welding axle tubes to housing

By FabCrazyGuy Date 01-09-2010 19:42

I hear and see alot of different opinions on how to weld mild steel axle tubes to the cast steel housings.
Some say 7018 with a little preheat..
Some say Ni rod with a 400-450 preheat and slow cool..
Some say any nickel rod..
some say 8018 or higher...

Some say also that no one really knows what the chemical composition and process they were made of so a specialty rod and preheat and slow cool is best.

So what's your opinion and reasonings behind it?

By DaveBoyer (*****)

Date 01-10-2010 03:04

I would bet the factory does it with 70S-3 mig wire and no pre or post heat.

By Joe Davidson (**)

Date 01-10-2010 04:12 Edited 01-10-2010 04:16

I have welded on axles using mig with 70s-6 wire and co2 gas, and have used 7018 as well. Have never had a problem with any of it. This ranges from 800 hp race cars to semi wreckers. Took a 9" ford, fabricated and welded the upper trailing arm mounts to fit a 1980 Cutlass, it had a Oldsmoblie 455 putting out 600 hp and running slicks. Just out of curiousity, are you welding the tubes to the center section to shorten axle? If you are trying to narrow a rearend they cut the tubes down and install new ends on the tubes. You can get the new ends from Summit or Jegs. This is much easier.

By FabCrazyGuy Date 01-11-2010 20:03 Edited 01-11-2010 20:05

No,i am just welding the tubes to the housing for more structural strength so the tubes won't spin because it will have 800 HP,over 900 ft lbs of torque and 42" tires for mud drag and 4x4 events.
I've just heard from alot people that no one really knows the chemical composition and process of the housings,so they recommend using a high nickel rod or Ni rod because it could possibly have alot of Iron or different carbon mix in the process,and pre'heat,but most people say they have good success with just 7018

By DaveBoyer (*****)

Date 01-12-2010 02:59

It isn't that "no one really knows", just that the information isn't readily available.

Had You asked Me this question 20 years ago when I worked for Dana Corp. I could have gotten You a good answer. The plant I worked for made car & truck frames, but it is now closed, and all My friends in engineering and the lab have retired so I no longer have the connections to find out.

By Bob Garner (***)

Date 01-20-2010 19:49

Or fasten your torque control arms to the differential so you don't have to transfer this torque from the diff to the axle tubes?

By weldwade (***)

Date 01-26-2010 03:52

Won't matter what you use because that type of differential will not last long anyway if that is really the kind of power the engine will make. Sounds like stupidity or BS bragging to me. I would recommend something that can handle that kind of abuse if that is realy what this guy is after.

By Duke

Date 01-20-2010 03:39

Can you get a couple of chips off of a casting fin maybe, and take to a testing lab, get a chem comp on it?

By C6.7weldrig (**)

Date 08-26-2010 02:14

I know this is a somewhat OLD topic.... But i am going to respond anyway, beause it may help sombody someday.

I have done a lot of welding on offroad truck axles.
In the OFFROAD and ROCKCRAWLING scene it is very common to weld the steel axle tubes to the cast diff housing.
From the factory the axle tubes are pressed into the differential housing, then they are plug welded through holes in the casting (usually only 2 per side). The problem is that they are not really plug welds because they do not really bond to the cast housing, they are only bonded to the steel axle tubes because they are only welded with mild steel MIG (probably ER70S) So what that does is create a button on the axle tube so the diff housing won't spin.
Well, with big horsepower, low gearing and huge tires it puts a ton of force on these 2 little "plug" weld buttons and they can break off allowing the diff housing to spin on the tubes, causing all sorts of issuse (broken driveshafts ect.)... not a fun situation.
I have never had an material analisis done, but I do know that using ER70S- or 7018 doesn't work very well and is not likely to hold up.
I have had 100% success using Nickel rod (Ni-Rod) though, I would not recommend using anything else. I have stick welded a lot of them with Ni-Rod, but lately i have been TIG welding them with Nickel rod. (just looks prettier)

Im not saying that MIG or low-hy wont work, because i have seen it done and hold up just fine... but its not the best choice for the job.
And i will also say that the material used in these castings varies with differnt axle types, I have had some weld quite well and hold up fine with 7018 or MIG but you never know if its going to hold or not.
If you use Nickel rod it will always hold, no worries.