Grinding Brakes

boatbirder

boatbirder

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Location
Kemnay, Aberdeenshire
Driving
MG3 Hybrid+ Trophy
Hi to all, I've owned my MG3 Hybrid+ Trophy since August and have 3,800 miles on the clock. Recently I've had a problem with grinding rear brakes. When braking I get an horrendous grinding noise from the rear. It literally sounds like the brake pads are down to metal and are grinding on the discs. I'd be stunned if this was actually the case on a new vehicle with such low mileage! I'm wondering if the regeneration (i normally use the regen 2 setting) causes the pads to wear down this quickly? I've also noticed the discs are slightly pitted too.

Any thoughts or has anyone had similar issues?

Thanks in advance.
 
I suspect that where you live and drive, has had some wet weather recently. If so, there is possibly a skin of surface corrosion due to the brakes being used less with the regen effect. If you set the first part of your next journey to regen one, that will let you use the brakes more and will clean off that coating. You can then set it back to two. The other thing to check is for grit or stones caught in the calipers, but I'd suspect it's the damp weather on the discs.
 
DeclanB said:
I suspect that where you live and drive, has had some wet weather recently. If so, there is possibly a skin of surface corrosion due to the brakes being used less with the regen effect. If you set the first part of your next journey to regen one, that will let you use the brakes more and will clean off that coating. You can then set it back to two. The other thing to check is for grit or stones caught in the calipers, but I'd suspect it's the damp weather on the discs.
Click to expand...
Quick response Declan, thank you. I'll give things a go when I'm out next and report back, thank you.
 
Totally agree with Declan, excellent advice. I had virtually the idetical problem. The sales guy at my local dealership said that they are having some cars in after a year with rust ring build up on the rear discs, simply vecause they are hardly used when you have regen on, he advised to not use regen 3 at all because the difference in charging is not that much between 2 and 3. He also suggested that if the car has been sat a few days, certainly afte wet weather is to use regen 1 when you set off, as suggested by Declan so that cleans them off.
 
Hi all, I've been doing Declan's suggestion since the new year and it hasn't made much difference I'm afraid. I'm actually taking the car in to Arnold Clark on Wednesday for a Health Check because of the issue. Plus a few gremlins. One being the car refusing to start on two occasions because it won't release the steering lock. Rectified by switching the ignition off and waiting several minutes and trying again. Another issue has been the heating with none of the options working on the console. Temperature, heated seats, heating steering etc. Press the buttons and they don't respond! I do like the car but it's full of bugs it would seem :(
 
I've continued with Decklan's advice and it is a lot better, just need to brake a few times to clear the rust when I first set off.
 
boatbirder said:
Hi all, I've been doing Declan's suggestion since the new year and it hasn't made much difference I'm afraid. I'm actually taking the car in to Arnold Clark on Wednesday for a Health Check because of the issue. Plus a few gremlins. One being the car refusing to start on two occasions because it won't release the steering lock. Rectified by switching the ignition off and waiting several minutes and trying again. Another issue has been the heating with none of the options working on the console. Temperature, heated seats, heating steering etc. Press the buttons and they don't respond! I do like the car but it's full of bugs it would seem :(
Click to expand...
Sounds like it needs a software reset somewhere..hope you get it sorted they are nice cars..
 
Every hybrid (and EV) has the problem of brake discs that rust. Mainly those of the rear brakes.
However, there is a cleaning trick.
You have an electronic parking brake, which works on all four wheels.
Owner manual page 126:

Emergency Braking Function
Inappropriate use of EPB can lead to accidents and injuries. DO NOT apply the EPB for vehicle braking whilst moving, unless in an emergency. During emergency braking using the EPB, DO NOT switch off the ignition/powersystem, this could result in serious injury. In the event of normal brake failure during driving, emergency braking can be initiated by pulling and holding the EPB switch upward. An audible warning will sound during emergency braking. The braking process will be canceled by releasing the EPB switch.

Occasionally activating the electronic parking brake will apply all brakes and "clean" the discs.
It will be clear that this cleaning trick can only be used safely on an empty, straight road!
Works perfectly with our Honda Jazz, shining discs! 😊
 
Last edited:
boatbirder said:
One being the car refusing to start on two occasions because it won't release the steering lock. Rectified by switching the ignition off and waiting several minutes and trying again.
Click to expand...
I had his happen and few weeks back posted it but no one had experienced it. Would be really interested as to what they say.
 
Every time I park the car wet, on starting up the next day, the rear brake unsticks and there is a grinding noise, as the corrosion is worn away.
 
I had it happen once, there is a separate entry about this somewhere, I'm sure it said the Ready light needed to be illuminated green before putting it into drive

IDC said:
Every time I park the car wet, on starting up the next day, the rear brake unsticks and there is a grinding noise, as the corrosion is worn away.
Click to expand...
Mines the same. I deliberately brake a few times when I set off to clean them and then it's fine. Odd but fine 🤔
 
boatbirder said:
Hi to all, I've owned my MG3 Hybrid+ Trophy since August and have 3,800 miles on the clock. Recently I've had a problem with grinding rear brakes. When braking I get an horrendous grinding noise from the rear. It literally sounds like the brake pads are down to metal and are grinding on the discs. I'd be stunned if this was actually the case on a new vehicle with such low mileage! I'm wondering if the regeneration (i normally use the regen 2 setting) causes the pads to wear down this quickly? I've also noticed the discs are slightly pitted too.

Any thoughts or has anyone had similar issues?

Thanks in advance.
Click to expand...
Got the same problem, bought June 2024, 5000 miles only. Dealer says all 4 discs and pads are badly corroded. Reported to MG for warranty replacement.
 
Anne said:
Got the same problem, bought June 2024, 5000 miles only. Dealer says all 4 discs and pads are badly corroded. Reported to MG for warranty replacement.
Click to expand...
I would really like to know how you get on with this as I think it is a fairly common problem
 
I think it's to do with the regeneration on car..turn it to number one and give it a run where you can brake quite a bit..mine does it after been stood in wet weather for awhile..
 
ptw said:
I think the parking brakes only the rear discs, but that's where the problem is so I'll give it a try 👍
Click to expand...
The parking brake also serves as an emergency brake (Owner manual page 126):
"In the event of normal brake failure during driving, emergency braking can be initiated by pulling and holding the EPB switch upward."

Since the parking brake also serves as an emergency brake, I assume that the parking brake really works on all four wheels. Like it does on our Honda.
If only on the rear wheels, this emergency braking system could cause nasty surprises if used on a not straight road. In a bend, full braking power only on the rear wheels... o_O

 
All that Jazz said:
The parking brake also serves as an emergency brake (Owner manual page 126):
"In the event of normal brake failure during driving, emergency braking can be initiated by pulling and holding the EPB switch upward."

Since the parking brake also serves as an emergency brake, I assume that the parking brake really works on all four wheels. Like it does on our Honda.
If only on the rear wheels, this emergency braking system could cause nasty surprises if used on a not straight road. In a bend, full braking power only on the rear wheels... o_O
Click to expand...
ptw said:
I had it happen once, there is a separate entry about this somewhere, I'm sure it said the Ready light needed to be illuminated green before putting it into drive


Mines the same. I deliberately brake a few times when I set off to clean them and then it's fine. Odd but fine 🤔
Click to expand...
OK, I tried it out and it does apply the parking brake to all 4 wheels and quite severely, you need to release it as soon as it starts to brake otherwise all the wheels lock as you would expect in an emergency. So doing it at speed would be a reall no-no and very dangerous. It did clean the discs as suggested, but a mechanic friend suggests it could cause damage to the handbrake mechanism, certainly over time and repeated use, he suggests just a few hard braking in the normal regen 2 would be better and safer, so that's what I will stay with. Hope this is useful
 
ptw said:
all the wheels lock as you would expect in an emergency. So doing it at speed would be a reall no-no and very dangerous.
Click to expand...

Then there is really something wrong with your ABS system!
ABS is an electronic control unit that prevents the wheels of a vehicle from locking when braking sharply, for example during an emergency stop.

I regularly clean the brake discs of our Jazz in this way. Never experienced the wheels locking up.
 

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