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Welding on a Kubota tractor

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Jax

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Discussion starter · #1 ·
I flipped a coin to decide if I should post this here or under General,Mig-Tig-Stick or projects and decided the park might catch attention of some who've ran across this before. 20 horsepower Kubota,B1750HST to be exact has 4 out of 8 bolt holes coupling bellhousing to engine snapped off. At the time I bought it I figured replacing bellhousing is no big deal. After checking on replacement bellhousing it turns out to be a common issue which pratically makes non-damaged used part non-existent with new being scarce and really pricy. My plan is to weld tabs to bellhousing to replace those missing. Browsing Kubota forms turned up a couple of people with good solutions to prevent reoccurrence but nothing on a work around without replacing bellhousing. I removed the front loader and brought it home but tractor isn't here yet where I can determine type metal (cast or stamped). Judging by rust,definatly not aluminum or same material as cars. Kubota mfgr's support doesn't reach beyond marketing new tractors and although dealers are abundant, I haven't found one that can give clue to type metal used. I realize until I can say cast iron or not,welders can't offer meaningful advice but my question is whether I should attempt to identify alloy beyond whether it is ferrous and if cast? I can use the time before tractor arrives at my shop to try and locate documentation of type alloy unless waiting to do a grind test is all that's recommended. Applogize for bringing a pig in a poke but i thought I might luck out and find someone that already been down this road. Drawing on years experience keeping domestic built farm tractors in operation my contribution to the masses is advice to check part lists for prices and shop manuals for proceedures before investing in a tractor built in foreign countries. Looking at shop manual for the first time I couldn't believe the number of fiddly-bit parts used in single components and clearances that must be maintained.
 
#2 ·
I'd be guessing cast iron and that's just a guess. It's not just Kubota's that break bellhousings. It's quite common on small tractors that have a 3pt mounted backhoe with no reinforcement running front to back that beefs up the bellhousing area. You get someone beating the crap out of a small backhoe, lifting the tractor up trying to dig out a 2 ton rock or a stump, the bellhousing is the weakest point. It'll usually crack open like an egg on the bottom. Would I try to fix it...probably if I've nothing to lose other than time and a bit of material but I wouldn't expect miracles...just my two cents worth :). I'm sure others will be along eventually with different opinions LOL
 
#3 · (Edited)
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Discussion starter · #4 · (Edited)
#6 · (Edited)
They are cast iron, ask me how I found out! The boys busted the housing on the m6060. Never did get a straight story on it either. My oldest took it to his shop to repair that was three years or so ago. I’m not supposed to get on the tractors, or loaders.
 
Discussion starter · #7 ·
mrmikey said:
I'd be guessing cast iron and that's just a guess. It's not just Kubota's that break bellhousings. It's quite common on small tractors that have a 3pt mounted backhoe with no reinforcement running front to back that beefs up the bellhousing area. You get someone beating the crap out of a small backhoe, lifting the tractor up trying to dig out a 2 ton rock or a stump, the bellhousing is the weakest point. It'll usually crack open like an egg on the bottom. Would I try to fix it...probably if I've nothing to lose other than time and a bit of material but I wouldn't expect miracles...just my two cents worth :). I'm sure others will be along eventually with different opinions LOL
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You are correct about people overburdening compact tractors by putting backhoes and loaders on them. Fact is folks try using their 80 horse tractor like a dozer and tear them up as well. We've always been very selective who operates our equipment and that gos double for anything with a loader. I have a tractor to handle anything I need (mostly round bales) but does too much damage to ground around the yard and garden. When I saw this I figured it would beat the hell out of an 80 year old with a shovel and wheelbarrow. As it stands the ROPs and exhaust are higher than stall doors so I have to pitch it outside with a shovel before I can get a bucket under it. That's like Brylcreem in triple digit heat and high humidity. Just a little dab will do you but dropping $10k for something used that doesn't need help before it's usable is out of the question.
 
#11 ·
It's most likely cast iron. Steel won't usually just snap off. If you have a cutting torch you could try to cut just a bit of the edge. Cast iron doesn't cut with a torch. It just kind of melts. It's much more difficult to repair being cast iron but can be done. Unfortunately the best way to repair it involves taking it completely apart and using lots of heat. Brazing would be good option but would be good to talk to someone who specializes in cast iron repairs. Maybe specialty cast iron rods from someone like Eutectic would work. Actually you contact Eutectic and ask their advice on the best way to repair it.
.
 
#12 ·
Pre-heat/post-heat won't be easy with a part that size... probably end up using a weed burner in a large barrel...

As noted in your original thread, it's going to be hard to get good advice from anyone when even if you know it's cast iron for sure, there's no way of knowing "which" variation of cast iron....
 
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Discussion starter · #13 ·
Good information gents I'm looking for preliminary to tractor arrival which is scheduled for August 4th. I intended to go pick it up this week but found a trucker that can haul it from over 300 miles away to withing 40 miles of me for reasonable cost. I have used the drilling test in the past suggested by Samm and grinding spark test but never tried torch cutting cast so I've leaned something today.
 
Discussion starter · #15 ·
Carbon-Arc said:
If I were you, I would braze weld those bosses back on. A vee or shear-vee joint should be plenty strong enough.
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If it turns out to be cast I will consider braze rather than remove part for proper pre and post heat during welding. I'm not familiar with terms vee and shear-vee as applied to brazing. What I plan if going that route is simple lap joint but I'd like to hear about those.
 
#16 · (Edited)
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#17 · (Edited)
Vee is just like a normal welding vee. Braze welding vees are usually 90°. A shear vee makes a shape like this:
\............... /
..\__ ... __/
.......\../
........\/

The step increases surface area. You should still do local preheating with cast iron brazing, usually in the neighborhood of 900°F.
 
Discussion starter · #19 ·
I'm dealing with in the range of 1/8 to 3/16 thickness but the vids as well as explanation of shear vee for brazing are appreciated for future use. Both are procedures I've been lead to believe in the past to not be advisable. Probably my misunderstanding when a different type brazing was being discussed. I'm surprised accurate terms weren't assigned long ago to differentiate type brazing (copper pipe,aluminum,steel,iron plus various fillers). At any rate I'm glad to learn about vee joint brazing,I can see how it not only wets deeper than normal but also adds surface area for better grip.
 
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