Brake Pads

Faults and Technical chat for the Volvo XC40
TazMone
Posts: 2
Joined: Fri Nov 19, 2021 2:00 pm

Post by TazMone »

HI

We just had our 1 yr old manual T3 serviced (7k miles) and they have reported that the rear brake pads are 40% worn. That sounds a lot to me considering the age and mileage. I dont use cruise control etc. Does this wear sounds normal to people?

Thanks

blastpipe
Posts: 565
Joined: Tue Aug 28, 2018 9:04 pm
Location: UK

Post by blastpipe »

Yes seems pretty normal these days.

Most seem to report getting around 20k out of pads these days given they wear so much quicker without asbestos in
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Deleted User 3629

Post by Deleted User 3629 »

The rear brakes do seem to wear more on the XC40, and do feel its more to do with set up of the re-gen system but brakes are a subjective to use - the more you rely on brakes than anticipation the more wear I guess - 40% worn @ 7k miles does sound a little excessive???
ciuncky
Posts: 205
Joined: Thu Jul 04, 2019 2:46 pm

Post by ciuncky »

Re-gen has nothing to do with brakes, Oldie! Quite the opposite actually. Besides that, OP has a T3.
I did manage to get about 15k miles (a lot of city driving) out of my T4 AWD - haven't replaced yet on the back but they're at 90%.

I did get into a row with the service as they told be i was at 60% during my Sept yearly service, then 90% early November when i took it in for a heating pad replacement.
A bit weird but will have to change soon, so i can avoid disc damage too.

So yeah, i'd say it's about what you can expect from it
Deleted User 3629

Post by Deleted User 3629 »

And you know that for certain ciuncky - it was explained that the brakes form part of a re-gen system and is located to the rear brakes, and pressure distribution of the breaking system is weighted more to the rear for that reason???
blastpipe
Posts: 565
Joined: Tue Aug 28, 2018 9:04 pm
Location: UK

Post by blastpipe »

AFAIK Regen doesn't use brakes. Surely regen is all about saving energy for re-use NOT transfer it as heat via braking system.

As the car the OP mentioned is a T model then it is not a mild hybrid anyway.
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Felindre
Posts: 777
Joined: Wed Dec 23, 2020 2:19 pm
Location: South Wales, UK

Post by Felindre »

Na, don't know who explained that to you, the brakes are just regular brakes.

Regen works by increasing the alternator charging load which adds drag to the engine (and thus increased engine braking) and increases battery charge at the sane time ready for stop start. The latest 'mild hybrid' they've replaced the regular starter motor and alternator with a much larger 48v motor/generator attached to the engine via belt drive. This is used the same way for regen, but also used to start the motor (starting no longer has that harsh motor noise, now totally silent) and I believe also assist with initial rolling away to reduce the fuel needed to move the vehicle from stop.

They also use the variable rate charging of the alternator to reduce the charging on starting to reduce the load on the battery.
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Deleted User 3629

Post by Deleted User 3629 »

As explained to me - Volvo recovers kinetic energy during braking in order to reduce fuel consumption and emissions. The battery symbol is shown in the driver display when the car is generating power for the battery. The function is available in all drive modes together with gear position D or B.
blastpipe
Posts: 565
Joined: Tue Aug 28, 2018 9:04 pm
Location: UK

Post by blastpipe »

Oldie wrote: Sat Nov 20, 2021 9:31 am As explained to me - Volvo recovers kinetic energy during braking in order to reduce fuel consumption and emissions. The battery symbol is shown in the driver display when the car is generating power for the battery. The function is available in all drive modes together with gear position D or B.
That is likely so...but the term braking often is used without implying the brake pads are used...it is perhaps meant to say slowing the car. To recover energy it mustn't be dissipated as heat. Heat is formed when pads are used. There will be other forms of regenerative 'braking' without the use of brake pads to capture the energy. Brake pads will last longer with energy recovery in use.

The key point is though is it relevant to the thread about a T3 brake pad wear. I say it isn't as it is a T3. Might be a different case if it is a B engine with mild hybrid.

All interesting stuff though.
T4 Auto AWD R Design March 2019
Deleted User 3629

Post by Deleted User 3629 »

Ok but they also explain - The energy efficiency of a conventional brake is only about 20 percent with the remaining 80 percent of its energy being converted to heat through friction. The important thing about the regenerative braking is that it may be able to capture as much as half of that wasted energy and put it back to work. This reduces fuel consumption by 10 to 25 percent , hence regenerative braking system plays an important role in the regenerative system. ???
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