11eaf]

I am one of them who believe it, and the head tech at my dealership also is of that opinion and I do not believe it to be a myth so will respectfully agree to differ with your point of view. If the brakes came off before the discs rotated you would roll back on a hill start, this along with pilot assist and adaptive cruise contribute to extra wear on the rear pads, you can not just say it is a myth just your opinion.

[volvo s60 2001]

How can someone think that a movement of 1 to 2mm maximum of the disk could cause any wear to the pads is out of imagination!
I absolutely agree what Clan is saying.

[Clan]

Originally Posted by nu11eaf

I am one of them who believe it, and the head tech at my dealership also is of that opinion and I do not believe it to be a myth so will respectfully agree to differ with your point of view. If the brakes came off before the discs rotated you would roll back on a hill start, this along with pilot assist and adaptive cruise contribute to extra wear on the rear pads, you can not just say it is a myth just your opinion.

Honestly its a myth , an old wives tale , .

I have not driven any great distance with adaptive cruise but are you saying it keeps putting the brakes on without your intervention? and for how long ? That leads me to think you are driving too close or too fast ..probably both ... the system does get updated on every service as they fine tune the system of course ...

[nu11eaf]

Originally Posted by Clan

Honestly its a myth , an old wives tale , .

I have not driven any great distance with adaptive cruise but are you saying it keeps putting the brakes on without your intervention? and for how long ? That leads me to think you are driving too close or too fast ..probably both ... the system does get updated on every service as they fine tune the system of course ...

Yes it does apply the brakes, you set the speed and the distance you want to maintain between you and any vehicle in front and if you approach a vehicle that is slower than you adaptive cruise slows the car down using engine or brakes as required to the same speed as the car in front to maintain that safe distance, the brakes are applied more using adaptive cruise than the driver would normally as we anticipate sooner than the cruise control radar and back off the throttle.
Or in stop start driving it applies the brakes rather than engine braking but the driver would do that anyway.
Its not a case of driving too fast or too close but quite the opposite and does away with the need to constantly adjusting the normal cruise control as you approach slower moving traffic and a great safety feature.
I do not mind having to change the rear pads more often as a small price to pay for this convenient driving aid.

[Philip Fisher]

Originally Posted by Clan

.....but are you saying it keeps putting the brakes on without your intervention? and for how long ? That leads me to think you are driving too close or too fast ....

Clan. Of course it puts the brakes on without your intervention. That is how it works. It uses radar to follow the traffic and adjusts the speed using the accelerator and the brakes. But it only sees the car infront, not 2 or 3 cars in front so it is not as gentle at slowing down as a good attentive driver would be.

[Philip Fisher]

Originally Posted by volvo s60 2001

How can someone think that a movement of 1 to 2mm maximum of the disk could cause any wear to the pads is out of imagination!
I absolutely agree what Clan is saying.

The disk moves far more than 1 or 2mm. The brakes do not release immediately and the pads definitely are still providing some resistance as the car starts to roll. This is the same as I experienced on my old XC70, my existing XC90 and my O/H's V60, so this is obviously a characteristic rather than a fault on one vehicle...... I think it is entirely plausible that this causes additional wear on rear pads and I have too heard this as an explanation from Volvo main dealer service dept.

[Clan]

Originally Posted by nu11eaf

Yes it does apply the brakes, you set the speed and the distance you want to maintain between you and any vehicle in front and if you approach a vehicle that is slower than you adaptive cruise slows the car down using engine or brakes as required to the same speed as the car in front to maintain that safe distance, the brakes are applied more using adaptive cruise than the driver would normally as we anticipate sooner than the cruise control radar and back off the throttle.
Or in stop start driving it applies the brakes rather than engine braking but the driver would do that anyway.
Its not a case of driving too fast or too close but quite the opposite and does away with the need to constantly adjusting the normal cruise control as you approach slower moving traffic and a great safety feature.
I do not mind having to change the rear pads more often as a small price to pay for this convenient driving aid.

Well in time they will refine it , that is what they have been doing with city safety for the last 10 + years , but in theory maybe they will make the transmission change down a gear or two to slow you first rather than braking .

[Clan]

Originally Posted by Philip Fisher

The disk moves far more than 1 or 2mm. The brakes do not release immediately and the pads definitely are still providing some resistance as the car starts to roll. This is the same as I experienced on my old XC70, my existing XC90 and my O/H's V60, so this is obviously a characteristic rather than a fault on one vehicle...... I think it is entirely plausible that this causes additional wear on rear pads and I have too heard this as an explanation from Volvo main dealer service dept.

Assuming a worst case on a hill , when you take off the rotation of the wheel can be measured by the abs wheel sensor which has a resolution of just a few mm . The pad retracts from the disc in a fraction of a second , it is all about timing , the motor releases the pads the moment you demand power , there is virtually NO brake applied while the wheel rotates .
ABS operates around 10 hz , that is 10 on/off operations a second , so you can appreciate how fast it lets go when the throttle first starts to move before the engine starts developing power . It's all about timing which is something a computer is king of of course ..
Your dealer person on the front desk has no evidence or technical know how to advise you , They say that to brush you off or they have picked up hearsay somewhere ... I've seen and heard it all before and i cringe when i hear it ... . ( yes that means i cant intervene as i walk past )