Sidecar Design Formula - IMPORTANT!

Discussion in 'Hacks' started by Get Back, May 25, 2009.

  1. ANKOF

    ANKOF Been here awhile

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    I just bought a tractor and have to support all my other bikes and the kids and the house and the gearbox on the car just broke down.... and yes, I long for a beer:-)
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  2. ANKOF

    ANKOF Been here awhile

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    well searching on international sites for clevis rendered some more stuff. on swedish I've only found very small ones or very big expensive ones for pneumatic operation. is 5/8" ok provided its set up corectly?

    edit. found a few on a swedish race car site, they use the english name on the one in the right sizes and they are about 10 times the price i US. seems like they are using heim joints for most car related solutions in europe.
  3. FR700

    FR700 Heckler ™©®

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    3/4 16 ( 19 mm ), $14.99 US.

    http://www.speedwaymotors.com/Heavy-Duty-Clevis-3-4-Inch-RH,1531.html


    [​IMG]



    :evil


    ANKOF.JPG
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  4. ANKOF

    ANKOF Been here awhile

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    what if I come by your place and bring some beer FR700?:-)
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  5. FR700

    FR700 Heckler ™©®

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    Sounds like a plan I could work with :thumb
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  6. FAHR451

    FAHR451 n00b

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    After 18 pages of thread the conclusion was nuts and bolts !
    Seriously a great many topics on suspension design were discussed here and at one point I was growing concerned that the all important technical aspect of the tyre contact patch had been overlooked but all was well when 'slip angles' were introduced into the equation. This is the point to start any new design and the choice of tyre has the data from the manufacturer .The conclusion to this thread really if there was one is that if you introduce one or more tracks to a motorcycle forget its a motorcycle ! The motor cycle benefits in suspension in infinite swing arm and GL roll centres must be taken into account but so must the design strengths of the materials involved , if we are not building from scratch . In racing sidecars were taken to their extreme with Bilands BEO Yamaha decades ago , but existing regulations can give you a clue as to what direction to go to improve handling . For example in F2 the maximum reduction of front track is 75mm , which suggests the closer the front wheel is to the centreline of the vehicle the more advantageous in handling , the maximum tracks and wheelbase is also set . Within these parameters a maximum ammount of adjustability has to be introduced .F1 sidecars have very little in common with motorcycles and all that was posted that applied to 4 wheeled vehicles with the calcs for CoG ( which can be done in many ways) roll centres below ground level etc applies here , and is not really what this thread was seeking to resolve although interesting to many readers .
    When it comes to altering a motorcycle for sidecar application most of the parameters are already fixed , tyres , suspension etc., so you start with the last as quite rightly demonstrated at the end of the thread . Build in as much adjustability as possible so that there is NO wrong position for the sidecar , its toe and camber or lead that cannot be corrected by adjustment . Heim and Rose joints play an important role naturally . The data for the strength of these things is again everywhere ,but if you don't understand raw data and are unable to calculate stresses and strains in structural frames , just look at what is already succesful on your bike or car . Look at a steering joint on a car for instance that can see 4 ton in hard cornering . If a 16mm or 5/8" joint can cope with that in compression and tension , in combination and triangulation in attachment points several of these in unison are more than adequate for a sidecar . Look at the Heim joint on the rear shock of your bike , this copes with massive tensile and compressive forces. Thes components typically have a factor of safety of around 2 dialled in will cope with thousands of miles 2 up without failure , so four of these will hang a sidecar off your frame .Stay within the boundaries of your knowledge .
    The problems with overdesign of components as with flight vehicle structures is that if the object you are attaching to your bike is structurally stronger than the important parts of the frame the danger here is failure of a more important component on the bike itself due to loading a component in a direction where loading was not factored in . Sidecar frames if solidly attached should never be stiffer than the bike frame for obvious reasons , in that critical failure in a lesser member in a sidecar is much less likely to be catastrophic than critical failure of a member in a bike frame .Take a look at some of the photos posted where front forks are seen to be bending under the load of a lifting chair . This is not an optical illusion this is the forks behaving within the elastic limit of the material they were manufactured from and as they were designed to do . A heavier chair or loaded excessively the forks will fail as the elastic limit is exceeded .
    There is another route to attaching a sidecar to a frame that was almost approached , that deals with the factors of safety and adjustability and that is simply using shock absorbers complete with Heim joints and full adjustability that are fitted to every rear end of every motorcycle built . These normally come with massively heavy springs (due to the leverage applied by the swing arm leverage mechanism , bump and rebound adjustment and are considerably less expensive than fabricating a strut from scratch .The use of such items would ensure that regardless of the design of the sidecar or it position relative to the machine a certain amount of flex and adjustment can be dialled in to cater for any unusual loading on the frame and forks , toe and camber of the sidecar wheel and provide some of the original rideability of the bike to a very limited degree when adjusted properly or reset when not carrying a load in the chair .This type of reactive loading has become very familiar in static structures in civil engineering when uncommon loads are applied such as earthquakes and hurricane force winds ( take the wibbly wobbly footbridge over the Thames for example - oscillation problem resolved by shock absorbers) and there is no reason why this cannot be applied here .
    For those interested in design of suspension systems the Millekin Moment Method by Millekin is very informative at every level . I believe some of the material included in this thread had its origins in the pages of that book .
    I like the approach to various engineers and designers in Bruhns Design of Flight Vehicle Structures very similar to a very early posting , where the powerplant engineer likes to see a tiny pair of wings attached to a huge engine , the structural engineer wants something that looks like the Forth or Golden Gate Bridge and so on . All engineering is merely a compromise on the sum of its whole and although some can be calculated empirically or modelled computeristically (I think I just invented a word ?) , it still ends up being what looks right works to most seasoned engineers !
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  7. DRONE

    DRONE Dog Chauffeur

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    :gerg and furthermore . . .

    :bueller
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  8. FR700

    FR700 Heckler ™©®

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    Paragraphs?
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  9. Old Mule

    Old Mule Long timer

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    I think that Stoye sidecars used (and use) spring-loaded upper struts, some have a big hand-nut to adjust the tension. G**gle "stoye-blog".
  10. Bobmws

    Bobmws Curmudgeon At Large

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    Nah, I'd rather watch my dogs play in the yard, & we don't even have snow ...............:-)
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  11. claude

    claude Sidecar Jockey

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    Comments: 1) MMD is not typically a deciding factor with most sidecar outfits. ........2) The structural integrity of a given Motorcycle frame is typically enhanced through the use of a proprerly designed subframe assembly . This is good practice as the quest in chasing weak spots can be a long and dangerous route to take ......3) All mounts between bike and sidecar are preferably sharing the loads as much as possible on all planes. The use of spherical rod ends is questionable if the design parameters of any said assembly is not taken into consideration. 4) Build it stout and there is less to worry about. ..... Nuff said from this corner...happy new year and have fun....SAFELY.
  12. JerryAtrick

    JerryAtrick Adventurer

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    Total sidecar newb here...old age leads me to three wheels. My education starts here.

    My goal is to hack a KLR650 for dual sport riding. The sidecar will be simple - a cargo box mounted on a flat platform with no passenger accommodation. I plan to ride forest service roads and jeep trails, although the younger two-wheel guys I ride with will undoubtedly try to lure me into more technical (and narrower) places where I don't belong. (That's their normal behavior when I'm on two wheels...I don't expect it to change!)

    I've plowed through much of this thread and don't find the answer to my first question - How does one determine the best track for the sidecar's intended use? It seems logical to me, for the above usage, that the outfit should be as narrow as possible, but I assume that will also make it less stable. Any suggestions for track width for the usage I've described?

    Similarly, I'm confused about weight. With no experience, my instinct points me toward a lightweight sidecar, onto which I will load perhaps 80 pounds worth of tools, spares, camping equipment, etc. But most everything I read indicates I'll need to add A LOT of ballast to such a set-up in the name of safety, especially during the early miles of my sidecar experience. (BTW I've ordered David Hough's book, registered for the three-day sidecar training in Virginia and FULLY understand that a sidecar is NOT a motorcycle and I need to approach this as a TOTAL novice.) Again, any suggestions (with accompanying rationale) for an ideal weight for a KLR dual sport sidecar?

    I have a million more questions...I'll start with those two...and thanks in advance to the inmates for sharing their knowledge. ADVRider is a HUGELY valuable resource.
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  13. JustKip

    JustKip Long timer

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    I'm sure some of the more experienced members of this little club will be along soon enough to clear up any BS I happen to spew.

    There is definitely such a thing as "Too narrow", and that number will likely be around 48 inches or less. More typical for a KLR rig is the low 50s. Too narrow, or too light will be a royal PITA, but you don't have to go overboard. It's just that the lighter and narrower the set-up, the more active you will need to be to keep it upright. As for weight, I imagine that if you build it strong enough for off road use, it's not going to be too light.

    I think it's a very good thing that you've signed up for the class. Do you have any idea what the rigs they'll be using are? That will be the perfect environment to ask these same questions...and move to the design phase after the class.

    Edit: BTW, here's one of the KLR rigs that were used at the class I took a few years ago. I didn't measure, but I figure the track width was right around 50"

    [​IMG]
    [​IMG]
    Flying the chair in a figure 8 was part of the class - great fun!
  14. JerryAtrick

    JerryAtrick Adventurer

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    Edit: BTW, here's one of the KLR rigs that were used at the class I took a few years ago. I didn't measure, but I figure the track width was right around 50"

    Thanks Just Kip. Was that Vernon Wade's school? I guess it's defunct. Anywhere else one can find dual-sport specific training?
  15. JustKip

    JustKip Long timer

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    Yes, it was, and I wish there was something like it available now. I'd do it myself if I was willing to spend the money on a couple dual sport rigs, like a KLR and a Ural.
    There WAS an inmate here that was going to do it in the CA desert, but nothing ever came of it. I have an acquaintance who runs a dirt bike and flat track school locally, and he'd be willing to let me share his facility, but one Bonneville rig don't make for a decent class. I'm close enough to retirement that I might just do it soon anyway. KLR and DR rigs are pretty inexpensive to build.
  16. claude

    claude Sidecar Jockey

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    The KLR and DR bikes do very well with a sidecar. .
    The simple cargo box mounted on a flat platform with no passenger accommodation is a popular choice.
    The forest service roads and jeep trails are more tha fine with many rigs.
    The more technical (and narrower) places are doable with some limitations of course.

    >>>>I've plowed through much of this thread and don't find the answer to my first question - How does one determine the best track for the sidecar's intended use? It seems logical to me, for the above usage, that the outfit should be as narrow as possible, but I assume that will also make it less stable. Any suggestions for track width for the usage I've described?<<<

    I would stick with no less than 48" and probablt would end up around 50 or so.

    >>>>>I'm confused about weight. With no experience, my instinct points me toward a lightweight sidecar, onto which I will load perhaps 80 pounds worth of tools, spares, camping equipment, etc. But most everything I read indicates I'll need to add A LOT of ballast to such a set-up in the name of safety, especially during the early miles of my sidecar experience. (BTW I've ordered David Hough's book, registered for the three-day sidecar training in Virginia and FULLY understand that a sidecar is NOT a motorcycle and I need to approach this as a TOTAL novice.) Again, any suggestions (with accompanying rationale) for an ideal weight for a KLR dual sport sidecar?<<<<

    You will be fine with anything over 150 pounds and I would not stress at all if it was heavier than that.

    >>>I have a million more questions...I'll start with those two...and thanks in advance to the inmates for sharing their knowledge. ADVRider is a HUGELY valuable resource.<<<

    Feel free to give me a call if you wish. I am much better at talking than typing. I have a KLR myself and love the thing. We do make a simple sidecar for these types of bikes. Pretty much plug and play with easy off and on once it is mounted. The bike itself steers fine in stock form although one can go with a leading link or whatever but it is not needed. Our sidecar, as mentioned, is an easy on and off setup and some have used then in such a way as to go out set up a base camp ..remove sidecar and explore in solo trim. The options are wide open on this type of rig use your imination.
    Shop phone is 570 837 5120 if you wish to chat.
    When we do a rig we really almost insist that time is set aside for some basic training and explaination of setup, adjusting etc if at all possible with the customer.
    The sidecar I am talking about has a fullyand easily adjustable torsion bar suspension and works very well with many different bikes. Simplicity at it's highest and easily adaptable to a box a body or just reamiling as a flat plate.
    Part of our klr subframe
    klr subframe.jpg
  17. claude

    claude Sidecar Jockey

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    More KLR mounts .......This is an aolder picture we have since mofified the mounting system for more simplicity and no need to cut body panels. It will also work with the aftermarket 10 gallon fuel tank. klr tube frame2.jpg
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  18. claude

    claude Sidecar Jockey

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    Antiswaybar is a great feature if desired klr3.jpg
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  19. 3legs

    3legs Real men ride sidecars

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    My 2c worth. Make the sidecar as light as possible and use your gear as ballast. Remember you don't have much horsepower to play with (when travelling on tarmac to get to your fire trails) but having said that you will have more than enough when you hit the dirt. Width? What is the most popular 4wd in the states?. Find out and use their track width. That's how we measure it here in Australia. Our most popular 4wd is either a Nissan Patrol or Toyota Landcruiser.

    As I said just my 2c worth. What works for me might not worth for others.

    3legs

    Ps. If Claude advises you to contact him for info, DO IT. He has forgotten more about sidecars than most of us know.
  20. Jeff 8

    Jeff 8 Been here awhile

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    Does anybody know if the threads on Watsonian fittings are BSC or UNF?

    Jeff

    :2guns