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Ackerman steering effect.

darius said:
Well robin you may be the rirst guy in wheeling that has actually gone through the step's of checking correct ackerman. Idealy you want your inside tire to turn a few degrees more than the outside and all is well, I don't feel that your spending you time wisely trying to get it perfcect.
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Like I earlier stated I respect those who have looked into it and decided to go with parellel arms.

I do believe backwards ackerman makes a 4x4 "plow" through corners.

that was my main point
 
It is taken in to consideration. And was taken into the design of the arms we use. the dynatac arm more closly resembles a factory setting (favors slightly turned out ward causing outside tire to turn at less angle than inside) where the arms we use are directly in line with the knuckle and centerd. so basically strait. I have seen people use arms moved inward getting the outside tire to scrub hard or push since it turns at a steeper angle than the front (common on 50 deg spider 9 stuff and how Robins factory mog parts where) in my eyes this does not work (or not as practical) since you would want the outside tire to turn in a larger radius and the inside tire to tun in a tighter one (more closely resembeling factory). But the benifit is while doing a front dig the front will drag the car around in a tighter circle due to the more agressive direction of the outside front tire. The down side is it would tend to push in a normal turn at close to full lock or towards the end of the steering cycle. So in that design there is a sacrifice for a gain elsewhere. now on Robins senario it is more exagetated and he will notice alot more defined characteristics. the reason being is the camber of the knuckle itself. from the front of the axle it will have between (typically) 7 to 10 degree angle. this is the point where the tire scrub comes into play. he is seeing an aplification since below the lower bearing 6" is the lower part of his knuckle where as a typical knuckle is up higher closer to the bearing since the spindle bolts directly in the center of it. also to add to the issue is a castor angle. this changes as well using a portal since the lower point is yet again moved down. as the steering cycles with 7 degs castor one tire will rotate up (outside) and (inside) will start to turn down or flat. in his senairo being that the pivot point is again 6" up from the centerline of the tire will amplify what is going on with his axles. Typically on the smaller cars the changes are not as drastic as the results Robin will see with the new saw-sage. This is a good thread.:awesomework: This is an issue that is very often overlooked. but in our case or porters car it is not... you have to think in 3D and not just look at one 2D point and factor in all of what is going on (ackerman vs castor vs camber vs wheel offset and is some cases VS portal box which will amplify every ratio in the steering cycle). I think the steering changes Robin has made will yeild good results. I think they would for the most part be lightly noticed with a non portal diff. Now on higher speed it will be alot more critical since your really wanting to define the tire movement.
 
Jason C said:
It is taken in to consideration. And was taken into the design of the arms we use. the dynatac arm more closly resembles a factory setting (favors slightly turned out ward causing outside tire to turn at less angle than inside) where the arms we use are directly in line with the knuckle and centerd. so basically strait. I have seen people use arms moved inward getting the outside tire to scrub hard or push since it turns at a steeper angle than the front (common on 50 deg spider 9 stuff and how Robins factory mog parts where) in my eyes this does not work (or not as practical) since you would want the outside tire to turn in a larger radius and the inside tire to tun in a tighter one (more closely resembeling factory). But the benifit is while doing a front dig the front will drag the car around in a tighter circle due to the more agressive direction of the outside front tire. The down side is it would tend to push in a normal turn at close to full lock or towards the end of the steering cycle. So in that design there is a sacrifice for a gain elsewhere. now on Robins senario it is more exagetated and he will notice alot more defined characteristics. the reason being is the camber of the knuckle itself. from the front of the axle it will have between (typically) 7 to 10 degree angle. this is the point where the tire scrub comes into play. he is seeing an aplification since below the lower bearing 6" is the lower part of his knuckle where as a typical knuckle is up higher closer to the bearing since the spindle bolts directly in the center of it. also to add to the issue is a castor angle. this changes as well using a portal since the lower point is yet again moved down. as the steering cycles with 7 degs castor one tire will rotate up (outside) and (inside) will start to turn down or flat. in his senairo being that the pivot point is again 6" up from the centerline of the tire will amplify what is going on with his axles. Typically on the smaller cars the changes are not as drastic as the results Robin will see with the new saw-sage. This is a good thread.:awesomework: This is an issue that is very often overlooked. but in our case or porters car it is not... you have to think in 3D and not just look at one 2D point and factor in all of what is going on (ackerman vs castor vs camber vs wheel offset and is some cases VS portal box which will amplify every ratio in the steering cycle). I think the steering changes Robin has made will yeild good results. I think they would for the most part be lightly noticed with a non portal diff. Now on higher speed it will be alot more critical since your really wanting to define the tire movement.
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Does that mean I wont be on my lid as much?
 
Jason C said:
OH HELL NO! :redneck: Besides I would rather have you on your lid VS breaking 5/8" bolts. How soon till the new and imporved saw-sage will be out?
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3-4 weeks if my wallet hold up. Then I have the problem of a tow rig with a busted clutch. back to beggin for a tow:looser:
 
briejer said:
3-4 weeks if my wallet hold up. Then I have the problem of a tow rig with a busted clutch. back to beggin for a tow:looser:
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Bummer... We had 2 full metalic dodge clutches here... chattery as FUK but they would have got you by for a while.... cleanin the shop bout a month and a half back we tossed them since they had been sitting for coupl years.....:rb: always day late dollar short.:rolleyes: wish I would have known...
 
briejer said:
3-4 weeks if my wallet hold up. Then I have the problem of a tow rig with a busted clutch. back to beggin for a tow:looser:
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Shoot me a PM when you get ready to roll. I have the opposite problem, tow-rig and a torn apart wheeler. :redneck: And I miss being on the trail. I need to put a new brake-controller in my tow-rig but I can do that any day. And I live in Covington (moving to Puyallup in September)...so I'm not far.
 
NAC25 said:
Shoot me a PM when you get ready to roll. I have the opposite problem, tow-rig and a torn apart wheeler. :redneck: And I miss being on the trail. I need to put a new brake-controller in my tow-rig but I can do that any day. And I live in Covington (moving to Puyallup in September)...so I'm not far.
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Looks to me we have ourselves a date:awesomework:
 
All in all this has been a good discussion. I am pleased I have axles that turn sharp enough and have selectable axles so ackerman will make it turn better.

Remember, this is only about turning, not climbing. We all know my buggy does not climb up a hill, it hops up it.....but still gets up the hill. Now I will be able to turn better as I hop like a cute lil bunny.
 

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