Brake disk scoring on 2019 Corolla Hybrid

[johnnylakes]

Hi all. Noticed scoring on the brake disks on all four wheels of my 2019 Corolla Hybrid Saloon 1.8. It has only 16000km/10000miles done. Has anyone seen this before. Some of the scoring is fairly deep.

[Mooly]

If all four are the same then my first thought is simply that they haven't seen enough usage to keep the disc polished. Discs get a coating of 'rust' on them within hours of becoming wet or damp and so if it stands outside and does low mileage and particularly if that is mainly at low speeds then the corrosion builds up.

I can't think of anything else. If you break hard enough and often enough then the pads will eventually (and it takes a long time) start to contacts the whole disc. Rear discs also do very little work normally (particularly with no weight in the car) as there would be a tendency for the light rear end to lock under breaking. 

 

[AndrueC]

The discs on all my vehicles looked a bit grotty. It's the price you pay for not using them. There are stories of light brakers having to replace discs because of surface condition rather than because they are worn. Hybrids don't use physical brakes much anyway (or shouldn't be) so I'd expect the surface to look poor basically from disuse.

The only time I'd expect my brake pads to make physical contact with the discs would be when stationary. Sadly, I know that once or twice I have had to go beyond electrical braking but that would be a mistake on my part. There should rarely be any need for that much braking force.

 

[Catlover]

Only when safe to do so - when I back out of my drive (which is not always) I will do a quick hard brake, just to try to keep brake sliders etc moving. Same going forward - when safe I will brake very hard.  As for scouring, you only need a larger bit of road dust, call it a small chipping, to lodge and get stuck and it can scour easily,.

[nielshm]

Mine looks just fine. The brightest photo is front, the darker one is the back. I've done 15.000 km. The car is always parked outside. 

[MagicBoy]

If OP lives near the coast that could explain it. As Catlover says, a hard stop can help shift corrosion before it takes hold.

[johnnylakes]

Could very well be from lack of use. Car could be parked up outside for a week or two at a time. Then when I'm at home all I would be doing is short journeys, only a couple of km. When it is used for long journeys it motorway driving and I try avoid hard braking. Might have to get more aggressive with my braking. Magicboy said about being near the coast. I live about 2 km from the sea

[Timmon]

In another topic I speculated what might happen. The Hybrid technology is all about energy recovery, and My T actively encourages light brake usage. If city driving mostly, the brakes will hardly be used. 

My last car, non hybrid, often needed new disks due to lack of use. I suspect, unless the Corolla is used very frequently, and on the highway with some hard braking, the disks will be replaced through corrosion rather than wear.

My car has 6720 miles now, just over 12 months old, the worst are the rears.

https://photos.app.goo.gl/aiUxpPqiDxmaWJrw7

[AndrueC]

Just checked my discs and somewhat to my surprise they look fine. No rust, no scratches and no pitting. My car just went over 10,000 miles Friday.

[johnnylakes]

The last car I had was a 2011 Avensis Diesel and couldn't keep brake pads in it. Had to replace a set nearly every service.

I would have thought that town driving would use more of the brakes than motorway because of bringing the car to full stops. I suppose really you would want to stand on the brakes now and again. 

[Mooly]

I suspect wear vs speed is very non linear tbh. Imagine dragging the top of your finger across carpet slowly for say 1 metre. Now do it quickly. Ouch!

You need fairly steady breaking from high speeds (50 to 70mph region) to put any kind of real heat into the disc (and particularly rears). Also don't expect just one or two such stops to make any noticeable improvement... they won't. It takes weeks and months of usage to get them polished back up again.  

 

[Timmon]

15 hours ago, AndrueC said:

Just checked my discs and somewhat to my surprise they look fine. No rust, no scratches and no pitting. My car just went over 10,000 miles Friday.

Maybe your garage helps you Andru? I can't use mine as it is too small and is my warehouse!

[Timmon]

13 hours ago, johnnylakes said:

The last car I had was a 2011 Avensis Diesel and couldn't keep brake pads in it. Had to replace a set nearly every service.

I would have thought that town driving would use more of the brakes than motorway because of bringing the car to full stops. I suppose really you would want to stand on the brakes now and again. 

I suppose it depends on how the traffic is. London, nose to tail, the brakes would get quite light usage. On a motorway, breaking for a tail back, coming off slip roads etc, 70 down to zero, I would say gives the disks a good heat up, and you are less likely to brake using the hybrid system only.  Just my logic, and with my old car, I often gave it a few good runs before the MOT, or I would get the phone call saying new disks needed, again!

[Mooly]

I suspect some garages are more objective than others when evaluating condition of discs. Our old Corolla (2003) has only done 36k even now and had the rear discs replaced in 2013 where they were reported as finally being in poor shape. They had looked 'bad' for years, and by that I mean only around 30% of the area with any shine at all, the rest just corrosion.

On the final MOT test before replacement (2013) where they called to ask about replacing them I noticed that the MOT issued actually said 'discs have corrosion but not structurally weakened' and in actual fact the car passed that MOT with the old fitted. So while I knew they weren't great I was slightly annoyed that they kind of implied it needed new to pass. It didn't. 

[johnnylakes]

Had a look at my old Avensis there and the disks are smooth. The Corolla is booked in for service next week so I'll see what they say about it. Must ask them too about the android auto. Amazing how the best practice driving brings up its own problems with brakes. Thanks to everyone for their input. If I hear anything from the service I will let ye know

[Timmon]

21 hours ago, johnnylakes said:

Had a look at my old Avensis there and the disks are smooth. The Corolla is booked in for service next week so I'll see what they say about it. Must ask them too about the android auto. Amazing how the best practice driving brings up its own problems with brakes. Thanks to everyone for their input. If I hear anything from the service I will let ye know

Good luck with the service, still waiting to hear from my dealer when they will be able to do it. 

Will be interested to hear what they say about brakes. With my old car, the garage said to take for a drive on the duel carriage way, and give the brakes a bit of welly when there are no other cars around, to polish them up a bit! I think we have been lucky during the lock down, that is has been dry. Not using the car for a while during wet weather, really gets a good film of corrosion on the disks, and it can be quite hard to shift, unless you take a few long trips to bed them back in again.

 

[MagicBoy]

Other option if you've got a proper handbrake is to drive round the block with it on a notch , so that the pads are lightly contacting the discs for a for a few hundred yards. That was the recommendation from a VW service tech about 20 years ago when my rear brakes were grumbling after the car had been parked up for a week waiting for a new gearbox to arrive from Germany! You just had to ignore the car beeping at you that the handbrake was on...

[Stivino]

1 hour ago, MagicBoy said:

Other option if you've got a proper handbrake is to drive round the block with it on a notch , so that the pads are lightly contacting the discs for a for a few hundred yards. That was the recommendation from a VW service tech about 20 years ago when my rear brakes were grumbling after the car had been parked up for a week waiting for a new gearbox to arrive from Germany! You just had to ignore the car beeping at you that the handbrake was on...

On some cars, the pads aren't used for the parking brake, they have a separate set of shoes to operate the parking brake.

[johnnylakes]

Just to give an update. Had they car in for service and the garage said the scoring was nothing to worry about. Like you all said it from the lack of using the brakes and dust getting in.

As for the Android auto that has been put back until later in the year in Ireland because of Covid

Edited July 2, 2020 by johnnylakes