Ackerman question,splitting hairs

[chimp koose]

So we know about the proper ackerman and how we come about these angles. My question is this ,do we measure from the center of the bottom of the king pin or from the center of the middle of the king pin at spindle height? I am inclined to want to do it from the center at spindle height.I have steering axis inclination of about 8degrees which puts the center of the kingpin at spindle height about .380" inward from the centre at the bottom of the pin.I would like to get on this part of the build right away so your input is appreciated.I have the 4130 rough cut and I want to make the chips fly and get this done. We have a car show in 2 weeks at the school and I would like to roll out the T with steering and suspension mostly complete.Thanks in advance for your input and reasoning behind it.

[enjenjo]

You measure at spindle bolt height, which makes sense if you think about it.

[phat46]

My inclination is to agree with you, although either would probably work, that's not a big difference, at least compared to a front steer setup.

[chimp koose]

Thanks guys for the quick response.I thought I had it right.I know most factory stuff is way off but since I have to make my own I might as well get it right.The econoline spindles would be 5/8" too wide PER SIDE.I thought I could do better.My steering rack is coming along nicely,with almost 6" of stroke and the open,non steering side covered with a closed aluminum tube instead of the rubber accordion you see on the unisteer ones.The cover tube ends at least an inch away from the 4 bar tubes so no interference issues.I had read complaints about the unisteer system not turning as sharp as others ,but with 6" movement and the narrow T frame I don't have the worry of the rack coming close to the 4 bar set up like you might in an A frame deal. Also with the narrow frame I can likely turn the wheels sharper than on the A frame.I will likely have to shorten the steering travel with the steering stops.Let the fun begin!