Why do brakes squeal ?

[BongoBongo123]

In short: Is it too much to expect for a garage to smear a 1/2 a fingertip of copperease over a brake pad (to at least try it, given it costs nothing) knowing full well that it is a tried method of resolving brake squeal ? And the answer is bl**dy obviously, no.

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The longer read:

Thanks for the replies it is interesting and reassuring to see Delphi advise against copperease. Although the fronts are ADL Blueprint disks and ADL front pads. Does that advice change from manufacturer to manufacturer ?

It is also interesting to see others use it with great success, on that basis alone seem either can work, so when it does not trying the other would be common sense, no ? Changing the pads was suggested after the job had been done, which I can kind of understand cause they would not have known the squeal is still there until they drove it again. But it would not have been £20.00 Teenmal, it would have been + labour. So another £50.00 + £20.00 presumably.

The squeal is not huge, it comes only when the brakes are feathered at low speeds. If I roll down hill at 15mph and gently touch the pedal it squeaks and continues as long as the vehicle rolls. (Not that you would typically do that)

Right now, I will put up with the annoyance cause I am not throwing more money away. At the very least I would expect a garage to change practice if/when a problem continues. A light smear of copperease would hurt no one and may have shut them up.

It cannot be the service life, they have only been on the Bongo for 6-8 months, I drive cautiously and so I am not generally heavy on brakes
but at the same time they have been used properly on M way runs etc.

I am not spending more money. And let's just say it was possibly the lack of copperease, putting a new set of pads with no copperease on may end up with a squeal again ! So you have to see where I am at, do you spend another £70.00 with there still being a risk they won't put copperease on, or leave it alone and suffer the annoyance.

No doubt there will be something actually wrong with the Bongo soon, for now I will save my money for that. It is a fine line between trying to judge things and get them resolved and leaving it alone instead of burning money.

This is the crap part of owning old motors. (But really any motor can get brake squeal I guess.)

With regards the "slightly sticking" caliper, the disks look very good and shiny/clean except for that marginal 0.2mm barely visible groove that caught the sun, and when I mentioned that to the mechanic when I booked it in he said that seems within norms. Bongo never pulls to one side either. It must have been extremely slight indeed.)

For a garage it's a £50.00 Friday job so why should they really care that much, for us it's maybe 10 years of driving with squealing brakes (low miles). I suppose I am just sick and tired of having to double check the work of plumbers, garages, roofers etc. I cannot remember a job that went right without having to get the person back or literally just giving up on them. Sad state of affairs in this country.

[BongoBongo123]

I just wish I lived near Allans, its 200+ miles away. Only person who has done Bongo stuff right in my experience.

I know life has small niggles, but I am sick to the back teeth of relentless double checking and unresolved problems, getting a good
job done has become the exception rather than the rule.

[mikeonb4c]

I'm a bit puzzled how copperease (copper grease?) would help squealing. It has to be used sparingly and well away from pad faces. So it may allow better release of pads when pedal lifted and perhaps thats it, but i'd always imagined squealing happened when pedal pressure was involved, and if pads were sticking that badly when pedal released, there ought to be other more serious symptoms (overheating brakes, accelerated pad wear etc)

[g8dhe]

Have to agree Mike, the squealing surely comes from the face of the pad rubbing on the disk ?
Only thing might be if the entire pad is vibrating and the grease behind it on the caliper damps the oscillating ?

[Bonneville]

Sounds counter-intuitive but it's not the friction, it's the vibration. The vibes cause the components to 'ring' at a certain frequency. Like a tuning fork. The squeal shim or rubber pad or grease is there to cushion the vibes and stop the squealing.

[BongoBongo123]

Delphi suggests using their "brake grease". That is definitely not "don't use anything."

https://www.delphiautoparts.com/gbr/en/ ... -comebacks

They clearly state apply brake grease.

"Lubricate: Apply a high-performance brake grease to all metal-to-metal contact points between the brake pad and caliper. Never coat the friction material, the disc’s surface or rubber parts/shims. "

I should have told them straight and wish you did not have to have eyes in the back of your head
with even the routine jobs.

[BongoBongo123]

Seems that ceramic brake grease is the one, good chemical/electrical reasoning here:

https://textar-professional.com/textar- ... rn-brakes/

I might buy a pot, it will last a lifetime and give it to the mechanic when they do them. In 10 years time.

[BongoBongo123]

I have some new Mintex pads coming with some Mintex Ceretec brake grease:

I will show the garage this image (they seem to be unfamiliar with using this brake pad grease so just to be sure)

I don't think I can hack the squeal for years and years.

[BongoBongo123]

Got my Mintex front pads and here is a photo between the 2.

http://geekpic.net/pm-ALD4AT.html

The 3 obvious differences are the Blueprint come with a painted thin mild steel
clip on cover on the rears (is this a shim ?) and the Mintex have nothing. 2) The Mintex smell strongly, a kind of fishy smell, and 3) the Mintex
main metal body which the abrasive material is adhered to is more roughly machined.

It looks to the eye that there is about 4mm more surface area (2mm each side of the pad where the abrasive material bevels away from the flat middle section of the pad) that would meet the disk on the Blueprint pads. It would appear that the Mintex seem to have at least to the untrained eye a little more metal in the formulation, slightly shinier, catches the light a bit more. I can see what looks like wire threads in the Blueprint.
I have no idea whatsoever how that may effect quality, if at all ? Both come with the shiny clips but I did not have them in the Blueprint side of the image.

Mintex say Made in great Britain although say TMD abrasives GMBH and "a Nisshinbo group company."

I have no idea what ones to put on tbh so it will be a punt.

Here is a pic of the 2 sets of pads where you can see the difference. (cannot seem to embed it so just click link):

http://geekpic.net/pm-ALD4AT.html

[BongoBongo123]

Front brake pads Mintex'd up (and Mintex Ceretec brake greased) and rear springs swapped so happy days. All quiet, no squeak at the moment it bodes well. £108.00 for both jobs. Will go easy (as always) and bed them in.

No discernable differences noted in the ride, as suspected. Old springs have surface rust and a bit pitted but will keep them, they croppsed up on a MOT as advisory and then it vaished I suspect on closer inspection they saw they were not too bad, the seocnd hand ones on now were very clean looking so it is for peace of mind. Wire brush might sort the old ones out, will leave that litle job for a quiet and rainy day, no rush.


They are decent chaps at the local garage and I give benefit of doubt might have been the Blueprint pads were just squeaky ones but now I have done all that can be done. Thanks for advices, I would probably go Mintex as advised for the Bongo just to be sure if doing your pads and it will do no harm to be armed with a tube of Mintex Ceretec when you get them done.

https://www.youtube.com/watch?v=sAGWc_gI-X0

Audio L channel only ! (also stops current flow / anodising corrosion between metals)