Leading Links

Discussion in 'Hacks' started by Strong Bad, Dec 17, 2014.

  1. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    I personally think that Leading Link (LL) front ends and sidecars go together like peanut butter and jelly. One of the selling point (to me) when I bought my first sidecar (a 2007 Ural Tourist) was the fact that it had a LL front end. We all know that a quality LL should have less flex and be more stable than "conventional" forks. A quality LL should also allow for a wider car wheel & tire combination.

    The Aussies and the Euros both embrace utilizing LL on their rigs while here in the good ole US of A, you simply can't find an off the shelf LL supplier. Buying from out of country is not cheep nor easy. Finally, I'm not interested in a center steering setup.

    So here is the deal, I'm a weldor/fabricator not an engineer or designer. I have access to all of the equipment needed (Benders, Notchers, water jet & plasma cutters and welders). That being said, I can't take over a race shop to play around with all sorts of different stuff. I can get in, do my work and get out of the way. The rig can't sit on the table while I scratch my ass & try to sort shit out.

    So what I'm thinking is that I would like to build a LL front end for my rig (2007 BMW R1200GSA). With a "standard" motorcycle front fork set up mounting a LL is fairly easy as you can use the stock triple clamps. BMW of course complicates things with what BMW calls a "BMW Motorrad Telelever; 41 mm fork tubes,
    central spring strut, spring pre-load with 5-position mechanical adjustment". So yeah there is one shock and then there are ball joints and arms and WTF?!! Of course there is also completely different Telelevers for the 1150 and the 1200 (is the 1100 different too?). This makes following TwinTwin & Davebig with their 1150s interesting but not directly applicable to my 1200.

    I'm thinking that is SHOULD be possible to adapt my Telelever front end into a LL setup. If the shock on my Telelever was replaced with a simple solid strut, why couldn't a conventional LL fork with it's two conventional shocks be used???

    So here is where I'm needing a wee bit of help with the design aspects of a basic LL fork.

    When I look at Twintwins LL setup I see several things that appear to be logical including:

    The LL fork tubes come out of the lower triple clamp and then are bent to vertical (90 degrees to the road).

    The shocks are mounted so that they follow the same angle as the fork tubes have through the triple clamps (prior to the fork tubes bending towards vertical).

    The axle, the lower shock mount and the swing arm pivot point are all on the same horizontal plane (parallel to the road).

    What am I missing or need to be considered?
    #1
  2. DRONE

    DRONE Dog Chauffeur

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    Can't answer your questions but wanted to observe that the telelever LL's I've seen all use a solid strut to replace the front shock. So the telelever and the ball joint essentially become a fixed mounting point for the LL lower fork brace. I don't know if a specific length for the strut is better than another. Some I've seen looked kinda short so the telelever is sorta pointed up, and others seem to position the telelever in more or less a midway position.

    If you can do this in a repeatable sort of way, I think you could sell copies to anybody with a 1200GS from 2005 all the way to end of the hexhead era.
    #2
  3. phyllis

    phyllis just another dummy

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    Just finished making a LL set for an R1150 GSA.
    One of the main concerns(not mentioned anywhere that I could find) was that the ball bearing in the Top yoke wasn't lined up (on the same axis) with the Ball Joint in the bottom yoke.
    This shows up as a telescoping action of the stock BMW fork legs when you turn the bars lock to lock (with the wheel off the ground).
    Think about that for a bit!!!
    If you don't sort this problem out by building a new Telelever arm to reposition the Ball Joint, you'll have a problem down the track with those rubber "knuckles" in the Top yoke! And the Top yoke bearing won't be happy either!!!

    I found this out by bolting in new legs, and the the bars only turned to about half lock and wouldn't go any further!! Loaded the steering bearings up like you wouldn't believe.

    Other Stuff:
    The Telelever arms on the R1150 and my old R1100 were exactly the same, don't know about the R1200.
    I like the wheel axle to be about 40mm higher than the LL pivot on the LLs that I build(static, loaded, with about one third travel used up). Gives wheel travel a bit like Telescopic forks, up and back over bumps.

    Hope this helps, will get Clancy to post a pic.

    What could go wrong???

    Phyllis (Phil):D
    #3
  4. DRONE

    DRONE Dog Chauffeur

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    SB, another off-topic reply from me, but when I saw these LL's I contacted the guy because it sure looked like he was using stainless. Nope--he got them nickel-plated.

    [​IMG]

    They look so cool I thought I had to show you -- so you could add the cost of nickel-plating to your design! :D
    #4
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  5. Clancy

    Clancy Long timer

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    Posted for Phyllis


    [​IMG]
    #5
    Combatscoot likes this.
  6. Wolfgang55

    Wolfgang55 Long timer

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    Why is this the best looking LL I've seen ?
    #6
  7. Wolfgang55

    Wolfgang55 Long timer

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    OK it's on POST 4.....damn quoting transfer thing
    #7
  8. davebig

    davebig Another Angry Hun !

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    Thanks Strong for starting a conversation !

    Drone it looks like Stainless, it's a PITA to work with, it cuts,drills and welds with allot of extra trouble ! But looks great !
    #8
  9. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    Nickel plating is cool, like the old Rickman or Cheeney frames. This particular design has thrown out all of my questions regarding stuff all being on the same planes. The shocks look to be on the same plane as the forks coming out of the triple clamps. The fork legs appear to actually bend back beyond vertical.

    Finally I have to ask, WTF is that black thing between the hack & the tub?
    #9
  10. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    Thanks for the reply Phillis, I believe that 1150 & 1200 have different arms, how that changes anything (if at all) I'm not sure. I must qualify myslef as not being very knowledgeable with Beemer specific suspension, this rig is my first and only Beemer. Your post will cause me to look closely while cycling everything through from lock to lock.
    #10
  11. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    Crap! Yet again a different layout!! The shocks look to have a slightly lower angle than the upper fork legs, and the bend on the fork legs again turn back beyond vertical. The axle is higher than the Pivot and the lower shock mount. I also see that a completely new lower Telelever arm has been made.
    #11
  12. davebig

    davebig Another Angry Hun !

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    Phyllis
    I was looking for you awhile back, on Twintwins rig it appears that EZS and What Claude entended to do with mine is tip telelever all the way up as you have, but convert the upper triple clamp to a solid mount and use the R11 lower bridge to bolt in the legs.
    [​IMG]

    Didier if your reading this could you post an image of your top triple clamp if possible.thanks.DB

    Didiers thread http://advrider.com/forums/showthread.php?t=921941&page=4
    #12
  13. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    In one of my former lives I was a weldor fabricator and actually specialized in Stainless work, so I'm used to burning up drill bits! Stainless isn't always any stronger, which particular alloy used is the key. If and when I do build, I would use 4130 (aka: chrome-moly) the fork legs would be doubled with one tube lining the other. I know of a quality heat treat company in LA, so I would at least normalize the bits after welding.
    #13
  14. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    Yes, please!
    #14
  15. rg sw wa.

    rg sw wa. Long timer Supporter

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    I am loving it, keep talking guys !!:clap

    :thumb
    Ron,

    ps: Clancy, can you please post pictures of Phil’s LL he just made ?
    #15
  16. Bobmws

    Bobmws Curmudgeon At Large

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    Other issue to be addressed:
    If going for an automotive front wheel, what wheel/or hub adapter? Stroker's?
    Brake mounting brackets, are all the GS calipers and discs the same?

    :pot :ear :lurk

    OK, once you get the GS stuff figured out, we'll talk K-bikes! :deal
    #16
  17. DRONE

    DRONE Dog Chauffeur

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    Got some inquiries about this, so had to go back and research where this pic came from. First off, my memory was off--these are not nickel-plated. They are in fact stainless. SORRY! :bash

    They were made by a guy named Paul Marlton who is the head "wizard" at Pointy Hat Wizard Fabrications in Tilbury, which is about 20 miles east of London.-- LINK --Also, I don't know what the black box is and didn't ask. I don't think the subframe and SC mount system is something Paul made, just the LL's.

    He's posted lots of pics on his website of other stainless jobs he's done. Here's another set of LL's --

    [​IMG]
    #17
  18. twintwin

    twintwin Been here awhile Supporter

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    Dave, I'm away from my computer and formost far away from my rig, but as soon as I'm back home (Bangalore, India), I will post some pictures that I have on file. The top of the 2 legs of the L. L. slide in the upper tripple clamp, secured with 2 big nuts and washers. And the OEM steering big bearing is replaced by a stronger one. That's it.
    #18
  19. claude

    claude Sidecar Jockey

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    Whichever route you take
    with a leading link I would suggest you go with floating calipers and not fixed ones.
    #19
  20. cleatusj

    cleatusj Dirt floor engineer

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    Claude, For some reason my frontend rose when I had the calipers floating, but does not with them fixed on top of swingarm.
    #20