AirSpeed VW Community Forums
General Forums => Air Speed Lounge => Topic started by: jim martin on March 22, 2004, 08:14:10 PM
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a friend of mine has a bunch of aluminum metric bolts that would be perfect for mounting fenders on to a beetle.anyone know if steel and aluminum will react.i can't remember i'm sure aluminum and stainless do??? but not sure if steel/aluminum do
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Steel and Aluminum are not compatable, you will get what's called galvanic corrosion, leaving a nasty white blistering effect, and will seize the two together usually stronger than rust.
Matt
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Did not know that!!!! :huh:
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Matt(Even though I'm no Metalurgist)
Hit it right on the head. Aluminum doesn't rust but it corrodes like mad... He hit it right on the head..
Good old chemistry.. knew it would come in to practice some day.
-Kirin
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I have a crap load of grade 8 allen head bolts, kinda a neat look - I use them for most of my hardware. If ya like I can hook you up Jim.
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well there goes the super light bolt plan.
james that would be great ,let me know how and when the best time too contact you is .
p.s thanks for the sticky on the s.t.f
jim martin
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Pm'd you.
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You can completely solve the corrosion issue by getting your aluminum bolts anodized. Then assemble with anti-sieze compound. This does work. I have at least 20 aluminum nuts on steel screws on my car. Been there for over 10 years. I know of many others using the same with no corrosion problems.
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question bruce were too get it done and cost
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Sounds expensive, how much Bruce?
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Hey Jim, We deal with Altech Anodizing in delta they have good pricing and a large selection of colors as well.
you can check them out at altech-anodizing.com.
shawn
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Hey Jim,
When i built my car i looked for alum bolts as well as plactic.....gotta save weight somewhere.
Let me know what you find out about the bolts.
Geoff.
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shall do geoff i have gotten prices for washers and bolts but am waiting for one more too come in.
a friend of ours at work builds parts for rc cars and gets parts anodizing all the time , he says its dirt cheap.
i will phone this other company and get a quote .
bolts seam too come in packs of 100 and for a 8x25 bolt with a hex head they are about a $1.00 each,
will post later.
will look into some 6mm sizes as well
can't be that quick for corrossion as porsche uses steel studs and aluminum lug nuts????
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I also need a full set of bolts for fenders, pan, seat mounting etc.
I'll take em!
Porsche uses anodized nuts, but NO CAD PLATED STUDS! ni/cad battery..........
:rockon:
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Fenders - yes, pan - maybe, seats - yikes!
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these bolts are less than a grade 2 ,i don't think they will work in too many places,
fiberglass fenders are a perfect choice ,maybe even steel fenders,nurf bars as well.not too be used in high load areas,safety first
a very close cost will be $1.25 a bolt/washer comb this will be a 1 inch fender washer and a 8mm/25 bolt
so cost should be around $50.00 for all fenders .i may be able too get a deal on anodizing but that will have too be looked at later.if you are interested post here and i will just order what is needed for everone,then distribute .bolts will take about 3-4 weeks too get here.
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only joking, Bruce. I got TI22 for the seat
:D
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I am a metallurgist, but no means an expert in corrosion, but I'll try my best here.
When aluminum and steel are in contact, aluminum becomes the anode, and is the metal that \"corrodes\" (disappears!). The problem with using aluminum in steel is that the corrosion rate is related to the area ratio between the two. So with a large area of steel, and a small area of aluminum, the aluminum will corrode quickly.
What anodizing does, as Bruce mentions, is to increase the thickness of the oxidized layer on the aluminum. Aluminum is a metal which \"passivates\" which means it forms an oxide layer that actually protects it (steel does not passivate because the volume change in forming iron oxide is such that it breaks the passive layer and that's why we get rust \"bubbles\" when rust forms on cars). Most people associate anodizing with fancy colours (oh, for the hey day of purple billet of the 90's, eh?). But anodizing is actually a protective layer. However, the problem is that if you scar the anodizing when installing it, you now have exposed bare aluminum with a small surface area, and it will corrode quickly.
One thing to bear in mind is that you still need an electrolyte to connect the two. Here in dry, dry Calgary it's not so bad. With Vancougar's nice humid sea air with salt in it, the electrolyte is puuuuurrrrfect. Plus your fenders seams are a perfect place to trap moisture.
So what's the conclusion? You know what, for fenders, aluminum bolts aren't going to matter. It's not like your fenders are going to fall off or anything, so go nuts. And at least if the bolts shear off when you ever remove your fender, they are easy to drill out. :P They look pimp, but aren't the best choice for everyone. I'll stick to stainless, personally.
Rock on. :rockon:
-Keith
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Good info Keith!
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when i was talking too a fastner company in the states and we talked about the corrosion factor ,he said if i put a layer of gasket sealer or similar product to stop both metal types from contacting it would help.
great info keith its great to get input from everone !!
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when i was talking too a fastner company in the states and we talked about the corrosion factor ,he said if i put a layer of gasket sealer or similar product to stop both metal types from contacting it would help.
great info keith its great to get input from everone !!
I was trying to find some info on something like that, but unfortunately most of the stuff I have around is Military/Aerospace specs, and go figger - they are a little anal retentive ;)
I think if you were to get bolts anodized like Bruce suggested (bearing in mind the anodizing may make them a tiny bit bigger and fit a little tighter) and make sure you run a tap through your fender holes first to make sure the bolts will fit easily, use a gasket sealer, and use plastic washers on the bolts to minimize contact with the steel it should be ok for \"non mission critical\" fastening.
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myself and one other test pilot will give these aluminum blts a test and let you know how they work out.
at the same time a have also brought in som 6/20 nuts and bolts i may use these too secure many none load bearing parts.
shooting for 12's ,wanting 11's
my car is on a diet,since i can't loose any weight