Aluminium weld for a hairline crack on chainstay

[edkin]

Some pics of the crack

 

[Hairy]

a question for you ... how were the bearings in that pivot when you took the frame apart?

[BikeisLife]

a question for you ... how were the bearings in that pivot when you took the frame apart?

They probably had turned into bushing with little or no movement 

[edkin]

Yip. Not good. I need to replace them

[Hairy]

Yip. Not good. I need to replace them

if that is the case, you may find the reason for the crack is the seized bearing putting undue stress on that area.

[BuffsVintageBikes]

You may also be in luck because that looks like a solid piece of alu and not tube so there's more material to weld.

[edkin]

if that is the case, you may find the reason for the crack is the seized bearing putting undue stress on that area.

That was my first thought as well but the mechanic at my LBS didn't seem to think so. I'm replacing the bearings anyway just to eliminate the possibility. I could kill for a decent bearing puller. Just can't seem to find one anywhere local

[edkin]

You may also be in luck because that looks like a solid piece of alu and not tube so there's more material to weld.

If you look carefully you'll see its been welded before. It seems to be a weak spot that I will need to keep an eye on

[MrJacques]

My suggestion: break it off completely, put something that can provide sufficient reinforcement inside the hollow parts on both ends (some kind of metal?) and then have it welded by someone competent. It seems to be a high stress area and just welding it might not be enough.

[DieselnDust]

The chances of an aluminum weld holding is very slim. Rather, the weld will probably hold but it will often crack again next to the weld. If you want to take the chance, I've got a friend who does laser welding, which is probably your best bet there. His name is Erich and their company is called Luxus Jewelers, they are based near Stodels.

 

 

Welding such a thin walled tube a 2nd time won't last. This is not like welding an engine block. Heat treatign and shot peening the affected area might add longevity

[Big_Al]

You can try Link Engineering in Salt River. They have welded some motor bike crank casings and swing arms for me before. Both came out quite nicely!

 

If there aren't any clearance issues maybe ask them to put a little gusset in to strengthen it. Running perpendicular to the crack, blending into the bearing flange and the cross member. 

[Andreas_187]

The best welder in CPT is Gerrie who works out of his house in Brackenfell. He's does phenomenal work. 0 eight four 469 3805

[edkin]

Ok so I've had a some great responses. Thanks again. I've put all the possibilities in a list and working through them. I'm trying Link first purely because they are closest to me. will report back on my exprerience.

 

Still haven't gone vegan    

[Hairy]

Ok so I've had a some great responses. Thanks again. I've put all the possibilities in a list and working through them. I'm trying Link first purely because they are closest to me. will report back on my exprerience.

 

Still haven't gone vegan    

well that was obvious ... if you had you would have told instructed us so already!

[Blackheart]

For the welding experts/metallurgists amongst us: Doesn't aluminium need to be annealed after welding to take out the brittleness the heat imparts? And how does the material respond to a second cycle of heat and annealing?

 

Or does one just go Vegan....(sorry couldn't resist, but the above question is a genuine one)

[edkin]

OK. so I went to Link because they were closest to me. The guy takes one look at the chain stay and says "No problem. I'll add a little gusset for strengthening Purposes" .

 

It took them a day. Here are some pics