Still working on the Sprint-T on a wreck-free Sunday

Yeah, the guy that has a bike safety blog that mostly blames cars is building a hot-rod. Let’s just say that “irony-poor blood” is not a big problem around Casa de El Poeta.

Anywho, I have been working on the adaptor design to run Wide 5 hubs on early Ford spindles so that I can use less expensive and easier to find commercial street rod or hot rod parts instead of custom fabricated axles to use what is essentially pure race spindles on the street. The Wide 5 hubs I’m using are rated for 5000 pound off-road racing trucks, so street use on a sub-1700 pound car is going to be extremely under-stressed. Ditto just about every suspension part on the car being under-stressed for street use at this weight, unlike the race spindles I mentioned earlier that are designed for a “heavy” pavement sprint car that comes in at about 1500 pounds because pavement sprinters use a lot more front brakes than dirt track sprinters that don’t even have a right front brake.

Getting back to that adaptor I have found a few things out by inference rather than by direct description. For instance I found out the inner bearing has a 2″ I.D. which means that the spindle adaptor has to be 2″ from the seal race out to the outer bearing which is 4.6″ from the outside of the seal race to the outside of the outer bearing. Somewhere along the line I need to gradually taper the adaptor from the 2″ inner bearing to the 1.813″ I.D. of the outer bearing, actually the 1 13/16” diameter of the spindle. The outer bearing is about .68″ wide, so the “landing area” for this bearing will extend from 4.6″ from the outside edge of the seal race (I know I’m using the wrong terms for these but I can’t find an article on the web describing the actual names of the various parts of the part of the spindle the hub runs on), to 3.85″ from the seal race and taper up to the 2″ diameter of the inner bearing over the next 3.1″ to 0.75″ from the bearing race, so there is a nice broad landing area for both bearings to slide in on. I also know the seal race is 2.375″ O.D. and at least 0.437″ wide, and that the entire adaptor is 5.687″ from the seal race (described as the “inner bearing shoulder” in this particular diagram) to the end of the piece, which will end up being 7.125″ long over all from where it bottoms against the Ford spindle to the end of the piece.

That’s the outside, the inside is much more fun from the designer’s (me!) standpoint. First of all the two main design parameters were to not introduce failure-inducing stress points into the design, and to have as little flex as possible. Fortunately the seal race on a Ford spindle is 1.5″ O.D. (edit: 15/8“) while the landing area for the inner bearing is 2″, meaning there will be a 0.250+/-” (edit: 0.1875″) wall thickness under the bearing if the I.D. cut is made straight across from the seal race to the end of the inner bearing landing area. This is acceptable if I use a high-strength aluminum alloy. Then the bearing shoulder on the Ford spindle for the outer bearing is 3″ from the bearing shoulder for the inner bearing, and 3.5″ from the face on the Ford spindle where the adaptor will be bottomed out. This will be the inside face of the bulkhead that runs from the Ford spindle outer bearing landing area to the landing area for the Wide 5 outer bearing, with generous radii where the bulkhead meets the I.D. of the adaptor after subtracting the 0.250″ (edit: 0.1875″) wall thickness from the bearing I.D.’s.

So basically there will be a Wide 5 spindle from aluminum on the outside, with a bulkhead the same I.D. as an early Ford outer bearing then and I.D. the same as an early Ford grease seal. The adaptor will have a shoulder on the bulkhead slightly larger than the O.D. of the washer of the early Ford spindle nut before going out to the end of the threaded area and the beginning of the Wide 5 outer bearing landing area on the adaptor. There should only be a tiny bit of added flex over machining the adaptor to rest against the Ford spindle solidly full length, but the adaptor will be much lighter and considerably easier to install than fitting against the spindle as a solid piece.

And it’s time for me to get ready for evening services now.

PSA, Opus


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