Hot Rods Model A front end steering issues

I had to cut about 1/4 inch off each end of the second leaf to keep them from binding into each other at the eyes. not really following the drag link angle thing. The only thing im thinking i can do to it right now is to run a shorter pitman arm.

 

All of the suggestions here are constructive and useful regarding your spring, shackles, and lack of shocks. But it seems the biggest issue is that your drag link angle is very severe in that picture. That is causing most of your bump steer. A cross steer setup would take care of all that. Attaching a drag link to the driver's side will always suffer some bump steer as that is just the price you pay for that particular style of steering. But your setup is amplifying it even further. Each bump in the road is yanking at your pitman arm as your front wheel travels up and down. A shorter arm may do something for you, but that angle would still be harsh.

If it can be done, set it up with cross steer. You'll enjoy the car more if you are not constantly fighting it.

 

Here is a very basic explanation.

every time you suspension rebounds or compresses up and down the drag link gets pulled or pushed. This in turn will "steer the car a little bit. In order to combat that your drag link should be parallel with the wishbone. And hopefully pivot at as close to the arc the wishbone travels as possible.

I'm sure someone else can explain this better.

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I understand how bump steering happens, i am confused about that string method of determining the correct angle needed. Also if anyone has any info about running a cross steer box with a drag link setup with the arm up, please share. I read up on it some but i am not shure about what modifications will need to be made for that.

 

my thought is: IF the drag link and the radius rod are PARALLEL you will Still have "Bump steer,"

If you have a four bar front end arrangement, then have yer drag link parallel with the two bars holding the axle, (steering side).

 

Ok. Gotcha. I was a little confused on the string method as well.

Side steer will always have some bumpsteer. No matter what you do.

Maybe parallel isn't the best word..

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Great expanation.
But based on those pictures, how much do you think the front end of this could possibly be moving. It's got articulate to get bump steer.

I'm wondering if the spring even needed spreading to be mounted. I'm betting there's witness marks from the spring hitting the axle or perches. If the axle is being bothered and pushes by the spring there is no way it will track correctly.

 

The drag link does not need to be parallel to the radius rod but not at that angle.
As the axle moves up and down it travels in an arch, the drag link does too. These must be as close as possible at the static ride height so that any discrepancy in the arches are at there minimum. Having no front shocks will allow more travel up and down and amplify the situation you have. JW

 

I have to agree with 31Vic. Even with the poor drag link angle, you shouldn't be wandering all over smooth roads with it. It would help to change it, but I doubt if it will solve your problems. That spring has to be fixed before anything else...looks like an old worn-out stocker. Shocks are also a must.
Your scribe on the tire is great but there is still a bit of a method to measure toe-in at home. It is best to have the car with the front facing up a slight incline. Have a wheel chock ready and push the car up the incline and place the chock before the car can roll backwards. Then measure with a static device like in the pic below (doesn't have to be that fancy). With bias ply tires, 3/16" is usually best. You can't measure this with a tape measure.

Also, here a diagram from Pete & Jakes to help you understand that front steering geometry...it's just like yours.

 

Thanks guys. I'm going to start with the spring issue and shocks. I have parts for the shocks. Just havent got around to mocking them up yet. And may try a short pitman arm just to see if that helps. I'll only change one thing at a time so I can learn how each issue effects the handling.

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