Gubu.ie

Meanwhile, back in the real world: those steep mountain descents have been unusually hard on the camper's brakes these last several weeks (yes, I know about engine braking - will start a separate thread on that in due course). A bit of abnormal noise meant I had to do a sooner-than-expected check on the pads. This is what I found on the left front:





Inside pad on the left, outside pad (or what used to be) on the right. So what's going on there? And how do I fix it? New pads are on their way; don't yet know whether the same asymmetric wear is evident on the other side, as I held off removing the wheel till SonNo1 was around, so as to give him a lesson in checking and servicing brakes.

Looks like a seized piston on a 4 pot caliper. Is it a 4 pot or 2 pot.
I suspect its 4. Caliper will need to be taken off, stripped and a rebuild kit fitted.

How did that pass a test???

Send him over to Ireland where I can give him a proper lesson on brake servicing, which has not been done due to your dancing .

4 pot? 2 pot? There are two pistons on the caliper, slightly different sizes, both on the same side.

kadman wrote: ↑Fri Mar 18, 2022 1:23 pm How did that pass a test???

The test was back in September.

Unless you div 75k miles since september, then it was evident at the last test.

The pot with the thick unworn brakepad is the stuck piston I would suspect, then other is probably moving.

I could have answered your thread question "Whats going on with these brakes" in one word. " Neglect".

But I am much too nice for that.

kadman wrote: ↑Fri Mar 18, 2022 1:28 pm The pot with the thick unworn brakepad is the stuck piston I would suspect, then other is probably moving.

Still none the wiser. Both pistons are on the same side (the unworn pad); I have no idea what a pot is when it comes to brakes. Never heard the term before ...

As a rule, I check and change (if necessary) the pads every time I switch from summer to winter tyres and back, so that should have been just before the test (coz I was heading into winter territory). But I don't have a written note to that effect. Without checking my receipts, I'm pretty sure these pads were changed in July-August 2020, after which the vehicle was essentially off the road until Sept 2021 - apart from three visits to the testing centre.

I've seen uneven wear but never that dramatic, could the friction material (or most of it) have fallen off rather than worn away. Friction material can break off both shoes and pads but I've only seen it happen when the parts have been on the vehicle for many years or after an episode of brake binding.

When you have made sure that both pistons are moving and releasing, make sure that the pins that the calipers slide on are not seized and that the caliper moves freely on the sliding pins. Like Brian says material can seperate from the metal backing, so buy the best pads, not budget pads.
Check the disc condition and thickness. If worn roughly they can be machined flat cheaply if they are still within spec. New discs are cheap.

Almost certainly seized caliper body.

If it were me driving a camper on mountain terrain, and those were my front brakes, I’d be fitting new calipers, disks and pads.

BrianD3 wrote: ↑Fri Mar 18, 2022 2:20 pm I've seen uneven wear but never that dramatic, could the friction material (or most of it) have fallen off rather than worn away.

Took the other wheel off yesterday, and the two pads on that side are the same size as the thick one on the bad side (and only a couple of millimetres less than the new ones). As there was no issue flagged by either the tester last spring/summer nor the mechanic who replaced the engine in the autumn (and he flagged up plenty of other things), and as the problem first presented itself when I applied firm pressure coming off a fast motorway run onto a short slip-road (non-services parking zone), I think I'm going to go with this "catastrophic failure" as the likely explanation.

Stripped everything down yesterday. One pin on the bad side was a bit sticky, but the matching one on the good side was worse, so no obvious cause-and-effect there. Have put everything back together for now in advance of my next trip, which will be over mostly flat (ish) terrain, and will review the situation after Easter when I switch to summer tyres.

Sounds very plausible given that three of the four pads are barely worn.

If the "worn" pad had worn that much compared to the others , you'd surely have had obvious symptoms of binding brakes - strange sounds, burning smell, hot wheel, camper not rolling back when you release brakes on a slope, signs of scorching on the worn pad (I don't see any) etc.