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Welding cast Al Brompton rear rack.... info please.

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Welding cast Al Brompton rear rack.... info please.

Old 08-25-19, 12:18 PM
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tmac100
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Welding cast Al Brompton rear rack.... info please.

My friend's Brommie rear rack was damaged when it was checked in wrapped in bubble wrap inside an Ikea Dimpa bag.

We didn't check the bike for about 6 months after the flight, so no "culpability" with the airline.

The rack is broken at the bolt hole where the front of the rack is attached to the frame. Anyone ever welded cast Al successfully? Should be able to fashion a new "attachment point" on the rack instead of buying a new one and throwing the old broken one away.
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Old 08-25-19, 01:53 PM
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Car racing acquaintances weld aluminum regularly. The welding equipment is large and expensive and you must be skilled to operate it. You might check with garages that specialize in motorcycle customizations. While getting a new rack might be the simplest, there might be some learning benefit in trying to fix it, for you and us reading about your or your friend's experiences.
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Old 08-25-19, 09:50 PM
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Sorry if I implied this was a DIY project. Welding is the technique best left to the experts. Thanks for your supportive suggestion. Next stop is the Al welders...
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Old 08-25-19, 10:24 PM
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For hobby car racers it is DIY. The welding equipment is pretty central to their hobby. However they will also have a lift to take the engine out of a car - pretty abnormal for most people .

Myself I tried soldering alu, following two different processes in the market, and I would not recommend it to anyone. The chances of destroying the soldered items was at 50% or so. If a joint was achieved, it would not be strong. Welding of alu is, of course, done regularly and correctly done joints hold well.
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Old 08-28-19, 11:05 AM
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Burned through plenty of aluminum learning how to TIG weld it. By the end of a class I took, I very inexpertly welded a cast piece of someone's ATV, a fender brace or something. Definitely no an expert, no longer have access to the correct equipment, and someone correct me if I'm wrong, but I also remember hearing that it's a good idea to heat-treat aluminum after welding to make it less brittle and prone to breakage. IOW: take it to someone who knows what they are doing.

If I was going to go DIY and didn't care about the aesthetics, I might try some of that carbon wrap where you wet it down, wrap the repair area, let it do magic, and then it is repaired. But ugly.
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Old 08-28-19, 11:46 AM
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Originally Posted by mconlonx View Post
...... take it to someone who knows what they are doing. ...
Yup, see the last sentence of my last post (#3). Some "things" are best left to acknowledged/professional experts who do those "things" for a living 😉
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Old 08-30-19, 04:10 PM
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The car racer, Jessi Combs, who perished while this thread was active, had a distinguished metalworking career. She was accomplished as a welder and created her own line of welding gear for women.

https://www.discovery.com/motor/jess...d-record-crash

https://www.bbc.co.uk/news/world-us-canada-49504222
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Old 08-31-19, 12:39 PM
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Originally Posted by tmac100 View Post
Anyone ever welded cast Al successfully?
Depends on the alloy.

Or perhaps it could be brazed.

Should be able to fashion a new "attachment point" on the rack instead of buying a new one and throwing the old broken one away.
Adding additional material to bridge the break is perhaps advisable, and in such case, there are some metal-epoxies that might accomplish repair depending on the future duty of the rack.

If in the future this rack will be loaded with 'around the world' dunnage...just buy a new rack!
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Old 08-31-19, 05:00 PM
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In 1987 or so, I had an aluminum engine block on a VW Rabbit diesel welded successfully.
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