If you install an I-beam font axle with split wishbones how do you set the caster angle, and if you find that you want more or less caster how then do you change the caster?
Right or wrong, the way I do it is to separate the weld where the wishbone joins the yoke that attaches to the axle, shave either the top or the bottom of the wishbone to get more or less caster, then reweld.
All bones are not created equally,what type of car?which bones? This is how I did mine. When we built the frame for my Deuce pickup and installed the Model A cross member and set it at 5 degrees making it possible to do minor adjustment with the ball joint ends in the split bones and not bind...I ended up with 7 degrees after everything was said and done. HRP
Fortunately, caster seems to have an acceptable broad range and if you get somewhere in that range you will be ok. For example, some people say 4 degrees and some say more. I have had cars with 7-9 degrees and all went down the road just fine. My current 27 is at 9 and has been there for over 25 years. I shoot for 7-9. But, to answer your question...........you kinda sorta have to prop the front end up (using the tires you will be running), put an angle finder on the top of the kingpin (available at places like Home Depot for $10 ) and then move the back end of the bones up and down until you get the caster you want. Then, block the back end at that level and see what you are going to have to build in the way of brackets to put the rod end at that spot. The tricky part is that the car will want to settle down when all the things like the motor, fenders, etc are on, so you kind of have to guesstimate how much that will be. I generally figure they settle 2-3 inches, and that is my starting point. It is best to tack weld your brackets on so that if you find your caster ended up WAY off, you can remove the brackets and move the rod end up or down as needed. No real magic to doing it, and every car is different. Don
Don seems to have covered this pretty well. The one thing we run into quiet often is some folks build their car, then change their mind on the tire-wheel combination. A shorter front tire will result in less caster,or a taller rear tire will do the same. SPEEDY
Ok thanks gents. I'm planning a build in which I'm thinking about using the I-beam/wishbone setup but I've always been concerned about how to arrive at a good caster angle . Although not traditional, a four bar arrangement with swivels on the spring perch bolts would allow for caster adjustment after the fact with no binding of the shackles. Thanks for the information.
Hairpins give you that ability too. You simply turn the front clevises in and out to increase or decrease the amount of caster. With split bones you don't have such and easy time of it and have to build the caster in from the beginning. Don
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