Ackerman fixing, and bumper swapping.

When we built our tractors, didn't know about ackerman angle, which is where the inside tire when turning, turns farther than the outside tire, to follow the turn better.

Turns out my tractor had backwards ackerman. The outside tire turned way farther than the inside tire. This caused it to plow the corners, and then drift like crazy because the front end was hard to push.

It's easy to set the angle, tie a string to the bottom of the kingpins, and run it to the center of the rear axle. The tie rod that connects the spindles should be in line with the string. I did mine wrong in the video, had the string in the wrong spot... Almost got pug too, had to message him that I had screwed up.. thankfully he hadn't welded it in yet.

Here's some pics and video...

You can see here, that the tie rod is way off from the string.



I didn't get a pic of the fixed spot, but it's in the video.



Also cut off the winch bumper. Want to drop weight for racing at inwoods. Bumper with winch was 38lbs. Made couple of posts, so I could swap the new race bumper with the winch bumper.

Here's some pics for that...

Sweet do I see aluminum!   

Those bolts could also help.

Say you were racing and slam the front-end into something really fast, those bolts could work as a breakaway point.  Then you won't ruin anything more important.. As long as they aren't really strong.

Shooooooot... our tractors can handle high speed collisions... just need to bend the bumpers back when done.

Good to see you've joined the Ackermann crowd! Because of my inner go kart self (lol) I have a tendency when I build a frontend to set it up as such- Ackermann principle applied, 0° static camber, 10° KPI, 8-10° caster, or thereabouts.

The Ackeraman principle cuts way down on scrub and improves frontend traction. The KPI and caster work together to create a jacking effect. In a turn, it removes weight from the inside rear tire and plants it on the outside rear.

Regarding the caster- that measurement is in relation to the road, not the frame. Example- General Mayhem sits with a bit of a rake- I measured the frame as 4° raked foreward, so I built 14° caster into the frontend so it's actually 10° caster in relation to the road, which is what matters.

Now- I'm sure a lot of people go "yeah, I can steer- I don't need to get all technical on it". True, somewhat. But I promise you- a properly set up frontend at speed, is a joy to drive, especially if you're locked in the rear. All the various elements work together, well- like a machine (LOL) to make handling predictable and controllable.

I seen some people in another thread talking about losing ackermann by going with a front steer set up. Not true. It just needs designed in. The front end kits for hot rods employ a Mustang II setup, which is front steer rack and pinion. They handle great. Being a stock car chassis tech for a long time, I've seen the effects of good and bad suspension geometry. Well worth the effort, as Doc says, considering the outcome. Handling is directly related to safety in this regard
If we follow the imaginary line from the differential across the kingpins to the forward side of the axle our tie rods should fall on this line. Being mowers without disc brakes to interfere, it is quite easy.

Didn't know that about caster, but in this case, frame/axle is very close to 90 degrees to the road.

I don't remember who it was, but this forum is where I learned about the ackerman angle/effect. After some searching on Google, it's a pretty easy thing to set up.

Yep, front steer axles, or axles with front tie rods, are just as easy, you just extend the line the string makes past the kingpin, and line it up at the front.


No aluminum, just shiny galvanized steel. Now sanded, primed and painted steel.

You will break before the bolts for the bumper break. Would have to shear a 3/8 bolt in 4 places. Tubing will fail first around the bolt, it's thinner steel. I hope I never find out what breaks, cause I'll be broke too!

Stretch44875 wrote:

I hope I never find out what breaks, cause I'll be broke too!

Don't break yourself, we need you around!

There's a lot here to read, but anyone genuinely interested in largely improving steering and handling should read this: http://www.diygokarts.com/vb/showthread.php?t=11760

Just an update, finally got the mower geared back to romping/racing speed, and drove it with the fixed steering.

WOW, what a difference. I can take turns much faster, without drifting the rear as much. Before the front end would push, then the rear would swing out. I couldn't get any more speed because the rear end was all over the place.

Now, the rear just barely steps out on the corners, and is biting hard the whole time. Have to shift up a gear for our track, because it's so much faster....