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Old 03-29-2011, 04:14 AM   #1
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Welding cast iron


I know this is a long-shot, but the membership is widely experienced.

I have a Gravely 4-wheel riding tractor, G-Series. Last summer the transmission broke, and over the winter I repaired it. One of the gears had broken and I replaced it. However, somehow (no one remembers it happening) the housing (a boss) holding one end of a gear axle chipped off. This was on the larger section of the case: not the cover portion. The case is, of course, cast. But I am thinking of welding the pieces back together and then honing the inside of the housing to tolerance so that it is smooth and even. Then reassemble and install it.

My question: is this is a workable solution? Has anyone tried something like this and if so, what advice can be given? Actually, any and all input about this would be greatly appreciated.

Secondly, if this is not do-able, does anyone have a source for a new transmission case --- or even a used transmission? I might even go for a new transmission.

Third: are there any other suggested solutions for my problem?

I truly do not want to retire this wonderful tractor.

Thanks in advance for any attention to this topic.

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Old 03-29-2011, 08:03 AM   #2
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Welding cast iron


I have welded just enough cast iron to know that I do not mind paying my local welding shop to handle that chore for me, and to say that unless no other options exists, I would not recommend doing it yourself, unless of course, you have prior experience welding cast iron, in which case I asume that you would not be asking. :-) Disassembling, machining, and reassembling, sure, but the welding can be very tricky, and, the last I knew, nickel rod was not inexpensive. The other thing that you might consider is JB Weld. I do not have a lot of experience with it, as I first learned to weld something like 40-50 years ago, and I don't even know if it was around then, but I have very frankly been surprised (in a positive way) by some of the repairs that I have seen made with it. The other option, of course, is searching the web or other resources for a boneyard. I am sure that you know they are out there, but, naturally, the problem is finding it.

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Old 03-29-2011, 08:50 AM   #3
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Welding cast iron


cast iron is a special beast when it comes to welding. Preheat and post heat is very important as well as the actual welding being more difficult than many other metals.

If this is structural, unless you are experienced in welding cast iron, I would load it up and take it to a local weld shop that is experienced in welding cast and ask them if
1. it is practical to consider repairing it
2. if the repair will withstand the loads applied.

Obviously they are not going to guarantee the longevity of the item but their input could be the difference between attempting a repair and simply starting the serious search for replacement parts. If it isn't going to be a repair you can depend on, there is no sense in trying it only to have it break right away.
I don't know if you have searched for Gravely on the net but here is a page from their website. This way you should be able to call out the part by name. Sometimes that helps when looking for a specific part.

http://www.gravely.com/Support/pages/parts.aspx

and Gravely's dealer locator page

http://www.gravely.com/dealerlocator/Pages/default.aspx
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Old 03-29-2011, 09:11 AM   #4
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Welding cast iron


Nap, sounds like you are familiar with welding cast iron, so just curious; the way that I was taught to weld it was to pack as much of the piece as possible in sand, to allow it to heat and cool at a more steady rate, heat the area to be welded red with an oxygen/ acetylene torch, with nickel rod weld maybe an inch, leave it alone for a bit, heat the area, weld some more, leave it alone a bit, heat the area, weld some more, etc., and when you are done welding, heat the entire area to an even color, and leave it alone until it has completely cooled. Sound anything close to right? I learned this from my dad and uncle, a good many years ago, but I haven't tried it in quite some time, and, obviously, things change. Oh yeah, and I recall that when the crack terminated someplace in th middle of the piece, we would drill a hole there, to keep it from extending beyond that point.

Last edited by DexterII; 03-29-2011 at 09:15 AM.
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Old 03-29-2011, 09:17 AM   #5
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Welding cast iron


http://www.muggyweld.com/castiron.html
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Old 03-29-2011, 09:31 AM   #6
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Welding cast iron


Sheesh! Thank you, Mark! I'm always thinking that a lot of the questions asked in forums could be answered faster by looking them up on the 'net than posting a question, and there you go; I fell into the same trap. So, again, thank you. I will do some reading on that. (Not that I have any desire to do anything with it right now, but interesting nevertheless.)
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Old 03-29-2011, 09:38 AM   #7
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Welding cast iron


As with everything there is the old tried and true, and then there is the new and easier way, isn't technology something.

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Old 03-29-2011, 09:50 AM   #8
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Welding cast iron


True. But you surely have to agree that, based on their old school description, it sounds like I might be able to do it again if I had to! Only thing is that they refer to an oven for preheat, whereas I was confined to a torch. (Ovens were where mom's homemade pie came from when we were done for the day!)
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Old 03-29-2011, 10:28 AM   #9
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Welding cast iron


dex, I am not experienced enough in welding cast iron to be an expert. I like the sound of your method but the oven is a better idea as it heats the entire part so you don't have as much of a problem of different levels of expansion across the piece. Your sand idea would help a lot with that if you could take enough time so the sand becomes heated as well. Not only will it help with a slowing of the cooling but it would help equalize the heat across the entire part. That equalized heating with slowed cooling helps remove stresses within the metal.

the welding of smaller sections helps in the same way. It allows a more even heat across the area.


the drill the hole at the end of the crack has always been a good idea.

The biggest thing I learned about welding cast iron; it is not a quick process and any attempt to speed it up usually is the cause of the failure you ultimately end up with.

so, if you don't have an oven available, I like your method. When you have a crack on a tractor in the field, it's pretty hard to get it in an oven and tearing it down isn't a possibility at the moment so your method definitely has it's place.
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Old 03-29-2011, 11:45 AM   #10
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Welding cast iron


What a great response! I am well aware of the difficulties in getting a successful weld in cast. Everything has been informative and very interesting. I do appreciate every response.

This will be done by a person with decades of experience and a flare for it too. So I expect the actual welding part to be successful.

I guess the real question is whether this approach would actually hold up to the stresses of transmission use. Would it work?

And I have read of some amazing uses for JB Weld. I use it myself for smaller jobs. Do you think it would actually work in this situation?

I think I have posted a couple of pictures to clarify things. The breakage is almost in the middle of the larger section of the tranny case in the first pix.

Thanks to all.
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Old 03-29-2011, 12:14 PM   #11
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Welding cast iron


is that a crack in the face of the boss at about 2:00? I also see a suspicious looking mark just to the left of the broken area starting right about at the rib and going upward.

is whatever plugs into that hole supported on the other end? is there a bearing or thrust washer that sets on the boss? In the hole?

can whatever fits in that hole wobble? Is the gear that broke possibly the cause of that damage?

It's kind of hard to determine if a repair would be successful without knowing the forces imparted on the boss.
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Old 03-29-2011, 12:21 PM   #12
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Welding cast iron


Particulary since you know someone who you are comfortable having do it, I would not hesitate to strip it down, remove the needle bearings, etc., and have it welded. I don't know what you found, but would suspect that one of the outer bearings was worn or loose, allowing the shaft to run on an angle to the boss, but now that you're rebuilding it, I would think that you should be in good shape.
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Old 03-29-2011, 12:34 PM   #13
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Welding cast iron


Ditto what Nap said. The second picture didn't pop up for me until after the fact, so I didn't even realize it was there, and was looking at a blown up version of the first pic, seeing the wrong thing. You'll definitely want to look at whatever is supporting the affected piece, to make sure that you've eliminated the wobble. As he said, it looks like it is cracked even further around, so if that is the case, something was quite amiss to allow it to pretty much rip the side of the boss out like that.
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Old 03-29-2011, 01:32 PM   #14
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Welding cast iron


Once again I did not give enough information. The boss broke after we had the original problem repaired. We had just re-installed it onto the tractor itself when we noticed an oil leak. A further and closer inspection led us to dis-assemble the whole thing and take apart the tranny. That's when we discovered the breakage. It was not there before. It has nothing whatever to do with the original malfunction. So somehow something happened to cause this --- we do not know what it was and no one admits anything untoward.

We examined the boss very closely and could not discover any wear or abrasions. It is as though something hit up against that housing to break it.

And that's why I am a little optimistic about taking the welding route.

Who knows --- enough of these additions on my part and the rest of you guys might eventually understand what I am babbling about.

But thanks enormously for the interest and the queries and direction. Believe me it all helps.
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Old 03-29-2011, 02:17 PM   #15
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Welding cast iron


It looks like it would have taken a pretty good "tap" to break it, but perhaps with a little bit of misalignment, well... there you go. Nevertheless, it's probably a safe bet to say that we've all been there. So, with that in mind, I'm going to go back to my original comment, and say that I would get it welded, and, obviously, keep a close eye on everything as you reassemble it! My guess is that the height of that boss is the same as the others, but I would confirm that before doing anything, and you may even want to make up a jig beforehand, in order to be able to set up a reamer once it is at that point. The next problem may be that the two pieces are not going to fit all of the way tight to each other, so you may need to Locktite the needle bearing in place, if that's whatgoes in there. As for final assembly, I have once in a while made some simple tools out of sheet metal to hold all of the pieces in place; like something notched in the middle to fit around various shafts, etc., and then bend over a casting to keep anything from falling out, then, once the shafts are started into their appropriate holes, straighten out the tin, pull it out, and push everything together.

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