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[omega3000]

To cs or not to cs that be the question  not investigating just yet as swmbo had me running to the tip all morning with garden waste 

[Cliffo B]

For a level playing field I think  you need newish calipers

[feeutfo]

As an example, I always remember Kai's rear brakes. Absolutely horrendous squeal. Touch the brakes and it was deafening. He drive it round to mine to fit new pads. I suggested oe as they have the rubber backing on all pads and come complete with pins shims and springs. He agreed a bought them with him to fit.

On removing the old ones that where drenched in copper slop that was poring down and dripping iff the caliper, the problem was clear. No shims, but also, the thick paint on the metal backing had cracked due to piston pressure. The weather had then got in and rust had raised the area causing the pads to rock on the piston over the raised rusted area. As the frequency of the rock increased with wheel speed, so did the squeal. Ferrodo skimping on shims.

[TheBoy]

Well. Lets chuck this in the mix. I should state its early days yet, but....

Went to change the squealy MV6 pads this afternoon. Turns out I've been a good boy, and the pads are little over a 1/3rd worn. So a couple of thousand left.

As I had new pads, I nearly fitted them, but then, to for research purposes, decided to refit the part worn ones.  Cleaned up, filed a better edge on the leading edge, and refitted.

Took it for a blat, the 'bite' feels better (or did before I cooked them), and the squeal is no longer present. Feel? I think its better, but might be placebo.

 

Early days, only done 12 miles. Fully expect squeal to return, as not really done anything different. But last time the squeal was there from the start 

[feeutfo]

They have enoooormous chamfers on them already... Almost a third of the braking surface is lost because of it. 

Anyway, as you say, in the name of research let's see.

[TheBoy]

I think the standard chamfers are naff - too shallow, thus lose a lot of area. I noticed the entire chamfer was clogged with dust.  Filed on a much steeper chamfer - about 45 degrees, down as far as about 4mm from backing plate. And only on leading edge.

[feeutfo]

Any cracks on the friction material surface?

[TheBoy]

Any cracks on the friction material surface?

No, if there had been, after hearing of Kevin Wood's problem, they would have been binned.

[TheBoy]

Thinking aloud, wonder if Kevin Wood's had been badly handled, maybe dropped or otherwise thrown about by dealer/courier/GM Warehouse, causing the brittle pads to start to fracture internally 

[feeutfo]

Possible I suppose, but fitting new pads, I wouldn't fit cracked friction material from new, mine where fine, yet showed minor cracks after less than 5k.

I wonder if a more even comparison between the in set pads, and on thier own pads, would be to swap them early? A more direct comparison?

[TheBoy]

Possible I suppose, but fitting new pads, I wouldn't fit cracked friction material from new, mine where fine, yet showed minor cracks after less than 5k.

I wonder if a more even comparison between the in set pads, and on thier own pads, would be to swap them early? A more direct comparison?

The part number for my new pads, and part number printed on the pads you fitted match...

Wonder if in Kevin Wood's case, if any mishandling was more hairline cracks, not immediately obvious when fitting?  Its a worrying thought if its poor manufacturing.

[TheBoy]

BTW, went out in it today, still no squeal

[feeutfo]

Do you reckon dust is/was getting dragged in between the disc and pad when braking and causing the squeal?

[dbug]

BTW, went out in it today, still no squeal

Think you may have cracked it Jaime

Normal way to get rid of/reduce brake squeal is to chamfer leading edges on disks or shoes

Do you reckon dust is/was getting dragged in between the disc and pad when braking and causing the squeal?

Possibly Chris - more possible that as pad wears a "raised" edge builds up on leading edge inducing squeal.

Agree that Vx chamfers on pads too shallow an angle over too large an area.