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Mr_Yogi

Original Poster:

2,563 posts

138 months

[news] 
Thursday 16th July 2009 quote quote all
Right, looking for some help from the PH collective biggrin

Not knowing much about how cars work, can someone tell me if there is an easy way to see how worn my discs and pads are?

The garage has said both front discs and pads need replacing, however alarm bells started ringing when the phrase "your pads are 95% worn" was used, something I read on here years ago.

The car is an 07 Aygo and it's just had a 30K service.

Cheers smile

The Wookie

Attendee

9,954 posts

111 months

[news] 
Thursday 16th July 2009 quote quote all
You need to take the wheels off preferably.

If it's your original set of pads, it's highly likely they will need changing at 30k

boyoM3

160 posts

60 months

[news] 
Thursday 16th July 2009 quote quote all
Around 3mm of pad on each side and its time to start thinking of a new set. Discs usually should last around 30k - 50k depending on how hard your pads are.

If you have any shaking when braking then discs are warped. Mine went recently because they were worn.

Edited by boyoM3 on Thursday 16th July 15:45

Mr_Yogi

Original Poster:

2,563 posts

138 months

[news] 
Thursday 16th July 2009 quote quote all
Thanks,

No problem with taking the wheels off, I can do that hehe

Are there indicators which become exposed as the pad wears down? are these easily visable?

How about the discs?

I thought the pads might need replacing, but I was a bit surprised by the discs too.

Oh well...

GingerWizard

4,691 posts

81 months

[news] 
Thursday 16th July 2009 quote quote all
Wheels off, if you can see the pads then you should know. They usally have a wear grove in the middle, thats the first thing (If your still not sure pop in to halfrauds and have a look at a new set of brake pads, this will then give you the comparison you require). Second put some vernier calipers accross the disk and measure its thickness. Then all you have to do is ask your local dealer (or look in the hand book) what the minimum thickness of the discs are before changing.

Its a good way of making money for some people......

oh and finally, hwo do your brakes feel? If they are as they alwasy where then worry not. Grumbeling and pulling to one side when braking can indicate worn/sticking pads calipers...
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WorAl

10,877 posts

71 months

[news] 
Thursday 16th July 2009 quote quote all
at 30k your discs should not be worn out unless you're one of those people who drive along on an open road and brake for no reason other than to check the pedal is still there. Pads, hmmm could be but shouldnt on your type of car.

Anyway to answer the question, look down through the spokes of the car, you will see the calipers, the pad is inside there, new pads have about 10-15mm of ferodo (the pad) on the disc side of the plate that holds them in place.

this image shows what i would say is about half worn pads.

You can take the wheels off to do this but i wouldnt.

if the discs are worn the 2 pieces of steel will be very thin or have a huge step near the top and bottom, you'll be able to feel this with your finger.

Edited by WorAl on Thursday 16th July 15:41

Mr_Yogi

Original Poster:

2,563 posts

138 months

[news] 
Thursday 16th July 2009 quote quote all
Cheers guys,

braking performance has not degraded as far as I can tell. I'll pop the wheels off tonight and have a poke around, any similar easy indication on the disc wear?

Edit:

or maybe I'll just look through the spokes hehe



Edited by Mr_Yogi on Thursday 16th July 15:44

mat205125

14,770 posts

96 months

[news] 
Thursday 16th July 2009 quote quote all
Without taking the wheels off, finger through the wheel to the edge of the disc. Is there a lip? Finger between the the metal of the pad and the disc. Is this low?

This only checks the outer faces of your discs, however putting the car on lock will enable a quick check the other side.

WorAl

10,877 posts

71 months

[news] 
Thursday 16th July 2009 quote quote all
when i feel mine and feel the rim around the disc, i take the wheel off and have a good look, if it looks thin, then it probably is, you'll get the idea when you have a look.

smele

1,275 posts

167 months

[news] 
Thursday 16th July 2009 quote quote all

I would recommend a micrometer or stepped jaw caliper for measuring thickness, as the jaws of a caliper will interfere with the outside lip of a worn disc.

Most disc brakes have the minimum thickness stamped in the outside edge.


Ozzie Osmond

15,989 posts

129 months

[news] 
Thursday 16th July 2009 quote quote all
I'll be amazed if the Aygo doesn't have a light which illuminates on the dashboard if the pads reach sufficient wear to need changing. Have you read the driver's manual?

Visual check of pads with wheels removed is never a bad thing but doesn't tell you a great deal without knowing what the manufacturer recommends and what the pads looked like when they were new.

Disc wear is again all a matter of the manufacturer recommendation and needs careful measurement, but you can get a rough idea by feeling the disc to see if there's a noticeable "lip" where the pads run on it.

There should always be a good safety margin because if the worst happens your pads can be ejected in extreme wear situations (usually needs both pad and disc to be totally knackered) and then your car has no brakes at all, which is a bad thing....


The Wookie

Attendee

9,954 posts

111 months

[news] 
Thursday 16th July 2009 quote quote all
hehe

Well if you're comfortable getting the wheel off, you're 80% of the way to changing the pads, it really is an easy job that dealers love charging lots for. Changing discs requires minimal effort on top.

As said, if the pads have less than a few mm left, then you should change them. Make sure you check the inner pad, as on single pot sliding caliper brakes it will wear more quickly. DO NOT rely on a finger check of the outer pad.

As said with discs you need to find out the minimum thickness, but a good indication is a significant lip around the outer edge.

Also as said, if the pads have lasted 30k I'd be surprised if the discs had had it as well. I'd expect a set of discs to last longer than that.

Edited by The Wookie on Thursday 16th July 15:53

Deva Link

26,934 posts

128 months

[news] 
Thursday 16th July 2009 quote quote all
There a few videos on YouTube that give you a bit of an idea - this ones not too bad, but DON'T turn the steering wheel of the car unless you've got both sides up on axle stands!
http://www.youtube.com/watch?v=CFFd3TCxC80

(rotor is American for brake disc)

GingerWizard

4,691 posts

81 months

[news] 
Thursday 16th July 2009 quote quote all
The Wookie said:
hehe

Well if you're comfortable getting the wheel off, you're 80% of the way to changing the pads, it really is an easy job that dealers love charging lots for. Changing discs requires minimal effort on top.

As said, if the pads have less than a few mm left, then you should change them. Make sure you check the inner pad, as on single pot sliding caliper brakes it will wear more quickly. DO NOT rely on a finger check of the outer pad.

As said with discs you need to find out the minimum thickness, but a good indication is a significant lip around the outer edge.

Also as said, if the pads have lasted 30k I'd be surprised if the discs had had it as well. I'd expect a set of discs to last longer than that.

Edited by The Wookie on Thursday 16th July 15:53
minimal effort if you have an impact driver my friend...... or arms like Vin diesel

The Wookie

Attendee

9,954 posts

111 months

[news] 
Thursday 16th July 2009 quote quote all
Actually, on the Focus the caliper mount bolts are really easy (lucky as IIRC they're those rubbish Torx heads), and then of course the disc just comes straight off, I'd expect the Aygo to be similar, especially as it's a newer car

Evo not so easy, but still cured with 1 expendable ratchet, both hands around suitable structure to brace, and a well placed foot on the end of the handle hehe

Alternatively you could jack it up a bit more and use a longer spanner

Orb the Impaler

1,881 posts

73 months

[news] 
Thursday 16th July 2009 quote quote all
There are a few examples of worn out discs (and other horrors) on here
http://tinyurl.com/lyz2vwyikes

(specifically Horror of the Week 28/05/09)

I'd suggest not letting them get to this state wink

Edited by Orb the Impaler on Thursday 16th July 16:21

stephen300o

13,568 posts

111 months

[news] 
Thursday 16th July 2009 quote quote all
Worn on left(obviously) less than about five mil is worth replacing.

There is usually a ridge left around the disc when it is worn and the surface will be uneaven, usually a judgement call if they need repacing as no one measures them wink

Ranger 6

4,809 posts

132 months

[news] 
Thursday 16th July 2009 quote quote all
Many discs these days have a wear indicator on them - it's a semi-circular 'imprint' on the outer edges of the disc itself. Once the wear surface breaks the circle then the disc is worn-out.

Look at the picture below and you'll see what I mean, there's no real need for calipers or any fancy stuff.



Be very wary of looking for a lip on the edge of the disc as that can be misleading.

Pads are simple, as has been mentioned.

I would expect a pair of front discs to go through two sets of pads these days before they need replacing.

Edited by Ranger 6 on Thursday 16th July 16:42

tinman0

18,231 posts

123 months

[news] 
Thursday 16th July 2009 quote quote all
Mr_Yogi said:
The garage has said both front discs and pads need replacing, however alarm bells started ringing when the phrase "your pads are 95% worn" was used, something I read on here years ago.
Garage has a lack of work on. Hence you needing new discs.

The chances are that your discs are absolutely fine. I have a Doblo on an 06 plate with 65k on the clock and the discs are beginning to get to the point of being changed, but I still reckon I've got another 15k on them yet. Your 30k is nothing.

Chances are your pads are also fine. You will feel when your pads are shot, because you will literally hear a graunching noise of metal on metal. Also, the brakes will feel a bit crap.

As other people have said, take the wheel off and have a look for yourself. The pads should have loads of material on them. As for the discs, unless you drive the car like you stole it, I cannot see how you would need new discs yet.


160steve

586 posts

75 months

[news] 
Thursday 16th July 2009 quote quote all
WorAl said:
when i feel mine and feel the rim
Sorry but this first sentence made me chuckle. Juvenile i know. getmecoat
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