Although the car passed the MOT a couple of weeks ago, its had a ticking noise from the front or rear (couldn't quite tell) which sounded like it was related to wheel rotation speed.
Since the MOT its been getting worse and today I decided to have a look. Although my mobile mechanic is good, there is nothing like checking it yourself. You know how it is.
After asking my good lady to stand at the edge of the pavement and with me driving up and down the road she could identify the noise was coming from the front offside wheel.

So today I jacked the front offside up using the standard jacking point and using wooden blocks under both rear wheels. I took some of the weight on the jack and then just slackened the wheel nuts off, then jacked it up until the wheel was off the ground.
Rotating the wheel by hand showed a tight spot and the clicking sound was clear.
After fully removing all 5 wheel nuts off came the wheel.
Observation showed the disc had uneven contact. Half of it was shiney and the other half had faint spots of corrosion where there was poor contact.
Turning the disc was not easy because it was binding, although I wasn't sure if it was an issue with the pads or disc distortion.
So I slackened off the lower bolt holding the disc to the carrier and removed the top bolt completely. The caliper rotated fairly easily off the disc with a bit of waggling, but the disc is not far off end of life tbh. Its well corroded and lost a lot of its thickness with a good ridge to the outside edges.Then I removed the brake pads and had a look at them.
The pads were meaty so that was good. However the inside of the disc is distorted and this was reflected in the inner brake pad.
The inside face of the disc has excessive wear on the inner edge creating
a dished effect and the pad is misshapen to match obviously. Not good because the disc is thin anyway from looking at the outer edge.

However the hub was then spinning fairly well.
I can now hear the wheel bearing clicking away as it turns.
But somehow the wheel bearing has very slightly tilted the disc or it could just be disc distortion or combination thereof. But this is causing the uneven disc marks and the brakes binding during approx 50% rotation of the whole wheel.
So now I know.
I've put it back together for now and will order a pair new front hubs and new discs asap. I already have a set of new Mintex pads for the front which I checked in the caliper for correct fit.

I'm going to do this myself because its not too difficult.
I am also not too chuffed with the MOT testers not picking this up and my mechanic not picking it up. He could hear the noise when driving the car but didn't think to check it.
With it being a major safety issue this is one for me to do because it will be done right and I will then be happy and so will my good lady.

Thankfully the weather was kind today and I did it in the dry and about 8 DegreesC outdoors.

I hope to take some photographs as I do it to share on here.
But I am glad I did check it out today. Even with a new MOT it wasn't too clever. It is quite possible the tester couldn't hear the clicking noise, but maybe they should have picked up the worn discs as an advisory.

A pair of discs looking at £70 and a pair of front hubs for £120.
A pair of new disc dust shields are about £20.
No labour or VAT of course.

 

A couple of photos from today so you can see the arrangement.
This is the front right hand side of the car when sitting in the car.
Offside front caliper in English money.


The forum S type "how to" guide for this job is most useful and very easy to understand.
Thank you guys.

 

A tip that might help. Put three lugnuts back on and snug them up. Sometimes the rotor will touch the lug studs and sound like a bearing. Now when you turn the rotor, if it is a bearing you'll hear it clearly.

 

Not sure why this is a 'safety' issue. Maybe it's why your MoT guy didn't flag it.

The rotor damage is very possibly from seized calipers pins, quite common on these cars when not maintained properly. I'd verify this first before assuming that new bearings, rotors and pads are required.

 

I'm surprised it passed the MoT's braking tests. Commonly you can both feel a pulsing and the (brake force) reading fluctuates, and is thus a fail.

For non-UK people: it's classed as safety because braking is impaired. The MoT tests many things, in this case brakes via rollers that can brake individual wheels or both on an axle (not that there are solid axles any more!) and measure what occurs. There's a display to show the brake force moment-by-moment. Each result is stored and compared with the others. (The EPB / handbrake is also tested.)

 

I am not too sure why two seperate MOT testing stations did not pick up the poor condition of the discs. I assume both front discs are equally worn.
Considering they are quite thin generally and even thinner on the inside half of the inside disc face.
I most certainly wouldn't want to drive it like this for very much longer.
I have found the standard of MOT tests varies a lot. Most years on my ford I had advisories which didn't need doing and I didn't do them. The next MOT at the same station didn't comment on the previous unfixed advisories and then gave some more new advisories. I don't know how much is personal discretion by the testers or how much is just poor quality testing.
Brakes and wheelbearings are things not to take chances with in respect to safety. It pays to check these things you self.
I trust me and I trust very few so called technicians.
I'm on a learning curve with my new mobile mechanic and cheap or not, I'm watching him.

 

Mikey, read my op again mate.

The pads on these are not held with pins they just sit within the caliper holding frame and the caliper slides over them. Only two short bolts hold the caliper to the frame. The frame is fixed too, no movement. The frame is so close to the disc that if there was any movement it would hit the disc. Sounds and looks a bit naff to me, but it works.
In engineering terms the caliper should slide in relation to the disc. But there is no means of this on the caliper or on the holding bracket.
I'll photograph this when I do the job. Perhaps other calipers fitted to this car are of a different design? Maybe.

The discs are too worn and with uneven wear on the inside where they are probably even thinner.
This is only the second worse set of discs I've replaced. The inner pad had a 3mm bulge where it's molded to the shape of the inner disc face.

With the caliper and pad off and by spinning the hub I can hear the wheelbearing crackling. Classic sound from a duff bearing. The hubs are dead simple on this which is not a bad thing when it comes to reliability and replacement.

Safety wise? Not replacing these is not an option.
As I said I have a new set of pads which I checked for fit on the caliper holding bracket. Well to be correct it's the caliper and pads holding bracket.

Some things are no compromise with safety, brakes especially..

 

Pics would help as the (non-Brembo) ones I've seen all had sliding pins.

 

Unless the short bolts are into the ends of sliding pins. Possible.
I didn't strip it down further than establishing where the problems were. But when I photograph the hubs and discs I'll do it better.

 

Second photo, top left corner you can see the bolt head of one of two caliper bolts.
The flexi-hose is where the short bolt goes to, so there must be a pin right there hence the compressible rubber hose/shroud.
Got it now !
As I said I didn't look at that in detail. But I'll clean the pins up before reassembly.

 

The OP made no mention of braking difficulty and the MoT guy apparently found no fault.

All the OP has mentioned is a visual deviation and the presence of an unusual noise. Neither are 'safety' items.

 

Obviously not true. I see in another post you've found where the caliper slides in relation to the disc.

Have you measured them to confirm that they are 'too thin'? That's the correct method of assessing serviceability.

Attempting to affect repairs when the fault(s) have not been correctly identified does not improve 'safety'.

 

Exactly. The pins are where the short 12mm bolts go. The pins move back and forth slightly. The pins should be clean and mildly greased with silicon brake grease (I use a 2800 degree tube of it). The black rubber dust covers must not have any cracks or splits. Torque to 26 ft.lbs (34Nm) The larger brackets must also be cleaned so the pins don't stick to the old dirt. Torque those bolts (15mm) to 76 ft. lbs (103Nm).

 

I identified the faults because MOT testers and technicians are not always trustworthy or necessarily any good. From experience that is.
The discs ARE sufficiently corroded, well worn and unevenly worn to be unsafe and should not have passed the MOT IMO.
Its called preventative maintenance. Do it before it brakes.
An ethos promoted by the forum no less.

 

Thanks, I appreciate the torque settings and specs.
Very helpful.

 

He's since reported on the bad condition of the discs, which indicates the car has not been braking as it should.

Looks like the tester failed to test properly

(The visual condition alone should have been a fail.)

 

Thats my stance.
In recent years I've noticed a deterioration in the standard and quality of MOT testing. A sign of the times perhaps.

 

A precis of my first post.

 

Is that a part of MoT testing?

 

Yes.

It's (meant to be) a thorough test.