Rear pads worn faster than front ones

[fc919]

Hello, my 2018 C-HR hybrid is at 29.7k miles. During the 30k service, the dealer mentioned that my rear pads are at 5mm. The front ones are still 8mm.

Having done some research online it looks like the rear pads may wear faster due to using the hill hold function or the auto electronic parking brake. 

Have any of you guys faced something similar? Just a bit confused as I thought the front ones would be the first to be worn out.

Also when replacing the rear pads should I get the discs done as well? They seem fine with no significant wear or lip.

Many thanks in advance for your help.

[Devon Aygo]

Yes repeated use of hill hold or brake hold will cause the wear you are seeing, under normal breaking your Hybrid uses regeneration ( uses the electric motor like a big alternator ) to slow the car down so use of the friction brakes and therefore wear is reduced

[fc919]

Cheers, yeah just wanted to confirm that. But is it really going to be that bad?

I'm gonna get the rear pads replaced soon then stop using hill hold. Let's see how it goes. 

[Devon Aygo]

A new pad will have approx 10mm of friction material, lose 1mm for minimum thickness and you still have 9 mm of useable material so 5 mm is only just over half worn at 30k so you will easily see another 10k likely 15k and possibly 20k before they will need replacing. After your next service perhaps follow up in 5k / 6 months with a free VSR to check how they are doing, no need to replace them yet

Edited May 23, 2021 by Devon Aygo

[Stivino]

If you are using your brakes to stop the car from moving while it is stationary i.e. hill hold etc, there will be no friction because the car isn't moving. 

No friction = no wear.

[fc919]

I think it's when the hill hold disengages and the car starts to move, the brake pads do get worn a bit. Same for adaptive cruise control, as the rear brakes may be used to slow it down(based on research on Volvos and VWs). Could there be any other reason for the rear pads to wear faster than the front ones?

[TonyHSD]

Hi,

I am not sure if hill start assist have helped for higher rate of wear but in general Toyota hybrids do wear rear brake pads faster than front since they use them more than the front one, front one are only hydraulically operated however rear one has electric pump that usually applies them first immediately after front wheels are hold by the electric motors regenerative braking, doing so the car equalises the braking force distribution between front and rear axles. I am not a Toyota technician but I am driving various hybrids since 2012 ,done  many miles too and do service myself all these cars and they all have their rear brake pads wear faster than front one, pretty normal. 
Here is the sequence of Toyota hybrid braking when slowing down the car normally, not extreme brake. 

1. Regenerative braking front axle 

2. Electronically operated braking on rear axle 

3. Hydraulic Brakes on front axle in addition to all above. 
4. Slowing down to about 6mph no regenerative braking is available and the car relays entirely on its brake system until complete stop. If you slammed on the brakes all that might be mixed differently to provide faster deceleration. 

Here is something interesting off topic: 
I can sense a strange noise coming from around abs, servo and brake pump area, something like pumping and releasing pressure., and does happens when start the car and immediately drive away slowly, something similar can be heard in aircraft cockpit when ailerons wheels rotates, ailerons trim on 737 particularly. 
Here is the sound that you can look and compare if you car does it too. 

 

[Stivino]

33 minutes ago, TonyHSD said:

Toyota hybrids do wear rear brake pads faster than front since they use them more than the front one,

That is never the case on any vehicle.  On anything that moves, the front brakes do the majority of the work.

[TonyHSD]

3 minutes ago, Stivino said:

That is never the case on any vehicle.  On anything that moves, the front brakes do the majority of the work.

It is here with all Toyota hybrids. Always rear brake pads wear faster than front. 

[Stivino]

9 minutes ago, TonyHSD said:

It is here with all Toyota hybrids. Always rear brake pads wear faster than front. 

Would you like to explain the science behind that?

[TonyHSD]

23 minutes ago, Stivino said:

Would you like to explain the science behind that?

No argument here, I just had explained in my previous post but I will do again : 

the car slows down mostly with its electric motors which are mounted on the front axle, when you further press the brake pedal more braking force is required and the electric motors apply higher regenerative power to the front wheels and an electric pump pressurised rear brake callipers to clamp the pads so the brake distribution is done somehow equally and when you further press the brake pedal direct force from brake pedal multiplied with servo goes into the front callipers, when the car reaches around 6mph the regenerative braking is not available anymore and the car continues to slow down with front direct and rear electric brakes. This is how Toyota hybrids brake system functions. When you drive smoothly and slow down gently front brake callipers will be activated at the end of your braking process if coming to a complete stop, if not there may never been in use for many slows down. These cars has cold brakes, you can travel at high speeds , slow down a lot even downhill and all that for hours then stop the car and measure the temp of the disc and they will be around 25-39C° depending on how hard you had been stopping and the outside air temperature. This is the reason also why hybrids get rusty brakes even on two years old cars. The reason also why vw id series has a rear brake drums instead of discs, they have rear wheel drive and the e motor applies  regenerative braking on rear axle. , front brake discs for safety which will probably last the life of the vehicle. 👍

[Stivino]

Thanks, interesting.

[bathtub tom]

I guess Farhan Chowdhury didn't like the answer they got on Honest John, exactly the same as described by TonyHSD above.

[fc919]

19 hours ago, bathtub tom said:

I guess Farhan Chowdhury didn't like the answer they got on Honest John, exactly the same as described by TonyHSD above.

Hi, no no not that at all. I appreciate the answers I got o of course and I've thanked everyone as well. I went on to Honest John because I was told there are quicker responses there. 

[Mooly]

On 5/24/2021 at 12:32 PM, Stivino said:

That is never the case on any vehicle.  On anything that moves, the front brakes do the majority of the work.

Normally I would have agreed, however my non Hybrid Auris had rear pads fitted this year at 73k. They were down to around 3 to 4mm. The fronts have what looks to be around 10mm or more and are the 11.5yr old originals and have covered 76k now. They look no different to how they were when new. Even the front discs have no detectable wear ridge. The rear wheels got filthy dirty with the original pads, the fronts never have a trace of brake dust on them.     

[TonyHSD]

5 hours ago, Mooly said:

Normally I would have agreed, however my non Hybrid Auris had rear pads fitted this year at 73k. They were down to around 3 to 4mm. The fronts have what looks to be around 10mm or more and are the 11.5yr old originals and have covered 76k now. They look no different to how they were when new. Even the front discs have no detectable wear ridge. The rear wheels got filthy dirty with the original pads, the fronts never have a trace of brake dust on them.     

I think most newer cars made after 2009 have ABS plus EBD electronic pumps (servos) that distributes brake force between front and rear axle so can get better shorter stopping. Yesterday I noticed a Mercedes Eclass estate late hard braking next to me and when he stopped completely the car did not rise the front like would expect from older type cars but the whole car rise up and rear axle was obviously loaded with more brake as it’s jumped up more than the front, I was surprised to see that but it’s not a first time, also noticed that on bmw 3 series. Your Auris even non hybrid may well have similar brakes as the hybrid ones and uses the rear pads more than the front. 👍

[Jamesmckelvie]

Not sure if the car has the corner vectoring system, this is where the car slows a wheel to tighten the line when cornering. 

[forkingabout]

On 5/26/2021 at 4:55 PM, TonyHSD said:

Yesterday I noticed a Mercedes Eclass estate late hard braking next to me and when he stopped completely the car did not rise the front like would expect from older type cars but the whole car rise up and rear axle was obviously loaded with more brake as it’s jumped up more than the front, I was surprised to see that but it’s not a first time

These have a self levelling rear suspension system fitted. 

[AndyRC]

All very interesting, the CEO is now doing nearly 1000 miles a month in her C-HR for business compared with less than 400. Previously rear discs were always looking rusty and unused compared to the fronts. Even now rear discs never look as well used as the fronts so it doesn’t indicate that the rear discs are being used as much as the fronts. Which leads me to think the pad wear issue is down to the electronic park brake. Several threads on hear about rusty rear discs with very low mileage on them. 
 

 

[TonyHSD]

Brake discs can get rusty even with daily use if you use the brakes always gently. You need from time to time to slow down more progressively and let the actual brakes stop the car otherwise it will be done mostly by the regenerative braking and the slider pins will get stuck and stop free movement of the outer pads and so the discs will not be cleaned from surface corrosion. Inner pads will still work and provide stopping power although not as good as it should be. This is happening so often with Toyota hybrids even on 2 years old cars cleaning and lubricating procedures on the brake components is a good idea. 

[Gerry Kettler]

I have a 2012 Toyota Camry XLE with the 3.5 L V6 engine, I have 74,000 miles on it. IJust replaced rear rotors and brake pads. My front pads still have half life on them and the rotors are fine. 

[Jamesae92]

Hybrid chr will most likely need brakes replacing for rotten disc before pads wear off but if you have the 1.2 petrol they wear the rear pads really quickly and its perfectly normal