Front Discs

[survey]

Car just had 4 year snd 30k service. Advised that front discs will need replacement very soon. Both drivers very light brake. Is this wear normal?

[Huskoda]

Standard advisory to generate work.

[KBPhoto]

I'd have a look yourself as I bet they don't need replacing that soon.

Pads might, but not discs.

See above post for reason why.

[Yety]

Not necessarily.

 

I'm coming up to 40k in three years this December, and it looks like my pads and discs will wear out together from new.

 

It all depends on your usage, type of driving style, removal of light rusting due to weather etc - loads of things. Funny scores, part rusting is irrelevant to braking efficiency.

My other cars do much less mileage with bigger wear, the MG because I thrash it over the Dolomites/Brecon Beacons, the SJ because it runs in muddy /gravel tracks at speed most of it's life.

 

The critical thing is the minimum disc width, if close to or approaching the wear limit, then new discs and pads to suit are required.

Minimum disc width is specified by VAG, so ask if it complies.

[survey]

I'd have a look yourself as I bet they don't need replacing that soon.

Pads might, but not discs.

See above post for reason why.

My thought exactly. The pads are apparently fine!

[Ryeman]

Is there a 'step' on the rotors?......usually inboard edge of swept area.

You can also usually see the depth of outer pad remaining through the wheel spokes.

[900000]

Just had my 38,000 miles and four year service last week. They did not give an advisory on the front ones, but said the rear ones are "pitted". Whatever that might mean. Checking the front ones they have a lip on the outer most edge and the rear ones are half warn as per most all Yetis (apparently) with only half the pad having ever touched the disc. They are making noises now when you step on or off the brakes... and after a test drive they said probably need replacing.

 

On Yeti-man's advice I will source some Brembo discs and Ferrodo pads - standard Ferrodo pads to the rear and some high spec pads to the front.  I'll get someone to fit them OR ask the dealer if they will.

 

Pics:

 

Front left:

 

Front right:

 

Rear left:

 

Rear right:

[Carlodiesel]

As a normal rule of thumb, 2 sets of Frt pads to 1 set of Frt discs. 

When you change discs & pads change brake fluid then.

 

Every year I would remove brake pads, clean with brake cleaner, re copper-slip back of pads & refit. 

 

If discs are in tolerance take the angle grinder & remove lip on disc.

 

I'm pretty sure frt discs are 22mm  Min' thickness 19mm.

 

YG

Edited 21 October, 2014 by Carlo diesel

[briskycat]

On Yeti-man's advice I will source some Brembo discs and Ferrodo pads - standard Ferrodo pads to the rear and some high spec pads to the front.  I'll get someone to fit them OR ask the dealer if they will.

 

Do not forget to replace sliders in the rear calipers as they usually are the cause of such troubles with the discs.

[muddyboots]

Do not forget to replace sliders in the rear calipers as they usually are the cause of such troubles with the discs.

Thanks for that, wasn't aware of this. Won't be long before I need to replace pads/discs all round, so it's useful info.

[kenfowler3966]

Mine were all replaced by the lease company on my first yeti at around 40k due to wear, pads lasted as long as the discs.

 

Brake fluid has a 2 year life whether the car is used or not as it absorbs water and must be replaced at that interval otherwise the contaminated fluid could boil under hard braking when the moisture contaminent boils in the fluid, leading to suddenly having no brakes with no advance warning.

[900000]

Mine were all replaced by the lease company on my first yeti at around 40k due to wear, pads lasted as long as the discs.

 

Brake fluid has a 2 year life whether the car is used or not as it absorbs water and must be replaced at that interval otherwise the contaminated fluid could boil under hard braking when the moisture contaminent boils in the fluid, leading to suddenly having no brakes with no advance warning.

 

Preston Motors London did the full service and told me over the phone the brake fluid needs changing and the Haldex oil.  Both "advisory" only...  eh? Brake fluid should be every 3 years and the Haldex every 4. So I said keep the car and do those too.  Was only £100 more.

[Yety]

Preston Motors London did the full service and told me over the phone the brake fluid needs changing and the Haldex oil.  Both "advisory" only...  eh? Brake fluid should be every 3 years and the Haldex every 4. So I said keep the car and do those too.  Was only £100 more.

 

 

Yes fluid does absorb moisture, and yes it "could" boil. But you'd have to drive down the Stelvio flat out before there was even a whiff of boiling - in fact you could run your braking hydraulics on old chip fat - yes I know the seals would swell etc, but you get my point?

 

A lot of old wife's tales seem to be preserved on the interwebby

 

Seriously there is a risk, very remote, of a problem. Probably more of a problem is sticky caliper and pad sliders. Pistons like to be exercised as well from time to time as well, but all this sort of "old fashioned" servicing has been dumped to present a picture of maintenance free running. All very well until some failure, and then you get a big bill to replace all the bits.

 

You might guess I'm old enough to belong to the "old school" of preventative maintenance, which doesn't fit well into today's modern world.

[muddyboots]

Yes fluid does absorb moisture, and yes it "could" boil. But you'd have to drive down the Stelvio flat out before there was even a whiff of boiling - in fact you could run your braking hydraulics on old chip fat - yes I know the seals would swell etc, but you get my point?

 

A lot of old wife's tales seem to be preserved on the interwebby

Have to disagree there. I've had fluid boil on me in the past, and it also happened to my mother once. 

Both during fairly normal driving in the UK, in hot weather driving down a long hill.

It's a horrifying experience to suddenly have your brakes taken away from you.

 

Suppose people don't bother changing fluid. You get away with it during normal pottering about, so you forget all about it.

Then you decide to go on holiday - load the car up to the max with kids, luggage, roof box etc etc for a holiday trip in the summer heat around some scenic (read: hilly) part of the country - and all of a sudden, the extra heat generated by your brakes is too much for the ageing fluid - and disaster.

 

Not worth the risk for quite a small outlay to get it done IMHO.

[900000]

Have to disagree there. I've had fluid boil on me in the past, and it also happened to my mother once. 

Both during fairly normal driving in the UK, in hot weather driving down a long hill.

It's a horrifying experience to suddenly have your brakes taken away from you.

 

Suppose people don't bother changing fluid. You get away with it during normal pottering about, so you forget all about it.

Then you decide to go on holiday - load the car up to the max with kids, luggage, roof box etc etc for a holiday trip in the summer heat around some scenic (read: hilly) part of the country - and all of a sudden, the extra heat generated by your brakes is too much for the ageing fluid - and disaster.

 

Not worth the risk for quite a small outlay to get it done IMHO.

 

 

Agreed...  I tow a caravan so want to be sure the brakes are good.  And it was £40 or so.

[muddyboots]

When I had my Ibiza on a service/maintenance contract, the Seat dealer did a brake fluid change.

 

After I got it back, I had the wheels off, and I could see that only 1 of the 4 bleed nipples had been disturbed - you could tell by the coating of dirt that the other 3 hadn't been touched.

So the only fluid that actually got changed was what was in the cylinder, and in the single line going to the bled wheel (which was actually the OSF, so the shortest line!).

 

So it wasn't a change at all.

 

Since then I do it myself, I use a Gunson's Eezibleed to pressure bleed, and flush plenty of good quality fluid through to all 4 wheels. I might use a little more fluid than necessary, but at least I know it's all done properly.

[Ryeman]

I use a suction kit but start by opening the nipple and pushing the worn pad back fully to expel the worst of the contaminated fluid.

When I pump the pedal I use a lot of very short (normal) strokes to avoid the master cylinder seal venturing into potentially pitted/corroded area which in my experience in the past has initiated a master cylinder leaking problem after doing preventative maintenance to avoid that occurring.

[FlintstoneR1]

Front discs on my 2010 CR110 Yeti are now on the minimum thickness of 19mm at 115,000 miles. Although I suspect they may have been changed during its life with the previous owner around 50-60,000. Brake performance is fine at this thickness, so I'm not in a huge rush to change them. But have laid in the new disks and pads ready from Euro Car Parts. Come the day when I can prise the Yeti out of SWMBO's hands for a day for me to do the job!

 

As to the brake fluid question - I'm with Johann and Muddyboots on this. Change the fluid on my cars every two years. Its surprisingly easy how you can boil the moisture in 3 yr old fluid. 

 - £20 for a new Gunsons Ezebleed kit from Screwfix, spread over two cars and N years of the kit's life. (My old kit was 35 years old and had gone opaque and brittle, so I thought I'd invest in a fresh one!). 

 - £7 for 1 litre of Castrol DOT4 from Opie Oils.

 - 30-45 minutes to whip off each wheel in turn and bleed fresh fluid through to that wheel.

 - Helps if you do the right sequence. On the BMW its left rear, right rear, left front, right front. Expect Yeti will be the same.

 - Job Done!

 - Plus the peace of mind its been done properly! None of this trusting a Main Dealer to say its been done then finding it hasn't as Muddyboots found.  Had a similar experience with a Renault being Main Dealer serviced when under lease. Took it back next day and asked them to do it again - properly.  They said it had.  Till I called Ren-UK Customer Services from their showroom, who then did the persuasion for me.

Edited 23 October, 2014 by FlintstoneR1

[FlintstoneR1]

I use a suction kit but start by opening the nipple and pushing the worn pad back fully to expel the worst of the contaminated fluid.

When I pump the pedal I use a lot of very short (normal) strokes to avoid the master cylinder seal venturing into potentially pitted/corroded area which in my experience in the past has initiated a master cylinder leaking problem after doing preventative maintenance to avoid that occurring.

When you use an Ezebleed, the master cylinder isn't disturbed at all. So this problem is avoided.

[Ryeman]

When you use an Ezebleed, the master cylinder isn't disturbed at all. So this problem is avoided.

But my priority is the more specific elimination of the calliper crud where the worst of the contamination exists rather than diluting that crud with fresh fluid.

Either way, if you're replacing pads, the 'short stroke' is what I use to bring the pads back into contact with the rotor.

And

Wearing rotors combined with worn pads will potentially start 'working' in the calliper bore which is long term damaging.

I know from previous experience the damage from cost cutting.

Or

Don't wear your pads below half life if you don't want to pay for new rotors.

[trundlenut]

Just had my 38,000 miles and four year service last week. They did not give an advisory on the front ones, but said the rear ones are "pitted". Whatever that might mean. Checking the front ones they have a lip on the outer most edge and the rear ones are half warn as per most all Yetis (apparently) with only half the pad having ever touched the disc. They are making noises now when you step on or off the brakes... and after a test drive they said probably need replacing.

On Yeti-man's advice I will source some Brembo discs and Ferrodo pads - standard Ferrodo pads to the rear and some high spec pads to the front. I'll get someone to fit them OR ask the dealer if they will.

Pics:

Front left:

Front right:

Rear left:

Rear right:

I would say that on the rears the pads are sticking on the sliders and not hitting the discs flat. Effectively the outer edge of the pads stick and so the piston twists the pads onto the disc. Hence the rusty outer section.

You may just get away with stripping them down and cleaning them up - particularly the metal shims which sit between the pad and carrier.

Sent from my Nexus 4 using Tapatalk

[FlintstoneR1]

Ryeman - No problem. While you're at each wheel with the bleed nipple open (and connected to the one-way vent pipe of course), push back the pads and pistons first - as you described. I do that when I'm swapping discs or pads as routine anyway, using a simple wind-back tool. Gets rid of the contaminated fluid behind the pistons like you say. Ezebleed just makes getting the fresh fluid through the lines and wheel cylinders so easy - without touching the master cyl or pumping the pedal at all.

 

I take your point about the pistons reaching the outer range of their travel. So also must be outer (dust/crud/wet) seals by the same token.  So I'll be changing the discs and pads on the Yeti this weekend then.  SWMBO will just have to slum it in the Beemer for a day.

Edited 23 October, 2014 by FlintstoneR1

[FlintstoneR1]

I use a lot of very short (normal) strokes.......

Does anyone else miss Bob's innuendo spotting?

 

OK - I'll get my coat and be off to "Bob's corner" then........... Bye!

[Ryeman]

I seem to recall an advisory relating to soft euro rotors and the Bendix Euro+ were developed with pads as well to address the rapid wear issue.

Has anyone heard of them?

[brad1.8T]

regarding fluid flushing - even if you don't get the brakes hot enough to boil the fluid, what will happen is the moisture will tend to sit on the bottom of the caliper or master cylinder & start to cause corrosion.  This isn't an issue until you push back the piston fro a pad change or bleed the brakes with the pump method - then in the master cylinder the seals chop out from the corrosion.  Eventually the corrosion can also cause issues with the calipers but it's usually only ruined pistons.

 

I'd be doing brake fluid every 3 years - max.

 

Dumb question: Why do the brakes corrode so much in the UK?