Cracked rim - worth repairing?

[bishboy]

I bought (and paid for) a set of YZ465 rims off ebay, the seller disclosed (no picture though) that the rear rim had a small crack, but for the price I was ok with that.

The seller, to their credit, has now advised that the front rim has a crack and sent some pictures. 

I know it has been discussed a hundred times, but is welding a rim going to reduce its strength,  I won't be re-anodizing the rim so issues there.  I just don't want it collapsing landing off a jump, so is it better to be safe than sorry and just try to find a good rim?

[shelpi]

welded up cracks on my Rm250X in 1981 and went on with out any problems obviously the 20 year old that gave it a hard time in the 1st half of that season gave it even more currie in the second  it was raced in the Mr Motocross to give an idea

[John Orchard]

Most of my rims have the cracks welded-up, not had a problem yet.

[Paul552]

http://www.torpedo7.com.au/shop/motocross/wheels---spokes

I bought some of these and they look ok at least 

[bishboy]

http://www.torpedo7.com.au/shop/motocross/wheels---spokes

I bought some of these and they look ok at least 

They're pretty good prices, but they only have 2.15 x 18 rear, I need 2.50 x 18

but then I only paid $60 delivered for the pair with the cracks and I will ask for a discount given the front now has a crack 

[jimg1au]

i think i have a 2.5 rear wheel 18"
jim

[farmer58za]

Both my Rokon's rims were cracked at the weld. And they were the nicest straightest Sun rims with tyre retaining pins. Nearly broke my heart to replace them. I don't take the chance to weld.
Regards
David

[yamaico]

Hey Bishboy,
Not many older rims around that don't crack at the join. I've had despoked rims that looked perfect just split completely while sitting on the rack. I've welded all mine and never had a problem - careful preparation is the key. Clean them thoroughly, vee both sides, pre-heat before welding and cool slowly afterwards. After welding dress the weld inside only where the bead sits. Leave the rest as welded. My opinion only, the choice is yours. By the way, I don't despoke now until I need them,
Pete.

[GMC]

Rims can be welded okay and you can get some more life out of them but the weld will be a soft spot as the heat from welding will take away the temper of the alloy in that area.

Not sure that welding and relacing a rim is worth it though unless there is a particular rim profile you want to keep. For the effort of relacing I would have thought it better to fit a decent rim
I have only welded rims that have been still laced, not sure how an unlaced rim would react? Possibly distort a bit more in the welded area??


Any closed loop metal structure will have some captive stress, frame engine cradles, rims etc. cutting through them will see the stress released, often to the destruction of the cutting disc.
While a rim will have a certain amount of stress it will not be enough to tear the alloy apart.
My theory is that if an unlaced rim cracks while sitting then the seam must have already been cracked / fatigued and it would probably have cracked not long after use anyway.

[yamaico]

I have only welded rims that have been still laced, not sure how an unlaced rim would react? Possibly distort a bit more in the welded area??

I haven't welded one that has opened up Geoff - the gap is usually at least 10mm and I've never tried to close it back up. Scrap alloy bin for them.

[GMC]

Yes I imagine they would be hard to pull back in.

Bishboys rim hasn't cracked right through and is unlaced, not sure how that would go. As there is not much holding it there is also the risk that the final bit may let go while welding.
Don't think I would want to be leaning over it if that happens.

Now that I look at it again I see it is a gold anodised rim making it even less favorable to weld as the anodizing will be lost in that area.

Also for any would be welders it is best to polish any anodising from the weld area, be it gold or clear as the anodising will effect the quality of the weld.

[oldyzman]

Having welded most other materials with MIG Stick and Tig and hearing that aluminium is more difficult, I have the utmost respect for a good aluminium welder (person) and even more when it is a repair....
Brett