Camber angle in ‘47 pickup?

[AnthonyG]

Hi all 1st let me correct the title, it should be Castor! I’ve been trying to improve front end alignment on my ‘47 pickup. Camber is good but due to an odd configuration from previous owner the Caster is negative & affects the steering at the extreme right or left position. This sounds weird but it looks like PO reversed the front axle & steering 180 degrees to fit a large engine w front oil sump. This has caused the Castor to be negative. I know the original Castor for it was positive. I made wedge shims & placed between the leaf springs & the axle & it’s improved the steering. I don’t want to go too far as I know it will affect tire wear. Does anyone know what the correct positive angle the castor on ‘47 S/B? If I know that I can approximate it on the shims?

[Bob C]

The Shop Manual show 4.5 to 8 degrees caster. The part number for the wedge
is 01-5336.

[Flathead Fever]

It sounds like you are saying they mounted the tie-rod in front of the axle. The problem with that is it also screws up the Ackerman Seering angle. One front wheel will be turning freely and the other one will be at a different turning radius making it difficult to turn. You will see this done on Bonneville land speed cars, like belly tanks where turning is not an issue but when you try and push that same car in a circle it's difficult because the front tires are fighting each other. The only time you see the tie-rod ahead of the axle on a factory vehicle is on 4-wheel drives where the tie-rod cannot go behind the differential because of the driveshaft. On those, the spindles' steering arms are further out to maintain the Ackerman steering angle, but the rims need to be large enough to not interfere with the spindle arms be way out past the balljoints. When you build a hot rod with a dropped front axle it requires you to bend the steering arms to clear the dropped axle. Plus you might be installing spindles front a different year vehicles. You will also need to bend the arms so they end of in the position in the illustration. I have a bracket I bolt to the top of the Early Ford rearend with a stud centered in the middle that I can tie a string to. Then I pull the spring tight over the center of the kingpin. Using a plumb bob hanging from the string I see how far off the center of the tie rod holes are. Then I remove the spindle and bolt it into a crude fixture I made, heat the arm and bend it the amount it needs and let it slowly cool. Never heat it any more than necessary to bend it. Doing this is a bad idea but when you are recreating 1940s hot rods with Early Ford spindles that's the way it was done.

Since that engine has the oil pump pickup in the front of the pan you might be able to find a pan with the pickup in the rear, this would give you room for the tie rod behind the axle again where it belongs. My neighbor was building a '40 Ford with a small block Ford. They have a front sump oil pan that interferes with the tie-rod. A 4X4 early bronco has a rear sump pan. Then he used a '41 pickup front crossmember which was deeper for the optional 6-cylinder engine. This allowed that SBF to move forward so the firewall did not need to be cut.

Wikipedia Ackerman info,

https://en.wikipedia.org/wiki/Ackerm...ering_geometry

You can see that if you flipped those steering arms around to the front the line between the tie-rod holes. kingpin and the center of the rearend would be way off.

[AnthonyG]

Thx FF. I’ll digest the Ackerman info. The PO looks like he had some professional work done eliminating all the old linkage that was originally behind the axle & had a Jeep CJ looking custom fab linkage built for in front of the axle. Prior to putting the 1/8”-0” shims under the springs moving the axle / spindle castor more positive improved it quite a bit. As the shim thing is fairly easy & inexpensive I think I’ll increase the shim thickness on the thicker side another 1/16” increasing the angle a bit more ti see if it improves more.
Thx.

[Flathead Fever]

Too much caster will make it a little hard to steer too little waill make it wander around. Its hard to visualize it on a vehicle but all caster does is put the centerline of the kingpin or ball joints a little ahead of the center of the wheel. The wheel is being pulled by the kingpin that is ahead. If you want to see caster in action watch the front wheels of a shopping cart. The mounting bolt is ahead of the wheel so wherever the bolt is pointing the wheel will turn to follow the bolt. That is a caster wheel. Pretty soon you will be in the grocery store diagnosing shopping cart front wheels that go into speed wobbles. If you lower the front of a vehicle or raise the rear, you have changed the caster. in the 1970s we used to put air shocks on the back of our Mustangs to raise them up in the back to clear big tires. As soon as put air in the shocks and raised the backs up high the cars wandered all over the road. That was because we had changed the caster by raising the rear.

[AnthonyG]

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FF That makes sense! Originally after getting the PU running a bump would start death wobble as ur description the shopping cart! Also turning steering wheel more than a few inches either way caused both tires to scrub. Must have been a combo of neg. Caster & Akerman issues. Both issues improved quite a bit w the increased pos. Caster. Here’s a pic what PO did but I had strengthened using solid steel instead of tubing & new joints.