Do I need new brake disks?

londonTiger

actually, 5mm was an overestimate in my part. the fronts have 6-7mm, one of the rear has 3mm and the other has 5mm -- puzzling.

I think the 3mm is making squaling noises when braking too.

The pads on my car are 17.2mm thick new - not 10mm. So it's gone through a fairly long life. I really don't mind changing the rears because they'll be due some time soon I imagine - and changing one wheel at a time is pointless. Might as well do the whole axle.

Flying-High_2

Those Discs from the Pic look fine to me... Is there a deep lip at the top? If not then don't worry. IRC you've a MK4 Golf?... Pads and Discs are cheap enough when the time comes. Straight forward job with simple tools but you'll ideally want a caliper rewind tool for the rears.

Norman_Castle

one of the rear has 3mm and the other has 5mm -- puzzling.

I think the 3mm is making squaling noises when braking too.

Its possible the pads are sticking in the calipers.

alastairq

Also, differnt types of vehicle may have differnt levels of [brake] servo effect?

it is possible a van [designed specifically to control the weight of heavy loads]...has a well servo'ed braking system?

[The servo magnifies the driver's pedal effort]

gilbert_and_sullivan

Those discs look fine to me too, but you never know what the inside surface is like till you actually see it.

Similarly you do not know what condition the pad material is in unless you actualy remove the pads, you cannot go by pad depth alone.

From the sounds of it the brakes could do with a flush through with fresh fluid, but more importantly with the uneven wear i too suspect a sticking caliper or slider, it would benefit from a full strip clean lubricate and bleed out.

red_eye

Weird_Nev wrote: »

DO NOT CHANGE PADS with 5mm on them!
They come with less than 10mm in many cases. You're changing your pads less than half way through their useable life!

If your brakes feel a bit spongy and indistinct, then a fluid flush by someone who knows what they are doing is the way forwards.

Those discs look absolutely fine to me. Of course they end up with circular wear marks on them: they are turning as they are clamped by the pads. If in doubt, ask a garage to use calipers to measure them. Manufacturers publish minimum thicknesses. But the thing that really kills disc is pitting and rust from under use. NEver wash a car and then let it sit in it's own juices. Take it for a drive afterwards, to clean and clear the discs of water.

For reference, here are pads I took off of my BMW: Working perfectly, no squeal at all, and passed an MOT a couple of weeks beforehand:

I would be changing pads long before whats left on the pads in your pic.

the more material you have on the pad the less heat the piston and the fluid will have to deal with.

surface rust is fine, its when its deeper down it acts like 10 grit sand paper

londonTiger

hmm, jsut spent £20 in new brake pads (rear axle). Only to takr the wheel off and find that it indeed has 5mm left and do not need replacing. Just from the angle I was looking at through the wheels, it seemed there was less pad thickness because the backplate is a lot lwider than the pad itself - which made the pad look thinner.

I have just bled out the the 4 brakes using gunson eezibleed and the braking is a tab bit sharper than before. Also the brakes used to squeal before and I thought that was the pad mechanism indicating the pads are worn out. But it seems that it was brake fluid related.

The brake system uses and clutch system share fluid reservoirs. I was not able to find the clutch fluid reservoir as it is located under the battery and requires quite a bit of different units to deassble before reaching it.

Is it a problem if I just bleed the brakes and not the clutch?

The manuals say that each corner needs 200ml bleeding, and the clutch needs 100ml bleeding. Am I OK with leaving the clutch bleed alone or will it affect the braking performance too?

colino

The squealing wont be fluid related unless you had such a large air bubble directly at the wheel to make the pad chatter in the caliper, not very likely and the brake probably wouldn't have worked at all on that corner.
No great worries not being able to bother bleeding the clutch line. They may share a common reservoir, but that's it. They don't share any other components and there is no crossover.

forgotmyname

You dislodged a bit of rust whilst bleeding them. Thats why it stopped squealing.

Remove the pads and check the anti-squeal shims are fitted. Add a TINY dab of coppergrease to the REAR of the pad and that will also help.

Norman_Castle

Also the brakes used to squeal before and I thought that was the pad mechanism indicating the pads are worn out.

Nope. Thats the pads sticking in the caliper.