Aluminium Alloy Repair?

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bikenav
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Aluminium Alloy Repair?

Post by bikenav »

Hello all, recently ripped off my GS rocker cover guard during a minor drop, trouble is it toke with it a chunk of the threaded boss it is bolted to, worse this is a part of the cylinder head casting, its no problem for the head as such but I am now unable to bolt the guard back on. I do not intend pulling the head off for a repair prefering to repair it on the bike, My options as I see it are, to risk having it TIG welded by a pro (spoken to him and he is willing), aluminium brazing myself or a chemical metal type repair. Using heat on the cylinder head is obviously risky TIG being quite a bit hotter than brazing but more localized and quicker I should imagine, I have used chemical metal types before JB weld etc with varying success but not really for a purpose where continuing knocks and force are likely again. My first choice would be TIG its a build up type job as opposed to attaching a broken bit, but really not sure of the heat transfer issue to the cylinder/head components, brazing similar less hot but more sustained, would a quality metal repair compound do the job, which would be the best method/product. Any thoughts/experiences? ta very much.

For reference right to left the black feature is the rocker cover gasket, broken boss on the "higher" part of the head, exhaust header, and the darker finned component is the cylinder on the left side of the pics. As can be seen the damage is a long way from the cylinder bore etc.
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redbikejohn
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Re: Aluminium Alloy Repair?

Post by redbikejohn »

Tig is only real option I reckon. I can't imagine any chemical metal holding any sort of strength.
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Richard Simpson Mark II
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Re: Aluminium Alloy Repair?

Post by Richard Simpson Mark II »

Hmmm...so a part that's designed to protect the relatively simple and easy-to-replace rocker cover, can break the expensive and difficult-to-replace cylinder head instead!

I can see what's in it for BMW, but not for the owner!
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Re: Aluminium Alloy Repair?

Post by bikenav »

In fairness they have a hard time with me, they get to kiss the ground quite often and sometimes I use them to turn the bike around on, they have just torn through the guard hole in the past I am not complaining all considered. The rocker covers were once cheap to replace as used items and I did not bother with any type of guards but the availability of cheap used items has diminished. On the ADV model they are used in conjunction with engine bars but I really dont like the added width of the bars for my type of riding, I would say a bit more meat on the boss would be nice, but the whole thing is just one of those many compromises thats part of this big bike puddle paddling we like to do, my own fault really for taking on a bit of a techy climb in the wet on a E07 mitas front, when I had a nice Anakee wild on the other front wheel should have passed on that lane on that day. c'est la vie.
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Re: Aluminium Alloy Repair?

Post by bowber »

TIG done correctly will pit a lot less heat in. I'd disconnect any ecu, abs and other electronic modules you can find though as the high frequency start can have an effect.

Steve
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Re: Aluminium Alloy Repair?

Post by johnnyboxer »

Richard Simpson Mark II wrote:Hmmm...so a part that's designed to protect the relatively simple and easy-to-replace rocker cover, can break the expensive and difficult-to-replace cylinder head instead!

I can see what's in it for BMW, but not for the owner!
Indeed
I have only had the sacrificial plastic GS head covers on my bikes

Sooner replace a £40 bit of plastic or at worst a head cover at £150 than a barrel Image
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Re: Aluminium Alloy Repair?

Post by bikenav »

The plastic covers have long since gone, they are pretty good for falling overs in car parks etc, once you start falling with any momentum on uneven surfaces I found them just not robust enough my experience anyway. As said I wont be pulling the barrel off for this repair, I have lost count how many rocker covers I have changed over the years and have spares here now, never new ones though, plus numerous trailside repairs with chemical metal, gone through to the rockers once (rock sticking out of a grass bank) they are still carrying the scars, its part of the price to be paid I suppose for a little short legged, moderately skilled, rider riding an oddball lower C of G fat bike in some would say in an adventurous way, I dont keep it just for hard pack and Spanish Trails.
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Re: Aluminium Alloy Repair?

Post by johnnyboxer »

bikenav wrote:The plastic covers have long since gone, they are pretty good for falling overs in car parks etc, once you start falling with any momentum on uneven surfaces I found them just not robust enough my experience anyway. As said I wont be pulling the barrel off for this repair, I have lost count how many rocker covers I have changed over the years and have spares here now, never new ones though, plus numerous trailside repairs with chemical metal, gone through to the rockers once (rock sticking out of a grass bank) they are still carrying the scars, its part of the price to be paid I suppose for a little short legged, moderately skilled, rider riding an oddball lower C of G fat bike in some would say in an adventurous way, I dont keep it just for hard pack and Spanish Trails.
Agreed
Good luck with the repair
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Dark Knight
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Re: Aluminium Alloy Repair?

Post by Dark Knight »

Must admit I would be nervous in getting the boss TIG welded.
One option may be to put in a threaded insert.
Do not know what the screw size is but if it is M8, you woud have to drill it out to take a M10 insert threaded to take M8 and the apply some good filler/bonding agent.
I suppose thinking out of the box you could thread the outside of the boss and fit on some sort of adaptor.
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Re: Aluminium Alloy Repair?

Post by bikenav »

Thanks for the constructive thoughts peeps will disconnect the ECU at least I did not think about that so ta, the original thread is a little M6 with a drilled depth of 15mm unsure of the boss external dimensions, liking the out of the box thinking, external spigot or similar not sure if practical here though will also think about an insert too. Will pass on progress when there is some, welding is still my first choice even without any real practical knowledge of the heat spread risk to the top end components/head etc. Thanks all happy to hear more if there is any.
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