Front Caster angle, with larger rear tires

OK I know that I'm dealing with a 50 year old vehicle. But like others my A100 wanders a bit much. I have adjusted the steering box, which helped. Looks like my TOE adjustment is not correct..Going to work on that.
From what I've found out , the Caster is to be 1-1.5* positive.  My rear tires are larger. So when I divide the total tire height difference by 2, I get that the rake of my truck is 2.225" higher back to front.
So when you figure that angle= out to 1.42*   So that would in turn make my actual caster about -.42* to + .08*
So have most or/ any of you had to put shims under the front axle to get the proper caster angle when you have larger rear tires?  Right now my front tires are 25.16/ rears are 29.61 DIA.
How much shim angle have you needed to set your caster angle ? Trying to do this myself. Will probably end up at a shop.
And yes, I do have to much time on my hands to figure this out.

So forget all that way over the top information of the last post. I just measured my Toe setting. Looks like I'm 3/16" Toe Out..not good!! I'm sure this has not helped with my wandering down the road.
So that will be the first thing that I work on. I'll try for 1/16"-18" Toe In.  
Have any of you needed to use shims between the front springs and axle, to correct the caster angle, when using larger rear tires?

I never ventured down that road. maybe give scottie a ring...

my van runs straight down the highway at 60 with my hands off the wheel. I have 255/60/15 in the rear and 185/60/15 up front. no wander at all. that toe situation needs addressed though.

[quote="diamond dave"]my van runs straight down the highway at 60 with my hands off the wheel. I have 255/60/15 in the rear and 185/60/15 up front. no wander at all. that toe situation needs addressed though.
Are you using any shims for the front axle ? by the way your rake angle is 1.05*, 1.655" higher in the back. I have an additional .57" rear raise (2.225"). Yeah the first thing I'm going to do is set that Toe In. I've only driven this thing about 300-400 miles. Getting better as you fix the thing that were neglected.

I didn't notice any shims up front, but I honestly didn't look fo any . it was like that when I bought it. I'm gonna get it out of storage today. Maybe I will check.

rustytoolss wrote:So forget all that way over the top information of the last post. I just measured my Toe setting. Looks like I'm 3/16" Toe Out..not good!! I'm sure this has not helped with my wandering down the road.
So that will be the first thing that I work on. I'll try for 1/16"-18" Toe In.  
Have any of you needed to use shims between the front springs and axle, to correct the caster angle, when using larger rear tires?

according to my FSM the toe setting needs to be one eighth

an axle is 0 caster,,,,,you need shims under the springs to make the front wheels tilt back like on motorcycle forks,,,,,,my Chevy is jacked up in back,,,,,,so I got 4 degree caster shims on it,,,,,(thats like 1 degree more than stock),,,Dodge is like 1 1/2-2 1/2,,,,,,offroad shops sell those caster shims,,,,,,, but unless you got or get a Caster gauge to check yours, stock shims probably will be OK,,,,I think the steering wheel not returning smoothly after making a turn, would be a caster problem,,,,,