Allright Welders!

Check the "back to square one" topic first. What is the best way to fix this crack? Pa has asked for help. and opinions, but it's on the last page. I guess a topic gets dead here pretty quick.


Duh...........Pa-Simers at it again. Looks like a chain gave out once and clipped the opening or something got dropped on to it. I'd lightly dremel the crack and weld from the outside, without breaking clear through. I'm thinking a qualified welder would agree. The welder, IMO, would patch stake, small areas equally spaced apart, in order to keep the heat down to a minimum. He would then most likely, fill in between the stakes, until the whole length of the crack was fused back together. He may even decide to drill a small hole at each end of the crack before welding it all up, to keep the crack from growing any longer. You still may have to disassemble it so the dirt and lube doesn't contaminate the welding process. Come on welders....am I close ?? Pa

It has to be taken apart. You will never get a clean weld with all the oil contamination in the crack. The crack needs to be v'd out on both sides and cleaned best possible. The v'd area should be heated with a torch to burn the remaining oil and grease and brushed clean with a stainless steel brush. Stitch weld the areas least likely to distort any mating surfaces first. It's a bit of a guessing game to find a pattern of weld that will minimize the distortion.I'm refering to a TIG weld using a soft alloy like 4043. Preheat to around 300F and post heat with a gradual temp reduction. Find a welder experienced with aluminum castings, a welder doing MIG welds on big rig fuel tanks will likely not be much help.

Thanks for the reply, and I already have plans to use the stainless steel brush, after a good soaking, and thorough cleaning. I have read here on this site somewhere, that you can weld aluminum, and when finished you can't tell it's been welded. Am I right? If so who here does it? I actually think it was a set of cases.

One person would be Don Sullivan.

http://www.headhog.com/index.htm

It may be a while before you'd get it back. $$ But it would be done correctly.

If it’s disassembled, you probably have a good welder close by that could do a fine job. But get the oils out before you take it to a local welder.

I weld as a hobby mostly on my restorations but this is what I have had success doing.

You really need to heat the oils out of the casting first. Soaking won’t get the oils out of the casting.
I once tried boiling the casting when the wife was out of town.
I don’t think that worked too well. I thought the oils would float to the surface away from the part.
A friend tells me we need to build a vacuum oven.
I have done this over a kerosene heater cleaning it with acetone or an evaporating degreaser
before heating again. and again until the oil smoke in my garage clears when heating.

Heat the V ed out area with a acetylene torch and clean with a new clean stainless steel brush.
Then heat as much of the casting as possible around the crack
Tig weld while hot with 4043 rod and heat as much of the casting as possible again.
I start from the drilled hole at the end of the crack and weld straight through in one pass.
Try to keep the casting from cooling too quickly. A bucket of ashes works.
You could also keep it over a kerosene heater and slowly move it further and further from the heat until it cools.
I‘ve covered the welds with gloves and heat every few minutes for 20 or 30 minutes than slow cool .

How you grind and finish the weld will determine how noticeable it is.
I think shot peening is something I have heard matches the original finish well.

i was advised me to pre-heat castings 3 times to 250-300F (through completely) to bring the hydrocarbons to the surface.
heat/cool/clean---heat/cool/clean---heat/weld (larger items/cracks, stop & re-heat/weld) then heat again, cool slowly.
If it splatters, stop & clean more. Vee it out completely, a crack under a weld will find air! Solvents & de-greasers are
hydrocarbons & will cause problems.
If you use the kitchen oven, your food will taste bad for weeks.
I'm just sayin...

On welding this..
I agree that it be cleaned, if possible, before welding...I've had some luck the local coin fed car wash to get the gunk off the parts then using ordinary dish soap and basic H to break the oil and grease off and out of the pores..Follow this by gently heating the part to bring out more oil and rewash as many times as it takes...
I'd use a peanut grinder (dremmel) and pointed bit and grind it beveled the length of the crack not compleatly through as you said..I'd also drill a hole a 1/4 inch beyond the end of the crack to ensure it doesn't crack again..Keep in mind that crack may be so fine that it is hard to detect where the end is or ends are...
All this done I'd prefer to bolt mated surfaces back together as they would be under running conditions..
Your ready to weld..........I'd tig weld it....
I'd cover it/insulate it between passes perhaps using K wool....I'd try to keep the temp. of the item consistently the same by gently ( carefully,slowly..evenly..) heating it just before each pass...You'll be very surprised at how much water will come out of the pores when heated...........
An old dishwasher makes a great aluminium parts cleaner... Also welding shops sell a liquid alum. parts cleaner which works really well...
Preheat it gently..200/300deg...run a light bead in the base...cover it and check the heat again in a few min's. bring the heat to the same level you had it for the first bead and weld another pass..Keep doing this till your done...The first few tries at welding might produce an ugly sooty effect..If this is so then I'd usually run a quick, no filler rod, dry pass pulling a slightly long arc. very quickly over the length of the crack...This brings up remaining scum/oil from the pores..Next brush it out with the stainless brush and Then try the weld again..Eventually it will weld cleanly..Be patient...If the crack runs into where the two parts bolt together then start the weld not far from where those parts mate.Not close enough to effect the mating surfaces.........
When done with the main body of the crack take it apart and weld the last tiny bit..,,....Remember always keep moving when welding alum. never pause and hold heat in any particular area for very long...I prefer lots of small beads rather than one big fill bead...If you stop and work an area you my find yourself fixing a large hole rather than a small crack..
When done wrap it in K wool and let it cool slow..,,..
Grinding off parts...My experience tells me that grinding the surface off a good weld for cosmetic reasons make the weld weaker..How nice you want it and how strong you want it are flip sides of the same coin...For something experiencing torque stress I'd not want to grind it off but would rather give it every chance I could.......

Tig welding antique alum. auto motive parts is a pain..Adjust your machine while running a few beads on something simular..( old alum. automotive water pump body should do it) Do you have a tig welder..?..
I've actually enrolled in weekend tig classes at the local comm. collage to get hands on access to a good quality tig machine and some good advice from the instructor...
I told them I just wanted to learn how to use tig to help with my antique motorcycle hobby..
Some people (mostly my boss) say I'm obsessive about maint. repair welding but I am a certified welder and I do a lot of equipment repairs..I'm not certified as a tig welder but I use the process at my job mostly on pump bodies...There we do not have the time to really super clean anything...They want it fixed now/fast..the enviroment is filthy and badly contaminated with oils and solvents..it's impossible to have anything clean...Often I can do nothing more than grind out a crack and spray it off with "I.D. red"..Heat it a little... pull a few long passes and then weld it...Yea..I KNOW...but it works...........Yes I'D'red is an actual aerosol product you can buy for cleaning which evaporates and leaves no residue........I think it's made by ZEP.....
Your local welding shop will sell you small amounts of the correct rod if you take the part in for viewing...They might want to sell you this new low heat alum. brazing rod , don't buy it...........There's lots of stuff that looks alum. out there...I'm not sure what exactly is in the casting material of a 45 servi. rear end...Year by year things change and the only way of knowing is to try working/welding the material...
If you want a professional result take it to a professional welder and pay a professional price...
Personally I'd do it myself...I'm working a few K heads right now and I've replaced the fins on an indian scout head...The fins came out pretty good..The K heads are a work in progress...
Looks to me that Indian used better material in their castings than Harley did...That'll get me a few howls of indignation I think...
Good luck