alloy wheel welding advice

[squazy84]

im welding a small crack on a bbs alloy wheel, now ive done the outer side first and it took me ages to get it right,i used 2.4 m filler with magnesium and needed a base setting on the plant of 205 amps,continous hf, about 9 lpm argon flow, white tipped 2.4 tungsten and a miller syncrowave tig,
i found it hard to get the puddle going first and some times it would splatter the filer back out at me,but eventually,it seemed better once i got the part to heat up,it was cleaned with thinners and veed out with a pencil grinder and cleaned with a new stainless steel wire brush, as ever all help appreciated,ill try get some pics up,(dont wory about safety ect, its my own test car ect)

 

[Garreth]

Did you pre-heat the wheel first ?

I've found it easier if you warm the wheel up (I used a big electric plate we use for bearings at work) as then it doesn't suck the heat away from the joint as quickly. If you do it "cold" the wheel acts like a big chill and its difficult to get the puddle going.

Ditto comments re safety - for my own use off road etc etc!

Garreth

 

[squazy84]

no i didnt pre heat, would be fairly hard unless i could set up the blow torch on it?

 

[Garreth]

You need to get an even heat into it - blow torch probably not the best way I would have thought. Sat on top of a radiator, in front of a hot air blower that sort of thing.

I have a big piece of 1/2 in steel plate that we sat on top of the bearing heater then left the wheel on that for 30 mins to get it nice and warm without being too hot. Have welded quite a few this way no probs (yet !)

Garrteh

 

[TechnicAl]

Must admit that im no expert on alloy wheels but they alloy is chosen for looks and its ability to be cast (ie it flows). Therefore welding is not a consideration. Im uneasy with welding these things and if involved in an accident, I would expect an insurance company would find it a very easy excuse should it be remotely blameable.

 

[squazy84]

perhaps i should have spent a few grand on a new set of wheels lol nope,it worked fine preheated with a blow torch on low heat

 

[langy]

I've done ally truck wheels and preheat is the way, also i wouldn't use thinner for cleaning as it leaves a residue behind, don't know what the residue is but it definitly welds better when cleaned with acetone.

im welding a small crack on a bbs alloy wheel, now ive done the outer side first and it took me ages to get it right,i used 2.4 m filler with magnesium and needed a base setting on the plant of 205 amps,continous hf, about 9 lpm argon flow, white tipped 2.4 tungsten and a miller syncrowave tig,
i found it hard to get the puddle going first and some times it would splatter the filer back out at me,but eventually,it seemed better once i got the part to heat up,it was cleaned with thinners and veed out with a pencil grinder and cleaned with a new stainless steel wire brush, as ever all help appreciated,ill try get some pics up,(dont wory about safety ect, its my own test car ect)

 

[squazy84]

pre heat saved the day i ended re grinding my first weld off,maybe it was the thinner,the next weld i did i just cleaned the joint with a grinder and stainless brush,then preheated the area with a blow torch and welded in a wide puddle this time with shiny aluminum filler rods with silicon in them,worked better than the dull mag filler rods

 

[hotrodder]

I'm with Al on this. Many of the alloys used for wheels are weldable but there is a hell of a lot more to it than that. Granted a personal track day car is going to see less use and more tlc than the daily driver but when it is used it's going to see far higher speeds, particuarly cornering speeds

BBS claim to use proprietary alloys, they are going to vary with wheel manufacturing process (cast, forged/spun etc) and wheel quality (lightweight = often heat treated, maybe cast maybe forged/spun or a mix with multipiece wheels). Cast wheels will virtually always be a silicon rich alloy, heat treatable wheels a silicon, magnesium alloy. Forged are often made from 5454 or could be one of the 6xxx series alloys in which case they'll be heat treated

Filler wire selection is dependant on the alloy the wheel is made from, not what it's like to weld with. Weld a silicon rich casting with an AlMg wire and there's a MUCH greater chance of cracking- fine if it's solidification cracking and splits in front of you but can look fine and be full of micro cracks (google 'liquation cracking' and 'magnesium silicide + welding'). Get the filler wire correct (luck/research) and the area local to the weld will still be softer and weaker than the rest of the wheel- if the wheel is made from a356-T6 or 6061-T6 could be looking at a 50% reduction in strength, or more if heat inputs were on the high side

At the very least buy some dye penetrant and crack test them. Won't show subsurface flaws but will at least highlight surface flaws that can't be seen with the naked eye. Inspect 'em regularly and at the first sign of air loss, tyres off and DPI again

 

[squazy84]

i drove the car with the crack for 2 years,fast. the crack was all the way through and somtimes leaked air! its 450 bhp for skids lol