caster angle question

CSArno

CSArno

Senior Member
I understand how to check caster with the vehicle level. My question is: should the vehicle be level sitting on the ground or is on a lift with no weight on the tires ok? And what should the caster angle be on a '49 F1?

Thanks,
Chris
 
Sitting at operating height and weight on the floor. I prefer more caster. I do not have the stock spec but it is probably about 1 degree positive. Not enough in my opinion.
 
I wouldn't say 1 degree is enough, I'm using 10 in my dragster but that don't count on a street car. I've got quite allot on my Model A. I remember my father bought a Int one ton new, if you hit a little bump you couldn't hang onto the wheel, had to put shims under the springs to tip the axel back, after that no problem. Walt
 
On a straight axle with kingpins how do you adjust caster?
Shims/wedges between the leaf spring and the frame?

And I imagine to adjust camber you would have to heat & bend the ends of the axle?
 
Scott H in Wheaton said:
On a straight axle with kingpins how do you adjust caster?
Shims/wedges between the leaf spring and the frame?

And I imagine to adjust camber you would have to heat & bend the ends of the axle?
Click to expand...

On an F1 style front (parallel spring) caster is adjusted with angled shims tween Axle and springs. On a transverse spring, it's lowering the wishbone mounting ball or pie cutting or bending the Front of the wishbone.
Camber is an axle bend job on both types.
I like 5-7 degrees caster low end for heavier stuff, high end for roosters, 10 for a rail job like Walt's dragster.
Martin.
 
I'm not following the 1 degree suggestions, stock spec was 2 1/2 to 4 1/2, correct? And most people like more castor so at least 4 degrees. The 1 degree sounds more like a camber number (1/4 to 1 degree).

To answer the original question, to check the alignment the car/truck needs to be on a level surface with the normal weight on the wheels.
 
On closer inspection with the truck on the lift, I have a little King pin play on both sides, front spring bushings tight, rear spring bushings are loose. With a loose steering box, this is all playing a part in my death wobble no doubt.
 
These are the specs
 

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After you deal with the kingpins and bushings which will make a big difference I would recommend you consider adjusting the castor to 6 degrees of positive castor. I increased the castor on the tonner to 6 degrees by using wedges made for off road vehicle use which made the steering more responsive and less prone to drift.
 
I had a "death wobble" with my 39 cs I wasn't able to fine anything causing the problem.I installed a Jeep stealing stabilizer,problem solved.Let the naysaying begin! Lol Phil
 
expavr said:
After you deal with the kingpins and bushings which will make a big difference I would recommend you consider adjusting the castor to 6 degrees of positive castor. I increased the castor on the tonner to 6 degrees by using wedges made for off road vehicle use which made the steering more responsive and less prone to drift.
Click to expand...

The added caster may be useful on your bigger truck (with bias plies?), but on a lighter truck you risk making it "dart" on even a slight change in the wheel.

If you use wedges, be sure to use steel, the aluminum ones are known for cracking at the center holes.
 
Ross F-1 said:
The added caster may be useful on your bigger truck (with bias plies?), but on a lighter truck you risk making it "dart" on even a slight change in the wheel.

If you use wedges, be sure to use steel, the aluminum ones are known for cracking at the center holes.
Click to expand...

I replaced the bias ply tires with radials which added about 2" more width of tire contact area with the road. That in combination with the additional castor improved the truck's steering and tracking substantially. You're right about being careful to add too much castor. When I was experimenting with the shims I used 7 degrees and found the steering to be way too sensitive at speeds over 50 MPH. I chose to use 6 degrees as a compromise, since most of my driving is less than 50 MPH. I would recommend that anyone thinking about adding castor use a similar trial and error method to set the castor that's comfortable for their driving needs. Also before adjusting the castor I discovered that there was about a 1/2 degree difference in the angle of the spring perches in relation to the kingpins side to side on the axle. This is another thing to consider when changing the castor.
 
With the F-1 and parallel springs there is a wedge between the spring and axle. Just be sure it goes in the right way. I wonder how I know that.
 
I built my A-V8 with a dropped axle in mind. To do this, I set up for 5 degrees caster by cutting the wishbone. As it turned out, I liked the ride height of the stock 33-36 axle I used. Abandening the dropped axle, I was left with 10-11 degrees of caster. I like the way the car handles. I also added a VW Superbeetle steering damper.

Karl
 
I think its caused by two factors working together like loose joints or box and a loose wheel or out of balance wheel it ,doesn't take much ,a shim washer on the nut can do it
trainguy said:
I had a "death wobble" with my 39 cs I wasn't able to fine anything causing the problem.I installed a Jeep stealing stabilizer,problem solved.Let the naysaying begin! Lol Phil
Click to expand...
 
I pulled out the steering box today. Man that steering wheel was a big B to take off. Used the bearing splitter around the hub method. Came off with a big pop. Probably would have taken me right in the chin if I wasn't ready for it. Going to do the steering box, King pins, and spring pins/bushings. They are all loose and I would feel safer if they were replaced. Plus it's fun!
 
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