Ackerman article

racingman

Member
I've searched the internet for a really in depth article on Ackerman but not any. They are all basic. Most writers are just repeating the same stuff. Obviously it's about having a different turn in for each front wheel because the inside tire turns faster than the outside.

I have Sniper gauges but all that tells me is there is about 1/2 inch difference. Basically I know that I have Ackerman but don't know how much is needed or not needed. Can anyone help with this issue?

Also curious: Does anyone change ackerman settings at the track? Or do we just leave it where it is and adjust elsewhere.
 

95 shaw

Premium User
The thing most articles do not tell you is that the toe out you gain turning left becomes toe in turning right.
So, most times, the benefit can be outweighed by the disadvantage of toe in, unless you are already compensating with enough toe out at wheels straight ahead to overcome the toe in at counter steer.
You should be able to see this with your gauges.

In LTO karts, the toe out is used to keep some heat in the Lf tire to help turn in. The added drag hurts you less than the penalty for not being able to turn in.
Everything is a compromise.

Just some food for thought.
 

flattop1

Dawg 89
That and tenths of a second or half tenths .
I myself am certainly not dedicated enough to the data to track it .
Baker used it and won a lot of races .
(Assumption : that's why he had degree turn plates )
Sprint racing with different amounts of turns it could be advantageous to change it .
 

racingman

Member
The thing most articles do not tell you is that the toe out you gain turning left becomes toe in turning right.
So, most times, the benefit can be outweighed by the disadvantage of toe in, unless you are already compensating with enough toe out at wheels straight ahead to overcome the toe in at counter steer.
You should be able to see this with your gauges.

In LTO karts, the toe out is used to keep some heat in the Lf tire to help turn in. The added drag hurts you less than the penalty for not being able to turn in.
Everything is a compromise.

Just some food for thought.
So are you saying use more toe than normal. We use about an 1/8th right now or 2mm per Sniper gauge.
 

95 shaw

Premium User
I'm saying, be aware that you may get to a toe in situation, with all the bad generally associated with it.

Use your gauge to see how much toe in you get with the same amount of countersteer. Can you live with that?
Some toe in can be compensated for with extra toe out. Can you live with that?

Testing will still be required to see if the ill effects show up on stopwatch.

I'm assuming oval, but the effects apply to either. It is not a win-win adjustment.
 

WPaul

Member
Look for "Advanced Race Car Technology" by Bob Bolles. Or his Circle Track Magazine articles. The magazine is no more but some of the articles are still on the web.
Food for thought;; On our Asphalt Late Model we adjust for < 1/16" Left Ackerman on a 1/2 mile track.
IMHO it's not all it's cracked up to be.
On a kart,,,, 90% tires 10% everything else, just MHO.

Best,WP
 

alvin l nunley

Premium User
There's an article in Wikipedia that describes "true" Ackerman steering. I know of no modern kart frame that uses "true" Ackerman steering.

If you want to redefine the term, i.e. Turn the inside wheel faster than the outside wheel, I suppose you could do that. How about "Ackerman like" steering?

As shown in Wikipedia, true Ackerman does not accomplish its purported task. I've done extensive CAD/CAM drawings to prove this, to myself at least. Getting tw o wheels turned to follow concentric circles with different radius isn't easy. It's possible, but not with any of today's kart steering solutions.
 

95 shaw

Premium User
For that chassis, moving the mounting points on the steering shaft creates a small change in steering geometry, but changes the driver feel.

A more significant change can be made if spindles have holes that require a shorter tie rod.
Most times the changes made will be the same for both sides to eliminate the toe in possibility.
Most would limit at track changes to the steering shaft adjustment, looking to change driver feel.

For lto karts, the adjustment is usually limited to making the left steer quicker than the right.

Hope I helped clarify that a little.
 

Pete_Muller

Moderator
Racingman,

My "recommendation" would be to set the chassis up the way Tonykart recommended --initially. Even trying to calculate how to get the inside front and outside front to each track their own corner radius is "flawed" because a sprint kart is really a 3-wheeled vehicle entering a corner and a 4-wheeled vehicle exiting a corner. That enters a WHOLE new dynamic into the ackerman idea!

There are so many calculations that "could be done", your time will be better spent setting up as the factory intended, and when you have some time... make some changes either side of that starting point and see how it feels. (and move things a lot so you can *definitely* feel it)

In road racing (like the photo you see to the left of this message), we ran little or no ackerman because those karts are narrower and run on faster tracks (so less turning of the steering wheel). I played around a bit with it on sprint karts, but to be perfectly honest, I did more messing with it pushing the kart around in my smooth/flat driveway than I did at the track. "Some" ackerman is definitely good (IMO) on a sprint kart, but there are far bigger fish to fry when it comes to getting the chassis dialed. (once again: IMO)

PM
 

Outrider

Member
Just my opinion, based on years with oval kart setup, plus additional years with sprint cars from 600 micro to 410s; The best thing you can do where Ackerman is concerned is to use setups that minimize Ackerman.
 

racingman

Member
This answered a big question for me. My sweep is off because my tie rods are not the same on each side. I replaced the steering column due to an accident and now I see where I made a mistake. Thanks a ton.
Ultimate cause I found just now is a bent king pin bolt. That's why my sweep was off. Thanks to you I learned the difference from sweep and ackerman and how and when to set those up. Learning every day. Thanks again.
 
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