As much as I want to make other people rich off my Hobby, I would rather build my own stuff as long as I am capable. Anyone built their own tube axle of Model A variety? I am in the process of gathering the dimensions I need, then I plan to build it out of 1.75" x .125" Chromoly. Mine will have a four bar attached, so I will fab my own brackets and four bar setup as well. I have access to an End Mill and a Lathe for whatever parts I need machined. We have a water jet company locally for the bracketry. Anyone out there doing this or should I "leave this up to the pro's?". Post up your thoughts and we will make this happen.
Not a real problem, we build them here at the school all the time. The larger you go on tube diameter, the stronger the axle will be. If you are planning to put some drop (bends) in it, you will have a few more complications. I would recommend having the bends done by someone who understands what needs to happen with the bend spacing (if you understand, more power to ya!). Keep any bends in a flat plane, and be very careful that the kingpin caster is the same on bosth sides. No idea what your skills are...just keep in mind that your batwing welds are the only thing keeping the axle under the car, so that is no place to learn.
Batwings will be double shear, TIG welded to the axle tube. Tube ends will also be TIG welded. This will be a straight axle, with no bends. Going with a four bar and coilovers. Did you use 4130 Chromoly or mild steel?
The easy way to get the the kingpins and alignment right is to use a true ford axle as a jig to weld the bosses on the new axle. I don't think you'll have any problems with it so long as you are a good welder. If you were as curious as I was, I did some calculations and a 1.75 OD .125 wall 4130 tube axle is about the same stiffness as a ford I beam.
We've done both... we use.188 wall DOM if it's going to be mild steel. Are you using the forged kingpin ends, or notching the tube for the kingpin bosses? If you are notching them in, go deep enough so you can wrap the end of the tube around the boss, and watch the weld heat. I've seen them snap off behind the weld from too much cookin'... For aligning them, I use a piece of tube the same OD as the boss in the first notch, and level that to the mill cutter. Make sure you figure the desired camber into the notch angle.
I built this one for my street-legal '60's sprint car. Piece of cake ! 2" O.D. X .250" wall DOM....bent with a Harbor Freight type pipe bender using a "feed along" method.
That looks cool Johnny. I can just never convince myself they don't need to be wrapped. Especially on my supermod axles!
My plan is to notch the tube for kingpin bosses. I do like the idea of wrapping the boss for strength. We will rough cut the ream in the kingpin boss, then do final reaming after the boss is welded in place.
Good idea. Reaming last is absolutely the way to do it. You still want to get all the angles right in the notching process. The kingpin hole has to be square to the end of the boss, or the thrust bushing isn't gonna last long...
I built mine for the dragster. Used 250 wall 2 inch mild steel. made the kin pin bosses on my lathe. Welded it with arc for good penetration. made an a lignment tol for builting as I went. Works good. Don
So, if I wanted to have the axle look like a "Stock" Model A where the front and rear were at the same level with no drop in the front all. I would just need a straight tube with round tube welded on the ends for the spindles with no caster or camber adjustment?
I do Xmoly with a heavy wall - like 1 1/2 X .250ish kind of thing. The fixture is what i weld them up in, they locate the spindle true to the ground. There is a spindle holder at each end that the spindle bolts into, the fixture with spindle clamp onto a box tube and you align your kingpin boss to the axle on each side so it can't move. What you see before you start welding is what the finished product will be when done. I also use that fixture for axle alignment into the chassis as you can fix it up for different wheel heights and work at true ride height.
I'm sure glad this thread came up, as I want to have a "smiley" curved tube axle on my next build like a vintage oval racer. I'd also like to run contemporary sprint car spindles, brakes and probably wide fives. Ifn anyone has some ideas or does custom builds along these lines, please PM me. Thanx, Gary
You realize that the kingpins are not vertical, right? They have an angle (KPI) built in that projects an imaginary line thru the center of the contact patch where the tire meets the road. Camber is the additional angle that may be used to tip the tires themselves from vertical when viewed from the front. Caster is the tipping of the axle assembly that allows the KPI to project the line ahead of the tire center slightly and aid the tracking of the car and help with the "self-centering" of the steering. Basicly like the casters on a shopping cart... You try to set the caster and camber during the axle construction but it can be adjusted later by bending the axle for camber or adjusting the hairpin rod ends or by dropping the attachment point at the frame for the caster. WCS...with a pair of split bones you could have to piecut at the forged end to set the caster but with good planning and the right bones that shouldn't be the case.
Use 2" DOM You are not building a go cart I use .250 wall for the street .188 and .156 for the track This is one of my ends it just slides in the end of the tube and you set your angle
This is a 4 bar set up for a dirt car 2.25 moly .125 wall I would never go that thin of a wall for the street. Most of race axles that we do are 2.125 DOM .188 and .156 wall
I got one hanging on the wall that my old man built back in the '60s. It is a '37-41 type dropped. He built several and this one someone up in canada had. I built a couple of sraight axles back in the '70s from mild steel, thought I could make some cash from it. Never made it fly but a few of my buddies had straight axles for their rides. So it weqsn't a total loss. Hot rod magazine ran an an article back in the later '60s I believe showing how to buld your own fixture to build your own dropped tube axles. Maybe it was popular hot rodding and not hot rod.
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