Finally got my low mileage, Model B on the road, no play in steering box, but car wanders badly. Tyres at 40psi,sagging front springs need re setting , will do this next winter, noticed that wedges have been fitted to alter the caster angle. Now I have 2 books on leaf spring suspension, both contradict each other, my wedges are thickest end to the front, book says thickest should be to the rear, So which way should they be, toe in is being checked also. hope someone can help. Also fuel gauge reads 10,when empty assume its a stuck sender, Phil.
The last thing you need is more confusion.. That’s what I get for working from my sieve like memory. Lets try this again.
As you mentioned the sagging springs aren’t helping you any but, other than that I would guess the wandering is caused by something other than caster angle. Since the box is good, I would look at tires, especially their age, toe-in, and tie rod ends. Adding some positive caster ( top of the upright tilted back toward the car) most often helps a shimmy.
One of the functions of caster is to make the car straighten itself out as it comes out of a turn, so if the caster angle is too negative (top of upright away from the car) it could be causing some trouble. Most likely the reason for the contradiction in the books is the axle to spring location. If the spring mounts under the axle you would shim from the front side. Since 30s Pierces have the spring mounted on top of the axle you shim from the back side. You would use the wedges as normal. In fact you don’t need a wedge. Old style front end shims will work or you can make your own flat shims.
Another function of positive caster is it makes the car steer heavier. Some folks crank in negative caster (top of the upright away from the car) to make the old cars steer easier. This could be contributing to your problem. You might try removing these shims as it sounds like the car has negative caster added. Establish a base line and go from there.
I don’t think the attachment came through fro your article.
Caster is referred to in opposite terms of camber.
I would think the sending unit would be a good place to start with your gas gauge.
Borrowed an Optical tracking gauge today, car checked & found to be Zero degrees i.e wheels parallel, , only a 1/4 turn needed on tie bar to give 1/8 toe in, also reversed the wedges (1/8 thick to nothing) so that axle was cannted back slightly, re checked tracking twice after driving back & forward , still at 1/8, Road test , quite a different car, lovely self centreing steering, aimed at a few potholes at various speeds & no front end shimmy, Car Cured, many Thanks to Rick for his advice.
WOW you work fast. Glad it worked out.