Re: TOY: All Pro Buggy

[Thom Singer <ntsqd@xxxxxxxxxxxx>]

It's hard to tell what the exact geometry of the suspension is in that pic. Take a look at an EB, they run two control arms and a trac rod. Steering can be an
issue with them, but mostly due to old, worn parts or badly matched lift components.
What is crucial is that the arc that the axle lateral locator travels in match the arc that the drag link travels in and that they be the same or very, very
close to the same radius. The further apart those two arcs are, the worse the steering will be. Read: Bumpsteer.

Randy Burleson wrote:
> 
> Did you guys check out the new front suspension or that ALL-TOYOTA front axle:
> 
> http://www.outdoorwire.com/gallery/trailshots/Trade_Shows/SEMA_2000/pb010088.jpg
> 
> 
> Jon started with a 3-link setup, but parked the rig after steering issues in
> the Montrose WRCC event. He torched off that 3-link and is now running this
> linkage with a track bar.
> 
> There has to be a good way to make a tri-link suspension steer short of full
> hydraulic... maybe they had bad geometry and insufficient lateral stabilization.
> What do you guys think about using a longer arm at the steering box, and a shorter
> arm on the knuckle, to be sure to allow lock-to-lock steering, even at extreme
> droop? The steering stops are on the knuckles for most axles, so you'd essentially
> be extending the range of sweep of the drag link while keeping the range limited
> at the knuckles.... if you reinforced the knuckles, this shouldn't be a big
> deal...

By shortening the knuckle arm you increase the leverage the tire has against the rest of the steering system which could lead to increased kick-back at the
steering wheel and faster wear of all the components affected.
I had to think that'n thru a bit. First inclination was to say just the opposite. The tire has X radius, the steering arm has Y length. The leverage ratio is
X/Y. Lets say the tire is a 33-12.50, so it's radius is 16.5" (nominally) and the steering arm is 7" long. That makes for a leverage ratio of 16.5/7 = 2.357. If
we apply a 100 pound load parallel to the tie rod at the edge of the tire, the load the tie rod end sees is 100*2.357 = 235.7 pounds. If you make the steering
arm shorter then the ratio increases. So if we make it 5" long the ratio goes to 3.3 and the load at the tie rod end goes to 330 pounds. Wrong direction, makes
those absurdly long steering armed Scout II D44 knuckles look better all the time.....

> The reason I ask is that my truck steering gets less sharp at full droop on
> the passenger side... I can't turn quite as tightly as I can when full-drooping
> the driver's side. The geometric cause of this is obvious -- when the passenger
> tire drops, the drag link has to stretch farther (if the wheels are to remain
> straight).

Are the steering stops set the same ? In trying to visualize this what I'm coming up with is that you should have more left turn potential than you will have
right turn potential at full right droop. What is the angle of the drag link at rest on level ground (elevation of the two end points off the ground)  ? How
long is it compared to the track width ? I'm assuming cross over steering.

-- 
TS
Chico, CA

Why is Bra singular, and Panties plural ?