Topic: steering axle

[jerb]

been racing mowers for a few years, i built an adjustable front axle and had a question about the kingpins! i understand toe in and out, camber and ackerman and how they affect handling but ive seen some kingpins that are tilted back at the top, what affect does this do to handling, mine are straight up and down, seen quite a few that are tilted! thanx for the help! awesome forum!!!!!

[Tom Fox]

Take a look at all the highlighted/sticky's at the top of each catergory.

Here is one all about geometry: http://www.heymow.com/index.php/topic,425.0.html

[jerb]

didnt quite word that right! the tops of some kingpins ive seen leen towards the rear of the mower, mine do lean in at the top roughly 10 degrees but they are straight up and down, seen some like mine but are leaned back also! i worded that clear as mud! thanx guys!

[redline]

The tilt in towards the centerline of the mower is kningpin inclination, this effects tire scrub anong other things. The tilt of the top of the kingpin as viewed from the side is caster, which effects steering stability and steering wheel return. It will also cause the vehicle/chassis to "lead/pull" to the side with less caster.

[jerb]

thanks for the info, guess i should of read a little more on the topic, if i was to tilt the top of the axle back a few degrees what would be a good starting point, or is it just trial and error, or is it really necessary for improved handling!  thanks alot!

[nor66]

It does make a difference, and well worth the effort, you might have to read the topic that Tom Fox give you many times but it is all in there!

[Seth Brunson]

I just read through EC's front axle geometry and it's pretty hard to understand. Not calling myself stupid but i was wondering if i could get a straight forward on the question because i was asked by several people myself and had no answer to give them.

[Squidd]

So what exactly is the question...?

[birdman_express]

I just read through EC's front axle geometry and it's pretty hard to understand. Not calling myself stupid but i was wondering if i could get a straight forward on the question because i was asked by several people myself and had no answer to give them.

It took me several times of going through it to understand it as well. Then it hit me. You have to understand what is going on with the chassis and why you have all these things going on at once. Your mower is going through the corner like a teeter totter on the left front and right rear. You get weight trandfer to the right front and right rear. The left rear becomes lighter and you turn the corner. Just having a good front end is part of the big picture. That is why a person needs to beef up a chassis. You never hear George talk about setting up a front end, he says "chassis setup". Being able to tune the front end to changing conditions is part of what makes the EC style front end so cool. Now understanding what to change to meet different conditions is the harder part. That will take some more research and study. All chassis react different to each track. More toe out on a wet sloppy track to get turn in grip, and the like. So go back over that geometry lesson again, and again. It will hit you and you will grin like a mad dog.

Marc

[michael a. formentini]

thanks for the info, guess i should of read a little more on the topic, if i was to tilt the top of the axle back a few degrees what would be a good starting point, or is it just trial and error, or is it really necessary for improved handling!  thanks alot!

The right front tire should be any where from 7 to 10 deg. negative caster. That is the leaning of the top of the king pin toward the back of the mower. This puts wight transfer on the right front tire in the corner. If you are only making Left turns leave the left front at about 3 or 4 deg. negative caster. If  you have any Right turns you may want more negative caster in the left front tire. Driver preference.

[mightymowe]

If you have different caster on each front wheel like you describe the machine will probably pull to the right.I would suggest that you have the same caster on both wheels so that the steering wheel will be neutral when driving in a straight line.But it is driver preference like you say.

[Butcher]

When adding caster to right front spindle you increase the amount the tire goes down when turning right, and amount it goes up turning left.

It takes a stiff chassis (or one that duplicates the same amount flex each time it's turned) to make the best use of this. Upon entering a typical oval turn while turning left the right front goes up (when using 90 deg. spindles: this is multiplied when using 7,10,13 or any degree spindle,unless installed upside down- I've seen this on a very fast, ill handling twin) and more importantly unloading the rear left tire allowing the mower to turn left easier (loose). While turning left as the rear starts coming around, you turn right to prevent spinning out ( more importantly lowering the right front and loading the left rear for enough traction to run through entire turn with out letting of the gas, while in control with minimal turning of steering which slows momentum) if cross is set correctly for your driving style.

As far as the amount caster, the more you have ( in general ) the
less you have to turn the wheel to steer.

From what I've seen and applied ( with solid axle ) is to only turn slightly right through turns (entering with quick release of throttle
with correct stagger sets itself up and follow with slight steering to the right to trim slide).

The tracks always change, when set right it appears the driver is not even turning the wheel and turning the best times at full throttle.

Opinions vary, this is how I use and see caster being applied, and it is only part of a good front end set up.

Butcher.

[nor66]

- I've seen this on a very fast, ill handling twin) Butcher.

You aren't talking about the beast I was driving at Rocky creek are you?

[Butcher]

NO!!   I seen a guy at our local track almost  wipe out every turn during a heat race, I knew he drives better than that, I went over to look at it and I think he put it on upside down in a hurry, ???  That yellow one had the type of setup i'm referring to, more than normal caster (normal being what most others run) and flatfooting it in total control. Basically, excessive cross where you have to over drive it to make it handle good. I hope this make cense.

ButcherIf you had a little more speed coming of the turns I believe you'd have been right with'em.

[nor66]

We are in the process of rebuilding the whole machine including the front axle which had excessive amounts of negative camber and zero caster!!! That setup made it feel like you were on a ice track I had no feel of the front end at all, really hard to control!!!! Although this topic was originally about kingpin inclination, right now we are not added that to the mix, but are considering it, I know it will change the way you set everything else, (IE caster,camber, toe in or out!)!