I removed my trans axle off my Imp to take my first look inside and noticed this 2 inch long crack across the flange and inside of the case. It appears no oil leaked out and I could not see the crack on the outside of the case. Has any one had success welding a case like this?
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Cracked Imp Transaxel Case
- Thread starter IMP
- Start date
Snowcat Pat
Active member
IMP, The OC4 I'm working on now has a crack in the same place as yours repaired by brazing, it looks like it worked well. I have more cracks to fix. The steering shaft hole is broken out so I did few test welds with heliarc and steel filler rod and I found the case to weld like steel, not cast iron. I'll get to working on it again soon, as I'm welding this week. I'm setting up my machine for 'cold wire(feed) heliarc'. A surprising number of planetary diff parts are made of cast steel, or something so similar that makes it weldable. I welded up some cracks in a M-29 case with heliarc and steel filler rod and it was a pleasure to weld, the base metal is so clean. I welded a spool that was completely broken in half at the base of the drum bushing journal and its still going strong, actually imroved the ring gear runout in the process. Heliarc and silicone bronze rod may work too.
-Pat
-Pat
If all you have is a Arc welder then Nickel rod works perfect a little spendy about $2.00 a rod but it is made for cast best to preheat cast with a torch first and it will also burn any oil residue off before you weld. 
Ok great info. I was a bit worried about this problem, But it sounds like a common one. I have a Arc, stick welder. A borrowed wire feed, and a oxy / acy gas welder. I am OK at welding / Brazing with them all but I really dont know much about the theory behind it. What is the best method to use with the equipment I have? and any more procedure tips would be greatly appreciated. I only want to do this job once.
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Not knowing the theory, pardon my ignorant question... given that this surface mates up with another surface that most likely (assumption) will need to hold a good seal (oil/some viscous lubricating fluid?), how does the weld repair such a hairline crack? Is it that the temperature melts stick and some of the base metal of the case? The stick adding some filler material and temperature melting both stick and case and then forming a bond? Then that is ground down to a smooth surface?
Pardon the welding ignorance... I do find it fascinating and will be buying a MIG to start with. I'll find a class to take on it.
Pardon the welding ignorance... I do find it fascinating and will be buying a MIG to start with. I'll find a class to take on it.
Snowcat Pat, It looks to me like there is room to weld this crack up with the gears in place. Or would you remove them? if so, whats the first step to taking the gears out.... drink a beer? I may hand this job off to a local welder, I will check around on Monday. But with a little guidance Im sure I could do it myself.
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mkntrakes
Active member
you can weld those cases best way tig weld with stainless steel rod heat case up in a three inch radius of crack weld will case is still hot and let cool naturally heating cases will also help get oil out of crack take time to get the oil out or you wont be able to weld also bevel the crack with a grinder
Snowcat Pat
Active member
Since I have a case to weld and so does IMP, now seemed like a good time to try it.
The brazing was done before I got the machine I just wanted to show that too. No cracks visible around that repair.
I sandblasted the pieces and heated them to steel gray hot, enough to burn the oil out of the cracks. Vee'd the weld area a little bit and welded with heliarc (tig) and stainless rod. It started to bubble just a little when I tacked it but when doing the weld it flowed sweet. Other weld options may work in this metal, the question still in my mind is will it crack when done on the case itself? I'll stick to the SS rod and heliarc for now. I'm not going to weld that piece back in the case its too cracked up. I'll fab a replacement part from steel and weld that in.
Imp, I hesitate to use wirefeed, its hard to get a perfect seal.
-Pat
Does this earn me a manuals disc
The brazing was done before I got the machine I just wanted to show that too. No cracks visible around that repair.
I sandblasted the pieces and heated them to steel gray hot, enough to burn the oil out of the cracks. Vee'd the weld area a little bit and welded with heliarc (tig) and stainless rod. It started to bubble just a little when I tacked it but when doing the weld it flowed sweet. Other weld options may work in this metal, the question still in my mind is will it crack when done on the case itself? I'll stick to the SS rod and heliarc for now. I'm not going to weld that piece back in the case its too cracked up. I'll fab a replacement part from steel and weld that in.
Imp, I hesitate to use wirefeed, its hard to get a perfect seal.
-Pat
Does this earn me a manuals disc
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Snowcat Pat. ASK BSKURKA for a manual CD. I believe they are still free to all members.
Do you have a pic of the part finally welded in Place? 
Thanks.
Thanks.
Snowcat Pat
Active member
I'm not going to weld that piece back in, its too cracked up, I'll have to make a new one out of steel to replace the entire hole. No time right now. I just wanted to learn and share at this time.
-Pat
-Pat
Re: Repaired Cracked Imp Transaxel Case
Its not a pretty weld but I think its going to hold!! First, I heated the weld and soaked the crack area with break clean to try and flush the oil from the crack and did this three heat / brake clean cycles. Then my welder friend tried to TIG with 309 stainless rod and things did not go right. The weld was really full of impurity. We thought it was more caste than steel so the only rod I could find in town that would do the job was a high nickel arc welding rod. I gave that to my welder friend to try. It turned out worse than the TIG job!! It bubbled and spat slag and looked like %$#^$#^.!!. So after grinding out all previous welds he tried 7018, low hydrogen/ mild steel rod. And it turned out better. So we ground out the weld again and laid several more beads and it looked ok. I was taking up more time of his than I wanted, so I called it good and took the transaxle home. Then I tried to fix a few minor flaws with my MIG welder with .030 mild steel wire and it worked pretty good. I found that my first pass into the case material with the MIG welder had impurities. So I would grind out that weld and make another weld over the same spot and it would turn out pretty good. I did this over and over until I had multiple passes several layers deep. I always let the area cool a little between welds. I dont know if this is the correct way to make this repair or not but it seems to have worked for me.
Its not a pretty weld but I think its going to hold!! First, I heated the weld and soaked the crack area with break clean to try and flush the oil from the crack and did this three heat / brake clean cycles. Then my welder friend tried to TIG with 309 stainless rod and things did not go right. The weld was really full of impurity. We thought it was more caste than steel so the only rod I could find in town that would do the job was a high nickel arc welding rod. I gave that to my welder friend to try. It turned out worse than the TIG job!! It bubbled and spat slag and looked like %$#^$#^.!!. So after grinding out all previous welds he tried 7018, low hydrogen/ mild steel rod. And it turned out better. So we ground out the weld again and laid several more beads and it looked ok. I was taking up more time of his than I wanted, so I called it good and took the transaxle home. Then I tried to fix a few minor flaws with my MIG welder with .030 mild steel wire and it worked pretty good. I found that my first pass into the case material with the MIG welder had impurities. So I would grind out that weld and make another weld over the same spot and it would turn out pretty good. I did this over and over until I had multiple passes several layers deep. I always let the area cool a little between welds. I dont know if this is the correct way to make this repair or not but it seems to have worked for me.
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Time will tell. BUT it sure was a matter of time before that weld creeped farther and farther! Looks good from here.
I just wanted to let those interested know that my weld did not work for very long. When I left the weld last it looked good but a few days ago I made a gasket for the OC4 cover and noticed the crack reappeared very close to the original crack. When it completely cooled it must have cracked or maybe a small amount of stress did it. Im glad it happened in my shop and not way out in the feild. Zimmermans has new and used OC4 cases in stock for $900/400. That is going to be my next purchase. The guy at Zimmermans said even if you can get a weld to hold in this cast it would be a marginal fix at best and the repair better not be in a stress location. With the IMP differentail only having 6" of ground clearance the hole thing is in a stress location in uneven ground conditions
Sorry to hear it didnt work. Maybe take it to a shop? BUT $900 isnt a bad deal considering its one of the most important items for reliability.
BUT alot more hours on them as well.
I ground out the old weld again and gave it another try. This time I preheated the cast so that it would sizzle if I spit on it. Then I used the High nickle cast arc welding rod. And It welded much better this time because of the hotter preheat. After welding, I kept the case warm with a heater overnite to slowly cool and peened the case often during cool down. The next day I wrapped the differential in insulation and tin foil for the final cool down. After it was cold I pounded on it with a hammer and no cracks yet. But Im still going to order another case to be on the safe side. Lessons learned are: Preheat until spit sizzles; use high nickle cast rod not mild steel; cool down slow as possible; peen often.