[Closed] What’s causing this? Unhappy car disc brake content

Bits of winter salt betwixt pad and disc?

Stone/grit stuck in pad. Don't worry.

Aye potentially, I did take the back roads to the shop.. it only started as I put it in reverse so maybe something sat there and when I moved backwards it’s jammed in. There's something in there alreet!

Looks worn out. Iirc some brakes (Vauxhall?) are meant to howl when the pads need doing rather than turn a light on. Might be bollocks as I was told it by a guy who used to work for Qwikfit, who also used to be a sniper.

It’s making a horrific noise at anything above 5mph. Tempted to absolutely nail it and then jab the brakes on.. bad idea?

If it was mine and not pissing with rain, I'd jack it up and spin each wheel in turn. Then take the offending wheel off for a closer look.

I got rid of my trolley jack and other tools a while back so not an option unfortunately, plus it’s peeing down with rain. Also not sure with it being twin motor EV if the wheel would even spin if I jacked it up? There’s not even a handbrake to operate.

Your pads are worn right down to the backing plate, get them changed soon as possible or you'll be replacing discs as well.

Those disc are already dead.

Cheers. I’ll go and have another look as car only has 5k miles on it and most braking is regen so not sure how it could be worn down so much

Defo looks like it's ready for new pads. Hard to tell from that pic but they could easily be down to the metal.

EVs can sometimes go through discs faster than a conventional car. The lack of actual braking means a significant oxide layer can build up on the discs. Each time they're then used, you scrub substantially more material from the surface than you would for a normal car.

The discs look ok, I think the photo above just makes them look thin due to phone camera flash. Here’s a better photo of disc and also pad

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[url= https://i.ibb.co/LkbFgcD/203-D121-F-7-E71-4-E8-F-BF7-D-41-C525-D37-CFC.jp g" target="_blank">https://i.ibb.co/LkbFgcD/203-D121-F-7-E71-4-E8-F-BF7-D-41-C525-D37-CFC.jp g"/> [/img][/url]

Looking at both photos, the pads have at least 5mm on them, I seriously doubt that's a wear indicator causing the howling. Your discs could do with a clean up really but rears and lack of use due to lockdown miles and regen braking has probably caused that. I personally would be doing some harsh braking to try and clean them up a bit, there's no obvious pitting on the surface though so I doubt that's your issue. Sudden squealing that has started and occurred regardless of you pressing the brake or not is most likely trapped debris, I would suggest from previous experience jammed between the disc and the backplate - the vibration seems to wedge it further down so can take some force/bending of the backplate to dislodge.

Might be a tramp or child stuck in them. I'd sober up and report to your closest police station.

As above - stone/debris causing the noise. Rear brakes don't work very hard and often get surface corrosion on the discs. Mine look pretty scaby when compared to the fronts which do most of the work.

Well there’s something noisy trapped in there! 😂

Cheers Retro. It’s been used regular by my wife to get to work at the hospital so most probs down to the regen doing 90% of the braking. Gonna get up in the morning and do some heavy braking see if that helps 👍

If you can manage to get an angle to look (much easier if you still had a jack) I would try and get a look behind the disc in the gap to the backplate as that's where my money would be first. Had it happen on a "surface dressed" road with a tiny piece of gravel before and made a hell of a lot of noise for something so tiny.

It's not the disc thickness I'd have concerns about. It's the braking surface. After driving, It should be smooth and wearing evenly. Hard to tell but looks scored to me, but could also be where the pad isn't contacting entirely to scrub off all the surface rust from being parked. Low carbon discs are worse for this overnight rust.
5k miles? I'd be back to the dealer with those. No brake disks aren't a warranty item but still worth a chat.
Maybe the do just need using up to decent temperature to refresh the braking surface. Trouble is all that rust dust ends up in the pad /fills the pad slot

Second pic shows plenty of brake pad left which means there's an easy solution to what will be (probably) salt build up leading to oxidation of the discs causing imperfect pad contact and squealing. Take it for a drive and build up braking gently then if safe to do so brake from 60 down to rolling a few times gradually building up pedal pressure on each try.

As it's an issue with the rear discs only (and modern automatic handbrakes), if its only you in the car on the majority of journeys then I'd load up the car with bodies/ballest in the rear as otherwise the load balancing sensor in the braking system may not apply full pressure to the rear caliper.

Should work.....probably.....if not and you crash then don't blame me, im only a gob on a forum.

It’s been used regular by my wife to get to work at the hospital

Ask her whether she's noticed any noise, or did she just turn the radio up? 😉

As somafunk says, try a few 60-0 stoppies. Even better if you do it in reverse gear.

a guy who used to work for Qwikfit, who also used to be a sniper

Could he take the wheelnuts off using the impact driver from 500 meters away?

No pics for me.

At 5k itll be debris and road salt I'd imagine go n give it a run and use the brakes a bit get the discs to clean up.

Who get's rid of trolly jacks and tools. Shock horror.

Mine are getting hammered, and we've even bought more - why, son has a car now and insists on doing everything himself. Changed the suspension top bushes this weekend !

Had exactly this on my wifes golf

The AA man was all doom and gloom like the above posters until he took a look.

It was a stone stuck between the backing plate and the disc near the caliper

Jack up take the wheel off and spin and get the stone out.

PS use those brakes hard every now and then or you'll be buying new discs often. Same happens with rear discs on my mums car as she never brakes hard enough for the rears to do anything.

Defo looks like it’s ready for new pads. Hard to tell from that pic but they could easily be down to the metal.

Your pads are worn right down to the backing plate

Those disc are already dead.

Wow! Quickfit are here in force today!

It was a stone stuck between the backing plate and the disc near the caliper

+ 1

No amount of hard stops will get it out, needs poking with a bike spoke or similar.

Thank you for the replies all, the sensible and the funny ones! I've had a good chuckle reading through the responses.

All sorted now. I've been out and kicked its head in for a good 20 mins and it's now silent again. the offending disc still has some visible marks on it but it looks better. Even did some of the suggested emergency brakes in reverse. I actually rather enjoyed myself!

re. the tools.. when you put it like that @fossy it does sound a bit silly of me! But the last car I serviced myself was a 2004 Passat NA petrol number in 2008.. and even that wasn't particularly straightforward.. I've got absolutely no business whatsoever poking around underneath my Tesla and the driveway is on a slope.. so tools have gone to someone who will hopefully use em.

Good advice re. giving the brakes a good hammering now and then. I need to make sure to take the time to turn regen to low now and then and give them some stick. Seems crazy putting huge discs and calipers on an EV but they do look nice and are no doubt helpful when trying to pull up the thick end of 2 ton of saloon car..

Cheers all

Seems crazy putting huge discs and calipers on an EV

It's done because you have no regenerative braking available when you drive away from a chargepoint at 100% fully charged - but you still need to slow the car. So friction brakes are still necessary.

In the alps there are chargepoints at the Cafe at the top of some of the mountains.You can imagine the sheer terror that would be invoked if you charged the car to 100% at the top of the mountain and then had to drive all the way to the bottom with no brakes!

Just to say, I wasn’t suggesting that it needed new pads. My money would also be on a stone between the pads and the disc.

I was just saying that disc usage in EVs can’t be as easily correlated to mileage.

<span class="skimlinks-unlinked">You</span> can imagine the sheer terror that would be invoked if you charged the car to 100% at the top of the mountain and then had to drive all the way to the bottom with no brakes!

I don't really think you'd need to worry about driving to the bottom of the mountain, with no brakes the car is going to find it's own way down, pretty quickly at that.