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front axle alignment specs

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30dodgeboy:
What are the recommended specs for the front axle alignment (caster, camber, toe)?

My car is a 144" wb, pretty stiff chassis, with 2.25S17 Avon Speedmaster (ribbed tread) front tires.

Thanks in advance.

dreracecar:
Camber is fixed unless building a new axle and not super critical with the avons.
Because the avons have a round conture (not flat like frontrunners) I like at least 20deg of caster so that the tire rolls around the tread when turning which helps drive the tread into the pavement.
toe @ 1/8"
The biggest issue is that for tire life and to keep the avons happy(you cant buy them anymore) is that you must have ackerman built into the steering arms. This when turning will allow the inside tire to turn sharper during a turn and will not scrub off the tire tread as it would if both tires turnd the same amount.

  I need to know how wide the front axle is at the middle/center of the kingpin bosses in order to tell you how much the offset is (I already know the w/b). Depending on what you have you may have to make new arms.  The pic shows .691 offset for a 120"w/b chassie and a 42" wide axle and a 4" arm

rooman:
The ackerman principle is fairly simple--the attachment point of the linkage to the steering arm should be on a line drawn between the center of the king pin boss and the center of the rear end housing. You can run a string from point to point and figure out where the hole in the end of the arm needs to be. If you are running the drag link to the spindle and simply using the steering arms to connect the front wheels the length of the arm is not a factor. If you are using a bell crank style linkage that opens a whole new can of worms relative to steering angle related to input from the box and arm length can be a factor.

Roo

ricci32:
1/8 in or 1/8 on toe im and old dirt racer.

30dodgeboy:
I don't have the axle width handy, but will measure it next time I am working on the car.

I do completely understand the ackerman principle, I learned and applied it when building go-karts as a kid.  Thanks for bringing it up.  Tires appear to have some wear from excessive toe (saw-toothed towards center of car).

Steering is with a bellcrank at the front.  The tie rod is one piece connecting both steering arms.  A second link connects the right steering arm to the bellcrank.  I have already learned how sensitive the steering linkage kinematics are to the various link lengths.  You are certainly right about that Rooman!  We used 1/2" EMT electrical conduit sections with 3/8"NF nuts tacked inside to determine what the lengths needed to be in order for it to steer properly.  Even pitman arm position is a factor - balancing frame clearance, header clearance (early hemi), steering angles, etc... its quite a balancing act.  Then I made the tie rods to the correct lengths.

Thank you guys for the replies. :)

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