[Flaken]

Picked up a used L120 and have a problem with the turning on it. Mechanically, it appears fine. You turn the steering wheel, the front wheels turn in the direction you want, BUT you continue moving forward only gradually turning in the direction you want. The turf tyres still have a well defined tread pattern and are inflated to sidewall spec. They just seem to float over the ground. On an asphalt paved surface they do grip a bit better but still appear to float. This is all at slow forward speed roughly one third to one half max forward speed and level ground.
Thinking of getting some ag style ATV tyres for the front or would some type of front weights perform better? Any opinions to solve the problem would be appreciated.

 

[greenmachine]

First thing I'd suggest is measuring the turning radius to see if it's near spec. I believe it should be around 18" measured at the mower deck, so that means it would leave an uncut circle approximately 3 feet in diameter.

Sidewall spec for inflation might be too high. Typically the fronts are around 12-14 psi on the 100-series.

 

[Flaken]

Thank you for the reply. Three foot diameter turning circle? Not even close, maybe eight feet at a crawl. The tyres just float. Have a number of trees to mow around of varying sizes and end up having to make 4 passes to cut close. 14 psi in the tyres, you can press on the middle of the tread and depress about a half inch, maybe a bit more.

 

[rayjay]

Google Ackerman steering geometry for an explanation of what is wrong with the L100 series. When you get near to full lock on the steering the Ackerman geometry is all wrong and you end up with a push in the front end. It would be interesting to add 50 lbs of weight to the front and see if it makes it turn a lot better but the steering effort would be a LOT higher.

 

[Flaken]

I somewhat understand the Ackerman steering as I have that on my recumbent pedal tadpole tricycle. That is, two wheels in the front and one in the rear. The other style of trike is a delta style which is opposite with two wheel in the rear and one in front. No, the problem here is that both front wheels are turned at a diagonal, not full turn, yet the lawn tractor still moves forward because the tyres float. Where and how should I attach the 50 pounds of weight?

 

[TundraBoy]

That is definitely not normal. I had an L120 for eight years and over 400 hours and never experienced anything like that. It is almost like the differential is locked up. What happens if you elevate the rear and turn one wheel by hand?

 

[Flaken]

That is definitely not normal. I had an L120 for eight years and over 400 hours and never experienced anything like that. It is almost like the differential is locked up. What happens if you elevate the rear and turn one wheel by hand?

Dunno, I'll have to give that a whirl and see what it does. But as I said, everything appears mechanically fine. What it more resembles is that the weight distribution is more towards the rear and that is why it floats without turning. I'm 6'4" and 280 but don't think that should affect it that greatly.

 

[rayjay]

Take the hood off and jury rig the weights as far forward as you can just for a trial. Your weight is part of the problem.
With correct ackerman geometry the inner wheel turns more than the outer since the inner wheel has a smaller radius to turn. With the ackerman out of whack one tire is sliding instead of gripping.

 

[rwmeyer]

Flaken, I think Tundra may have the answer: locked rear end.

Your tractor weighs approx. 530 pounds. That weight s roughly distributed between the front & rear wheels. Now, add your 280 pounds, pretty much over the rear wheels. This is rough numbers, but you've 1/2 your tractor weight, 275#, plus your 280#, or 550# on your rear wheels trying to drive you straight forward...rear end locked and equal power to both wheels. So 550# driving forward with two 9.5" tires tires and 275# (1/2 tractor weight) on two 6.5" tires, guess what's going to happen....you're gonna go straight, or straightish!

As Tundra said, jack up the rear of the tractor and turn one wheel. If the opposite wheel turns in the same direction, your rear is locked...and putting all power to BOTH rear wheels. If the opposite wheel turns in the opposite direction, your rear is OK. Jack it up, check, and report back. Bob

 

[Flaken]

Flaken, I think Tundra may have the answer: locked rear end.

Your tractor weighs approx. 530 pounds. That weight s roughly distributed between the front & rear wheels. Now, add your 280 pounds, pretty much over the rear wheels. This is rough numbers, but you've 1/2 your tractor weight, 275#, plus your 280#, or 550# on your rear wheels trying to drive you straight forward...rear end locked and equal power to both wheels. So 550# driving forward with two 9.5" tires tires and 275# (1/2 tractor weight) on two 6.5" tires, guess what's going to happen....you're gonna go straight, or straightish!

As Tundra said, jack up the rear of the tractor and turn one wheel. If the opposite wheel turns in the same direction, your rear is locked...and putting all power to BOTH rear wheels. If the opposite wheel turns in the opposite direction, your rear is OK. Jack it up, check, and report back. Bob

Cool!!! That is the best polite way to say I'm fat I've heard in awhile :sidelaugh

All that aside, your explanations make sense.
Was just going to get the lawn tractor out of the shed as I have to move some dirt in a Gorilla trailer. Figger it's easier to pull it with that than me doing it if only for a short distance roughly 30 feet.

 

[Flaken]

OK, just jacked the rear wheels off the ground about two inches. Rotating left rear one by hand clockwise, the right rear wheel turns counterclockwise.

 

[rwmeyer]

Well, that proves one idea, your rear is NOT locked. My only other suggestion is to add weight to the front to increase traction on the front wheels. Bob

 

[Flaken]

Then I am somewhat in luck. The dirt I'm moving is for a water flow barrier alongside my driveway and have some concrete & rebar. Should be fairly simple to construct a box, embed the rebar to fit over the bumper with concrete and see. 80 pound bag might do it then?

 

[TundraBoy]

OK diff not locked then. Not sure I buy into the weight issue. I'm only a half a tanks of gas lighter than you and never had this problem with the L120. Have you checked the front spindles and bushing. Are they worn out? That machine does have some toe-in as I recall. Does yours?

 

[Flaken]

Yes, there is a degree, or two, of toe in. Quite the same idea on my recumbent trike. The wheels are a degree or two off from vertical so that when sitting on the trike, it forces the wheels into the vertical position. Has to do with traction and tyre wear.

 

[rwmeyer]

Tundra, Another excellent point!

Too much toe in or out may confuse things...the tractor won't know which way to go.

Flaken, Put a tape measure on the inside front of your front rim, close to the center of your axle, and extend tape to opposite wheel. LOCK tape measure. Move tape measure to rear of front rims and see if end of tape hits or misses opposite rim. If tape hits, wheels are toed out. If tape misses, wheels are toed in. If tape misses, "eye ball" by how much...this is the amount of toe in. I don't know the exact spec, but worst case is probably 3/16". Adjust tie rod to 1/8"...unless you have actual spec. Bob

 

[rayjay]

Tundra, Another excellent point!

Too much toe in or out may confuse things...the tractor won't know which way to go.

Flaken, Put a tape measure on the inside front of your front rim, close to the center of your axle, and extend tape to opposite wheel. LOCK tape measure. Move tape measure to rear of front rims and see if end of tape hits or misses opposite rim. If tape hits, wheels are toed out. If tape misses, wheels are toed in. If tape misses, "eye ball" by how much...this is the amount of toe in. I don't know the exact spec, but worst case is probably 3/16". Adjust tie rod to 1/8"...unless you have actual spec. Bob

Exactly where do you adjust the tie rod ?

 

[rwmeyer]

Not familiar with the L120, just assumed they were adjustable. Bob

 

[TundraBoy]

Not familiar with the L120, just assumed they were adjustable. Bob

We don't know if they are original or aftermarket. I believe some aftermarket are adjustable.

Also need to know if status of the front wheel bushings and spindles. There might be some binding there.

I can confirm that weight of the rider/front end is not the issue. Unfortunately!!!! This is just not normal for this machine.

 

[Flaken]

OK, measurement at the front of the rim to the front of the other rim is 24¼ inches.
Measurement at the rear of the rim to the rear of the other rim is 24½ inches.