Hot brake discs (rear)

[NX01]

Hi

 

Can I get peoples thoughts on a query.

 

After a 10 mile county road drive with light brake usage should the back brake discs be very hot to touch.  Fronts are fine.

 

Noticed a warm smell for a while but this is all I can find.  To start with i just thought new tyres Goodyear F1 6s but that was back in April and have now dkne about 3000 mile since they went on.  Rims are not warm and neither are tyres.  Fuel consumption is normal, so far got 1/4 tank left and have done 450 miles which for the 220TSi is good.

 

One thing I have noticed is an increase in road noise from the back when you get above 30.  

 

Garage tell me there is nothing they can see and have checked brakes and done a recalibration on the electronic handbrake.

 

Thanks for any and all advice.

[Carlston]

3 hours ago, pentaxian said:

Hi

 

Can I get peoples thoughts on a query.

 

After a 10 mile county road drive with light brake usage should the back brake discs be very hot to touch.  Fronts are fine.

 

Noticed a warm smell for a while but this is all I can find.  To start with i just thought new tyres Goodyear F1 6s but that was back in April and have now dkne about 3000 mile since they went on.  Rims are not warm and neither are tyres.  Fuel consumption is normal, so far got 1/4 tank left and have done 450 miles which for the 220TSi is good.

 

One thing I have noticed is an increase in road noise from the back when you get above 30.  

 

Garage tell me there is nothing they can see and have checked brakes and done a recalibration on the electronic handbrake.

 

Thanks for any and all advice.

 

I suspect a sticking brake caliper and/or brake caliper piston, or a faulty flexible rubber brake hose. Sometimes a flexible rubber brake hose can swell internally, so that brake fluid can pass at high pressure such as when you operate the foot brake, but when you release the foot brake the brake fluid doesn't return easily due to the internal swelling...hence causing the brakes to stick.

 

Jack the car up so that at least the wheel that gets hot is off the ground.

 

Start the engine and aApply the footbrake firmly, then see if you can easily turn the wheel by hand. The engine is started because the brake are only power assisted with the engine running.

 

If the wheel doesn't turn easily by hand, then you have a problem.

 

Edited 13 September, 2022 by Carlston

[NX01]

23 minutes ago, Carlston said:

 

I suspect a sticking brake caliper and/or brake caliper piston, or a faulty flexible rubber brake hose. Sometimes an internally swollen flexible rubber brake hose can swell internally, so that brake fluid can pass at high pressure such as when you operate the foot brake, but when you release the foot brake the brake fluid doesn't return easily due to the internal swelling.

 

Jack the car up so that at least the wheel that gets hot is off the ground.

 

Apply the footbrake firmly, then see if you can easily turn the wheel by hand.

 

If you wheel doesn't turn easily, then you have a problem.

 

 

Thanks, will give that a try on both back wheels, it is both that are getting hot.  I would have thought the garage would have done something like that, they said that they had stripped both sides - cleaned and checked.

 

The car does not appear to be 'being held back' if you know what I mean and it will coast without loosing speed in neutral and as I say fuel consumption has not changed either.  I would normally get about 500/550 from a tank and am on track for that consistently.

 

Could it be bearings at all?  Car is 7 years old and 55k+ miles.

 

Over Covid due to living within someone in the extremely vulnerable category the car hardly moved I think I managed 2500 miles which is about a 5th of what I would normally do. 

 

 

Edited 13 September, 2022 by pentaxian

[Carlston]

37 minutes ago, pentaxian said:

Thanks, will give that a try on both back wheels, it is both that are getting hot.  I would have thought the garage would have done something like that, they said that they had stripped both sides - cleaned and checked.

 

The car does not appear to be 'being held back' if you know what I mean and it will coast without loosing speed in neutral and as I say fuel consumption has not changed either.  I would normally get about 500/550 from a tank and am on track for that consistently.

 

Could it be bearings at all?  Car is 7 years old and 55k+ miles.

 

Over Covid due to living within someone in the extremely vulnerable category the car hardly moved I think I managed 2500 miles which is about a 5th of what I would normally do. 

 

Not using the car regularly, ie. weeks or months, could cause the brake calipers to start to stick especially on an older car.

 

The MOT checks for wheel bearing play, and would fail if significant wheel bearing play was felt. I doubt that is what is causing the smell and heat. Do the foot brake test with the engine running first and see how you get on.

 

After you've done the footbrake test, you could also apply the handbrake and then release to see if that is causing the problem, ie. a sticking handbrake.

 

Edited 13 September, 2022 by Carlston

[NX01]

11 minutes ago, Carlston said:

 

Not using the car regularly, ie. weeks or months, could cause the brake calipers to start to stick especially on an older car.

 

The MOT checks for wheel bearing play, and would fail if significant wheel bearing play was felt. I doubt that is what is causing the smell and heat. Do the foot brake test with the engine running first and see how you get on.

 

After you've done the footbrake test, you could also apply the handbrake and then release to see if that is causing the problem, ie. a sticking handbrake.

 

 

Will do, will be doing that tomorrow.

 

My last MOT was well before this noise started

[KenONeill]

1 hour ago, pentaxian said:

 

Will do, will be doing that tomorrow.

 

My last MOT was well before this noise started

I'd agree @Carlston eventual diagnosis of sticking food or hand brake. Except that I think a sticking handbrake is more likely if both back brakes get warm at he same time.

[NX01]

Thanks Both

 

Just got in from work and having a drink before looking at this a bit deeper and a slight update.

 

Today both journeys had back discs of much reduced temperature.   The difference being the start of the journey.

 

Handbrake off

Pause

Handbrake on

Pause

Handbrake off

Leave

 

Rather than just handbrake off and drive off.

 

The car did feel or whether it was just my imagination a little more sprightly tonight driving home.

[Carlston]

1 hour ago, pentaxian said:

Thanks Both

 

Just got in from work and having a drink before looking at this a bit deeper and a slight update.

 

Today both journeys had back discs of much reduced temperature.   The difference being the start of the journey.

 

Handbrake off

Pause

Handbrake on

Pause

Handbrake off

Leave

 

Rather than just handbrake off and drive off.

 

The car did feel or whether it was just my imagination a little more sprightly tonight driving home.

 

It sounds like the brakes are freeing up with a little use. Maybe just use the car normally for the next week or so and see if things continue to improve. The fact that your brakes are now at a much reduced temperature sounds very promising.