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Welders, fabricators, motorcycle people?

This topic can be found at:
https://sigforum.com/eve/forums/a/tpc/f/320601935/m/4110086464

December 26, 2019, 02:00 PM
ffips
Welders, fabricators, motorcycle people?
quote:
Originally posted by 1s1k:
It looks like a super weak design that would break again. I would go to a local machine shop and have them fab up a much stronger bracket designed to replace the one that is cast into the original part.

I would then grind the original off and have the new piece welded on. There are plenty of radiator shops who have competent aluminum welders. It will be a much easier wild than trying to repair what is there.


Good in theory. My concern would be why it was designed as a weak point? It it breaking instead of something else because it is repairable? If this is strengthened, what part fails next? Is that part repairable? Sometimes bigger isn't always better.

Smile
December 26, 2019, 02:33 PM
XLT
quote:
Originally posted by Valpo Fz:
I broke a subframe mount on my BMW and want some advice.



It’s not an uncommon issue and can be welded but the only guy that I know and trust that can weld it is packed up until spring with a house he is trying to sell. Should I look around and try and find someone else? A couple Of people have made brackets either by welding them, machining or hand forming(sawing and filing).

Here are some of the examples:







This is a lower mount that a guy made from a solid block and bolted on:





Should I use steel or aluminum? Find someone else to weld it? What size plots should I use if I make a bracket 6,8 or 10mm? Any advice or ideas are welcomed. I want to get it back together so I don’t have parts spread all over the shop.

Thanks
Ed


I would have a bracket machined and bolt it on welding cast is not the strongest way to go, the top two pictures of the self made brackets are complete Hillbilly quality.
December 26, 2019, 06:18 PM
limblessbiff
If it broke before, a welder repair will definitely break again as I and others said earlier, welding on cast aluminum is weak. Doesn’t matter how good of a welder you are. Just grind that shit off and put a bracket on there and you’ll be good to go
December 26, 2019, 09:50 PM
hrcjon
That does not match my experience in repairing a number of similar motorcycle frames. See that big weld already in this area? This is how BMW made the frame. This is a material that will weld well. Just welding the tab back on won't last, but a gusseted repair with a newly fabricated tab will last just fine. And it will certainly be much stronger than a bracket attached by a couple of SS fasteners tapped into that casting (even if you use some form of threaded insert).


“So in war, the way is to avoid what is strong, and strike at what is weak.”
December 26, 2019, 11:25 PM
aileron
Make a new tab from 6061-T6 plate, and have it welded by someone who TIG welds aluminum on a regular basis. Be 100% sure the new tab isn't made from 2024, 7075 or ... you want 6061 "for sure".

Do not re-weld the broken cast tab back onto the frame.