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Technical Tube Axle and Spit Bones ?

Discussion in 'Traditional Hot Rods' started by tinhunter, Dec 14, 2013.

  1. tinhunter
    Joined: Jul 28, 2010
    Posts: 68

    tinhunter
    Member

    Wondering if the guys that have had experience with this set up could/would shed some light. have recently purchased a 40 pickup , been on the road for approx. 20 years so is a proven driver, my question pertains to the 4" dropped super bell ( i think) TUBE axle and split bones ( 35/36 i think). From what I have been able to figure out, most of this set up probably consists of speedway parts. I guess from everything I have read over the years says that using a tube axle with split bones is a no-no BUT,I have no first hand experience, like i said, truck has been on the road for 20 years and to my knowledge, without problems so Question is..: is this a safe set up or ?? I'm about to begin freshening the truck up and hate doing things over so a bit of direction would be appreciated...
     
  2. Here's the biggest argument in a nut shell explained so its easy to see.

    In your garage or thoughts
    Build a square out of 2x4s 36" x36". Now lift one corner and observe what happens.
    Build a triangle out of 2x4s 36x36x36. Now lift one corner and see what happens.
    That explains Henry's design vs split bones.

    Ok. Take a beam axle and twist it like the square. It gives.
    Take a tube axle and twist it like the square. It doesn't give.

    Radius rods are better because they give a little.

    That's the argument- make good choices.
     
  3. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    Split 'bones twist the axle when one front wheel hits a bump. Tube axles don't stand up to twisting very well, although lots of them have been set up that way.
     
  4. tinhunter
    Joined: Jul 28, 2010
    Posts: 68

    tinhunter
    Member

    Yep, Thanks, my thoughts also, just needing confirmation i guess, actually I'm just a cheap pr..k..trying to avoid doing what i know i should do..lol..appreciate the reponse..
     

  5. metal man
    Joined: Dec 4, 2005
    Posts: 2,949

    metal man
    Member

    That's right. With split bones you really want an I-beam axle because it needs to twist as the caster changes through suspension travel.

    Sure, you always get the "mine has been that way for X amount of miles with no problems" guys, but it's still wrong. Something is trying to bend all the time and that is a fact.

    A change to an I-beam axle will also improve the ride quality, because of the ability for the axle to twist. That alone is reason enough to change the axle.
     
  6. Or change to radius rods/ hairpins.
     
  7. metal man
    Joined: Dec 4, 2005
    Posts: 2,949

    metal man
    Member

    True, but the steel d.o.m. tubing that hairpins are made of isn't really something I want constantly bending on my car. I would rather have a genuine Ford forged axle doing the flexing,as it was very well designed to do.
     
  8. tinhunter
    Joined: Jul 28, 2010
    Posts: 68

    tinhunter
    Member

    Thanks Guys !!, will be doing dropped forged axle..
     
  9. tinhunter
    Joined: Jul 28, 2010
    Posts: 68

    tinhunter
    Member

    and using the split bones...
     
  10. They say the same thing about tube axles and hairpins. How much do you think the axle is going to twist with a buggy spring and 2 or 3 inches of travel? Frank Kurtis built over 500 midgets, and 40+ Indy roadsters, and champ dirt cars with tube axles and hairpins. The only time one of his cars suffered a broken axle was when a driver stuffed one into the wall. He built the tube axle and hairpins for my first RPU in 1960. They are still under the car 53 years later. My current RPU has been running a 4" bell tube axle and hairpins for 18 years without a problem.

    If you buy all the stuff about tube axles must use 4 bars, then I guess you think the world really is flat.
     
  11. tinhunter
    Joined: Jul 28, 2010
    Posts: 68

    tinhunter
    Member

    Thanks Dean, appreciate your perspective, t'was why i was asking as my 40 was a daily driver for the past 9-10 yrs with the tube and split bones, however being as I will be freshening it up, will be using a i-beam, Just not going to chance a major wreck for a couple of hundred bucks..
     
  12. metal man
    Joined: Dec 4, 2005
    Posts: 2,949

    metal man
    Member

    No one is saying it won't work, just that it is not ideal. Geometry doesn't lie. Race cars really don't count, they have different requirements than street cars and see a lot fewer miles.

    The fact is, the OP's vehicle will be better off with a forged I-beam, especially since he has split bones.
     
    Last edited: Dec 14, 2013
  13. metal man
    Joined: Dec 4, 2005
    Posts: 2,949

    metal man
    Member

    If you leave one front tire on the ground, and jack up the other one, an I-beam axle will twist enough to easily see it with the naked eye.Even with only two inches of travel. For me, it's as much about ride quality as anything else. You will notice the difference.
     
  14. thirtytwo
    Joined: Dec 19, 2003
    Posts: 2,640

    thirtytwo
    Member

    The part you guys are missing in the equation is most fat fender cars have the wish bones split where they are only 2" apart which means the axle pretty much articulates like an unsplit bone... Now if the bones were mounted on the frame rail outboard that is a different senerio
     
  15. metal man
    Joined: Dec 4, 2005
    Posts: 2,949

    metal man
    Member

    That is true.T.C.I kits and similar kits put them 3'' or4'' apart. I didn't think about that. Is that how yours is, Tinhunter?
     
  16. tinhunter
    Joined: Jul 28, 2010
    Posts: 68

    tinhunter
    Member

    yep, about 7" apart
     
  17. metal man
    Joined: Dec 4, 2005
    Posts: 2,949

    metal man
    Member

    thirtytwo is right, that makes it less of a big deal. I stand behind everything I said above, but that was all based on the ends of the wishbones being mounted out near or under the frame rails, typical of pre-35 Ford hot rods.
     
  18. tinhunter
    Joined: Jul 28, 2010
    Posts: 68

    tinhunter
    Member

    Sorry, Guess I could have clarified that, wasn't thinking of them being split to the frame rails..fact is, axle that is in it is wider than I like so will go with the I-beam anyways but the opinions and info are much appreciated..and if my pension check doesn't arrive, will feel ok using what is there now...lol
     
  19. ty johnson
    Joined: Mar 16, 2006
    Posts: 597

    ty johnson
    Member

    I know it's not right to do it, but i built a 31 sedan 7 yrs ago and sold it. Used a V8 60 axle with split bones. It's still being drove without issue. Not saying it's correct, but it hasn't cracked yet. That being said, wish i knew more about the v8 60 axle then, cause it'd be hanging on the wall. The I-beam axle is the way to go.
     
  20. Back in the early 80's I had a 39 Ford convertible and decided I wanted a dropped axle,I had the original axle under the car and I had split the wishbone to accommodate the transmission a few years earlier.

    I purchased a Superbell tube axle and installed it and drove the car for several years with no problems until...

    I was on a back road and I was following a truck and I didn't see the rather large hole in the asphalt and dropped the passenger front tire into it and the sudden hard thud sheared the spring perch bolt & nut even with the bottom of the axle. :eek:

    The tube axles do not have any flex,,that was the last time I used a tube axle and will only use forged axles today. HRP
     
  21. tinhunter
    Joined: Jul 28, 2010
    Posts: 68

    tinhunter
    Member

    Pretty much my conclusion as well, thanks.
     
  22. birdman1
    Joined: Dec 6, 2012
    Posts: 1,143

    birdman1
    Member

    I did not take time to rear all the responses to your queston, but I THINK the 60hp 37-40 fords used a tube axle? a tube can take twisting as good as a I beam, look at all the tubular torsion bars and anti-sway bars. I am just a dumb mechanic, but if it works, it works..It's all just iron.
     
  23. ty johnson
    Joined: Mar 16, 2006
    Posts: 597

    ty johnson
    Member

    A nice Henry Ford axle with a fellow HAMBER drop is the way to go.
     

  24. sorry, you need to rethink that.....a tube axle doesn't twist
     
  25. A tube axle functions fine when the bones are stock and still pivot off the ball where the bones are attached,,spread them apart and that's when the problems occur with a tube axle. HRP
     
  26. woodiewagon46
    Joined: Mar 14, 2013
    Posts: 1,816

    woodiewagon46
    Member
    from New York

    I have a Chassis Engineering Kit in the front end of my"46 "woodie". Split stock radius rods with a tube axle. When I questioned the fact they said because the radius rods were split so slightly there would be no problems. I have 40K on the car and it's fine.
     
  27. CAE had the answer they had a bird cage on one side and a solid mount on the other to stop the binding or twisting
     
  28. mj40's
    Joined: Dec 11, 2008
    Posts: 3,301

    mj40's
    Member

    First off, I know the 40 pickup tinhunter is talking about well, for I drove it the past 9 years before I sold it to Ken. I had the same concerns as he has and was going to change to I beam axle. Before I done anything I started on another 40 pickup and never got it done. The wish bones were sort of split but not moved outwards. Instead of using the chassis engineering kit the builder chose to mount them on the x member with heims and homemade brackets. The angle was the same as stock and was only shortened a few inches from stock. It handled and road great but yes the axle was a bit wide which is common in narrow sheet metal 40's. It had a Chevy disc brake conversion which didn't help by adding 3/4" to each end. I was running 5" rims with 195 tires to get it to clear the fenders. The only rubbing I had was in tight mountain curves and my wife ridding with me. Don't tell her I said that. :eek: I have over 250,000 miles on my 40 coupe with stock axle and I found the tube axle on the pickup to be a little noise driving through subdivisions. Not bad but I hate cracking and popping noises in anything. We have talked about this and both agree a dropped I beam would be the best choice. I'm not sure what the wishbones came off of but my plan was to come up with something a bit narrower. I even looked at the 4 bar set up Speedway sells for 40's. You don't see many 4 bar set ups on anything other than 28 to 34 stuff but why not?
    Tinhunter when are you going to change your avatar?

    [​IMG]
     
    Last edited: Dec 15, 2013
  29. I drove many miles with my 39 convertible with the same setup from CE but mine failed,,I'm sure hitting a deep pot hole contributed to the failure. HRP
     
  30. tinhunter
    Joined: Jul 28, 2010
    Posts: 68

    tinhunter
    Member

    Hey Mel, thanks for the input !! Yep, will change the avatar...just got to find my camera..didn't want to use one of your pics .. lol ok,ok, you shamed me into it...
     
    Last edited: Dec 15, 2013

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