Puggy 107 brakes under warranty?

It didn't turn out to be diagnosed one way or the other. I had the car done elsewhere and much cheaper rather than tit about.

Ah, sorry. I thought you said it was grooves worn into the surface of the disc. I must have misremembered.

& replacing the discs and pads cured it.

Yes grooves make them faulty.

You think that brake shudder comes on in binary fashion? Anyway it isn't my car and many people drive with slight shudder blissfully unaware that anything is wrong which is what happened until I drove it and wasn't happy with the brakes.

The car came from a main dealer who boasted that it was mechanically

100% so the fact remains that with the pads only in contact with the discs for X amount of the rotation the braking efficiency was affected. I.e the brakes were faulty.

There were grooves. Whether this was the fundamental cause of the shudder was not decided (by me) as I found it easier just to have the pads and discs replaced.

I did ask the guy who changed them if it was worth skimming the discs and he shook his head with a laugh.

Yep drove it tonight and the car is as straight as a die and shudder less.

As I say undiagnosed but a blanket change solved the problem.

So it wasn't diagnosed, but replacing the worn discs with new ones fixed it.

But it wasn't wear.

I have to admit, I'm starting to see the dealer's point.

Can I just confirm you believe the grooves in the disc are a manufacturing fault?

Think we can now add a lack of understanding of how a disc brake actually works. When you apply the brakes the pads will always come into contact with the disc - even if it were warped. Unless the caliper pivot, sliding mechanism or one of the pistons is seized, depending on type.

I think it is you who doesn't understand. When a flat surface becomes warped the surface then has a curvature on it. This means that a flat brake pad can no longer cover the disc with its entire surface. Of course if the pad were to wear to fit the curvature then as the disc rotated to its unwarped section the pad would no longer be flat against that part of the disc. No matter which condition is met the braking efficiency would be affected.

Of course the pads riding in grooves is a totally different condition.

For my money I am going with the theory that discs very seldom if ever warp, well not to the extent that would cause them to shake the pads/calipers from side to side.

The friction generated is largely independant of the surface area.

Just about every disc will have appreciable grooving in normal service after many miles. Doesn't effect the performance in practice.

True.

So long as the disc variations are constant which they are not or the brakes wouldn't shudder!

Yes I know that but only the nearside disc was grooved. The offside had the wear that I would expect from OEM parts at 7k which was minimal.

I once had a new Citroen ZX and the front brake disks warped within the first 18 months causing a bad shudder when braking. The replacement disks lasted 8 years+ without me changing the style of my driving. Some disks may be made of some kind of cheese that warps when warm.

But at what cost to your company was there any work involved, was there an ongoing relationship were they are large company with repeat business or someone wandering in off the street

Where is your income base from what equipment did you need to tie up

the two are not comparable.

A warranty doesnt cover wear and tear

Having had a van in at citroen birmingham for an electrical fault i couldnt agree more, after several revisits and finally me shouting they soughted it, only after me going through how to test out systems, just as well soughted it myself

You dont know how hard the car was driven prior to you owning it so you can't really blame the dealership , you don't even know if prior to trading the car in they didnt swap out the discs and pads to another vehicle

It was when you bought it.

Like lightbulbs they can be fine when you drive off, but next morn ing they may fail doesnt mean its a warranty issue unless ts a brand new vehicle

If the disc is warped the pad will contact the whole of the disc but the brakes will judder because of the ocillation and the increase and decrease of the bite.

This varies depending how much the disc is warped . No disc is perfectly flat, 0.1mm is about the max allowed