Hamb’ers, is there a difference in the 28-31 Model A spindle vs 37-48 spindle where I marked in red on example photo. I know the hub areas change but just wanting to know on where your king pin goes to the I beam. Looking to get a front drop axle. Thanks.
The difference is that on ‘28-‘36 spindles the span between the yokes of the spindle is less. The thrust bearings are on top of the spindle with the forged thrust flange and mechanical brake cup on top of the king pin exerting force to the bearing. The later spindles have the thrust bearing between the bottom of the axle and the lower yoke of the spindle. Bottom line? You will be happier with the ‘37-‘48 spindles. You can adapt early Ford hydraulics to the A spindle with some minor machine work and an adapter kit, but you are still limited with steering arm options. There is no aftermarket support for steering arms on the early spindles and the same is true if you plan on disc brakes- no caliper brackets bolt to the Model A spindles.
Go with later (round) spindles. Though there is a difference between early '37 and later '42-'48. Early are round. Later are square. If you want juice brakes that are self energizing, use F100 Ford PU with the same drums. These require using different seals and bearings, and is an old trick. As to newer solutions I am not knowledgeable enough to give a heads up on that. Some of the other chaps on here can chime in with their own ideas and solutions. The one I mentioned, I have done. With early spindles you have to grind the the top of spindle flat, because of the F100 backing plate It works good unless you drive fast and stop hard, as there can be some brake fading.
This brings up something, what is the difference in the round back and square back spindles? other that the shape of the back. They fit the same brake backing plate right? king pin angle the same?
46: Here's the traditional answer to your question. http://www.clubhotrod.com/hot-rod-talk/38015-ford-spindle-differances.html Plus, there's a ton of great info here: https://www.google.com/search?q=rou...ome..69i57.14004j0j4&sourceid=chrome&ie=UTF-8
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