Building a home built tractor.

Plan on getting some pictures taken to go along with the following text but for know this is what I have.

I always admired my Father Duane’s ability to fashion something workable from others scrap. Feed mills, payloaders, semi trailers, he was simply a wizard.

Some twenty odd years ago I built a small tractor which worked out better then I could have imagined. We have used it to spray, push cars into the shop, mow the lawn, pull at the local tractor pull, lift up motors and other heavy items with the back cherry picker, and most importantly, take nice long drives on gravel roads during warm Iowa summer evenings.

I would like to share my design with you and in particular point out the solution I stumbled onto which resolved the problem of multiple transmissions which stretch the drive-line out in length and make most home-built designs awkward with the engine hanging out over the front axle and the back transmission under your butt.

Simply put I incorporated a transverse frt. wheel drive trans-axle and engine and turned it around so the engine face forward. OK, now we have one drive axle pointing forward and another pointing backwards both hanging off to the right side of the center line.

As you only need to use one of the axles you will have to split the trans-axle and weld the spider gears up in the internal differential. Spiders welded up you can pull out the axle pointing to the rear and plug the hole left in the case. I simply fashioned a piece of aluminum which fit into the seal and then drove the seal into place.

The engine and drive-line I used came from a1984 Nissan Sentra. A garden variety 1600CC SOHC with a five speed manual trans-axle it was an engine , and trans-axle, I was familiar with and at the time of the build easy and cheap to procure.

Lets take a look at just what it gives us. A nice short little four cylinder overhead cam engine which runs smooth and is very reliable coupled with a quiet easy to shift fully synchronized five speed trans-axle Also tucked into the gear box is a final drive set which further reduces the rpm by about a 3.5 to one ratio.

Hi-Lo range

1984 Nissan 4x4 pickups used a divorced transfer case which rather then hanging on the back of the transmission were mounted to frame rail with a drive-shaft from the transmission powering it. Mounting one of these on the right hand frame rail in front of the engine allowed me to run the drive shaft from the trans-axle right into the transfer case then hook up to the output shaft which would have originally ran to the front axle with another drive-shaft which then had a straight shot at the nine inch Ford rear end in the back of the tractor.

Wow! What a difference this layout makes. I was able to set the engine and trans-axle in place and simply slide it back and fourth on the frame rails to a spot which gave the best balance. And talk about luck. I was able to use one of the stock drive-axles from the Nissan to couple to the transfer case and then the stock 84 Nissan pickup rear drive-shaft to couple to the nine inch Ford rear end.

All I had to do with the back driveshaft was hybridize the rear u-joint, the front axle shaft simply required an adaptor to couple to the transfer case.

The frame.

I used 3x3 3/16s square tubing . Tricky part with the frame is you need to know the height of the back and and the front axle. Better get the front axle and the rear end set up with the tires you plan on using. Your front axle is going to have to a pivot a few degrees so you need to determine how much clearance you need between the top of the axle and the bottom of the frame members. See specifications.

For me all that was required was to overlap the frame rails just ahead of the back axle. This gave us the three inch drop needed to keep everything level. See pictures.

One little tweak which worked out well. Before I tacked the frame together I laid the rails up in the drill press and put some holes through the rail centers both vertical and horizontal. Believe I used a ¾ inch bit. Holes in place I fitted them with short pieces of ½ inch black pipe welded into place and then ground flush with the frame surface. This gives nice mounting points to bolt any future attachments to. With the pipes welded into place you can cinch the bolts down tight without worrying about collapsing the frame. Much easier to do while the individual frame members can be placed in a drill press.

Rear end

The differential used was a Ford nine inch from a sixties something Ford pickup. A nice thing about the nine inch Ford is that ratios are available all the way down to about 6.5 to one. Initially went with the 6.5 to 1 set. Worked good, pulled tractor pulls in second gear low range. By over reving the engine to about 7 or 7.5 K RPM we were able to top 50 MPH in high high. Not recommended, but felt we had to do it once.

The width of the rear end was good the way it was, no narrowing of the housing or axle shortening needed. I will caution the back wheel studs stick out a little further then the widest point of the tires. Yo get used t it and not a problem. Certainly makes a mess though if you get to close to a woven wire fence.

I will mention the nine inch Ford will do anything within reason, very easy to work on and set up. That being said if we got a tacky track at the tractor pull it would crack the spider gears like walnuts. I was able to locate a twin pinon nine inch differential which has four rather then two spider gears. Since making the switch we have had no further problems . If I was building another one though I would move up to a fourteen bolt GM rear end.

When building the tractor I assumed the weak link was going to be the welded spider gears in the Sentra trans-axle. These are not much larger then a silver dollar. I was so in love with the drive-line layout I could not resist going against my better judgment and going forward with the build. The last thing I expected problems with was the nine inch ford.

The little spiders in the Sentra trans-axle have never given a bit of trouble whereas those Ford spiders caught between all the reduction in the drive-line and the height of those tall semi tires have not. I might also note the Sentra clutch, no bigger then a pie plate, has been replaced once in twenty some years and am sure if it wasn’t for starting out those heavy sleds at the pulls the original would still be doing fine.

Steering

Used a tilt steering column out of a 80s GM car. As you can see in the pictures rather then mount the column to the frame I mounted it to the trans-axle. This has worked well. I had thought I would use a steering box below the column and then transfer the motion forward via a drag link to a pivot which would hook to the tie rod between the two front wheels.

What we ended up mounting a power steering rack from a mid eighties GM front wheel drive car parallel to the frame. The steering column hooks up to the rack with a knuckle, the one tie rod end is not used and the one pointing forward attaches to the aforementioned pivot. Using the rack eliminates the use of a drag link. This has worked well. We mounted two power steering pumps both from mid eighty vintage Nissan Sentras. One pump handles the power steering while another taps into a larger welded reservoir which takes care of the rear lift cylinder.

Wheels.

My father had a small fleet of semi trucks. The aluminum Bud wheels they use are scraped if they develop a crack. For the first five years they are warrantied after that they are simple pitched. Dad had a couple with cracks which I felt comfortable using due to the tractors light weight and low air pressure, ten lbs. To adapt them we used ½ plate steel. Takes some time to get everything centered up and drilled but using the five bolt axle flange, with the studs knocked out of it, for a pattern on the small circle and the truck rim for a pattern on the large circle it worked.

My Friend Larry who at the time ran a machine shop turned the adapter plate into a circle with his lathe. He also turned the center to fit the hub of the axle. The wheels, tires and adapters have never given any problem, following from behind they run true. Note rather then bevel the holes in the adapter to match bevel of the lug nuts I simply turned the lug nuts around. Also note although I put ten holes in the outer diameter lug nut holes when I started fitting the studs I realized on my light little rig ten big studs was overkill so we just used every other one.

Front Axle

I spent the better part of a weekend building the first front axle. Not happy with it when done I threw it out and started over this time using a set of front spindles of an old Datsun 620 pickup truck along with some 3X3 by ¼ inch square tubing. I doubt you would be able to find a set of them anywhere now as all those old Datsuns have rusted away. That being said the Datsun spindles mated with a pair of wheels from a Dodge D-50 have worked well.

Setting up your Ackermen angle.

My Father always preached setting up the Ackermen angle. When you turn the outside wheel has to turn a lesser angle as it is making a wider turn. If your steering arm tie rod end holes are both straight back from the spindle center line when you turn both wheels will turn the same angle the outer tire being partially drug around the corner. You can feel this when driving as it will feel like the brakes are being applied on corners, the tighter the turn the more noticeable. Also, the shorter the wheelbase the more noticeable.

Dad said to set it up properly draw a straight line from the center of the back axle through the spindle, or king pin, center line. Drawing the line on each side you end up with a vee. Now just make sure where your tie rod end hooks to the steering arm is on this imaginary line. Interestingly if you extend the line past the center of the king pin so it goes forward of the frt. axle you can hook the tie rod up there also.

Look at some trucks or even cars, some have the tie rods in frt. of the axle, some in back but if you look they all will be set on that imaginary line. I have heard on some heavy trucks they have different steering arms available for different wheelbases.

I got in a hurry and did not pay close attention to my steering arms, simply left them as they were.. Sure enough, with my shorter wheel base I could coast along, turn the wheel and feel everything bind up bringing me to a stop. Some cutting and welding to put my tie rod connections on the magic line and it rolls very smooth during even tight turns. Remarkable difference. Note most of the steering spindles and arms are malleable cast steel, not cast iron. As such they weld up nice. When I needed a good tapered hole to hook up the drag link to the tie rod it was a simple matter of going to the junk yard and cutting an end off a 80s something GM front wheel drive steering arm and welding it into place.

Radiator

Hard to find an automotive radiator narrow enough. Mine came off a 1980 water cooled Volkswagen Fox with a 1800 CC motor Nice package in that the cooling fan is controlled by a temp sender which is screwed right into the radiator. This is one of the few cooling senders or switches which has heavy enough contacts it can carry the load of the fan without a relay. just power in and power back out. This package has been trouble free.

Roll over protection.

The ROP is simply built with square tubing. I angled it back about 14 degrees. It has ½ inch thick pads on the bottom which bolt to the base. This allows the ROP to be unbolted if need be. The cherry picker as you can see is built off the ROPs. Also has a set of lift arms and a center link for three point use. Not used much now but for several years I mowed with it. Had an older 5 foot three point mower which I converted from PTO to its separate engine a 16 hp Briggs Van Guard. A chain hooked up from the cherry picker arm to the mower deck which allowed it to be lifted about a foot. Always worked good with the exception of being awkward around trees.

Fenders.

When building the tractor I figured the fenders would be the big easy. I planed to buy a pair of used flat top tractor fenders and bolt them up. Ready for them I found used scarce and when found expensive. Plan B worked out well though. Made use of some ten inch channel iron and cut one edge off. I welded on a piece of 3X3 angle iron to widen it out then as I remember welded some steel to the frt. And back edges to add some more depth then took string from the center of the axle and drew a arc on the fenders edge and cut it off with a torch.

Using some 5/16 steel rod I put it on the fenders edges to give a nice rolled finish to it. As I spotted in place we used the torch to heat it so I could make the tight corners. Once in place welded it on solid with 1/16 inch rod then went over it with a die grinder and three inch 36 grit sanding pads to smooth it all out.

I like the fenders, they are sturdy and we often use them to stand on when spraying with a hand wand.

Fuel tank

For a gas tank we used a 6 gallon marine tank. Located under the seat it sits loose with a ring of 5/16 steel rod welded to the floor to keep it in place. You can grab the tank with your hand and lift up on it to see how much fuel is left. Simple is good. Five gallons of fuel lasts forever.

Hood.

I had a lot of fun playing around with different hood designs. I ended up using a pair of front fenders off a late seventies Dodge D-50. You can see in the pictures they were trimmed right above the top of the wheel opening. We then used a piece of common steel for the center section. The hood tips forward.

I am not a body man but am happy with the way it turned out.

Dash

The dash is formed of 1/8 inch flat steel. How to make those nice round curves. I stumbled on to this trick. I have a shop press which has a base of steel channel irons on edge three inches apart. Lay the flat steel across them then take a good heavy piece of heavy angle iron and place its sharp edge against the flat steel parallel with three inch gap between the press base, now bring the ram down into the angle of the angle iron and start pumping. The sharp edge of the angle iron pushing through the three inch gap will form the smoothest bend in the flat steel you could ask for.

Spider gears

Welding the spider gears. I asked about welding spiders on one of my auto tech sites, iATN. A ton of responses with a number of different techniques. The take away, they all work. I simply went down to the local farm store, bought some cast iron rod and burned it together, no finesse to it.

Choosing an engine and trans-axle.

At the time of building mine non computerized car engines were plentiful. Today finding a good one is hard. This means you may have to make use of a car engine which is fuel injected and computer controlled. A lot more wires but fuel injected is nice. There are two kinds. Pre 1995 and post 1995 . 1995 engines and later are called OBD 2 . OBD 2 cars have advanced diagnostics, more inputs, more outputs, more wires. Some such as the Evap. system can be discarded. Of course this means you will always have codes set in your computer so a check engine light is not gong to do you much good as it will always be on. Other systems such as fuel control, ignition and such will have to be maintained.

Just keep in mind when you find your donor motor and transmission you will want not only the engine and trans-axle but the engine control module, or ECM , and all the wiring which goes with it.

You could do a lot worse then finding an early nineties four cylinder pre-OBD Toyota..

A decent scan tool and a good wiring diagram will be needed to sort through everything. Once hooked up and properly wired no reason it shouldn’t be trouble free. A good friend who is an auto tech with access to online wiring diagrams and service information would be very useful.

Automatic trans-axles?

What about an automatic trans-axle? I believe it would work good and stand up well. The hardest part would be pulling the automatic all apart to get to the spider gears and then getting it back together without screwing something up. Automatics are easy to work on, if that is what you work on all the time. For the rest of us it can be trying. I have another project I have been working on, an articulated loader which makes use of a G.M. three speed automatic trans-axle. I welded the spiders in it, they are the very last thing to come out of the case, everything else has to come out to access them. So far, knock on wood, it is working well.

Building one today.

Let me tell you how easy it could be. I spent, “wasted”, a bunch of time trying to figure out where everything went, the dimensions needed for the frame, how much offset in the frame, how everything would fit. Doing one today I would simply start with a frame the dimensions of mine. I would use the three inch overlap knowing it would be perfect for 14 inch front tires and semi truck rear tires. Once I got the frame rails cut I would spot weld the the frame members together. Next I would build adapters for the rear truck tires and mount them up to a rear end and spot weld the rear end to the frame. Next I would grab an old wheel barrow wheel and build a fork for it and spot weld the fork to the front of the frame giving me a rolling chassis.

Once you have a rolling chassis it is much easier to deal with. Yes, it will be a lot of work but once you have it roughed out and rolling on wheels you can break it down to one project at a time. One key point I cant stress enough, spot weld everything until you are sure how everything is going to fit together, only then do your final welding.

So, how does it work? A slick nickel. I have a little thirty horse L series Kubota. With it's ag tires it is pretty lumpy on the road, only goes 12 MPH. Straight cut gears in the transmission are loud. No synchronizers so you have to pick out your gear before you start, no shifting on the fly.

Compare with the home-built. Tires are smoother for a much nicer ride, the transmission is synchronized, and quiet as a mouse. You can run around town at twenty MPH without over revving, smooth as can be.

My grandson Evan loves going for evening rides in the summer time. We have a lot of gravel roads here in Iowa that have little traffic. We often go out ten mile or even fifteen before turning back.

During the county fair we put a straight pipe on it and go tractor pulling. If the track is tacky we can get the wheels up and, in second gear low range, pull the motor right into the dirt. The front push bumper makes moving cars and trucks around at work a piece of cake. Always our choice for spraying with a spray bar up front and hose and wand in the back.

Despite the rear end not being posi traction you have to work pretty hard to get it stuck.

Yes, it takes some time to get it all together. But of all the projects I have done this is the one I enjoyed building the most, and the one I have got the most use and enjoyment out of once built. Never been any regrets for the time spent on or with it.