Question about welding axle tubes to center section

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I'm taking a welding class at the local college and was discussing a personal project of mine with the instructor but left with some questions still.  I'm wanting to stitch weld the axle tubes to the differential on an AMC 20 axle. This is out of a 1982 Jeep CJ-7.I have the axle out of the Jeep to regear from 2.73 to 4.56 and install a locker and 1 piece axles (these come factory with 2-piece).  I've done a lot of research and found the AMC has a few weak spots that when fixed it will last a long time with my application.  These axles have a tendency to spin the diff on the axles after you throw in lower gears and a locker.  Stitching them to the center fixes that.My welding teacher recommended going with a cold weld and peening method. He said I could weld it cold and then peen on it for a good 5 minutes to blend the molecules (think is how he phrased it).The hang up is deciding on the type of rod to use and thats what I created this thread for. I've read everything from high-nickel rods, regular 7018 and even just Mig welding with regular solid core and gas. I'm not sure how to tell if the center is cast steel or cast iron if I don't have anything to compare to (test with the grinder method). And, if I can tell the difference does it matter when it comes time to weld, as in would you use the same type process either way?The other method we talked about was pre-heat, weld, post heat but my teacher thought if I'm just doing short 1" or so welds the peening way would be easiest and just as good.This is an example of what I'm looking to do (picture stolen off the net);And here's mine as it sits.  I will have all the internals removed when the welding occurs;The usual answer for curing the AMC 20's weakness are to find a Dana 44 out of a scout or something and just toss out the 20.  Not a bad idea but I've been collecting parts for this project for a year now so I've gotten good deals on the locker, carrier, master kit, 1-piece axles and gears.  So since I'm cheap, my labor is cheap and don't have the money to drop Dana 60's front and rear this is what my plan is.  I'll also be doing a basic truss on the axle, after-which the axle is stronger than a stock Dana 44.Ok, sorry I'm so long winded but I'm just trying to get it all out in one post. Thanks for "sticking" with me this far
Reply:Welded dozens and dozens of axle housings - Here's how I do itPre-heat to around 350 deg.  Weld with nickle rod (I use Crown 220m), wrap it in a welding blanket when done and let cool as slow as possible.  I don't peen the centers - only smaller pieces like knuckles when I weld them.Never have had a failure - The rigs I build take major abuse!Some say the centers are not cast iron, some say they are - Doesn't really matter, welding them with this method holds up either way.
Reply:preheat and weld with mig then post heat if you want , if you look at the rear end you will see that it was welded at the factory with a mig .Life is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:Do a spark test so you know what you are welding. If its CAST IRON, the sparks will be small, no tails, a little red and only go a foot.  If its cast steel, the sparks will be yellow with tails and go 3 or 4 feet.If its cast steel, just weld it!DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Good idea to eliminate the weaknesses of the AMC 20 I had a '76 CJ 7 with the quadratec system with a 304 V8 and turbo 400 tranny. I almost had the drivers side axle walk out from under me going down the road. The real weakness with them is when you put them together the hub is not splined. When you tighten the hub nut is when the splines get cut in the hub very very weak.So anyway kudos to you for seeing it out and making it worthy of what it should have been.Ok guys sorry back to the topic.
Reply:I would scratch the whole idea and consider finding something else. Just cant justify all that work for a 20Thats a tough one. weld it like you own it
Reply:Originally Posted by lewrayI would scratch the whole idea and consider finding something else. Just cant justify all that work for a 20Thats a tough one.
Reply:Ok yes .... I do know a guy who ran a 20 w/ 38" swampers... wheeled for a long time without a problem and had folks in awe.  Infact never broke an axle. He was light footed which helped matters.  But the secret was he had an ARB selectable locker.  Like I said I can see your point thats a tough one.Still I know you can go to tennesseeoffroad.com and find the "parts for sale section" and find something better.  Really.....go for it and get bragging rights.  I have cut and turned my knuckles on my FJ 40 front axle and folks thought that was far fetched... but hey it has worked flawless.  Also I put cromies inner and outer w/ ARB so gosh I have like 3500$ in a stupid axle,  ... crap that doesnt include hydro steering and high steer arms with all the other good stuff oh my goodness I could have bought a rice burner bikebut I do like it.  Last edited by lewray; 02-13-2008 at 10:19 PM. weld it like you own it
Reply:Well, another time bomb I have is I put a Ford 302 in front of the stock Jeep T-5, cause again, I'm cheap.  I had a worn out 258 in the Jeep and a good running 302 in hand.  A mustang bell-housing and other odd's n ends and I was on the road again.So, if I don't stay off the skinny pedal it's hard to say whats going to blow up first.  I've never been hard on my stuff so it's no big deal.
Reply:I did the grind test last night and it threw short little sparks and also did a drill test and got tiny little dark gray shavings.  So, all signs point to Cast Iron I'd say.
Reply:Then use the nickel rod.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Originally Posted by coronet440I did the grind test last night and it threw short little sparks and also did a drill test and got tiny little dark gray shavings.  So, all signs point to Cast Iron I'd say.
Reply:Originally Posted by Mr.NI'm not sure on The Jeep 20... but I'd guess they are similar to Spicer axles, and I know a little about Spicer axles.  I know Spicer use Nodular Iron for their center sections, pumpkins.  The Nickel rod is what I'd use.Edit -> I've a 5.0 Mustang in my Jeep, love it.  Some reading to help you in your swap -> http://www.pirate4x4.com/forum/showthread.php?t=45309
Reply:The welding rod my teacher gave me is UTP ECONOCAST 55 NiFe-Cl.  I couldn't find anything about the rod online but I did find what I thought was a comparable rod (86FN) on UTPs website so I followed it's guidelinesI worked on my practice axle tonight and it went well.  My welder is an old AC Forney 230 and it doesn't have a knob, it just plugs into the different settings (pretty fancy I know  ).  I set it to "105-115-120" and Medium Ground. I heated the area around where I was going to weld to around 100* and ran a 1" pass, checked the temp and highest reading was around 230*.  I immediately went to lightly peening the area with my pointed chip hammer for about 3-4 minutes until it cooled to hand touch again, around 100*. After I was done peening the first weld I rolled the axle over and hit 1" on the opposite side using the same process, then did the other two perpendicular sides.  Whole thing maybe took an hour for the that side of the axle.Any thoughts from you veterans on this process?  After I was done, everything was around 100* but I still wrapped it with some jute padding stuff I had just to help it cool down slower but since it's only 100* cooling down I'm not sure if it really matters.  I'll post some pictures later.My teacher thought this process would be better fitting than the pre-heat to 350* and weld because the tubes in the AMC 20 are thinner than a heavy axle like a Dana 60 and thought the cold method would better avoid warping.Thanks.
Reply:Originally Posted by coronet440I worked on my practice axle tonight and it went well.
Reply:Originally Posted by lewrayI would scratch the whole idea and consider finding something else. Just cant justify all that work for a 20Thats a tough one.
Reply:Originally Posted by coronet440.....................Any thoughts from you veterans on this process?  After I was done, everything was around 100* but I still wrapped it with some jute padding stuff I had just to help it cool down slower but since it's only 100* cooling down I'm not sure if it really matters.  I'll post some pictures later.My teacher thought this process would be better fitting than the pre-heat to 350* and weld because the tubes in the AMC 20 are thinner than a heavy axle like a Dana 60 and thought the cold method would better avoid warping.Thanks.
Reply:Originally Posted by RojodiabloNo kidding. The Heep axle is about the WORST choice for an axle in an offroad project. Dana 44's are a dime a dozen, much stronger, and have just as many options for lockers, brakes, etc.
Reply:Here's my practice axle;Will hopefully be doing it on my Jeeps axle this weekend.  Hardest part for me was knowing when to stop.  I tried marking it with soap stone but can't see the line when welding.  The last weld I actually taped a piece of bailing wire perpendicular to my welding so I would see the rod nearing it to know when to stop, kind of goofy but it works.
Reply:Keep us posted... Good project weld it like you own it
Reply:Finally had a chance this weekend to work in this some more.  I got the tubes welded to the center section yesterday and everything went well;I then worked on building a simple truss.  The truss piece is just sch. 80 pipe bent on my Harbor Freight pipe bender.  Since I didn't want to do any more welding to the center section I built a plate that bolts to the differential cover that ties into the truss.  I will be bending and welding a cage made of 1/2" pipe that will protect the cover as well as help evenly distribute the load to the face of the differential.  Since this is a bolt on I'm not sure if it will really work but It's got to be better than nothing;Jordan
Reply:As good as you have done so far I'd weld it solid.  Weld looks good to me from the picturesAs David says do the spark test.  Maybe find a piece of known casr iron and compare.I've welded a bunch of these with TIG for the drag cars. Dana 60 and GM stuff as well as 9 in Ford.  If it doesn't bubble and look like **** it is probably cast steel and will weld ok.I have a rear end narrowing kit so I just slide the bearing plugs in and the line up bar and have at it.  I've put 3 different sets of 4 link plates on my streetrod 9 inch Ford and it is still straight.I'd use a Dana 44 at least for what you are doing however.
Reply:Originally Posted by bentwingsAs good as you have done so far I'd weld it solid.  Weld looks good to me from the picturesAs David says do the spark test.  Maybe find a piece of known casr iron and compare.I've welded a bunch of these with TIG for the drag cars. Dana 60 and GM stuff as well as 9 in Ford.  If it doesn't bubble and look like **** it is probably cast steel and will weld ok.I have a rear end narrowing kit so I just slide the bearing plugs in and the line up bar and have at it.  I've put 3 different sets of 4 link plates on my streetrod 9 inch Ford and it is still straight.I'd use a Dana 44 at least for what you are doing however.
Reply:Originally Posted by lewrayIf I remember...    the ring and pinions will be stronger and much cheaper than the 44.  Good stuff.  Now you have bragging rights when everybody including me  tried to talk you out of it.  Looks good so far.
Reply:Originally Posted by coronet440I too think it's nodular iron from what I'm finding on the net.  My welding instructor has given me some high nickel rod, UTP brand but can't recall the size, I'll post it later.  He is saying hit it cold, weld about a 1" pass and peen it until cool.  He said weld until it's hotter than you can touch then walk away till it's cooled again.  I've got a broken 7 1/4" axle out of a Dodge Dart I'm going to practice on.That is a great link on Pirate, I've been a member there for some time and have participated a little in that thread even.  I went with a 1979 302 out of a pickup.  Carb'd and points ignition.  It's as stock as can be to keep the HP low and keep the drivetrain from getting hurt too bad.  It has plenty of go for what I do.Originally Posted by down19992000that 302 must not have been the stock motor in that truck if it still has pointsford went to electronic ignition in 1975
Reply:Finished the truss, diff cage, 4.56 gears and 1 piece axle install for my AMC 20 and was ready to get it put back in today.All buttoned up..........And I ran into a problem installing......cage hits the fuel tank skid plate    It looks like there is space there but I can't get the axle into the dowels so it's rocked forward a little.When I built it I knew it would be close but thought it would fit, obviously I was wrong.  I think I'm going to just cut the top part of the cage off.  Looking at it now, if I ever had to service the diff then either the axle would need to be unbolted or the gas tank removed.I'll have to move the bottom tubes in a little still or they'll hit when the springs compress.  I'll just cut a chunk out mid-section and weld them back up.Jordan
Reply:Originally Posted by coronet440And I ran into a problem installing......cage hits the fuel tank skid plate    It looks like there is space there but I can't get the axle into the dowels so it's rocked forward a little.
Reply:Originally Posted by Craig in DenverMy question is: "How do you know that those tubes are straight; you know, 'line bored' through the differential?"
Reply:OH, I misunderstood. I thought you had replaced the tubes into the diff carrier; not that you had 'reinforce' welded the existing tubes. I haven't kept up with off-road suspensions since I sold my 350 Chevy Landcruiser, many years ago.9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:Here's what I ended up doing, seems to fit fine now;