Swingarms leading or trailing, ? For Builders

Discussion in 'Hacks' started by davebig, Aug 20, 2013.

  1. davebig

    davebig Another Angry Hun !

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    Inquiring minds want to know ! My welder friends brother stopped the other day said my sidecar was very cool and liked the engineering (unusual)He's a Ford chassis Engineer in Dearborn does the F150 he's an engineer thru and thru we tease him mercilessly. Has 16 -17 motorcycles mostly Norton and Ducati and a few Yamaha RD's.
    We talked about swingarms he liked Claudes which got me to asking about leading swing arms rather than trailing. He says leading will ride better and wanted to help us cut my frame up and reverse the swing arm. Not this fall or winter or ever but maybe I should consider that for my next rig. I know that at least some Hannigans are leading swing arms and much shorter.
    The question is why don't we see more leading swing arms ? Advantages liabilities ?
    I was drawing my next rig in my head Claude LOL:norton leading swing arm, swaybar in the middle under the chair more weight centralization.DB
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  2. claude

    claude Sidecar Jockey

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    Watsonain has done short leading (rear pivot swingarms for a zillion years). Hannigans are rear pivot except for their high performance outfits.

    Do they work? Obviously.

    We prefer the front pivot system for a couple of reasons.
    1)If Pivot bushing and or bearing loosen up or wear on a rear pivot swingarm the thing will go from toe in to toe out at will. Toe out will make a rig pull to the right. Tire wear can be weird also. On a front pivot swingarm the wheel will kind of caster around behind the pivot point seeking it's own path in spite of possibly bad swingarm bushings/bearings.

    2)Rear pivot swingarms must have the pivot point lower than the wheel hub to work well. It Is easier to pull a wheelbarrow over a curb than to push it.

    So, due to the above factors alone we prefer the front pivot system although from a manufacturing standpoint the rear pivot would save us some effort.

    If you want to split hairs think of wheel lead variations when the swingarm goes through bump and rebound. No, nevermind it ain't worth it...lol.


    Swaybar? We have done them up front before. I like the rear mount better though. The weight to the rear is not doing any disservices. So lets move the swaybar up front and reverse the swingarm so we move more weight to the rear??
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  3. davebig

    davebig Another Angry Hun !

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    ( Hannigans are rear pivot except for their high performance outfits.

    Do they work? Obviously )

    This answers my question, I'm surorised that no one else has chimed in.DB
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  4. claude

    claude Sidecar Jockey

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    When thinking rear pivot also think pivot point location/ swingarm angle and ground clearance. Drawing some simple pictures to some kind of scale with desired ground clearance considering the above can be interesting. Also shock mounting and the angle thereof can be interesting.
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  5. Old Mule

    Old Mule Long timer

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    Leading arm suspensions are better if the sidecar wheel has a brake, as they do not dive under braking like a trailing swingarm.
    Steib used a leading arm for decades and they work very well.
    In general I think leading arms handle better- just in my experience.
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  6. GypsyWriter

    GypsyWriter Yup, I'm a girl.

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    God, I know I might open a whole can of worm with my question, but here goes anyway.

    I'm still fairly new to sidecars, having hacked my 1150GSA with one of Jay's M72DX cars. I love the thing, it's right now in the shop getting some new shocks made up specifically for the rig and myself, and I can't wait. Anyway, I've gotten conflicting information re: swaybars on a rig. I understand that for on the road it's good, but off road it can be bad.

    Um...why?

    I plan to take my rig off road quite a bit, but it'll probably be more 50/50 given how many highways we have in my area. Claude mentioned in another thread that people can "disable" them for offroad, is it that easy or advisable? Since I plan a bit of dirt travel with mine, would a swaybar be a good thing? Or is it something that's up to each driver?

    (And it's not like I'll be doing the TAT or Road of Bones with mine, mainly just Jeep trails and two track dirt forest/desert roads.)
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  7. davebig

    davebig Another Angry Hun !

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    Now the Red Head's asking questions were almost out of control here OMG !!!!!! LOLOLOL
    Gypsy your from the anti swaybar region PNW the NE and Claudes customers are the swaybar users, it's only my personal opinion DMC doesn't sell swaybars so they are against them,they don't sell 15" front wheels so they are bad also Claude sells them and that's why I bought from him to begin with.
    The idea that they get in the way off road is obnoxious at best they act as though old /2 BMW and various European sidecars never went anyplace they have about 4" of ground clearance and about 3" of suspension travel and have been going everywhere since the Germans headed east in WW II.
    Swaybars add lots of stability 96% of the time your riding the machine, they really stabilize things on the road and make operation much easier and safer. Guys like Stroker and Twintwin and myself would probably not own a sidecar without one.People who are against stability and traction have allowed their egos to cloud their judgement.
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    I've had allot of fun with my rig and in 15K miles never stuck due to swaybar, if I was in 8-12" of mud in S America I'd want a winch also but I'll keep the swaybar.I also weighed my rig its around 1000 pounds it has one wheel drive I ride with my 17 pound dog he's not allot of help if I get stuck so I'm careful.
    One of the DMC riders had his rig on its side not long ago, I wonder if he examined his spill if a swaybar may have saved him.
    Since your a writer Gypsy I'll throw this in also, the Hacks column is full of men trying to deal with mid life crisis's by being adventurers wondering whose a poseur and who's not. There ain't a Jack London amongst them !!!!!! DB
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  8. Strong Bad

    Strong Bad World's Foremost Authority

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    What's that you say??? Anti-sway bars bad for off road??? All of the unlimited "Trophy Trucks" raced in Baja for 1000 miles use them!

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    The more suspension you have the more you NEED all the anti-sway you can get!!! Believe me! I've got a 2007 GSA and a sidecar with no anti-sway system and I will be building one.
    #8
  9. davebig

    davebig Another Angry Hun !

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  10. hahnda

    hahnda Been here awhile

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    Staying out of the swaybar thing...


    A leading axle can be just as good as a trailing axle but in my opinion a trailing axle makes more sense from a design point.

    Swingarm pivot along the yellow line - acceptable.

    Swingarm pivot along the green line - better as it not only pulls the wheel forward but also has a force vector in the up direction that helps to pull the wheel over obstacles.


    Swingarm pivot along the red line - not advised as it has a force vector in the down direction and will be pushing the wheel into the obstacle.



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  11. claude

    claude Sidecar Jockey

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    As far as disabling th swaybar goes it is easily done. Hannigan uses a quick disconnect system where you pull a pin. On our system you can take out one bolt. Why disconnect them? Good question ..lol. Yes, it would give back the fully independent 'qualities ' of the bike rear suspension and the sidecar suspension. With that being said we have had outfits we have built do global tours and so far no one has said they desired the outfit with the swaybar unhooked. Rock crawling maybe but in the real world the rigs do quite well with the swaybar hooked up.
    A blanket statement about swaybars being bad is off the wall at best. The effective spring rate of the swaybar is a big variable on how they work under various conditions. This all depends on the length of the bar, the diameter of the bar and the length and actual movement of the arms. Antiswaybars are not rigid members but rather torsion bars that need to twist to work. If one is far too stiff both swingarms would work together and it would be a joke as far as handling goes. If they are too soft they won't do a lot.
    Ground clearance? It does not really have to be affected by the swaybar. We have mounted them in different ways over the years and yes some were lower than others. Today we do most as a rear mount which seems to work quite well all around and maintain ground clearance. We have also mounted them above the sidecar frame and even though the body on one outfit.

    Hey we don't want to get into a Ford vs. Chevrolet debate here that is dumb. But I do have a question if anyone who is against swaybars has ran a swaybar that worked well and compared it to the same outfit without the swaybar? Just curious.
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  12. claude

    claude Sidecar Jockey

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    I really don't think everyone understands what the anti swaybars do. Those trucks and such have a ton of suspension travel and still run a swaybar. The purpose of the swaybar is a real one. The function of the swaybar can be harsh or soft dependent upon it's design.
    Heck the formula type cars that run them have a simple adjustment that could be made while underway to stiffen or loosen up the amount of swaybar effective spring rate being used depending upon the part of the track they are on. Most all road going cars have swaybars in the front and some in the rear. Some motorhomes have swaybars.
    Folks this isn't something new even though it may seem foreign to some.
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  13. GypsyWriter

    GypsyWriter Yup, I'm a girl.

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    I have an old Ford project car that has a sway bar that we beefed up, so I do understand the basic concept that it allows more rigidity and less flexion/twist for the frame on the road. What I guess I didn't understand was why people didn't want it on their offroad rigs. I quite liked your explanation on various "levels" of twist, how you can make it beefier or more flexible while still being stable. So I guess the real concern is that a bar will be too rigid (since not rigid enough doesn't seem to make a big difference) and create additional torsion to the attachment areas (namely the bike/sidecar frames), thereby causing needless damage? It sounds like, if someone knows what they're doing and can accurately measure how much rigidity is necessary before flexing becomes NECESSARY to keep anything from breaking, then sidecar swaybars can be a good thing?

    Maybe I should keep my mouth shut but some people seem rabidly for or against and I'd like to know why. :ear
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  14. davebig

    davebig Another Angry Hun !

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    Conversation is good, there is allot more positive results with swaybars than without, the rabid fear of them is interesting its regional and seems to stem from one builder, and his customers.I'm loud and opinionated myself and I wish some of the other inmates would be more forthcoming with good arguments but there doesn't seem to be any other than "I feel that they would interfere off road" I've yet to meet the man who can rescue a 1000 plus pound rig without external help, winch, come along, rope pull or whatever giving up a little ground clearance for road stability seems a cheap price for the benefits.DB
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  15. Old Mule

    Old Mule Long timer

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    that force vector chart is interesting and makes sense, but there have been dozens of leading link front ends designed, and only a few trailing link forks. The Vespa comes to mind- it dives when the break is applied, as opposed to the BMW leading Earles fork, which rises.
    Wouldn't the same rising action be desirable on a braked third wheel?
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  16. claude

    claude Sidecar Jockey

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    A torsion bar gains spring rate as it twists the same basic way a coil spring gains spring rate as it compresses. Make sense? So.....a lite bar can still be effective and still do a good job off road. Long arms with a stiff bar will act like short arms with a lite bar. There are lots of variables and we have tried a lot of them. In fact ther eis a vcalid argument that a softer suspension with a heavier bar may do better all around on and off road....but.... even then there are variables to contend with..on it goes.
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  17. davebig

    davebig Another Angry Hun !

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    Now that is some good info, I don't understand anyones fear that the sway bar inflicts damage on either swingarm.My own opinion is it stabilzes the suspension and adds a bit more spring when loaded.DB
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  18. BigFatAl

    BigFatAl Been here awhile

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    This one I built worked awesome !!!!.
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  19. Old Mule

    Old Mule Long timer

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