Copper grease on sliding brake parts?

Hi all,
I was talking to a mate earlier who saw on the web somewhere about not using the likes of copper grease on the sliding parts of (disk) brake
assemblies, like where the pad slides in the caliper etc?
The reason given was that the brake dust mixes with the grease and forms a hard material that then resists the free movement of the pad?
I have typically added a small smear of copper grease to such parts and rubber grease for any pins running in rubber boots and can't say I've ever had an issue?
Cheers, T i m
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T i m submitted this idea :

Nor I, though I have in the past had issues caused by sticking due to lack of any lubrication. I use CG on sliding brake parts, the backs of brake pads and on the interface between wheel and hub to prevent them seizing on. Just a light smear, you understand.
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On Tue, 17 Jul 2018 15:04:43 +0100, Harry Bloomfield

Likewise.

As do I if they are metal to metal and load bearing, not if metal pins in rubber bushes.

Yup.

Sure, and as long as it only goes there, not between the back of the wheel and the front of the hub etc.
Cheers, T i m
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On 17/07/2018 14:10, T i m wrote:

It is better kept for non sliding parts, such as the back of pads, wheel centers, exhaust fittings etc, and is not recommended for anything near abs. Use mintex Cera-tec grease on slidey bits. Most car shops sell it.
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On Tue, 17 Jul 2018 15:08:55 +0100, MrCheerful

Thanks, that's probably what my mate was advised to buy / use (he said it was from Mintex).
https://mintex.com/copper-slip-vs-ceratec/?lang=en-gbr
"The advantages of using this grease are abundant, with the first being that it can withstand the braking system’s high temperatures."
So, not snake oil///grease then?
https://textar-professional.com/textar-training-center/the-use-of-copper-grease-on-modern-brakes/
"Copper grease is used for mating surfaces which work under high temperatures."
"It is also worth noting that using copper grease even on cast iron calipers will still show a voltage difference of 0.50V so a significant reaction will still occur.
What should we use then?
The simplest way to prevent a galvanic reaction on brakes is to electrically insulate the two metals from each other. If they are not in electrical contact, no galvanic reaction can occur. This can be achieved by using a non-conductive material between the two metals."
So they are suggesting that you wouldn't get a metal to metal contact between say a brake pad backplate and the caliper because a layer of Cera-tec brake grease?
I would have thought that with the load of the pad on the caliper (under hard braking) and the movement of the action, only the rust would resist there making a good electrical contact between the two?
How could CG cause issues for ABS systems OOI?
I'm not suggesting anyone is wrong ... just interested to know if it's the case ITRW. eg, might any high temperature grease work equally well in that role?
Cheers, T i m
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T i m was thinking very hard :

You can get a galvanic reaction any poorly connected bits of metal, with sliding caliper designs, there is really no easy way to avoid it.

I would be interested to know too, it just does not ring true..

I would suggest it would, but CG does seem to remain where applied for many years of service. I CG'ed the hub/wheel interface of my car 6 years ago, as I had really struggled to remove them. The CG is still good, still working now.
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On Tue, 17 Jul 2018 18:30:28 +0100, Harry Bloomfield wrote:

Can anyone spot what this bloke is doing wrong?

https://www.youtube.com/watch?v=0X04SjjYnDM

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Cursitor Doom submitted this idea :

Oh, no problem there he is only putting grease on the breaking surface of the pads. So long as he doesn't put it on the braking surfaces all will be fine lol
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On 17/07/2018 18:30, Harry Bloomfield wrote:

Apparently there is a problem, particularly with aluminium calipers where the CG can give rise to galvanic reaction and stray voltages, this is sufficient to interfere with ABS and ESP systems. The approved grease is cheap and easy to obtain, so why run the risk?
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On Tue, 17 Jul 2018 20:42:37 +0100, MrCheerful

I think I'd be slightly worried to find out either system could be so sensitive?
Isn't the only bit of an ABS system at the wheel a toothed ring of some sort that probably uses magnetic inductance to 'sense' the lobes?
Any voltage buildup would be between the caliper, pad and leg?

No, quite, if it is really 'better' (for whatever reason(s)) than say CG.
FWIW, I don't think I've ever had a vehicle with ally calipers and ABS / ESP. I think all of the cars had cast iron calipers and even if the bikes had ally ones, none of them have ABS. ;-)
The most 'sophisticated' bike I've had (got) is probably the GPZ550 with anti dive and anti squat (and a fuel gauge!). ;-)
Cheers, T i m
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MrCheerful explained on 17/07/2018 :

So it is galvanic action between alloy and steel/cast items. I still cannot see how any grease can help eliminate that, unless it is highly conductive. I have not checked, but would expect CG to be quite conductive.
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On Tue, 17 Jul 2018 23:17:05 +0100, Harry Bloomfield

I think the idea is that the ceramic based greases are *insulating* and that's how they are supposed to help?
I can't see how any grease could resist metal to metal contact amongst brake components but might prevent surface rusting and hence the components binding?

Again, it may 'depend'. Whilst the copper is conductive, it's presumably in suspension within the grease and so not 'conductive' as we would know it?
Again, I'm not saying the ceramic grease doesn't do it's job, but some of the pro <> con blurb seems to be contradictory and so it may be that in the more basic / common situations, either would work equally well?
<shrug>
Cheers, T i m
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It happens that T i m formulated :

Well, they recommend grease/vaseline on battery terminals and that is not conductive. The idea is that prevents oxidation of the terminals, yet there must be metal to metal contact.
There are two ways to prevent galvanic action, one is to electrically bond parts together, the other is to well insulate them. Grease alone cannot adequately insulate parts, so I would suggest this comes into the range of snake oil - unless someone can convince me with logic how it might work better than CG?
CG works on the hub to wheel interface, by preventing oxidation of the contact surfaces and pressure welding.
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On 18/07/2018 06:50, Harry Bloomfield wrote:

have a read of this page: https://textar-professional.com/textar-training-center/the-use-of-copper-grease-on-modern-brakes/
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On Wed, 18 Jul 2018 09:28:04 +0100, MrCheerful

"The simplest way to prevent a galvanic reaction on brakes is to electrically insulate the two metals from each other. If they are not in electrical contact, no galvanic reaction can occur."
So, are you supporting that statement MrC?
That a layer of grease with ceramic in it *will* prevent say the steel backing plate of the brake pad from making electrical contact with the caliper, including when under full braking load?
Isn't it more likely a film of rust on both parts will prevent them from making electrical contact?
(On ally calipers, don't they typically have a steel insert that carries the load from the pad)?
Just asking etc ...
Cheers, T i m
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On 18/07/2018 11:36, T i m wrote:

I am quite happy to take the advice of experts in their field, I don't have time or inclination to do investigative work to authenticate theirs, life is too short.
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On Wed, 18 Jul 2018 13:18:18 +0100, MrCheerful

No, sure, but have I missed the independent expert tests on the situation here, rather than the product placement of those with a vested interest?
More importantly, could those who work in the trade here provide even anecdotal evidence that a ceramic based grease really works better than a copper based grease ITRW?
I'm all for using the right / best stuff (dedicated penetrating oil over WD40 etc) but I have been using CG for such duties over a very long period and can't say *I've* observed any negative issues with it's use?
If you / others can, I would be very interested to hear them.
Whilst I have no issues buying some of said ceramic based grease (it's cheap enough), and may very well use it in future, however, I would prefer to do so based on either RW or independent tests for fear of being in a position where someone asks me 'Who sold you that then'?
Cheers, T i m
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MrCheerful explained :

The bit where it explains galvanic action I understand and accept is correct, but the earlier paragraphs explaining the benefits of using the companies own products is much less convincing.
Any company selling a specialist product will sing its praises, even if it has to make up the details of the benefits.
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On Wed, 18 Jul 2018 12:57:31 +0100, Harry Bloomfield

Quite.

Agreed ... and my / our desire to get a better feel about these 'alternative' (over time) products.
As I said to MrC, I have no issue buying some of 'ceramic grease' as it's cheap enough and a small tube would probably see me out ... however, that would mean I'd need to have 'another' container in the collection and potentially only for use in one specific role?
My mate has run his own garage for over 40 years and AFAIK uses basic CG on such jobs (but I will check). I'm not aware of him having issues with customers returning because of such use or because anything has not worked efficiently because of it? <shrug>
It is very easy for people (including me) to get 'drawn into' something because it sounds good rather than it is good (and by that I mean 'better than the traditional alternatives).
I would be happy to learn that this ceramic grease *is* better than alternatives but I'd like some provable scientific 'why's', rather than 'just because' (as salesman says so)?
I'd say we all know the likes of PlusGas, EasyStart or even Copaslip are seen on the shelves on mechanics all round the country (World?) or many will have a preferred alternative that was found by chance, recommendation, because it was easier to obtain or just cheaper than the mainstream brands and that works as well.
"Copaslip is an anti-seize compound. It is a very high temperature (up to 1100°C) anti-seize assembly compound, bentone based non-melt grease with copper, polybutene, and anti-corrosion additives."
How do we know that the 'anti-corrosion properties' of say Copaslip are any less capable than Cera Tec?
Interested minds etc. ;-)
Cheers, T i m
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On 18/07/2018 06:50, Harry Bloomfield wrote:

Electrically bonding dissimilar metals promotes galvanic corrosion. There has to be a circuit. Just putting zinc and steel in a glass of salt water won't create a galvanic cell. They have to touch or have an electrical bond.
If sacrificial anodes where insulated from the ship's hull they wouldn't work. The ship would be gone to holes while the anode remained.
It is not physically possible for any grease to prevent metal to metal contact in brake assemblies. The pressure loads are way too high. Most brakes have stainless steel face shims on the carrier that the pad bears on. One or more of the shims between piston/claw and steel brake pad backing are usually stainless. The hard chrome plated piston is in a steel or aluminum caliper bore.
CG should not be used on hub faces or wheel bolts/nuts. Unlike center lock wheels you don't have drive pegs and all the torque is transmitted by the friction from bolt clamping force on the wheel/hub joint. Nearly all cars can brake 60 to zero in sub 5 sec, it takes as much power to stop as it did to get going, how much power does a 3 sec 0-60 take? You really don't want the hub bolts in shear. A bit of grease on the inner/outer spigot that ensures concentric fit will be ok but not on the torque carrying faces.
When the transport grease has dried out CG leaves a soft layer of copper in the thread. The soft copper smeared between the threads will shear easily allowing disassembly.
Q: Where should CG be used? A: Any nut/bolt that will be assembled for a long time and that is likely to seize. Exhaust manifold nuts are a good case but many have copper plated threads so CG isn't needed if new nuts are used (as per manual). Spark plugs. The bolts that hold brake caliper to the knuckle. Any screws that retain the brake disc to the hub (common with bolted wheels). Suspension bolts such as strut to knuckle. Water pump bolts. Cam belt cover bolts. Alternator and other adjustable ancillaries.
Head studs, big end, main and cam bearing cap bolts should not use CG.
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