We have a tandem axle dump truck at work that has a crack in the rear diff housing (cast). It's a 6"-8" crack across the top of the housing (think 11 - 1 o' clock on a clock). And it's leaking oil to the outside. I've welded some cast before but nothing this big or that needed to be water tight or rather oil tight. I figured I will relief holes at each end of the crack, vee it out and pre-heat. My welding approach is where I'm hesitant. I'd like to weld it in a continuous pass to make sure it seals up but am not sure if that will get too hot. I had an old timer tell me before to back step cast an inch at a time but I think all the starts and stops will not seal up correctly. I've got some NI-99 electrode I've used before with good success. I also have some NI-99 filler but have never tig welded cast before. The cool down is the next obstacle. It's a big axle (20000 lb. GAWR). And it's still in the truck and they're not taking it out/apart. I can probably round up a handful of welding blankets and try to wrap it up. Thoughts? Suggestions?
Crack in a rear diff on a dump truck
SJC
1 - 20 of 25 Posts
We have a tandem axle dump truck at work that has a crack in the rear diff housing (cast). It's a 6"-8" crack across the top of the housing (think 11 - 1 o' clock on a clock). And it's leaking oil to the outside. I've welded some cast before but nothing this big or that needed to be water tight or rather oil tight. I figured I will relief holes at each end of the crack, vee it out and pre-heat. My welding approach is where I'm hesitant. I'd like to weld it in a continuous pass to make sure it seals up but am not sure if that will get too hot. I had an old timer tell me before to back step cast an inch at a time but I think all the starts and stops will not seal up correctly. I've got some NI-99 electrode I've used before with good success. I also have some NI-99 filler but have never tig welded cast before. The cool down is the next obstacle. It's a big axle (20000 lb. GAWR). And it's still in the truck and they're not taking it out/apart. I can probably round up a handful of welding blankets and try to wrap it up. Thoughts? Suggestions?
Joined
·
18,333 Posts
I'll kick it off.
Clean, clean, clean and you'll still get oil cookin' out as soon as you strike an arc. You could use a case of Brake-Kleen (stand by for all the "You'll die if you use Brake-Kleen before welding" warnings) and still not get all the gear oil out of the cracked area.
Are they going to pull the center section out or leave it in?
Member castweld has described what he calls "cold welding" cast using the short back-step method you were told about. Only I think he's suggested 1/2" beads and let it cool to the point you can rest your hand on it before laying the next 1/2" or so.
Clean, clean, clean and you'll still get oil cookin' out as soon as you strike an arc. You could use a case of Brake-Kleen (stand by for all the "You'll die if you use Brake-Kleen before welding" warnings) and still not get all the gear oil out of the cracked area.
Are they going to pull the center section out or leave it in?
Member castweld has described what he calls "cold welding" cast using the short back-step method you were told about. Only I think he's suggested 1/2" beads and let it cool to the point you can rest your hand on it before laying the next 1/2" or so.
Make sure they remove both axle shafts and drain the oil. Also keep everyone away from the end of the axle tubes when your heating and welding the diff housing.
The diff unit should be removed since your welding right above it.
I always hated the smell of burning gear oil.
The diff unit should be removed since your welding right above it.
I always hated the smell of burning gear oil.
Years ago that was an issue with the International axles. It was a common thing to weld up a crack around the the cover on the differential housing. Drain the oil v it out and weld it up with 7018. They are cast steel. I have never seen a cast iron axle housing In a truck. Stop and think about it. Cast iron won't take the abuse a truck axle will get.
Yeah, they will. They use them in tractors all the time.
Cast Iron verses Cast Steel? Tractor verses Truck?
Tig? Too many contaminates. Braze? Too much heat required.
Weld it in 1/2" to 1" steps and back step them to help keep it cool.
As far as the Cast Iron or Cast Steel? You'll find out when you start grinding on it as the sparks will tell you.
I will mention that if it is indeed Cast Iron, then get after it with a Die Grinder and Burr to pull the "Grinder induced Carbon Smear" out of the groove.
Tig? Too many contaminates. Braze? Too much heat required.
Weld it in 1/2" to 1" steps and back step them to help keep it cool.
As far as the Cast Iron or Cast Steel? You'll find out when you start grinding on it as the sparks will tell you.
I will mention that if it is indeed Cast Iron, then get after it with a Die Grinder and Burr to pull the "Grinder induced Carbon Smear" out of the groove.
I am with scsmith42 on the ground being close to the area welding. DO NOT Ground on the axles or pinion shaft as the bearings and gears will get arc trails on them and ruin them also if the gear housing is bolted to the housing Do Not ground their as their is a gasket between them causing the same problems. Friend of mine welded new flanges and mounts on a rear axle and could not use it because all the bearings welded them self's together. We finely got it to turn but not good would stop and start. Took it all apart every berrying had little spots of weld as well as the pinion and ring gear.
Just My 2 cents worth!
Just My 2 cents worth!
While it is.good info about grounding close to the repair anyone who doesn't know this should probably not be doing the repair. I would question why it cracked is there a suspension bracket applying tension or some other reason until that is figured out the repair may be futile
Joined
·
60 Posts
I agree with your questioning of the source of stress/cracking, however I strongly disagree with your criticism of this guy attempting to do this repair. He is doing his due diligence to learn what he needs to know before he starts. There is a first time for everyone, how else do guys like us get experience? And he obviously does have prior welding experience, even experience with cast.
I say go get 'em! If it doesn't work you'll probably get the chance to grind it out and try again.
I've preheated/post weld cool-down'ed large cast parts in a bigger BBQ before. Just kinda whatever you have that works for you. I've seen guys use batts of fiberglass insulation too... Obviously that comes with its own risks. Just use your brain.
Sent from my HTC Desire 626 using Tapatalk
This happened from over abuse due to testing. It's not being operated under normal circumstances I'm pretty sure the truck is fully loaded (60000+ lbs.) and actually leaving the ground. So if testing continues to be this aggressive it may break again. I hope it doesn't but sometimes that's the way it goes. Technically all I have to do is band-aid it but I prefer to fix it once (that's why I'm doing a little homework).
Actually it's a cab and chassis with a frame/bed made strictly for holding weight, it doesn't move. I think I can actually lean over the rear bumper and reach the rear diff. But thank you for looking out for me.
Ha Ha Ha you just answered my question before I asked it
over loading will break a lot of stuff
I think you will find it's cast steel and I would grind it out and use some 8018 to weld it back together with some peening and heat blankets and call it good to go.
over loading will break a lot of stuff
I think you will find it's cast steel and I would grind it out and use some 8018 to weld it back together with some peening and heat blankets and call it good to go.
Joined
·
380 Posts
Was going to say, if you had access to some Esab Dual shield II 80-NI1H4, that is some pretty tough stuff. Expensive, but tough. I use it alot on P&H 37 yard dipper buckets, withstands alot of stresses. Otherwise an 8018 is fine too.
Joined
·
1,924 Posts
If you are breaking it to test the strength of the housing new .Fixing it and breaking it again doesn't test anything except the repair which can change from person to person
1 - 20 of 25 Posts
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
