Twin shocks vs. monoshocks?

Discussion in 'The Perfect Line and Other Riding Myths' started by SloMo228, Apr 30, 2014.

  1. ttpete

    ttpete Rectum Non Bustibus

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    There were two shocks in there side by side, but being so close together, effectively they were the same as one heavier one. Phil Vincent built HRDs with that setup and bought in Rudge Python and JAP 500 cc single engines from 1928-1934.
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  2. doxiedog

    doxiedog Been here awhile

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    Why does a single shock cost twice as much,as a pair of shocks?
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  3. ttpete

    ttpete Rectum Non Bustibus

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    You might compare equal quality shocks. Look at the price of an Ohlins monoshock compared to a pair of Ohlins twin shocks.
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  4. markk53

    markk53 jack of all trades...

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    Yes, but they weren't a single shock. If there was actually any kind of patent that would be a difference. Same as having one shock in standard positioning versus having two. If memory serves me right Honda's Gold Wing had a single shock on a twin side swingarm, with the shock mounted on one side. But I could be wrong and will quickly know so if I am
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  5. SloMo228

    SloMo228 World Class Cheapass

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    Depends on what Goldwing. I'm not sure what the 1800 is like but all the older models were twin shocks. The 1500 did have kind of an odd setup where one side was an adjustable air shock and the other was a standard-type shock.
    #45
  6. k-moe

    k-moe Long timer

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    Sort of. There are two spring housings on either side (visible in your linked photo), and one hydraulic dampener that is fitted inbetween them.
    The single dampener is what makes it a monoshock rear suspension system (Vincents are also monoshock front).
    #46
  7. markk53

    markk53 jack of all trades...

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    I will have to look, next time I'm up at one friend's place. All pictures I've seen do not show a damper beyond the shocks and Pat Williams mentions the dampers. The patent was on the swingarm layout.

    I did read about a friction damper in there somewhere with the dual springs.
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  8. k-moe

    k-moe Long timer

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    Jump to 2:05
    <iframe width="560" height="315" src="//www.youtube.com/embed/jeFpdiV2Z6I" frameborder="0" allowfullscreen></iframe>
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  9. markk53

    markk53 jack of all trades...

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    Now, to really screw with you on this...

    The original set up used two spring boxes at the top. The friction dampers were on each side - two spring sets, two friction shocks do not equal monoshock.

    Now maybe a later model had the hydraulic damper between the spring boxes when they finally went to a hydraulic rear suspension. That's what I'd like to see. Is it still the spring boxes with a single shock or is it that they actually went to two hydraulic dampers with springs. Leno's bike had the twin spring box/twin friction dampers. Two does not mean mono.

    Maybe this summer I can get back up to see a friend who has Vincents to actually physically see it. In all the reading I did I found nothing really clear on it.

    But sufficie it to say the one thing they did mention was Vincent's patent on that triangular swing arm set up. Everyone else, if they had suspension, had plungers.

    Of course for the sake of argument, does it mean you have a mono-shock fork if only one side has damping? There have been set ups like that - damping in one side only, the other only has a spring.
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  10. ttpete

    ttpete Rectum Non Bustibus

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    Here, I think we're moving from discussing suspension types to dissecting minor hardware differences. :deal
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  11. markk53

    markk53 jack of all trades...

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    I don't think so. It's a good discussion making me want to do some research, but also making me think.

    Joe Bolger developed a linkage system using twin shocks for a rising rate system just like a Pro-Link or Uni-Track, but one on each side. Because it is similar in what it does is it now a monoshock too?

    [​IMG]

    Someone brought up the subject and I made the comment. The Vincent suspension really wasn't worth mentioning here since it was pretty much vintage technology.

    Regardless, the discussion is the fun part. How else would some of you ever hear of Joe Bolger, doing linkage setups with twin shocks before the factories ever did the linkage set ups, in 1975.

    Now if you really want to hose it up, here is Death of the Rising Rate from MXA back in 2000. But it makes sense. And in turn, if you stick a shock out to the side, why not two, since they can be smaller allowing a better air box and possibly not be any heavier, with the right research and work...

    and on and on and on. Something to think about.
    #51
  12. ttpete

    ttpete Rectum Non Bustibus

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    You need to put things in context. In 1932, the Vincent system was modern technology. Two spring units 2 inches apart on common pivots are effectively one unit in a mechanical sense. Whether it was done for convenience or for mechanical reasons matters not. The end result is the same. If you put everything in chronological order, you have a valid chronology of suspension development. Coil-over came later and is the technology of today.
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  13. SloMo228

    SloMo228 World Class Cheapass

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    That's pretty cool. Never seen a suspension like that before.
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  14. markk53

    markk53 jack of all trades...

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    I do, I just don't count 1+1=1. First it was having monoshock, but it seems the friction damper was one on each side of the swing arm, now it is counting two springs as one... does that make a twin cylinder bike a single if they have them real close together? :huh

    Fact is with a rigid swingarm assembly any common twin shock works as one in a mechanical sense. After all, that is the plan, keep the wheel going up and down in the same plane with both shocks moving exactly the same amount - aka no swing arm flex. Why is it any different if the separation is two or six inches in that case? Makin' ya think.

    Vincent's design clearly was superior in many ways to a plunger, if nothing else than because they actually had the friction dampers. That's fine.
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  15. k-moe

    k-moe Long timer

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    The spring is not considered to be a part of the shock. Whether they are mounted seperately, or set up as coil spring mounted over the shock, they are seperate units. The friction dampeners on the Comet/Rapide/Lightning/Prince are not shocks; they're not much more than an expeditious way to hold the seat up without needing a strut triangulated to the engine, or a heavy subframe. At best they could be thought of as a (very) remote dampening adjuster.

    In practice the further apart the shocks are, the more tortional flex the swingarm has, which is another reason for wanting a monoshock for some uses. Two seperate shocks absorbers count as two seperate shock absorbers, no matter how many springs there are. One centralized shock abosrber counts as one shock absorber, no matter how many springs there are. How about you call up Eurobrit and ask for a full set of rear shocks for a Comet. I'll bet they quote you a price and shipping on one shock, and ask if you'll be needing new springs too.
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  16. markk53

    markk53 jack of all trades...

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    Ah! but the friction dampers have that magic word - "damper" which is what a shock does either by friction (mechanical) or by fluid flow (hydraulic) to control movement in compression or rebound. So seems like you are splitting hairs too.

    When it comes to swing arms they are ideally intended to have no torsional flex, no matter how many shocks or springs there are. Thus the bracing and all when on older racers (bridged twin shock swingarms on old superbikes and even on some single shock versions) and the huge vertical cross sectional design on the single shock bikes.

    By the way, if I called Eurobrit and said I wanted to rebuild my friction dampers on an old Vincent how many kits would I get? :D Thanks for pointing out that two shocks are two shocks, not a monoshock, therefore the two friction dampers are twin shocks, regardless of how effective they are. My bet is they're more effective than some of the chrome screen door closers on some of the old cruisers and at least can be adjusted to stiffen the action.
    #56
  17. slartidbartfast

    slartidbartfast Love those blue pipes

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    SOME Vincents had the articulated friction dampers and SOME Vincents had a centrally mounted monoshock, between the springs, under the seat. THOSE are the Vincents which had a monoshock before Yamaha did-not the ones which didn't. Clear?
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  18. markk53

    markk53 jack of all trades...

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    I said I understood that and fact is I've never argued or stated WHO had a monoshock first. Just that the earlier Vincents clearly didn't, having two friction dampers, in spite of the implication they were "monoshock" because the two springs were "inches apart".

    For all I know if enough research was done, we might find out Vincent wasn't first to have a monoshock either. I've not actually done any research on that. Wouldn't surprise me either way. I will say clearly Vincent was the first with a somewhat mass production set up like that.

    In addition I have been looking for the images that would show the single centered damper on the Vincents, but have yet to see a good clear one showing a damper there. Not to prove or disprove, but rather just to see. I did not say they did not exist, fact is I said I hoped to stop by and see a friend who has a couple, to see it in person.

    Clear?
    #58
  19. ttpete

    ttpete Rectum Non Bustibus

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    The Series D Vincents have a single coil-over suspension unit. The upper frame member is completely different than the Series B and C models.
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  20. markk53

    markk53 jack of all trades...

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    I take it that was the factory frame on that one to the viewer's left (speaker's right) in the video. I wondered if it was stock or modified since a lot of them (most every image I've seen) had the dual enclosed springs. Did Vincent use an open coil/over or enclosed?

    Seems you can get images of everything BUT the rear suspension set up. I did find one that appeared to have something like a damper between the spring cases, but the darn school filter won't let me view the image (huge image too) and by the time I go home I forget.

    Regardless, it is still enjoyable to me at least, to banter a bit and learn something else. Thanks.
    #60