4x4 ATV / Tractor?

Ted

The pilot formerly known as Twin Engine Ted
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When we moved to our new airport, we bought an older 42" lawn tractor and welded brackets and a ball on the front of it for use in moving the 310 in and out of the hangar. While the concept works very well, this unit would really be better suited to a larger single rather than to the 310 I think. The main issue that I'm having is that it doesn't have enough weight to get decent traction in poor traction situations. That said, the tires on it are pretty bad and a better set would probably make a big difference. The transmission is also having trouble getting into reverse and is popping out of it semi-regularly. It's also not really shifted great in general between forward and reverse. Unit is an MTD of some sort, probably 10 years old. Engine runs and starts great, my primary issue is the traction and secondary issue is the transmission. So questions:

1) I've never messed with one of these transmissions before. Are they rebuildable? Is there any way for me to turn it into a limited slip or locking differential instead of open?

2) Should I just try to get a set of ATV tires that will have better traction for this?

3) Should I just not mess with it and get something bigger/heavier, and if so, what should I ideally be looking for? I was thinking a 4x4 ATV might make the most sense on the traction/utility front. Want to spend as little as possible since this is something that only gets used to pull the plane in and out, so minimal use.
 
No, you can't do anything to make it a limited slip differential, you can make it a locked differential by welding the spider gears. Yes, you can rebuild the transmission, but likely you will find worn parts or loose bolts in the shift fork mechanism that is not engaging the reverse fully that you can repair. Have a tub of grease ready to hold bearings in place if it all falls apart when you open it. Hang weights off the back to increase traction and see if you can't get some fork lift tires for it. The problem with turf saver tires is they are hard and low traction by design. ATV tires are a good second choice to fork lift tires.
 
Fill the tires with an antifreeze, add weight as required.
 
MTD has a good parts supply operation so repair of the tranny shouldn't be a major problem. If they third partied the tranny then all bets are off.

Add weight and tire chains for traction. I wouldn't lock the differential since it wouldn't steer.
 
MTD has a good parts supply operation so repair of the tranny shouldn't be a major problem. If they third partied the tranny then all bets are off.

Add weight and tire chains for traction. I wouldn't lock the differential since it wouldn't steer.

I have chains, the mower actually won't move when attached to the plane with the chains on. The chains seem to do a great job with just the mower in the snow/ice, though. That's part of why I was thinking better tires might do more, and/or locking/limited slip diff to help the traction, but locking probably would be sub-optimal.

I'll probably find a period when the plane won't be flying for a few weeks and then bring the mower back here for some better tires, transmission repair, and see what weight I can add on to the back end to aid in the traction. I might even have some lights laying around I could add on for night operations - the one on there is worthless.
 
I have chains, the mower actually won't move when attached to the plane with the chains on. The chains seem to do a great job with just the mower in the snow/ice, though. That's part of why I was thinking better tires might do more, and/or locking/limited slip diff to help the traction, but locking probably would be sub-optimal.

I'll probably find a period when the plane won't be flying for a few weeks and then bring the mower back here for some better tires, transmission repair, and see what weight I can add on to the back end to aid in the traction. I might even have some lights laying around I could add on for night operations - the one on there is worthless.

Interesting info. I've pushed a lot of snow (MT and CO winters) with just chains on my tractor...haven't tried to push an aircraft though. The A&P used the wheel weights on their MTD and seemed to do okay without chains but set up a ball on the front of a pick-up as a back-up.
 
Interesting info. I've pushed a lot of snow (MT and CO winters) with just chains on my tractor...haven't tried to push an aircraft though. The A&P used the wheel weights on their MTD and seemed to do okay without chains but set up a ball on the front of a pick-up as a back-up.

I think pushing snow would probably have been fine, but the 310 as it sits is usually around 4,000 lbs with three small tires, so there's some rolling resistance there compared to the tractor.

I do wish there was a way to limited slip the rear or alternately have a manual locking setup. One of the big issues I'll get with this setup is that one side will just sit there and spin.
 
You need wheel weights, and you need to look up the Spicer parts # for that tranny. I'll bet it's a stock unit.
 
You need wheel weights, and you need to look up the Spicer parts # for that tranny. I'll bet it's a stock unit.

MTD uses a trans-axel - at least they did on the one I bought. Dunno if Spicer made it or what.
 
Don't know much about modifying the lawn tractor, but if you do decide to get something else, a used golf cart would be cheaper than a 4X4 ATV. I use one at my FBO and have moved sizable aircraft (C510 and L35) with no problems.
 
3) Should I just not mess with it and get something bigger/heavier, and if so, what should I ideally be looking for? I was thinking a 4x4 ATV might make the most sense on the traction/utility front. Want to spend as little as possible since this is something that only gets used to pull the plane in and out, so minimal use.

Depends on how you define spending... If you mean little as possible cash out, that is one thing, but if you have the cash to invest, it appears that the John Deere X749 garden tractor holds its value pretty well. Depending on how long you need it, it may be possible to get most or all your money back from a used one when you no longer need it. I have one and it is fantastic for traction and steering control. It is All Wheel Drive AND 4 wheel steer. So, maneuverability is great!
 
Pile sand bags on the rear fenders - low cost.

I did that for years when I was pushing snow with a 10 hp MTD lawn tractor.
 
Depends on how you define spending... If you mean little as possible cash out, that is one thing, but if you have the cash to invest, it appears that the John Deere X749 garden tractor holds its value pretty well. Depending on how long you need it, it may be possible to get most or all your money back from a used one when you no longer need it. I have one and it is fantastic for traction and steering control. It is All Wheel Drive AND 4 wheel steer. So, maneuverability is great!

I mean cheap purchase price, and really not looking for anything fancy. I'm not too interested in resale value, because my intent is to keep it until it explodes. My experiences with lawn mowers have typically been pretty good.

I think I'll start out with trying to fix the transmission and buying new tires for it, as well as the wheel weights. Any specific tire recommendations for maximum traction? Usage is pavement with the potential for snow/ice in the winter.
 
I have a Bolens, which is prolly the exact same thing you have. If there is a shift lever on the floor with a kind of Z shaped gate for F-N-R, then it's the same. I broke the hell out of my transmission going over stuff and just replaced the whole member with one from a lawn care place. Look on Craigslist for lawnmower repair, and they will likely have the trans you need sitting in a chassis on the back lot. Don't be concerned about the name on the rig, just look at the trans unit, and match it up. Replacement takes about 3-4 hours.

But first, look at your linkage from the shift handle on the floor center, and the trans. There is a kind of clevis pin in the back that shifts the rod inside the trans. If that clevis pin is loose in the arm or rod into the trans, then the fork inside is not being securely pushed and it will pop out. I had this problem too, but with forward gears. I bored the clevis hole and used a slightly larger pin so that it was more secure.

When you are in there, get new belts. The belts are the gear change on most older MTDs so there is no 'gear' change inside the trans, just forward and reverse. Buy the best belt you can get, and don't slip the pedal. I also changed the rear pulley as it was pretty worn, although you can prolly reuse the one that's on there.

I doubt you'll have much option in tire design. I also don't think it will matter much as the tires are all about the same in traction. Rather than external weights I would also fill the tires with about 50-70% antifreeze. Use a sand bag, or concrete bag as needed, sometimes I stand one on it's side just behind the seat and tie it to the seat for temp. Check the air in the plane tires too. That can make a lot of diff in rolling resistance.
 
I have a Bolens, which is prolly the exact same thing you have. If there is a shift lever on the floor with a kind of Z shaped gate for F-N-R, then it's the same. I broke the hell out of my transmission going over stuff and just replaced the whole member with one from a lawn care place. Look on Craigslist for lawnmower repair, and they will likely have the trans you need sitting in a chassis on the back lot. Don't be concerned about the name on the rig, just look at the trans unit, and match it up. Replacement takes about 3-4 hours.

But first, look at your linkage from the shift handle on the floor center, and the trans. There is a kind of clevis pin in the back that shifts the rod inside the trans. If that clevis pin is loose in the arm or rod into the trans, then the fork inside is not being securely pushed and it will pop out. I had this problem too, but with forward gears. I bored the clevis hole and used a slightly larger pin so that it was more secure.

When you are in there, get new belts. The belts are the gear change on most older MTDs so there is no 'gear' change inside the trans, just forward and reverse. Buy the best belt you can get, and don't slip the pedal. I also changed the rear pulley as it was pretty worn, although you can prolly reuse the one that's on there.

I doubt you'll have much option in tire design. I also don't think it will matter much as the tires are all about the same in traction. Rather than external weights I would also fill the tires with about 50-70% antifreeze. Use a sand bag, or concrete bag as needed, sometimes I stand one on it's side just behind the seat and tie it to the seat for temp. Check the air in the plane tires too. That can make a lot of diff in rolling resistance.

Good suggestions, thanks. I suspect our mowers are effectively the same. It's got the F-N-R on the floor, and then on my right side it has the "gears" of 1-7 (plus Park), but I'm pretty certain that it's all belt-driven anyway. So I'll look into that. I like the concrete bag idea since it's much cheaper than wheel weights and can probably do something that way.

Looking at dedicated mower tires, I'm not seeing a lot of options. It looks like there are probably some ATV tires I could get that are better, though. Ideal would probably be studded snow tires. I see some are available for ATVs, so maybe I can find one in the right general size.
 
No prob. Take a good look at that rod and clevis. It gets a lot of action, and most older ones are thrashed by now.

Although it's not ideal, you might want to pull from the rear rather than the front. That puts the torque load right over the rear wheels. I'd use a pretty high up pintle point which will help going forward, but hurt going back. It's then a hassle to see what you really want to see, which is the plane.

One other mod I made is to bypass the darn seat safety switch. There's one right under the seat that is a simple ground break sensor, and one in the reverse gate under the center plate. Just bypass the seat and you can get on and off with the engine running and in reverse as well.
 
If you replace it with something else, a hydrostatic drive is much smoother engaging than anything with a clutch and a zero turn radius machine is better than anything except an omnidirectional for maneuverability. We put a ball on the front of our ZTR mower and haven't used the ATV or purpose built tug since for anything that isn't to big for the mower. You can turn the plane front wheel without moving forwards or backwards and you can push in directions not in line with the chassis.
 
If you replace it with something else, a hydrostatic drive is much smoother engaging than anything with a clutch and a zero turn radius machine is better than anything except an omnidirectional for maneuverability. We put a ball on the front of our ZTR mower and haven't used the ATV or purpose built tug since for anything that isn't to big for the mower. You can turn the plane front wheel without moving forwards or backwards and you can push in directions not in line with the chassis.

Yeah, there are certainly options that would be more ideal, although there is my willingness (or lack thereof) to spend money on some of the best options. Part of the goal with this was to have a solution that would be cheaper than some of the dedicated aviation solutions out there, with other advantages such as being able to sit on it and more easily tow it longerish distances, such as to the pumps and back.
 
Have you looked at the powered tugs that have a ?10? hp motor and a single wheel? We used one to move crop-dusters (sometimes loaded) around the ramp.
 
Ted -- I've never known you to use less equipment than necessary. You could add a few points to your man card and buy something way overkill, maybe something with two engines. You know you want to.
 
Have you looked at the powered tugs that have a ?10? hp motor and a single wheel? We used one to move crop-dusters (sometimes loaded) around the ramp.

More money than I want to spend.

Ted -- I've never known you to use less equipment than necessary. You could add a few points to your man card and buy something way overkill, maybe something with two engines. You know you want to.

I was thinking about buying a 4x4 Chevy Blazer and putting a front hitch on that. I see those cheaper than most lawn tractors, and if it never left the airport, it should be perfectly legal to not have it registered or insured.
 
Pulled the plane to the pumps and back today and it was really bad. Tires slipping like crazy, couldn't do even the slightest incline without some significant momentum, and kept popping out of reverse.

We're flying to see the in-laws for Thanksgiving, the weekend after I'll bring it home and work on it.
 
Have you checked the trades and surplus rags for actual aircraft tugs? I haven't looked lately but they used to be available for a few hundred bucks. I know we gave $300 for one with a Chrysler slant six in it and it took all of a set of points and a Jiffy kit and float for the carb to get it running good.
 
Have you checked the trades and surplus rags for actual aircraft tugs? I haven't looked lately but they used to be available for a few hundred bucks. I know we gave $300 for one with a Chrysler slant six in it and it took all of a set of points and a Jiffy kit and float for the carb to get it running good.

It's probably worth another look, but keep in mind transport is also an issue. I'm not interested in going a long way for a tug.

Good thought, though, I'll take a look.
 
It's probably worth another look, but keep in mind transport is also an issue. I'm not interested in going a long way for a tug.

Good thought, though, I'll take a look.

I would consider using screw in studs vs. changing tires. I doubt any tire is going to get enough purchase to do the job on ice. These are also cheap:

http://www.maxigripstore.com/categories/Tractor-Tire-Studs/

I would go to a garage sale, craigslist, etc. and find an old set of exercise weights. Much easier to add to the tractor than sand bags, no spillage, bulk, etc.

I would definitely weld the spider gears as Henning mentioned. In effect you are doubling the traction for the cost of a couple of rods. The reason they don't come that way on most lawn tractors is because it would tear up turf in a tight turn, something you don't care about.

Assuming your tractor is still useable, these three things would cost less than $100 dollars, could be done in an afternoon, and will make a world of difference. Alternatively, you could always just do the gears and weights and try that before spending the money and time on studs.
 
I would definitely weld the spider gears as Henning mentioned. In effect you are doubling the traction for the cost of a couple of rods. .

Disagree. Traction is split between both tires with an open diff until one slips. On something as small as a lawn tractor, just shift weight(lean) slightly over the chattering tire and it will not spin, or spin both sides. I do this all the time when I mow on uneven hills.
 
Disagree. Traction is split between both tires with an open diff until one slips. On something as small as a lawn tractor, just shift weight(lean) slightly over the chattering tire and it will not spin, or spin both sides. I do this all the time when I mow on uneven hills.

It seems to be a problem for Ted as it is with an open diff.

Probably the reason a real tractor has a diff lock switch.
 
I've never tried welding the gears on a lawn tractor, but when we were kids starting in drag racing I welded the spiders on a 12bolt Chevy rear end. After 3 passes the carrier exploded in the turn onto the return road. Probably the lawn mower doesn't have enough traction for this result, but I didn't mention it as a suggestion, just to point out that it is the only reasonable modification available. One could make a limited slip differential by machining the axle gear and carrier seat to accept a clutch pack one could make and then install a heavy spring pack that would fit between those gears. Then you would have a positrac differential, however that is not a realistic solution to this issue. Outside of that I don't believe there is a 'bolt in' solution.
 
I explained how to solve it on a garden, or lawn tractor.

A real tractor has a lot of things a lawn tractor doesn't. Apples - lobster.
 
I would look at the strength of the transmission before investing in any extra weight or studded tires for a lawn tractor. Most lawn tractors were not designed with pushing/pulling 4,000lbs in mind. Locking the diff or adding weight to the point that the wheels can't spin is likely to explode the transmission if the internals can't handle the load.

If you could find an old GARDEN tractor like the old Sears or Cub Cadet models, the transmission might be durable enough to handle the load.
 
Some good additional thoughts.

Regarding welding the gears to make it a locked differential, what would that end up driving like on pavement? Given the ease with which I'm currently having tire slippage, maybe it won't be too big of a deal to have the one tire dragging around, but I do need to maintain some level of precision for steering. Shifting weight is not working as a solution in this scenario, I've tried it and am familiar with the technique as I've used it on hilly lawns before as well. What's especially bad is when one tire gets on a slicker part (like a localized ice patch, etc.) and then it spins entirely.

As far as the transmission goes, Chris makes a good point. I'm sure this transmission isn't rated for it. It also isn't slipping, the popping out appears to be more of a linkage issue than anything. Doesn't make any funny noises. For the use and duty cycle it receives, I'm not terribly worried about it. I also think it's one of those belt-driven (effectively a CVT) so you really can't jerk/lug it.
 
If you want to lock the rear, remove the trans from the chassis, split it, get a welder and just weld the spiders in place on the inner hub. Not a hard job, but time consuming. Seal it back up and put it back in the tractor with a new belt.

It'll drive ok at low speed. The inside tire will scuff some on tight turns. It will help somce in cases where one tire is on good pavement, and the other is on a low friction surface. the breakaway torque will be basically the same as with an open diff, but the low friction side will still just track.

I used to have the cheapest cheap of old Craftsman riding mower with the engine right over the cut deck, the seat above and a tiller type steering. It had a locked diff, and it worked ok, but had to do some leaning to get it to go around tight corners. Might help, won't hurt much, takes time to setup.
 
Some good additional thoughts.

Regarding welding the gears to make it a locked differential, what would that end up driving like on pavement? Given the ease with which I'm currently having tire slippage, maybe it won't be too big of a deal to have the one tire dragging around, but I do need to maintain some level of precision for steering. Shifting weight is not working as a solution in this scenario, I've tried it and am familiar with the technique as I've used it on hilly lawns before as well. What's especially bad is when one tire gets on a slicker part (like a localized ice patch, etc.) and then it spins entirely.

As far as the transmission goes, Chris makes a good point. I'm sure this transmission isn't rated for it. It also isn't slipping, the popping out appears to be more of a linkage issue than anything. Doesn't make any funny noises. For the use and duty cycle it receives, I'm not terribly worried about it. I also think it's one of those belt-driven (effectively a CVT) so you really can't jerk/lug it.

Here's a video of what's involved:

http://www.youtube.com/watch?v=8_91-8ssxt8

Simple.

There are some other things you can try depending on the results of the easy stuff, but I'm sure this thread is going to get even more contrarian. Let us know what you decide to do.
 
Yeah, the welding doesn't look bad to do, even for someone like me who is not a very good welder. If it really won't be too bad as far as driving/steering on pavement, I might give it a shot. Hell, I might give it a shot anyway, it can't be any worse than it is right now.
 
Yeah, the welding doesn't look bad to do, even for someone like me who is not a very good welder. If it really won't be too bad as far as driving/steering on pavement, I might give it a shot. Hell, I might give it a shot anyway, it can't be any worse than it is right now.

That's the spirit.
 
I brought the mower home and decided to go ahead and see what I could do. Sure enough, the transaxle was just a simple forward/reverse setup with a reduction gear and an open differential. Easy to get the wheels off and drop it, then split the case open with the 10 or so bolts that hold it in place.

The differential I had was pretty well sealed. It had heavily torqued allen bolts holding it to the ring gear that I couldn't easily get off. The videos I watched on YouTube showed the people welding the spider gears together. I took a slightly different approach after having no luck getting the differential apart, and realizing that this was just a $100 lawn tractor that I was rigging.

The open differential has 4 gears in it that all go together. Two are attached to each of the half shafts, and the other two allow the wheels to spin at different speeds. Those were held in place with a single bolt going through the differential. So, I took the nut off that bolt, leaving the bolt, the back of the gear, and the differential housing exposed. I then welded that side all up, ground the bolt head off of the other side and repeated the process. So, both gears are welded to the bolt, which should prevent them from rotating in opposite directions (which by itself should be enough), and they're also welded to the housing, preventing them from rotating at all (which by itself should be enough, also). So I think I'm set there. Filled it up with grease, put it all back together, and it seemed to spin freely.

The shift lever (which is just F-N-R) is just a bent rod that pivots in one area and then moves the shifter fork back and forth, which is what causes it to engage forward or reverse. It had worn away in the pivot areas, so I put a bit of weld on them to get them back to the appropriate diameter.

Put it all back together, it shifts beautifully, and it moves backwards and forward well. This weekend I'll take it back to the airport. The 310 should be done with annual by next weekend, and then I can see how it does.
 
Ted, I'm not sure how big the tractor tires in question are, but would it be worth weighting them for traction? I know beet juice is pretty popular. I'm with jesse though, if that fails just buy a $300 junker off craigslist, weld a ball to the front and call it a day.
 
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