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6 cyl Bristol cars Type 400 to 406 - restoration, repair, maintenance etc

aluminium

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Old 28-02-10, 06:19 PM
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Default aluminium

Does anyone know what sort of the aluminium alloy Bristol used for their
cars in the 1950s?

Mike
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Old 28-02-10, 06:29 PM
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The same as they use now 16 swg (1.6mm ) in alloy NS4 H3 ( old BS designation ) or 5251 H22 in EN modern designation.

The first bit tells you it has 1.5 percent magnesium and the H bit is the "half hard" temper.

Greg
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Old 28-02-10, 08:15 PM
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Default aluminium

Very much obliged Greg, most helpful

Mike
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Old 28-02-10, 08:30 PM
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Let me know if you need any as if it's a small amount I may have some samples in the garage that are suitable.

Don't be tempted to buy "aircraft grade" (covers loads of alloys ) they are generally too hard and have poor corrosion resistance in a car environment.

Another thing worth mentioning is epoxy glues have come on a long way and cause no distortion as opposed to welding. I worked with the Virgin Atlantic Challenger a few years ago which was an all aluminium glued craft.

Greg
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Old 28-02-10, 08:50 PM
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Default aluminium

Greg & Mike ,



some sections of the Aerodyne bodies were a different thickness, for
example the tops of the front wings are thicker to stop mechanics from
denting them .

Geoff
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Old 28-02-10, 09:12 PM
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Quote:
Originally Posted by Geoff Dowdle View Post
Greg & Mike ,



some sections of the Aerodyne bodies were a different thickness, for
example the tops of the front wings are thicker to stop mechanics from
denting them .

Geoff
Interesting, especially as 5251 is a strong alloy already. It's amazing that the Atlantic Challenger was only 16 swg. The modern aluminium caravans and motorhomes I supply aluminium for are down to 0.6 mm ! although it is bonded.

I would also imagine that the Aerodyne varying thickness was as much to do with fabricating techniques as a heavy handed mechanic repellent. Just a guess.

Greg
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Old 28-02-10, 09:25 PM
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Default aluminium

That's interesting, I should like to weld it if I can, I have a TIG welder
and I gather the trick is to use square wave.
I had wondered if the alloy was something special as I haven't had problems
with other (non Bristol) ally welding.
I did try a couple of small tack welds a couple of years back,
unsuccessfully as they cracked post weld but it was all very hasty and I
probably didn't have the machine or myself set up properly ( I hope).

Mike
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Old 28-02-10, 10:45 PM
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Default aluminium

I used an adhesive from Henkel to bond a repair on my 408. The adhesive
used was one developed for the tunnel TGV trains.
So far so good [eight years]
David
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Old 28-02-10, 11:11 PM
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Forgot to mention. 5251 is available from any stockholder in the UK but in mainland Europe 5052 would be the nearest. 3103,3003 and 5005 are a bit softer and 5754 H111 a bit harder. All would be adequate.

The term " aircraft grade " makes me laugh. It's meaningless drivel that is just designed to imply quality and command unjustified prices.

I wish that I could TIG weld. Only done MIG on thick sheet.
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Old 01-03-10, 12:51 AM
UK6 UK6 is offline
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Default On Aluminium and Aluminium Welding

Mike,
I suspect that the original aluminium would be very similar to the modern 3003 grade. Fully annealed sheet would be ideal if you can get it for panels that need a lot of shape wheeled into them. Having said the former, I am currently using medium temper 5005 1.5mm gauge sheet to build panels for my replica FN - unfortunately, I can only purchase 5005 sheet in my state (Western Australia)! For the record, I have formed the nose and tail cones with a fair bit of annealing - the upshot being that the 5005 makes for a stiff panel.

I am a self taught panel guy but I am having a degree of success oxy welding the wheeled 5005 sheet. I find that the oxy weld zone is less prone to cracking vs TIG - especially post wheeling and or dressing the panels! I am using a very useful little Meco torch (no:2 tip - less than 4psi), 5005 rods, TM 2000 lenses and special yankee flux - I figured that I needed everything going for me!!! I have found Kent White's instructional videos and gear at Tinmantech to be invaluabe- in particular his TM 2000 lenses which "cut out" the flux's orange flair.

I have used a Eutectic brand aluminium solder (512S I think!) to seal the rivet heads holding my baffles in my aluminium fuel tank. The solder is not cheap, but it flows beautifully on new metal. As the melting point is only around 180 deg, a small propane torch is ideal. Again, I have used this around my filler neck with a mechanically strong "turned in" flange. Clearly, engine bay application is out of the question for this low mp metal alloy.

Brett
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Old 01-03-10, 12:56 AM
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Mike, do check that your TIG welder has an AC setting, this is fairly crucial for alluminium, although if you've welded the soft stuff before I'm sure you know this already. TIG is the most gentlemanly method of welding, compared to the anti-social behaviour of a MIG it's pleasurable.
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Old 01-03-10, 01:17 AM
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Quote:
Originally Posted by UK6 View Post
Mike,
I suspect that the original aluminium would be very similar to the modern 3003 grade.

Brett
The original was NS4H3 / 5251 , this is a magnesium alloy.I have talked with Bristol cars on this. 3003 is a manganese alloy and is softer but okay -- used a lot on panel vans and buses.

In my opinion the best quality to use would be 5083 "0" it is what I have supplied to RR for the new car bodywork. expensive of course.
5251 is 1.5% mg and 5083 is 4.5% mg the higher the magnesium the better the strength and corrosion resistance in this application.

I bet you wished you had never asked
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Old 01-03-10, 01:22 AM
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And for panel work glue is not a bodge and is definitely the future -- remember the alochrome to protect.
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Old 01-03-10, 11:35 PM
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Default aluminium

Thanks very much to all who responded re. ally welding

I do have a couple of sheets of ally I bought from a local stockist a little
while back but unfortunately havn't a clue what they are.

I also have to figure out what filler rod to use, I have some 5356 but
wonder if perhaps 4043 might be better as I think I've read that this is
less suseptable to cracking.

Mike
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