Cracks.

[J_K]

So I've just bought some nice wheels to refurb for the drifter and found that one has a crack on the inside lip.
I'm planning to weld it up but wondered if people normally drill the end of the crack to stop propagation when they weld these things up?

I suppose the same question for cracked sumps too.

 

[Engineer]

If its a cast wheel, vee out the crack entirely and TIG weld with 4043 rod. If its spun, then a repair is still possible but failure is very likely.

 

[Drains]

Yes, definitely drill the end of the crack.

 

[Delgado]

+1 on drilling the end/s of the crack. Also, might be an idea to use die pen on it first to make sure you actually get the very end, as sometimes cracks extend further than is easily visible.

 

[J_K]

Die pen ordered.
Thats excellent info.
So die pen. Drill the ends then V prep and use 4043.

Thanks.

 

[Engineer]

No need at all for DP testing or drilling the end of crack! Clean up the damaged area both sides with P60 flap disc, go over the crack with TIG torch to determine exactly where crack ends, mark the end of the crack with a scriber, then vee out 10-12mm beyond this.

If its a spun wheel though, and you intend using for competition its probably not a good idea to repair it unless failure is not going to be a big problem.

 

[J_K]

I'd like to be able to repair sumps for one of my sponsors so having the die will be pretty useful.
I drift so never going very quickly. And wheels can get damaged due to some of the crappy surfaces we get to use.
It's a BBS wheel. I have no ideal if it's spun or cast. I would imagine it to be cast though.

 

[Engineer]

Again no need for DP in order to repair sumps.........cleaning them effectively is the only real difficulty, and cracks are easily detected by using your TIG torch.

Most BBS wheels are cast, but if its a 3 piece than it may possibly be spun. If its spun the part that is cracked will be quite thin and light in comparison to a cast rim.

 

[J_K]

They're only 2 piece rims.
And it's quite chunky and thick.

 

[Engineer]

It will be cast then, and repair should last quite a while as long as it doesnt suffer direct impact damage. In the main you only find a few AMG wheels and Japanese chav-tune aftermarket wheels are spun.

 

[bawjaws]

another +1 on drilling the ends of cracks, dont know how many 2 stroke exhausts ive welded back up over the years and it has started cracking again a week later, but done it properly last month to both mine and my brothers crossers by drilling the ends and then tigging it up and its certianly lasted alot longer than any of my previous attemts, and there the most rattly bikes ive done it to aswell.......

 

[hotrodder]

Be aware that cast wheels are often heat treated which'll be locally destroyed by welding. Both BBS and Mercedes/AMG have published info on the heat treatment they use and both of them 'flow form' (akin to spinning) the inner rim of some one piece cast wheels. Mercedes/AMG wheels are cast from an AlSi7 group alloy and heat treated, probably A356.0-T6 or something very similar.

I generally don't touch cracked wheels personally, only time i make an exception is for something that's effectively irreplaceable i.e. paying for some proper NDT is now fiancially viable. I'd be dye pen testing before to look for other cracks i.e. not yet visible by the naked eye. The few times i've broken my rule and repaired wheels i've nearly always found other 'previously unknown' cracks. I'd then test again after repair before sending the wheel out for further testing as dye pen will only find flaws that break the surface

 

[Engineer]

Never repaired a cast wheel thats been heat treated, so thats a new one on me!..............Spun rim sections used on some 3 piece European and Japanese are certainly heat treated though and effectively are not repairable if cracked.

In terms of cost bigger OE wheels are going for around £300-800, and as not everyone is rich many people are unable to afford replacements rather than repair.

As for DP or NDT its really a total waste of time as it increases costs for no real reason, and anyone who is not familiar with just how poor many alloy wheels are from the factory may well scrap wheels which are perfectly serviceable, due to flaws shown up by NDT.

Finally I wonder what sort of competition do you take part in hotrodder? I ask as there are awful lot of drivers of comp machinery who are quite happy to run on repaired wheels?

 

[TechnicAl]

What would happen if the wheel was to fail due to these cracks or the repair?

 

[hotrodder]

Never repaired a cast wheel thats been heat treated, so thats a new one on me!..............Spun rim sections used on some 3 piece European and Japanese are certainly heat treated though and effectively are not repairable if cracked.

How can you tell whether a wheel's heat treated? Can't tell by looking at it, hardness testing could give a clue but if NDT takes too long/costs too much...

Less than 5 minutes with google and i found out what alloy several of the big manufacturers are casting from, every single one of them also claims to heat treat, both solution treatment and artificial aging. Have a play with terms like 'cast wheel heat treatment alsi7' 'Rota A356.2-T6' and 'gk-alsi7 cast wheel'

In terms of cost bigger OE wheels are going for around £300-800, and as not everyone is rich many people are unable to afford replacements rather than repair.

True although most of the time when i've been asked to repair a wheel a good used replacement can be picked up for next to nothing- pick one that hasn't just been refurbed and there's less chance of buying a repaired wheel

As for DP or NDT its really a total waste of time as it increases costs for no real reason, and anyone who is not familiar with just how poor many alloy wheels are from the factory may well scrap wheels which are perfectly serviceable, due to flaws shown up by NDT.

Yeah i'm sure looking at an x-ray of some cheap wheels would be scary in that they can probably look like an aero bar. X-ray isn't the only option though and besides you're not looking for perfection, some porosity is acceptable, any cracks are not

Finally I wonder what sort of competition do you take part in hotrodder? I ask as there are awful lot of drivers of comp machinery who are quite happy to run on repaired wheels?

Don't see what my hobbies have to do with anything but competition means several things...
Tracks are designed with crashing/exiting at high speed backwards in mind and tyres don't last as long i.e. there's a greater chance (or at least the opportunity exists) for more frequent inspection

The biggest problem i have with wheel repair is what some of the repairers are claiming- people i know (personally) have been told their wheel is 'as good as new' or that the welded repair is 'stronger than origional' which is blatently untrue.

 

[PhillipM]

Competition on tracks is often much less harsh on wheels than road use to be honest, poor roads, salt, corrosion, negelect, potholes and kerb damage don't often factor on a track...

 

[scott0031]

This subject has been discussed in a lot of depth on this forum.

I am with hotrodder on this one and fully support his views. I think what some members here fail or refuse to see is hotrodder's knowledge goes way beyond the average tig welder, those people are few and far between. For some it's a job, they do it, get told what to do then go home collect wage packet. With the rare ones like hotrodder it goes way beyond that. I think due respect should be given to his knowledge and view point. You ignore good advice at your own peril. But don't say you were not warned!


The bottom line is this and this is exactly what it boils down to. Someones life hangs on that repair, if you are prepared to run the risk that someone could get hurt or even worse die from such a repair failing, then fine, go ahead. Just remember YOU are the only one that has to live with it. This is the bottom line.

If only some of the people here really understood the real technical side to structural ally work and the risks involved and seen the consequences of it going very wrong at first hand experience, you would have a different view point.


Kind regards,


Scott (Ward engineering)

 

[Engineer]

Interesting that people with little or no hands on experience of doing a particular job, become an expert when discussing with others who might very possibly have even less understanding.

In the real world things are quite different though, and the current economic situation means that many people simply cannot afford expensive new wheels, or in many cases to replace a whole set of wheels if a replacement is not available!

Not to worry though, and I am glad that most people using these forums seem to have the money to replace a damaged alloy wheel, rather than have an inexpensive repair carried out.

I ask about what form of competition you are involved with hotrodder, as anyone involved with competition is very familiar with repairing alloy wheels, which is a something that has been going on for many years without any big problems.

 

[PhillipM]

^^Well, I'm in competition too, and we throw cracked wheels as they just shatter the next time out 90% of the time, unless it's just a repair to the bead. Might be alright for the roundy-roundy boys on smooth circuits...

 

[hotrodder]

I've never claimed to be an expert in anything not that doing so would carry any weight in itself on what's essentially an anomyous forum on the interweb. All i've done is point out that personally i generally avoid welding wheels because even plain ol' cast wheels are often heat treated and suggest some search terms to back that fact up. Did a little more searching tonight as i'm over my stainless sink obsession (sorry Al)...

Enkei (OEM to GM, Nissan, Mitubishi and Honda?), Rota, Speedline, O.Z. Mercedes/AMG, BBS and Rays all put castings through a solution treatment and artificial age. O.Z. use AlSi10Cu and AlSi7Mg alloys in the T6 temper (T4 for their magnesium wheels) and 6082-T6 for forgings. The others in the list all describe a similar heat treatment process even if they don't spell it out with an exact alloy and temper designation
Compomotive use LM9 in the tb7 condition (AlSi10Mg / A360.2-T7, solution treated and stabilised) for their wheels and the various repros they also cast like those old Campagnolo mag jobbies

Answer TechnicAl's question* and i'll post a list (not an impressively long list but pretty diverse) of the various areas of motorsport i've fabricated/repaired parts for Not one of them has ever asked me to repair a wheel not that it means much in the grand scheme of things- they may not trust me with something so critical, they may use someone else that can do the entire job including NDT & refinishing 'in house' or they may junk 'em/turn them into tables/hose reels like Phillip. I'm pretty sure they all would have reasoned i was capable of physically sticking a wheel back together and ending up with something round as they typically found me when looking for someone/somwhere that could repair a mag gearbox casting or something else odd/exotic at short notice

* hypothetical situation... serious RTA, loads of carnage including a broken wheel. Wheel may have broken as a result of the collision, maybe it caused it but anyway...the accident investigators/insurance assessers are drawn to this wheel (the fracture looked odd) and discover from the owner it was recently repaired- yeah it's a hell of a long shot but so's the lottery. AFAIK there's no regulations covering this sort of repair, VOSAs take being something like 'must be competant design/engineering/workmanship' or something along those lines. How do you answer to that without a specific welding procedure and NDT?