Sway bar

Discussion in 'Hacks' started by Andrew2, Sep 24, 2008.

  1. Scott Davis

    Scott Davis Which way did they go?

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    Ok, but cold bending to get the right angles would be very hard to do. So how is it done? I agree with you on the heating and quenching. I use to be a gun smith so I know a little about this on a small scale.

    Ideas?

    Scott
    #21
  2. Bandit Bill

    Bandit Bill Newfie Rocketeer

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    n/m .. question was specific to ural
    #22
  3. chairhead

    chairhead HAIRY

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    Scott,the Anti Roll Bar/swaybar Is Sprung Steel,
    Yes Its Hard To Form But It Can Be Done Without Heating It Up,
    All You Need Is A Strong Length Of Tube To Fit Over The Sprung Steel, A Good Vice And Some Elbow Grease,
    If It Were Me I Would Make A Template First Using Small Diameter Bar/tube,at Least Then You Have A Pattern To Work To Rather Than Doing It Blind
    #23
  4. Scott Davis

    Scott Davis Which way did they go?

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    Good idea with the small pipe template. I think I will look for a swaybar off a small car and see if I can modify it to fit the bike. I am very interested in how much it help the bike corner. We live close to the NC Mountains and ride there often. I would like to be able to keep up a bit better with my riding buddies while in the twisties.

    Thanks!

    Scott
    #24
  5. claude

    claude Sidecar Jockey

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    Copied this , written by Bill Ballou, from Roger Symington's site.

    http://hometown.aol.com/sidebike99/

    SWAY BAR
    By Bill Ballou

    It's easier to discuss how a sway bar works on a car and then talk about the special considerations when installing a sway bar on a sidecar.


    In the basic form, a sway bar is a rod that runs from one side of a car to the other with equal length arms roughly 90 degrees to the rod on the ends. Typically the sway bar is mounted in isolastic bushings mounted near the ends of the bar. With the bushings mounted to the chassis/body of the car. the equal length arms that are roughly perpendicular to the bar, are then attached to the suspension. The best thing to do is to look under a car to get a closer look how it's done.


    A sway bar is a torsion spring. If for example you were driving down the road in your car and one wheel were to hit a large bump, that wheel would travel upward against the suspension. In addition, the torsional stiffness of the sway bar will be added to the shock/spring combination to resist compressing the suspension. Since the other wheel didn't hit the bump, the end attached to that side is essentially fixed. So the wheel that hit the bump is twisting the sway bar and trying to compress the suspension on the opposite side. If both rear wheels or front wheels hit a bump at the same time or a dip in the road, the sway bar does nothing. Since both ends are of the bar are moving the same amount, the bar just rotates in the chassis mounts. In another example, when you go around a curve or corner quickly, the outside suspension begin to compress as centrifugal force the transfers of weight to the outside wheel. The sway bar react the same way in this case as well and reduces the amount of body roll as it tries to keep the vehicle flat. If there wasn't a sway bar on the vehicle, the suspension would need to be much stifler to resist the more extreme demands on the suspension. The beauty of a sway bar is that it only works when it's needed. Suspension can be more compliant, resulting in a smoother ride when you have a sway bar. It also does a better job of reducing body roll better than simply cranking up the suspension. A sway bar helps to control the darting and diving that can happen as a result of normal road deviations, high winds or the wind from passing a truck, swerving to miss something in the road. The effectiveness of a sway bar is a result of several things but for the most part, the larger in diameter the sway bar is the stifler it will be and the stifler the suspension will be when it comes into play. Sway bars certainly contribute to a safe handling vehicle. I doubt there are any cars made today that don't have some sort of sway bar. Without sway bars, cars, truck, and vans would be tipping over regularly,




    Unfortunately sway bars have been overlooked on sidecars. What is typically done on a sidecar, myself included during my early sidecaring, is to stiffen the suspension to resist the tendency for the outfit dive in the turns. It's really not the solution. I have sway bars on both my GL1200 and FJ rigs. They dramatically improve the handling of both rigs. I wouldn't put together another rig for myself without one.


    A sway bar installation on a sidecar will likely be a compromise from an ideal sway bar setup but can still work very well. Because of sidecar wheel lead, the sway bar will often be on an angle and the arms will probably not be 90 degrees to the bar. On cars they use some sort of rubber or urethane busing for the bar to pivot in. The're used to help isolate road noise from the inside of the vehicles. In a sidecar that's not really an issue so it's better to use bronze or delrin type bushings. the bar will work immediately since it doesn't have to take up the slack in the rubber bushings before it begins to work. I've used both urethane and bronze and I believe I can perceive the difference between a solid bushing and a flexible one. You will also need to have some sort of flexible connection where the arm attaches to the suspension. There are standard automotive sway bar links that can be adapted. Rod ends can also be used.


    On the FJ I used the same material that is used in some cars, 4130. I used 4130 because it can be welded to without cracking at the welds. It's possible to bend the bar on the ends to get the arms but it was easier for me to get exactly what I wanted by welding arms onto the end of the sway bar. After I built the sway bar, I had it heat treated to 65 Rockwell C and tempered to 45 RC. The effectiveness of the sway bar is determined by a lot of things and it would be nearly impossible to calculate the exact specs for a bar. I think it's done with a combination of science and prior experience. My best guess is that you would need a bar 3/4" in diameter and the arms would probably wind up being between 10 and 16" long. In some cases it's possible to run the sway bar straight across.

    Anyone with a sidecar can perform an interesting test. While your rig is sitting still, push down on the rear of the bike and then push down on just the sidecar suspension. Basically what happens is that the rig just pivots around the opposite wheel without any compression of the opposite suspension. When you do that with a rig with a sway bar, you see the opposite suspension begin to compress as it tries keep the vehicle flat. In practice, it makes a significant improvement in the way a sidecar handles.

    Bill
    #25
  6. Bandit Bill

    Bandit Bill Newfie Rocketeer

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    Claude is the expert in all things swaybar related, and Bill Ballou is something of a pioneer in the use of them also - at least on this side of the pond. When i had my swaybar welded up, I took Bill's exact instructions printed out for the welder to read first - so he could get his head around exactly what i had been fabricating and what he needed to do to make it safe.

    I've built exactly one swaybar setup, so i'm strictly at amateur hour here, and the welder still thinks i'm nuts ... but here's my opinion.

    Forget about adapting from an automotive design - once you are finished bending this and cutting that, you are likely going to end up with a weakened compromise. You can't think of a swaybar as a slapped on add-on for the rig - it has to be put together as an integral part of the rig - designed into it, if you will.

    As said - I'm no expert - but i learned a lot about suspension rates, swingarm travel in ratio to suspension load, and the principles of leverage on differing swaybar end lengths over a winter, to make me appreciate that this is one area of sidecar setup that shouldn't just be slapped together.

    Follow Bill's general 'recipe' as posted by Claude - i did.
    #26
  7. claude

    claude Sidecar Jockey

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    Bill,
    I really don't think there are any 'experts' in the use of swaybars on sidecar rigs. We have tried various things over the years and all of them worked okat with some being better than others. Our typicall approach is different than Bill's but both seem to work. I do feel that a dual sport type rig works a lot better with a havy swaybar than with a soft one. Lots of variables to consider an dplay with. I could go into a lot of detail but it may not be worth it here. It also may not jive with other's experiece but so be it. Bottom line is that a working swaybar is like night and day and is probably the best single handling modification that one can make to ANY sidecar rig.
    #27
  8. rohdster

    rohdster The Leaping Wombat

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    10945376_1031621070199916_7995343445423993174_n.jpg

    I've read through this post and believe my outfit could benefit from anti-roll bars of some sort.

    Eager to learn if GS owners have ever fitted them and if so whether they could post photos of their configurations.

    It looks to me that it is a very specialised modification. Are there companies out there that are known to make anti-roll bars for sidecars?

    rohdster ... Queensland, Australia

    https://www.facebook.com/pages/BMW-...stralia/578854588809902?sk=info&tab=page_info
    #28
  9. davebig

    davebig Another Angry Hun !

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    Being a GS guy and one of Claudes customers, anti sway devices are a must for tall rigs.

    Here's Zippers thread sway bar work starts toward the bottom of this page http://advrider.com/forums/showthread.php?t=852181&highlight=zipper&page=8

    Claude, can I increase the diameter of mine 1/2 to 3/4" 4130 OK ? DB
    #29
  10. claude

    claude Sidecar Jockey

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    Yes you can. In fact we are doing all 3/4" now and adjusting the ;stiffness' of them by varying the effective lengths. Of course the swaybar arm length comes into play as well as the 'pick up point' for the connection links on both the bike and sidecar swingarms. it's a balancing act like so many things.
    Note to all! Be sure the connecting links move th eswaybar. Wrong angles an dth elink will just move for and aft doing basically nothing. Also make darn sure that the geometry is such that the connecting link itself will not go 'over center' when the arm moves. If it does than the swaybar function can be lost for a moment.
    Another note..... some may think th ebar isn't doing it's job if you can't see the motion from left to right when you jump on the bike or the sidecar. This may or may not be true. If the bar is winding up as it should it is still creating spring rate on the opposing swinagrm whether you see the movement or not.Remember it is a torsion bar and is made to twist. The stiffer the bar the less twsit it will have and the more you will see the opposing side move. What happens here or doesn't happen can also be the result of th e torsion arm lengths as well as the link positions. We run our bars through a tube with a bushing at each end to alleviate any vertical flex .... we are looking for a twisting action NOT a vertical deflection of the bar.
    Google antiswaybars.... read Bill Ballou's write up....look at almost any automobile and study it a little.... and this stuff will begin to make sense. If you want to take the time to temporarily unhook the swaybar on your car see how that works out .
    #30
  11. FR700

    FR700 Banned

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    Being that your chair's swingarm pivots from the rear (I'ma guess that the blue tube and pillow blocks are the pivot), which effectively means that it and the bikes move in different directions, you'll need to incorporate something to reverse the direction at the chair.

    Failing to do so will result in the total opposite of what you are try to achieve.


    .
    #31
  12. claude

    claude Sidecar Jockey

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    Not really FR. We do rear mounted swaybars pretty often on these types of setups. Hannigan sidecars mostly. It all comes down to placement of the swaybar and links to it that make it twist as desired. Kinda tricky with a rear pivot but more than doable. It can be done with a front mounted swaybar also. Hannigan's STOCK dual sport sidecar swaybar is front mounted. They also feel that a high stance outfit should have a swaybar on it.
    #32
  13. claude

    claude Sidecar Jockey

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    The tricky thing here is having the bike swingarm on the opposite side or the bike from the sidecar. We have done these various ways . Long swaybar that runs all the way across, a bell crank type linkage and what we would call a 'birdcage' on a sprint or midget connected to the center of the wheel with a radius rod running forward. All work fine.
    #33
  14. FR700

    FR700 Banned

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    Perhaps I could have rephrased that, somewhat.
    #34