Hello all, I’m interested in buying a small 2cyl Kubota diesel and throwing it into a project of mine like a buggy, old school riding lawn mower etc. one question I have is I’ve seen they all run hydrostatic transaxles which are probably geared to be slower. Is there any other option I can use for a rear end? Even if there’s a little fabrication involved? Just curious if anyone has done this thanks.
Kubota diesel buggy/ go cart/ lawn mower swap
- Thread starter Getsome5427
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Old Machinist
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Kubota LX3310 cab, JD 4310, NH 575E cab backhoe, JD F725, Swisher 60", etc.
I think it is more of a gear ratio consideration. The diesel may be designed to run at 2500 to 3000 rpm max.
Would this be a concern as far as speed goes after you put the engine in?
Engine RPM limit seems to be the real issue...
Would this be a concern as far as speed goes after you put the engine in?
Engine RPM limit seems to be the real issue...
if I’m able to go say 15-20mph I would be happy, think that is achievable?
No clue. But what was the top RPM of the original engine. How does that compare to say 3000 RPM. Original engine probably higher, so what is the ratio? Multiply the previous top speed by the ratio, and it should show what the reduced top speed would be.
armylifer
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If you use a geared transmission you could put whatever rear end gearing you want in it. The engine torque would be the more important determining factor on how fast you can go, not so much as how high the RPM of the engine is.
Old Machinist
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Most lawn machine gas engines run at 3600 RPMs. The diesel will be lower but should have more torque enabling a higher ratio.
The challenge would be finding an old metal geared transaxle. I don't think the K46 hydro and later plastic gear transaxles would handle being spun up faster than designed.
Many years ago I built my daughter a go cart using bed frame angle and lawn mower parts. I used a 4 speed transaxle from an old Craftsman lawn tractor and a 5HP 2 cycle Lawn Boy engine. With a one to one ratio that thing would hit 20-25 on a downward slope and easily over 15 up hill or on a flat.
This guy outlines a bunch of great ideas for building a race mower which could be incorporated into a utility cart. The centrifugal drive would add expense. I actually used the pulley type clutch on my go cart and it worked fine.
The challenge would be finding an old metal geared transaxle. I don't think the K46 hydro and later plastic gear transaxles would handle being spun up faster than designed.
Many years ago I built my daughter a go cart using bed frame angle and lawn mower parts. I used a 4 speed transaxle from an old Craftsman lawn tractor and a 5HP 2 cycle Lawn Boy engine. With a one to one ratio that thing would hit 20-25 on a downward slope and easily over 15 up hill or on a flat.
This guy outlines a bunch of great ideas for building a race mower which could be incorporated into a utility cart. The centrifugal drive would add expense. I actually used the pulley type clutch on my go cart and it worked fine.
it would not be that hard to double that speed.
Had a Wizard riding mower many moons ago, was given to me (freebie) at work. Pretty trashed but it did kinda run. Carb had something wrong with it. I was trying to figure it out, it ran out of fuel and I grabbed the can and refilled it. Started it back up, ran perfect. What? Dad filled the gas can with Methanol, which we used in the race cars. Well, it ran, so why not. Never touched the carb to figure out what was wrong with it.
later on I changed the pulleys. They come with a 3" pulley on front (roughly 3" I didn't measure) and about a 9" pulley on the back. Tractor went about 5 mph in 4th gear (4 speed) at 3200 RPM. Well I changed it up and put a 7" pulley on front and 3 on back, and in the process had to re-route and re-plan the entire belt drive,, add guides and whatnot, but it worked excellent. 1st gear was about 6.5mph. 2nd, 3rd I don't remember. 4th was about 30 mph. I had to heat and bend the front axle so it had some caster, without caster it was uncontrollable above about 12mph. With caster, it drove excellent at 30+. Also put a "tractor style" throttle pedal on the RH floorboard. The engine would run 3600 RPM on the governor, but the pedal would increase that to about 5200 RPM, so at 30mph on the governor, mash the pedal and it would kick it up to about 38 or so, just didn't have enough power to go much faster (12.5hp briggs dump valve motor).
so yes changing pulleys makes a HUGE difference. Not on HST though, they are designed to run a certain RPM and not much more. Gotta use a gear drive, and you WILL probably have to fabricate a whole new belt drive system. Dont' forget tire size will play into as well. Bigger tires=more circumference=more speed (so long as the engine will make enough power to overcome the additional drag).
Sweet so I just actually today picked up a Kubota G4200 with a Z430 2cyl diesel 12hp I believe at 3600rpm. I kinda want to lower it and slam it low to the ground not too sure yet.. but my main concern is taking the pulley from being vertical on the motor to a horizontal “flat” rear transaxle from a different mower or whatever route I go. I would need to implement some sort of mule drive. Do you have any suggestions on a particular rear end I should swap it with? Because it does have the hydrostatic transaxle now. Thanks for input!
Old Machinist
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Kubota LX3310 cab, JD 4310, NH 575E cab backhoe, JD F725, Swisher 60", etc.
That's a different animal than the weak K46 lawn tractor transaxles. I would just work with what you have and see where it goes.
some of the real old Deere 200 series had a 4 speed transmission that MIGHT work. I wanna say they were Peerless transmissions but I could be wrong. That setup, you may be able to turn the engine sideways in the frame and run the belt down the side like the Deere's are from the factory. IIRC 210, 212, 214 and 216 were set up that way, but that's going back about 25 years so I may be wrong.
there were probably also some old crapsman mowers and maybe cub cadet's set up similarly. About 35 years ago I worked very briefly under a guy at the lawn mower shop that played with them but I cannot remember which transmissions he used. I want to say Peerless. Do a little digging and I bet you'll figure it out.
there were probably also some old crapsman mowers and maybe cub cadet's set up similarly. About 35 years ago I worked very briefly under a guy at the lawn mower shop that played with them but I cannot remember which transmissions he used. I want to say Peerless. Do a little digging and I bet you'll figure it out.
North Idaho Wolfman
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You could use an OLD simplicity transmission, they are driven just like a Kubota transmission with a propeller shaft.
But I would think you would be much better off with something much newer like an automobile trans and rear end.
Think a little outside the box (think front wheel drive) installed in the rear.
Independent suspension, handle all thew HP you could give it, and smooth shifting at speed, where most Lawnmower tractor transmissions do not shift at speed, you must shift them at a stop.