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...................................................--- Front Spindles ---
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I decided to work on the front spindles to improve the scrub radius. To determine the scrub radius you project a line down through the kingpins to the ground. This point could be under the front of the tire or in front of the tire depending on the castor angle. Ideally this point should be in the center of the tire patch or projected tire patch. When the tire turns this is the point the tire will want to pivot on. Now we are going straight at B'ville, but I've talked to people where the scrub radius point was way inside the tire patch and they had problems at higher speeds. Factors that will effect it are tire diameter (the taller the tire the further it moves out from the car); castor (more castor will also move it out from the car; wheel backspacing (more backspacing moves it out from the car); kingpin inclination (you can't change this unless you can make your own spindles), but you can look for different axles/spindles with different kingpin inclinations; and how far in or out the hub is on the spindle, which is what I'll address on this page.
I put my back wheels/tires on my front spindles and placed the tires perpendicular to the ground and then rotated the spindle to different castor angles. With castor angles of 20 to 30 degrees I found the scrub radius to be about the inside edge of the tire patch, which was about 3 inches in towards the car from ideal. Ideal being if it was located in the center of the tire patch. I then ordered wheels for the front of the car with the maximum offset they could give me with the narrow 5 inch rim. This will move the scrub radius in the right direction away from the car another inch. After talking to Harv I also figured if I did some machine work on the front spindles I could move the wheel/tire/hub in about 1/2 inch towards the kingpin. So with the wheels and the machine work below I'll pick up about 1 1/2 inches and that will leave me about 1 1/2 inches from ideal. I think I'll be fine with that.
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I couldn't get my spindles in the lathe with the steering arms attached to them as they would hit the bed. I wasn't going to use them anyway, so I cut them off at this point with a cutoff wheel and reciprocating saw. The first picture shows them on and this picture shows them cut off.
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What I needed to do was cut part of the spindle at the back where it is a larger diameter down to the same diameter as the area in front so I can move the hub in towards the kingpin. Here you can see I am cutting that area down. I'm about half way there in the picture.
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The reason I'm cutting it down is to allow this bearing adapter to move in towards the kingpin. This bearing adapter allows you to use stock Mopar rotors/bearings and seals on the stock '37-46 Ford spindle. The inner bearing rides on the left side of this adapter and the inner seal rides on the larger diameter to the right. After this shot was taken I turned down the surface the seal rides on to the right to the point where the seal has very little friction on the surface. Probably won't make much difference, but at least I'll know I've done everything I can to make the car fast.
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Here you can see the spindle cut down and I also put a 45 degree taper on the back of the cut to allow the adapter, that is also cut at 45 degrees on the inside (see last picture), to slide almost all the way to the spindle back.
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Here is the spindle with the adapter pressed on.
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And the spindle with the cut-down Mopar rotor/hub mounted. This also meant
that the outer bearing had to move back on the spindle. If I would have cut the back much more then the outer bearing
would have started to run into the taper on the spindle. I only picked up 1/2 inch to help with the scrub radius
doing all of this, but it only took about 4 hours and I work cheap, at least for myself.
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