Brake Pads

Faults and Technical chat for the Volvo XC40
ciuncky
Posts: 205
Joined: Thu Jul 04, 2019 2:46 pm

Post by ciuncky »

Oldie wrote: Sat Nov 20, 2021 5:31 pm Am not and never have been and don't care a hoot anyway - simply responding to points raised i.e. blastpipe hadn't heard of energy efficiency of brakes, so explained the theory - however, having driven many many cars the XC40 is a first for me to have a reverse logic to brake wear - i.e. rear's wearing out before the fronts - don't care why, don't matter why - they just do - and seems expensive to replace too - oh, and in the world of thermoelectric devices seems you only need nano-semiconductors to convert, and guess they would be very small???
You seem to insist in some idiotic points, totally useless to OP.
As OP mentioned he has a T3, so no re-gen there.

If Volvo indeed uses KERS in the true sense ie capturing heat, converting and storing, i'm sure they'd have made a point of explaining that. And that would be at least 35-40 kgs IF they used top-of-the-range tech such as in F1 cars.
Regardless, it wouldn't apply to OP's car.

Besides Hill Start, handbrake etc, you'll surely notice the car doesn't lean forward very much when braking, so perhaps more pressure is applied to the rear to keep the car as level as possible, or as comfortable as possible going by their Comfort driving mode.

So yeah, maybe learn when to stop and accept that you're wrong, or learn to read the question properly

Deleted User 3629

Post by Deleted User 3629 »

oh dear that's me told off, Just having a giggle ciuncky so don't take any of the points too seriously, however your suggestion of KERS sounds cool??
eugen61
Posts: 1211
Joined: Sun May 10, 2020 7:33 am

Post by eugen61 »

Just had my second year maintenance service with 19k miles on board, T4 FWD, no regen brakes. 90% of my miles are driven on country roads and motorways, with no passengers and no luggage. I never use auto hold brake and in the rare occasions when I engage the parking brake I always release it manually .

My brake pads turn out worn 50% back and 25% front, will have to be changed when wear reaches 75%. Asked Volvo’s mechanic and got a simple explanation for the higher wear in the back vs. front: back pads have a smaller contact surface with the disk, so in order to apply equal stopping force the smaller surface back pads will wear faster than the bigger surface front ones (front and back pads have identical thickness).
Deleted User 3629

Post by Deleted User 3629 »

Many car manufactures apply brake bias to their systems, often with the front brakes receiving more pressure, hence why larger discs at the front than rear, or drums at the rear, its an extra reason why front tyres wear quicker and why the front can dip quite a lot on some cars. Some manufactures do apply more pressure to the rear brakes to help lower front tyre wear and reduce the dip on the front during braking - the evidence seems to suggest Volvo is one of these manufacturers that apply either equal or more pressure to the rear - my argument would be, surely if your are going to apply more pressure to the rear of the car then the disc should be of equal size to the front and/or ventilated as the front?
Deleted User 3359

Post by Deleted User 3359 »

The basic physics of braking is that the Centre of gravity of the vehicle transfers far forward under braking... Any motorcyclist (I am one) will tell you that the front brake does a high percentage of the work and the rear you just have to stop locking up. Additionally on 2 wheels you make sure the front tyre is only doing one job - in this case only braking, not steering... doing both on the road is the way to high side and get badly hurt.

When cars are front wheel drive the front tyres have three jobs to do; applying drive, steering and braking, when the weight is transferred as described above, it's no wonder that front tyres wear more quickly and that brakes are larger...
eugen61
Posts: 1211
Joined: Sun May 10, 2020 7:33 am

Post by eugen61 »

Cornishman wrote: Fri Nov 26, 2021 7:22 pm The basic physics of braking is that the Centre of gravity of the vehicle transfers far forward under braking... Any motorcyclist (I am one) will tell you that the front brake does a high percentage of the work and the rear you just have to stop locking up. Additionally on 2 wheels you make sure the front tyre is only doing one job - in this case only braking, not steering... doing both on the road is the way to high side and get badly hurt.

When cars are front wheel drive the front tyres have three jobs to do; applying drive, steering and braking, when the weight is transferred as described above, it's no wonder that front tyres wear more quickly and that brakes are larger...
Larry, you’re right about the physics of braking a front wheel drive car like my T4 FWD. But having eliminated parking brake, hill assist and auto hold it’s hard for me to find a definitive explanation for the higher wear on back pads…
drjamesr
Posts: 34
Joined: Sun Feb 10, 2019 4:54 pm

Post by drjamesr »

But as a cyclist, I know it makes sense to apply the rear brake before the front, in order to not be tipped over the handlebars. Does Volvo apply this principle to the XC40?
XC40 Inscription, D4 AWD, Pine Grey, black leather faced, 19” double spoke #924, Xenium, Intellisense surround, Winter/Htd wheel, Spare wheel
jamie307
Posts: 367
Joined: Mon Apr 15, 2019 8:01 am

Post by jamie307 »

Surely it's cruise control and speed limiter using the rear brake? I guess people who use these functions and drive a lot on gradients most frequently will see the greatest wear of the rear pads.
T3 Momentum Pro Auto MY20 - Thunder Grey - Intellisafe Surround - Winter Plus - 360 Camera - Tinted Windows - City Map inlays - Spare Wheel
Deleted User 3359

Post by Deleted User 3359 »

drjamesr wrote: Sat Nov 27, 2021 9:23 am But as a cyclist, I know it makes sense to apply the rear brake before the front, in order to not be tipped over the handlebars. Does Volvo apply this principle to the XC40?
The physics are the important thing a near 2 tonne car doesn't behave like a push bike, where the main weight is the rider - hence the propensity on over application of front brake to propel the rider over the bars... I've seen motorbikes do "stoppies" (the opposite to a wheelie) but NEVER a car...
Deleted User 3629

Post by Deleted User 3629 »

Have read BMW use brake bias more to the rear on some of its cars. Physics are often mentioned so hear is some observation physics - more brake dust evident on the rear wheels, more wear on the rear brake pads, more wear on the rear brake disk - apply the observation and the conclusion is ...., wait for it.... simply, the rear brakes are working harder than the front - how can this be you may ask - must be, operating systems and brake bias - maybe..............?
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