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Technical Split-beam Front Axle - Am I nuts?

Discussion in 'The Hokey Ass Message Board' started by Boryca, Apr 12, 2019.

  1. gimpyshotrods
    Joined: May 20, 2009
    Posts: 15,895

    gimpyshotrods
    Member

    A while ago, I drew up plans to cut a 4" dropped Ford I-Beam axle and add offset tubes, that went all the way to the other side of the frame. Using the longest available 'bones, the camber change would be minimal, over the short suspension travel.

    With a transverse leaf, there would be no outward sign that it is installed.

    I might do it, on my mid-engine Model A.
     
  2. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,141

    57JoeFoMoPar
    Member

    My FIL and I campaign an 89 Ford Ranger in the 24 Hours of Lemons series, which has twin-I beams in the front. It steers like shit, but it was his idea. That being said, it steers better than a solid axle in my opinion.
     
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  3. Stueeee
    Joined: Oct 21, 2015
    Posts: 165

    Stueeee
    Member
    from Kent, UK

    Quite a lot of 30s-50s modified cars and "Specials" in the UK had Ballamy IFS usually using the small Ford E93A or Brit built Ford V8 beam. I have an OT 30s car with a pre war Ballamy IFS installed. The key to making them work really well is to have the pivot point as low as possible - the space between the two pivots is the roll centre of the front suspension -also having the lowest possible pivot point gives the least camber change as against suspension movement. The photo of the Lotus 11 in post 28 shows the pivot is right at the bottom of the chassis, the Lotus 6 had a similar setup. Mallock Clubman racing cars used one of these swing axle setups on their clubman sports racing cars some way into the 60s -they regularly beat other cars that had wishbone front suspension, so swing axles can be made to work. But an extremely low pivot point would certainly be an issue for a road car in terms of ground clearance.
     
    Last edited: Apr 15, 2019
    Ned Ludd and metalshapes like this.
  4. Rootie Kazoootie
    Joined: Nov 27, 2006
    Posts: 7,558

    Rootie Kazoootie
    Member
    from Colorado

    The John Timmanus sports racer was quite successful in the 50s early 60s road racing. It was originally a Lotus 11 which James Dean had ordered but was killed before he could take delivery of. Not sure how he overcame the camber issues of the twin I beam but in this shot it appears he had it figured out.
    10x-18-c.JPG
     
  5. Boryca
    Joined: Jul 18, 2011
    Posts: 541

    Boryca
    ALLIANCE MEMBER
    from Detroit

    Appreciate all the input, positive and otherwise.

    @Stueeee - interesting point about the roll center location; something to consider...
    @Rusty O'Toole - Thanks for the torsion bar points! Might revisit that as a front-runner. I do like how much it cleans up the front end if done right, which is important. I'll be running fenders, but that doesn't mean I want to have to hide a mess up under there!
     
  6. lostone
    Joined: Oct 13, 2013
    Posts: 731

    lostone
    Member
    from kansas


    Heavy sway bar, the trick is to keep the suspension as level as possible going thru turns. Limit the suspension travel and you can get away with certain things.

    That's why it's a working possibility on a race car, not much suspension travel and low mileage use of tires.
     
    Andy, 31Vicky with a hemi and Boryca like this.
  7. Hair pins and a solid axle is a pretty good heavy sway bar
     
    seb fontana likes this.
  8. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,925

    Rusty O'Toole
    Member

    I would forget about the twin I beam or split I beam axle. Too much complexity for no benefit.
    First choice, IFS. If you don't like that choice, use a straight axle. If you want it to have the best ride and handling use some kind of 4 link to control it, and coil or torsion bar springs. Second choice, parallel leafs. Third choice, transverse leaf spring.
     
  9. That’s pretty sage advice right there

    Once the argument of ride height vs ride quality is settled ,,,
    once you have settled on the amount of suspension travel needed or tolerance of it,,,
    Once you’ve decided that the design mantra of form follows function is good or BS

    Then pic your poison
     
  10. Split axle on Hollywood Hot Rods Mulholland speedster.
    545px-Bruce-wanta-1936-packard7.jpg
     
  11. metalshapes
    Joined: Nov 18, 2002
    Posts: 10,733

    metalshapes
    Tech Editor

    Whenever this comes up, a couple of things get mixed up and confused with eachother.

    Bumpsteer.
    Swingarm suspension has nothing to do with bumpsteer.
    My Mallock U2 has no bumpsteer, and my '03 Superduty has it under control enough that the rear tires wear a lot quicker than the fronts.

    Camber control.
    Depending on springrates, a long swingarm on a racecar can be really effective.
    Arthur Mallock and Max Mosely both drove Formula2 Mallock U2 Mk6's , in the mid to late '60s, and they did very well.
    Even in combined F2 & F1 races.
    ( and no, your modern streetrod is not going to outcorner a mid '60s formula racecar )
    And BTW, A arm suspensions are still calculated in swingarm lengths.

    Not trad.
    Yes it is.
    Bellamy has already been mentioned before.


    In other words...

    Just because it has been done wrong many times in the past, isn't proof it cant work if its done right.
     
  12. metalshapes
    Joined: Nov 18, 2002
    Posts: 10,733

    metalshapes
    Tech Editor

    Action pic of my U2 Mk6 on the limit.

    Camber angles are pretty close to ideal, on all 4 corners...

    13374020115_38f44c2f4e_b.jpg
     
    Last edited: Apr 15, 2019
    gimpyshotrods likes this.
  13. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,316

    greybeard360
    Member

    Everyone keeps talking about the camber change on twin I beam... It isn't any more dramatic than on unequal length control arms.
     
    s55mercury66 likes this.
  14. s55mercury66
    Joined: Jul 6, 2009
    Posts: 3,258

    s55mercury66
    Member
    from SW Wyoming

    Nor is the caster change on loaded vs empty, and unless you put the load clear in the rear, the ride height change in the front is not as drastic as some would like to believe.
     
  15. Rootie Kazoootie
    Joined: Nov 27, 2006
    Posts: 7,558

    Rootie Kazoootie
    Member
    from Colorado

    There are those who may argue that point, but it can be delt with.

    8-10-lo.JPG
     
  16. metalshapes
    Joined: Nov 18, 2002
    Posts: 10,733

    metalshapes
    Tech Editor

    That is a famous and very successful Mk6 Lotus.

    The positive camber is because the swingarms were too short, and the pivot points too high.
    Which gave a roll center that was too high, and that gave the jacking effect.

    Exactly like Bellamy patented it, and later massively improved on by people like Arthur Mallock .

    Even Chapman's own Eleven was a lot better than that, with lower pivot points, but still not as good as it could have been with longer swingams.

    Again, just because there are some early versions out there that could have been improved upon, doesn't mean the system itself doesn't work.

    If that kind of thinking was valid, double A arm front suspensions would never have been tried again after the Lister Jaguars...
     
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  17. lostone
    Joined: Oct 13, 2013
    Posts: 731

    lostone
    Member
    from kansas

    It's not the caster change it's the camber change, and indeed the camber change is more dramatic on twin ibeams vs. Control arms.

    Take two exact vehicles, 1 with twins, 1 with standard control arms in a average street driven vehicle, now take camber reading with both vehicles, now load the front 1" . The ibeam will have a greater camber variance not only from static height but also side to side.

    And that 1" inch load change ? It's easily achieved just by the weight of and number of passengers in the front seats.

    Again run twin beams but stiffen springs rates, heavier shocks, bigger sway bars and you help alleviate problems with STREET DRIVEN ibeam design. But at the cost of ride.

    People keep mentioning race cars and that's fine but who wants to drive a stiff suspension car thru the average city streets ? I sure don't.
     
  18. metalshapes
    Joined: Nov 18, 2002
    Posts: 10,733

    metalshapes
    Tech Editor

    The racecars absolutely belong in this discussion to illustrate that in competition, where all out cornering performance is vital, a well designed swing arm setup can hold its own.

    As far as springrates and street driven cars, my '03 250 Superduty has a softer ride than my '28 Roadster with its I-beam...
     
  19. David Chandler
    Joined: Jan 27, 2007
    Posts: 1,055

    David Chandler
    Member

    The picture of the split I beam, with quarter eliptic springs looks better than Ford's ugly coils, on their trucks. Torsion bars probably could make it even more appealing, in the looks department.
    I have own 2 twin I beam trucks, and never had tire wear issues on the front. And handling was more than acceptable. I drove them empty and overloaded too. So yes, weight at the time of alignment is a factor, but some middle ground must have been settled upon, otherwise, all of them would be out of alignment, almost all of the time. And with no real issues with tire wear, they must have picked the right number, when it was set up.
    I have seen a Willy's front end in the junkyard. It looked interesting to say the least. I do have to wonder about the spring twisting from front to back though. If something had slop in it, I think it would become a problem.
    But if you are going to use a V12, then perhaps you should consider an I beam with springs on both sides. I recall International advertising it was used to spread the load over more points of suspension, on the frame.
    Good luck!
     
  20. gnichols
    Joined: Mar 6, 2008
    Posts: 10,403

    gnichols
    Member
    from Tampa, FL

    Dominator Street Rods has a similar front clip available. Gary
     
  21. BigChief
    Joined: Jan 14, 2003
    Posts: 2,036

    BigChief
    Member

    Do a search for Lee Osborne and Steve "The Greek" Panarites....they do a ton of the torsion bar suspension chassis with great success.

    Sent from my SM-G950U using The H.A.M.B. mobile app
     
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  22. gnichols
    Joined: Mar 6, 2008
    Posts: 10,403

    gnichols
    Member
    from Tampa, FL

    We are getting off topic... but I just got a frame from Steve. Only TB in the front. Back is still TBD. Gary
    DSC01561aW2400.jpg
     
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  23. This is the car I was referring to on page one.

    SR cover 1978b.jpg SR cover 1978 2b.jpg
     
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  24. metalshapes
    Joined: Nov 18, 2002
    Posts: 10,733

    metalshapes
    Tech Editor

    So to get back to your original question...

    No, I don't think you are nuts.

    A Swingarm IFS has lots of potential.

    It has its drawbacks and strengths, but it can be made to preform very well if designed and dialed in right.
    Even compared to systems that, at first glance, look to be superior.
    Same could be said about something like a McPherson Strut, and those are everywhere.
    (but for some reason, not nearly as many old wifes' tales are told about those...)

    It would take some determination, because it looks like there are no off the shelf setups that are suitable, but the right guy with the right skills can do it.
     
    31Vicky with a hemi likes this.
  25. chrisp
    Joined: Jan 27, 2007
    Posts: 720

    chrisp
    Member

    When I say the McPherson is a OK design with it's limits that are reached quickly even mechanics look at me funny, usually their answer is : why do you think they're everywhere?
    Me : because they're cheap with ok results.
    Then they argue.
     
    metalshapes likes this.

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