Strait axle caster?

[Longknife]

Hello, I have a straight axle on an old Plymouth gasser. It steers very hard. I checked the caster and found that it has a ton of Positive caster. I made temporary shims to tilt the axle and have almost zero caster now and it steers great. Do I want pos or neg caster and what degree of caster am I looking for? Also where can I get axle shims. These Shims will need to be at least 3/8 thick and taper to 0... Thanks, LK

 

[69a100]

Also where can I get axle shims. These Shims will need to be at least 3/8 thick and taper to 0... Thanks, LK

Search engines are your friend, good luck!

 

[#41]

Positive caster makes it go straighter (good for race car), but harder to turn. Shims are usually sold by the degree. I'm not a gasser guy, but I'd start in the same range as any other car 2-6 degrees and go from there. Summit has loads of them.

 

[Daliant]

Got any pictures? There could be more going on than just caster angle.
If the caster is that far off you might want to cut the spring perches off and weld new ones on at the right angle, this is assuming it's a tube axle.

 

[Longknife]

It an original cast axle and I don't know enough about straight axles to ID the maker, There are no shims under the axle. The spring is mounted with the front higher causing the axle to tilt ang give excessive pos caster. The shackles are in front and longer shackles would probably help. The plate under the spring is actually made of hard plastic and it has no taper. When I got the car I could only steer it halfway through the turn cycle and it was very stiff. You could almost see with you naked eye that the axle had a lot of pos caster. When I jacked up the car I could turn very easily stop to stop. After I put in temporary 5/16 shims to get the caster closer to zero it was very easy to steer, and I did several circles turns in both directions in the parking lot. WOW, what a difference! Here is the axle with out shims.

 

[Longknife]

PS, I have just been experimenting with this, and guessing at this but s there any way to check caster angle without an alignment rack?

 

[#41]

You can buy a hub bubble and rotate the wheels to measure - see Youtube vids for info. This is easier with turn plates, but something like smooth plywood under the tires can also do the trick. Otherwise, the super low tech way is to set up a sturdy vertical level and measure to the approximate center of the upper and lower spindle center, the distance between, and then do some math. This is rough, but if you are careful, repeat your measurements several times, you can actually get reasonably close.

 

[1 Wild R/T]

On the back side of that spindle you have access to both ends of the spindle, yes it's the rough casting but if you throw an angle gauge spanning the top & bottom of the spindle it'll give you a reasonably close number for your caster....

 

[RemCharger]

You can use a decent garbage bag folded over a few times for turning plates.