Classic cars forum & vehicle restoration.
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BigJohn
Joined: 01 Jan 2011
Posts: 954
Location: Wem, Shropshire
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 Posted: Wed Oct 02, 2013 2:08 pm Post subject: |
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Yup, this one
John. |
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ka
Joined: 03 Dec 2007
Posts: 600
Location: Orkney.
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| Posted: Thu Oct 03, 2013 7:33 am Post subject: Rover |
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Thats a fine old beast, you must feel as though you have shares in the Petrochemical business!
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KA
Better three than four. |
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wristpin
Joined: 15 May 2013
Posts: 12
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| Posted: Thu Oct 03, 2013 9:32 pm Post subject: |
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Interesting to read your comment about the possible use of gear oil as an anti seize product. I came across exactly the same thing while browsing engine rebuild recommendations on the Imp Club Forum where ep90 was recommended.
What I was unaware of before was that proprietary copper based anti seize products can actually set up a corrosive action between aluminium and steel.
Have to admit to smearing the stuff on ad lib in the past but will now be more careful!! |
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Mog
Joined: 30 Dec 2007
Posts: 661
Location: Sydney
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| Posted: Fri Oct 04, 2013 6:57 am Post subject: |
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You should never use copper based grease on ball bearing races. The copper plates on to the metal, the bearing heats up and fails.
For years I have used molybdenum based anti-seize mixed 50/50 with oil. Paint on with a small brush. |
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BigJohn
Joined: 01 Jan 2011
Posts: 954
Location: Wem, Shropshire
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| Posted: Fri Oct 04, 2013 1:01 pm Post subject: |
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| I like moly grease for anti seize, but, if I get the tiniest bit on my hands it spreads all over the workshop and house, a bit like Billy Connolly's ramblings on dog poo travelling the world. These bolts will be dipped in my remaining supply of Spirax EP140 before assembly. |
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V8 Nutter
Joined: 27 Aug 2012
Posts: 587
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| Posted: Fri Oct 04, 2013 8:06 pm Post subject: |
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Wristpin,
I think it is called electrolityc action. It is one of the reasons it was so difficult to remove alloy heads when they were on a cast iron block with a copper gasket |
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BigJohn
Joined: 01 Jan 2011
Posts: 954
Location: Wem, Shropshire
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| Posted: Fri Oct 04, 2013 8:20 pm Post subject: |
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| I think the worst example of this I had to deal with was an alloy head/cast block/copper gasket/steel head bolts on a Standard Flying 8. I cut down the bolt shanks with a tube drill as advised by my old tech books, tried using wedges in the specified points smote with a bfh, no chance. Then I tried to pop the head on compression using the starting handle, ripped the engine mounts doing that. Then it was engine out, sump off, engine clamped to the floor, a lump of tree of the right dia up the bore and a series of smotes with a 14lb sledge spanner. That sod was tight on, but I beat (to death!) |
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wristpin
Joined: 15 May 2013
Posts: 12
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| Posted: Fri Oct 04, 2013 9:28 pm Post subject: |
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Seems that everyone has their favourite "brew" but that copper based products are out!
However, I found this browsing an outboard motor forum !
http://continuouswave.com/ubb/Forum3/HTML/001642.html
I learnt a lot of my "mechanicing" in the late 50s working with a guy who had worked on aircraft engines in WW2 and he used to say that one could be "put on a charge" for failing to use graphite grease on exhaust manifold studs and nuts!
Looks as though I should have been "put on a charge" for using copper based anti seize in alloy blocks! |
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swampy
Joined: 30 Dec 2009
Posts: 3
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| Posted: Sat Oct 05, 2013 1:22 pm Post subject: |
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Just a quick comment - the well known copper based brand name also produce one that is aluminium based. Its called alum rather than copa (getting close to using brand names here - so I won't push my luck any further  ). They even do one that mixes nickel, aluminium and graphite. It's worth a look. |
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wristpin
Joined: 15 May 2013
Posts: 12
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| Posted: Sun Oct 06, 2013 12:22 am Post subject: |
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| swampy wrote: | | Just a quick comment - the well known copper based brand name also produce one that is aluminium based. Its called alum rather than copa (getting close to using brand names here - so I won't push my luck any further ). They even do one that mixes nickel, aluminium and graphite. It's worth a look. |
Nearly slipped up there!
Found this post on another forum.
Back to re-address the topic, this time with some solid information. While I've gotten some pretty varied opinions on this subject here, unfortunately no one with any real knowledge on the question has joined in with the discussion. With nothing forthcoming from this web site, I turned to my engineering contacts, Permatex, and Locktite for some real info.
The primary problems faced when using steel with aluminum (especially stainless steel) are galling and galvanic corrosion. Gallling is where a harder metal comes into frictional contact with a softer one (as in the case of SS and aluminum), which results in the softer metal smearing onto the harder stuff. To eliminate this, a lubricant is all that is required and, in fact, the old school bikers would use grease, oil, or even wax on their bolts in an attempt to alleviate this problem . The condition is especially prominent in areas of high temperature, where most lubricants simply break down and evaporate; and the different expansion rates between different materials in high temp conditions comes into play here, as well. All of these factors can cause things like steel spark plugs and exhaust studs to seize tight in an aluminum head, and their removal can result in damage to the threads they're screwed in to as the aluminum smeared onto the steel is distorted or even removed with the bolt.
To combat this, Loctite, Permatex and other anti-seize manufacturers have developed an anti-seize containing copper in suspension. Copper is well known for its excellent high temp properties; that's why it's used in in applications ranging from colliders and tokamaks to back-country stills to the bottoms of your (steel, not aluminum) cookware. It absorbs heat evenly and dissipates it just as well, all the while maintaining it's own molecular properties. In paste form, and under pressure, the particles bind together to create a lubricative barrier between adjoining metallic faces that remains soft without melting or otherwise dissipating. And its excellent electrical conductivity is especially important in areas like the sparkplugs, where a good path between the head and plug body is absolutely essential.
However, use of copper outside of high temp conditions can result in problems due to galvanic corrosion. An in-depth investigation of galvanic corrosion would take up more space than I'd care to expend, so I'll try to thumbnail the whole problem.
The Galvanic Series (abridged)
Galvanic Corrosion occurs when two dis-similar metals are in direct contact with each other and an electrolyte (water, acid, etc) is present. The electrolyte can begin pulling electrons off each material (oxidation), which sets up an electrical current between the two metals, creating a galvanic "cell" with the more stable ("noble", or more resistant to corrosion) metal acting as a cathode, and the more "active" (or more easily corroded) metal serving as the anode. This acts to strip electrons from the active material at a greater rate than would be normal in non-galvanic conditions; i.e. two similar metals in contact with a corrosive agent. If the two metals are far enough apart on the galvanic chart (based on the electrical potentials between the two, or "corrosion potentials"), the active metal will corrode at an exponentially greater rate than the more noble metal will; in fact, it can result in no corrosion of the noble material at all, while the active metal is consumed. And in conditions where the electrolyte contains a lot of free electrons, like near the ocean or in cities with a lot of CO2 and sulfide pollution, the condition can become a real problem. It has been the bane of ship builders since the dawn of copper-bottomed boats, and of mechanical engineers since the first time they tried to attach their fancy new iron axe blades to their old copper handles, and they've all been looking for solutions ever since.
To help eliminate this, engineers are encouraged, first of all, to avoid mixing dissimilar materials. Since this is pretty near impossible, their next form of defense is a good offense; or rather, it's more properly a case of "if you can't beat 'em, join 'em". They use the galvanic series to their advantage, and kind of trick mother nature with distraction by introducing a third metal into the mix; one that is even less noble than the first two. It acts as a "sacrificial anode" which is consumed by the electrolyte in deference to the other two more noble (but dissimilar) metals, slowing their corrosion (kind of like having a bear invade your picnic and tossing him the strawberry cobbler in order to save the pork roast and the green bean casserole). This is a pretty common practice; in fact, your hot water heater has a "sacrificial anode" made of either magnesium or aluminum that saves the steel tank from corrosion due to galvanic potentials between the tank and the minerals in the water.
Honda's engineers have addressed this by plating all of their steel fasteners, and a considerable number of other steel parts, with zinc. Zinc is right at the top of the galvanic chart, being less noble than either steel or aluminum, and cheerfully gives up its life for the greater good. The use of zinc, in fact, is an industry-wide practice, and you see it everywhere; plated, it has a nice, shiny metallic blue tone. Cadmium. with its distinctive mottled red/green/gold coloration, has been used for the same purposes; and though it's being phased out due to its high toxicity, it and zinc are commonly used world-wide as barriers against galvanic and other forms of corrosion.
Another approach is to introduce the "sacrificial" material in the form of a corrosion-inhibiting paste, which is where anti-seize comes in. It works to stop corrosion in many different ways: by introducing a less noble metal into the galvanic mix; by forming a barrier that, at least temporarily, keeps water (electrolyte) from entering into the system (most are at least 50% grease, which acts to eliminate galling, as well); and by creating an anaerobic condition that inhibits oxidation. For most of our case bolts, where steel and aluminum come in contact, Locktite (and others) recommend an anti-seize containing (surprise, surprise) zinc . Its use reduces the corrosion potential between the more noble steel and the more active aluminum, and it's pretty much a requirement when stainless bolts are used instead of the standard zinc plated fasteners.
I know there are a few who swear by the copper-based anti-seize (some quite rabidly, actually) and use it for everything they can lay their hands on; not only that, they've been using the stuff for (insert number of years/decades/eons here) without a single problem. And that may be the way things appear to them. Copper and aluminum are pretty widely separated on the galvanic table, and in galvanic conditions aluminum always loses out to copper. That's why you don't mix copper and aluminum wiring in your house, for example. Honda uses copper on the bike primarily as crush washers (not including electrical switches), and in all cases except one, they are plated to prevent corrosion. The exception is the exhaust port crush rings, or exhaust packings. Four copper rings that fit between the head and the exhaust pipes, copper being utilized here because of its high-temp properties, as already discussed. These are protected by the high temp paint on the head, which eliminates one condition necessary for galvanic corrosion: direct metal to metal contact. In addition, the high temperature at this location (as at the plugs) and the angle of the head make it difficult for an electrolyte to form; and, as the washers are tightly formed into the port by crushing, it's fairly anaerobic in the contact point between the washers and the head. All this doesn't eliminate corrosion altogether; the next time you replace your pipes, check the contact perimeter on the face of the exhaust port and I can almost guarantee you'll find a faint circle etched into the aluminum that delineates the outside edge of the copper/aluminum contact patch.
The thing to keep in mind, here, is that all of this is based on events occurring at the molecular level while in real life things aren't so black and white. Metals alloyed, formed, forged and cast into widgets can react differently in structure than their molecular components would indicate, some becoming more noble in solid form (chromium is a good example), others less so, and the whole galvanic table kind of squishes together so that reactions aren't quite as extreme as you might expect them to be. Still, the strictures regarding dissimilar metals need to be heeded, so while using copper anti-seize along with your stainless steel case bolts won't necessarily cause the engine to crumble before your eyes, it isn't how Honda designed things, nor is it the best thing you could do for your bike in the long run; and since I want my bike to outlast me, I won't be using copper anywhere other than the spark plugs and exhaust bolts, which is where its use is recommended. If Permatex, Locktite and all the other anti-seize makers had wanted the copper stuff to be used as an ubiquitous cure-all, they wouldn't have gone to the effort and expense of formulating other versions, especially those aimed specifically at steel/aluminum interactions.
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ka
Joined: 03 Dec 2007
Posts: 600
Location: Orkney.
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| Posted: Sun Oct 06, 2013 9:16 am Post subject: Coppergrease |
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What a brilliant article, obviously prepared by someone far cleverer than me,!
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KA
Better three than four. |
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Bitumen Boy
Joined: 26 Jan 2012
Posts: 1735
Location: Above the snow line in old Monmouthshire
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| Posted: Sun Dec 15, 2013 3:52 pm Post subject: |
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| wristpin wrote: | For most of our case bolts, where steel and aluminum come in contact, Locktite (and others) recommend an anti-seize containing (surprise, surprise) zinc . Its use reduces the corrosion potential between the more noble steel and the more active aluminum, and it's pretty much a requirement when stainless bolts are used instead of the standard zinc plated fasteners.
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This makes sense, but does anyone know of a UK retail source for zinc anti-seize? I've spent a couple of frustrating sessions with google getting not very far, found retailers in the US etc but no joy closer to home. I know from past experience that manufacturers tend to treat the direct approach with thinly veiled contempt  so at this point I'm toying with the idea of mixing my own - fine zinc powder seems to be readily available via fleabay, including suppliers I've used before for other stuff with no hassle. Any thoughts? |
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baconsdozen
Joined: 03 Dec 2007
Posts: 1119
Location: Under the car.
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| Posted: Mon Dec 16, 2013 10:28 am Post subject: |
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Rather than start another thread,this seems a sensible place to ask this.
I remember a long time back a process called "Spark erosion" was supposedly the answer to removing the remains of broken studs or bolts. I can't remember hearing of it again. Does it ring any bells with anyone?
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Thirty years selling imperial hand tools for old machinery(Now happily retired). |
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petermeachem
Joined: 23 Sep 2013
Posts: 358
Location: Chichester Sussex
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| Posted: Mon Dec 16, 2013 11:13 am Post subject: |
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Spark Erosion.
I used it to get a broken stud out of the Austin. It worked brilliantly. I think it was fairly expensive as it takes a while to set everything up. I think I'd broken an easy out stud remover at which point there are few options left. When I got home I threw the easy outs away, evil things.
I don't think it would have helped with the Rover engine without completely dismantling and degreasing first |
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baconsdozen
Joined: 03 Dec 2007
Posts: 1119
Location: Under the car.
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| Posted: Mon Dec 16, 2013 12:43 pm Post subject: |
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I sell easy outs and other thread in type extractors. The big danger is if they break and being hard they will do if bent, it become impossible to them drill out with conventional tools.
I did a google search on "Spark erosion machines" as you say it seems expensive although presumably the results are worth it.
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Thirty years selling imperial hand tools for old machinery(Now happily retired). |
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