Front steering, vs rear

[MTScott]

The grand daddy kart plans call for the steering in the rear (behind the A-arms), but, I'm curious... does anyone ever see it in the front in either plans or OEM karts?

One of the issues I've had is the inside wheel of a tight turn will sometimes buckle. The angle at the arm-rod joint is close enough to flat that the pressure on the wheel over comes it, and folds the joint past straight and locks the tire up. If I did front steering, the arms would turn out instead of in, keeping more angle at the rod-arm joint.

I suppose I could attack this in a few ways by adding a stop somehow, or, simply moving the steering rack a bit farther forward, but that'll change how the rods interact with the arms for ackermanns as well.

 

[Denny]

I prefer to have the tierods in extension regather than compression (rear steer). With the tierods in extension (front steer) better control is maintained over the tires. However this makes Ackerman more difficult to achieve. Especially with a steering rack. But hey, you can’t have everything.

 

[MTScott]

I prefer to have the tierods in extension regather than compression (rear steer). With the tierods in extension (front steer) better control is maintained over the tires. However this makes Ackerman more difficult to achieve. Especially with a steering rack. But hey, you can’t have everything.

Okay, that makes sense to me... and it'll actually hlpe the build in a couple ways.

First way... I eliminated bump steer in a simplistic way by making my tie rods the exact length as my A-arms, since the GD plans make them parallel. This gave the tie rods the same arc as the A-arms. In order to do this I had to make a goofy adapter to attach the rods to the 11" rack to maintain this length (they were too wide otherwise). Putting them in front would actually make this simpler, the would be the proper length to attach to the steering rack the way they were intended.

Second way, in order for the rack to be positioned behind the A-arms, it put a lot of angle on the U-joints in the steering column. Moving it forward will keep it further from our feet, and a smoother angle.

I imagine my ackermanns isn't perfect anyway with the steering rack. I went with the easy technique of finding the angle from the kingpin to the rear axle center, and setting the arms at that angle. Given the rods actually attach at the end of the rack, I suppose it isn't exactly perfect, but for an offroad kart it seems to do okay.

 

[Denny]

GM figured out many moons ago on rear drive cars that steering parts last longer and is better for tire life on front steer. Longer tie rods and pivot points like you have done is the correct solution to bump steer.