Ackerman?

[Ralphy]

I've searched for the answer an could not find it. I'm trying to figure out what zero-ackerman steering, like the new losi rig claims to have, actually means. What is ackerman and how does having zero of it help? Just wanted to know.....

[EeePee]

http://www.smithees-racetech.com.au/ackerman.html



Losi went without Ackerman.

[Manning]

Ackerman...where the inside tire turns more than the outside tire, and both tires follow the proper radius during a turn. This helps tremendously at low speed, like crawling.

The Axial Scorpion has reverse ackerman, the inside tire turns less than the outside tire. So the tires are fighting each other when turning and the turning radius isn't what it could be..... It's my biggest gripe with the Axial. I have a simple idea on how to somewhat fix it, but I haven't tried it yet.

The Losi steering looks good to me. I'm not sure it has zero (can't see exactly from the pics), but it's much better than the axial.

[RobCam]

does the bta steering solve this ackerman problem on the ax10

[Calderwood]

Originally Posted by RobCam

does the bta steering solve this ackerman problem on the ax10

Yes.

[miniwheeler]

Originally Posted by Manning

Ackerman...where the inside tire turns more than the outside tire, and both tires follow the proper radius during a turn. This helps tremendously at low speed, like crawling.

The Axial Scorpion has reverse ackerman, the inside tire turns less than the outside tire. So the tires are fighting each other when turning and the turning radius isn't what it could be..... It's my biggest gripe with the Axial. I have a simple idea on how to somewhat fix it, but I haven't tried it yet.

The Losi steering looks good to me. I'm not sure it has zero (can't see exactly from the pics), but it's much better than the axial.

You know what ackerman is but you dont know what it does for crawlers.
"Proper" ackerman angle has no benefit to a crawler because of the locked dif. In order for ackerman to work properly both front tires have to turn at different rates. Having the outside tire not turn as sharp as the inside tire actually decreases turning radius. The only benefit to a correct ackerman angle, is at high speeds not low.

The Losi crawler as well as the new venom crawler both have a zero ackerman so that they can turn as sharp as possible.

[dkingston]

http://www.rctek.com/technical/handl...principle.html


- David

[tubed-n-lubed]

Ok maybe it is just me but doesn't the fact that we run solid axles & most of us run locked front axles combined with the low speeds mostly nullify any advantages that perfect ackerman would add?

[EeePee]

Yes which is why Losi has chosen to go with the no ackerman, just turn both wheels as far as possible method.

[Calderwood]

Originally Posted by miniwheeler

You know what ackerman is but you dont know what it does for crawlers.
"Proper" ackerman angle has no benefit to a crawler because of the locked dif. In order for ackerman to work properly both front tires have to turn at different rates. Having the outside tire not turn as sharp as the inside tire actually decreases turning radius. The only benefit to a correct ackerman angle, is at high speeds not low.

The Losi crawler as well as the new venom crawler both have a zero ackerman so that they can turn as sharp as possible.

I strongly disagree. My axial turned considerably sharper after I did the bta. I am not saying "Proper" ackerman is better than zero ackerman but it is definitely better than the reverse ackerman that comes stock on so many crawler axles.

[onefstsnake]

Are you sure the BTA kit didnt allow the knuckles to turn farther than the stock steering setup thus making it turn better?

[Calderwood]

Originally Posted by onefstsnake

Are you sure the BTA kit didnt allow the knuckles to turn farther than the stock steering setup thus making it turn better?

Absolutely sure.

[EeePee]

Arm length and angle will dictate what kind, or amount of Ackerman you get.

Most of the crawler knuckle arms have a falling rate, so they fall off as they go through their range of motion. A shorter arm length might not fall off as fast. Don't you guys cut your AX10 arms when you go to a behind the axle set up?

[EeePee]

Yeah and check out the arm length and angle on the Losi. Interesting. Definitely will need a STRONG servo.

[miniwheeler]

Or a shorter servo arm

[Calderwood]

Originally Posted by miniwheeler

Or a shorter servo arm

Agreed, with the appropriate length servo arm you wouldn't need anymore torque.

[LincolnBlack]

My thought with the positive vs. negative ackerman. On a crawler, in many circumstances the outside tyre is the one with the most weight on it (like turning uphill), and thus probably the most effect on steering. This why I would think zero to negative ackerman would be an advantage.

[EeePee]

You also don't need a long servo horn just because the knuckle arm is so short. Not much distance to travel. But we all know a shorter arm is harder to push.

And I ain't worried, I got the Airtronics 423 oz'r.

[whoodie]

Strong servo, probably, it will depend on the scrub radius.

As far as a locked diff negating the effect of ackerman, that cannot be further from the truth. Turn your steering, drive forward slowly. Notice which tire is following the turn radius. More than likely it is the inside tire. Now proper ackerman will have the inside tire turning at a sharper angle, now wouldn't you guys want a tighter turn radius?

[sourdojack]

Originally Posted by whoodie

As far as a locked diff negating the effect of ackerman, that cannot be further from the truth. Turn your steering, drive forward slowly. Notice which tire is following the turn radius. More than likely it is the inside tire. Now proper ackerman will have the inside tire turning at a sharper angle, now wouldn't you guys want a tighter turn radius?

I think the point a few guys are trying to get across is "It is best to have BOTH front tires turn as sharp as possible (zero ackerman angle), not the outer one turning less than the inside one (proper ackerman angle)."

Wouldn't it just make sense to have both front tires turn all the way to the stops. So it doesn't matter which one is catching traction.

In nigels_world's case with his BTA set-up, it probably improved his turning by having his inside tire turn sharper than his outside tire. But I bet his turning on the rocks would be even better with zero ackerman angle.

To sum it up,
Bad: Reverse ackerman angle
Better: Proper ackerman angle
Best: Zero ackerman angle

Just my $0.02

TOM