Tamiya Semi - MAN Steering (Ackerman Steering Principle)

[aseejr]

Just thought I'd share this:

I was comparing the steering radius of my Tamiya MAN semi against my Knight Hauler. And thought, why the longer wheelbase truck (the Knight Hauler) had a tighter turning radius. Looked at this site first but couldn't find anything but found a thread on a build by Tamiya Cowboy posted on Scale.... , someone had mentioned correcting the steering geometry on short wheelbase trucks by moving the connecting steering rod behind the axle as opposed to the stock setup of being in front of the axle (Ackerman Steering Principle). Needed more explaining by Jordy (The Machinist) to get me convinced.

Tonight I moved the connecting steering rod to behind the axle and presto. Tighter turning radius. I would say it cut it down by 1/3 (maybe exaggerating a little). Before when backing up a trailer and I get a little twisted and you couldn't get the semi around fast enough to correct the trailer, well, not a problem anymore. Much more fun to drive now.

Albert

[Espeefan]

Albert, I'm curious to see some photos of the stock set-up and what you are running now. I am mainly interested to know what the difference is, in simply moving the steering link to the rear. Is it better because the inside wheel turns in more then the outside wheel, as it should be? The throw is still the same, right?

[aseejr]

Yes. It is because the inside wheel turns sharper than the outside wheel. Throws are the same before and after as I always max them on both sides using my travel adjust on my transmitter. Sorry I don't have before pictures.

Albert

[Espeefan]

Thanks. That's what I thought! I was wondering to if the knuckles had different ears on them for the tie rod to bolt to, and your picture pretty much confirms that they do also, which I can definitely see making a big difference in the geometery. Makes me wonder why Tamiya doesn't just recommend the set-up you have, out of the box.

[roadranger]

Is the steer servo always mounted on the side rail instead of the front?
Or did you move the servo too?

[aseejr]

Originally Posted by roadranger

Is the steer servo always mounted on the side rail instead of the front?
Or did you move the servo too?

That is the stock setup for the steering servo.

Hi Albert
It was me that wrote something about the Steering Issue into TCs Mercedes Stock Build Thread.

Most of you run the King,Knight,Aeromax and Globe Chassis with a long Wheelbase and the Steering in the Right(Ackermann) Position.

At the short Wheelbase 2 Axle and the Scania 3 Axle Chassis the position of the Steering is wrong.
The Reason is,at this Chassis the Tranny Case is nearer to the Front Axle than on the other Chassis.
So Tamiya just put the Steering Rod in Front of the Axle.

You can fix it,but maybe you have to cut the first Fixing Point from the Tranny Case.
Michael