3 piece wheel cracked barrel repair

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Finally documented a repair halfway decent. One of my friends is in the process of restoring some vintage BBS RS wheels, and one of the barrels had 2 cracks in it. It still appears to be pretty round which made this repair fairly straight forward. Steps were1. Sand off paint on both sides of crack2. drill 2mm in front of the visible end of the cracks3. use a carbide burr to v out both sides of the crack4. weld inside5. weld outside ensuring the drilled hole was fully fused6. shape inside and outside using some files, dremel, and sand paper 7. filled a couple low spots at a lower amperage and sanded some more Welding was done at about 110 amps no preheat, no pulse no pedal scratch start. Filler was 4043, not the cleanest looking welds but I had the cleaning action pretty low I wanted to get a lot of heat into the rim. In the past doing one piece cast rims I have preheated, it definitely makes it easier to start the first bead. Last edited by chrisbmx68; 10-28-2011 at 10:36 PM.
Reply:Is the hole to stop the crack from spreading? Or is it to make using the carbide burr easier?Looks like a good repair!
Reply:When possible drilling the ends of a crack s is a good idea. It theoretically relieves the stress in the material and prevents the crack from continuing past or through the weld. Grinding down into the crack out and welding hot can be acceptable but isn't as ideal. If I had just welded right over these cracks they probably would have just come right back on the first big pothole.
Reply:That's what I figured, but it is good to know. Thanks!
Reply:Ive welded A lot of rims and I would never just put a little bead on to the crack like that. I would bet that it will crack again in the same place.  It needed ground out completely and welded completely and peened severely. Ive never had one come back. and never heard of one of mine breaking.  Mac
Reply:Am I missing something Mac?  He said and showed that he fully ground out both sides of the crack, drilled the end point and welded from both sides.--Wintermute"No man's knowledge here can go beyond his experience." - John Lockewww.improvised-engineering.comManufacturer Agnostic:Blood----------Sweat---------Tears----|------------------|----------------|----Lincoln Red, Miller Blue, Esab Yellow
Reply:correct I left out a pic of the back side after i ground it out. I actually did more grinding after those pics my first pass was with a ball shaped burr as it is easier to get into the corners then I went back with a triangular pit to make an actual V and get into the meat of the crack (didnt take pics of that) The material in question is less than 5mm thick as well durability was not really top of the priority list when bbs made these. IMHO there shouldn't bee any need to peen a repair like this its not like cast iron. It is fully fused and the crack was removed adequately. If it fails I will be the second to know after the owner and will gladly post the failed product up on here. Last edited by chrisbmx68; 10-31-2011 at 04:35 PM.
Reply:Wow...those look great all polished up.  What type of car are they going on?--Wintermute"No man's knowledge here can go beyond his experience." - John Lockewww.improvised-engineering.comManufacturer Agnostic:Blood----------Sweat---------Tears----|------------------|----------------|----Lincoln Red, Miller Blue, Esab Yellow
Reply:that's not the actual wheel, but they should look that good when completed. He still needs to get his centers re powder coated and put everything back together they will be going on a 1991 bmw 318is should look something like this but I think they are staying silver.
Reply:Aluminum shrinks more than almost any other metal you will ever weld.  It shrinks so much when it goes from liquid to solid that when casting you have to put in small hollows for excess aluminum to store in for when it shrinks otherwise you have major shrink cracks.  If you immediately peen aluminum when you finish welding it normalises the shrink stress in the weld and the surround.  mac
Reply:Pretty much all cast metals shrink...it's just a matter of physics.  I've never heard anyone on the forums here state much about peening aluminum welds (even on the numerous aluminum transmission housings and small engine casings that have been fixed and posted here).--Wintermute"No man's knowledge here can go beyond his experience." - John Lockewww.improvised-engineering.comManufacturer Agnostic:Blood----------Sweat---------Tears----|------------------|----------------|----Lincoln Red, Miller Blue, Esab Yellow
Reply:great repair
Reply:Would a needle scaler be suitable for peening?