Hum from brakes after replacing pads
Hum from brakes after replacing pads
Author
Discussion

BabysharkDoDo

Original Poster:

5 posts

78 months

Friday 22nd February 2019
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Replaced pads on my Hyundai i30, and now when braking lightly at low speeds I get a hum. Took the wheels off today and checked everything over and it all seems ok, never had this before. Any ideas as to what it could be? Braking at higher speeds or with more force theres no hum just when at low speeds?

E-bmw

11,126 posts

168 months

Friday 22nd February 2019
quotequote all
So, if I read your post as it was written you have JUST done the job & it has JUST started making the noise?

I ask because several time recently people have posted in the technical sections that "so & so just started after so & so" and then when a question gets asked it turns out that, that was months ago & the car has had several different fixes since then.

So, is that the full story?

BabysharkDoDo

Original Poster:

5 posts

78 months

Friday 22nd February 2019
quotequote all
Sorry if it wasnt clear

Replaced the pads Weds, discs are fine no scoring and maybe 1mm of wear on them

Drove yesterday (Thurs) approx 60 miles and noticed that braking was fine from over 30mph to 0mph was fine, braking below 30mph to 0mph I get a hum as I come to a stop. Did wonder if it was fitted wrong or something so took the wheels off today, checked I'd fitted them right way round and wear indicators were on the inside which they were so a bit stumped as I've never had this before and changed pads and discs on other cars before with no issues?

Thanks

E-bmw

11,126 posts

168 months

Friday 22nd February 2019
quotequote all
Thanks for the clarification, it was clear, but it was (seemingly with others) and then it wasn't. wink

So the discs are previous & the pads are new?

What pads are they?

Have they been used "in anger" yet?

BabysharkDoDo

Original Poster:

5 posts

78 months

Friday 22nd February 2019
quotequote all
Yes left the current discs on, and pads are Bendix ones from GSF.

Used in anger? Do you mean slammed on? If so then no?

E-bmw

11,126 posts

168 months

Friday 22nd February 2019
quotequote all
The reason I ask is even if they were in good condition the surface of the disc will have worn such that it isn't perfectly flat, whereas the pads are.

I wouldn't worry about it if you have checked them & they seem OK.

Perhaps consider a few heavy braking manoeuvres (not to a complete standstill and with time to cool down between applications of the brakes) & see how you get on with them in a few days when they have bedded in to the same shape as the disc surface.

Oscar011

169 posts

89 months

Friday 22nd February 2019
quotequote all
E-bmw said:
The reason I ask is even if they were in good condition the surface of the disc will have worn such that it isn't perfectly flat, whereas the pads are.

I wouldn't worry about it if you have checked them & they seem OK.

Perhaps consider a few heavy braking manoeuvres (not to a complete standstill and with time to cool down between applications of the brakes) & see how you get on with them in a few days when they have bedded in to the same shape as the disc surface.
This^^^

As E-bmw says the pads are just trying to locate them self’s. Probably just skimming a slight lip on the discs. If the humming noise is still annoying you get some new discs.
What made you replace the pads? Were they low in thickness or did you have any previous problems with them?

BabysharkDoDo

Original Poster:

5 posts

78 months

Friday 22nd February 2019
quotequote all
Thanks for the replies, changed them as they were getting low. Will see if they go in a few days and go from there!

GreenV8S

30,904 posts

300 months

Friday 22nd February 2019
quotequote all
Take a look at the paperwork for the new pads and see whether they have any bedding-in instructions. Sometimes they just want you to avoid harsh braking during the bedding-in period, but some pad types need to be bedded in following a specific pattern of heat cycles.

E-bmw

11,126 posts

168 months

Saturday 23rd February 2019
quotequote all
[quote=GreenV8S] Sometimes they just want you to avoid harsh braking during the bedding-in period, [quote]

Don't you just love it when manufacturers come out with statements like that?

Judge - "Why did you run over the Mother & twins in their pram?"

Plaintiff - "The instructions on the brake pads I just fitted said.................


Edited by E-bmw on Saturday 23 February 09:22

tapkaJohnD

2,000 posts

220 months

Sunday 24th February 2019
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Bedding-in - whuch manufacturers do NOT recommened it?

Prescise instructions vary, but the intention is to raise the pads' temp to their maximum working temp all in one event.
Choosing the right time and place, brake from progressively higher speeds to slow, until you have gone from your maximum speed to a walk, as quickly as possible. Don't stop doing the process, and then drive normally for a few minutes to allow the brakes to cool.

This is to mature the pads and drive off any residual volatiles, not to shape them to irregularities in the discs, although it will do the latter too. Try it, and see if your brakes still hum.
John

Coilspring

577 posts

79 months

Sunday 24th February 2019
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Most brake pads need to be used normally for approx 150 miles before any heavy braking, a little more if mostly motorway. Using them too hard, too soon will burn the surface, possibly distort the disc because of the pad not fully contacting the disc evenly, and possibly glaze the surface.

Most likely reason for the hum is the discs and pads surface not meeting well, suggesting discs should probably have been changed too. Or no chamfer on the edge of the pads, how did they compare to the ones taken out?

Were they the cheapest option, or the brand you set out to get? Why go for the cheapest ?

BabysharkDoDo

Original Poster:

5 posts

78 months

Tuesday 26th February 2019
quotequote all
Coilspring said:
Most brake pads need to be used normally for approx 150 miles before any heavy braking, a little more if mostly motorway. Using them too hard, too soon will burn the surface, possibly distort the disc because of the pad not fully contacting the disc evenly, and possibly glaze the surface.

Most likely reason for the hum is the discs and pads surface not meeting well, suggesting discs should probably have been changed too. Or no chamfer on the edge of the pads, how did they compare to the ones taken out?

Were they the cheapest option, or the brand you set out to get? Why go for the cheapest ?
Ones taken out had a few mm left on them, the hum seems to have subsided now get it every now and then but suspect it was just them wearing in.

They wern't the cheapest the next ones up, there were 3 options and the next one up was twice the price so opted for the "mid range" of what was on offer.

Coilspring

577 posts

79 months

Wednesday 27th February 2019
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Sounds like good news, the pads are settling and the hum is going.

Middle choice of price was sensible, but not a brand I would use (personal choice, not technical).

What condition were the discs, within measurement limits I assume, but possibly not fully smooth?