Rambling stream of consciousness: Bonneville suspension and cooling

Discussion in 'Hacks' started by JustKip, May 13, 2020.

  1. JustKip

    JustKip Long timer

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    I love a lotta things about my Bonnie outfit, but one thing I Don't like is the lack of ground clearance. I might have high-centered on a gum wrapper once. I don't know exactly what the dimension under the engine cradle and center stand bracket is, but I'm sure it's less than 4 inches.

    And so that's got me thinking about how to get more air under the bike. The simplest solution would be to just swap out the OEM suspension parts for shocks and fork stanchions from the same year Scrambler. This would give another 38mm on the rear shocks, and 31-36mm for the forks. That's about 1-1/2 inches, in my world, and maybe going from under 4" to over 5" would be all the difference I'd need(?).
    That would be the most affordable method. But then I start thinking crazy shit. I could cut and extend the swingarm, and use a bigger wheel/tire, for up to an additional inch. That would, of course, call for a leading link front end to level it out, and a bigger front hoop and rubber as well....

    is there a bottom to this rabbit hole?
    #1
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  2. propforward

    propforward PIE!romaniac

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    I’ve never found the ground clearance to be an issue, but those mods sure sound like a lot of fun.

    Of course, that's only based on solo riding. Don't know how it is as an outfit yet.
    #2
  3. High Octane

    High Octane Long timer Supporter

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    No. No bottom.
    #3
  4. Wolfgang55

    Wolfgang55 Long timer

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    Only bottom to worry about is to ''bottom out'' hard.

    Besides, you just might have fun going up in the world.
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  5. JustKip

    JustKip Long timer

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    The bike is carrying about half of the CSM/Freedom sidecar's 400 lbs. I weighed it a couple of years ago, but forgot the exact distribution. So it's an extra 200 lbs, with more on the rear than the front. Before I even climb aboard, it's carrying the weight of a large man. I'm close to 220, not counting riding gear. So, without a passenger in the tub, and just me on the bike, the bike is loaded with about 450 lbs. Add to that (subtract) the fact that the triple clamp modification not only reduces trail, but the ride height. I'm guessing that, between the weight and front suspension mod, I'm riding at least an inch lower than stock. I have to be very slow and cautious on every speed bump...and I spend lots of time looking for dirt roads. I've bottomed out hard a few times.
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  6. davebig

    davebig Another Angry Hun !

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    Longer rear shocks ? Weigh all 3 corners and see Klaus at EPM , after fooling around with my GS that got progressively heavier and finally getting weighing and getting springs I prefer stiffer and well damped to softer and movement. If you have more than 35% sag your under sprung, 50% sag isn't going to work well.
    Last week I stuck the road sidecar on a not maintained road, it wasn't ground clearance under the tug it was the sidecar frame and associated hardware. If you look at the WW2 rigs the tugs are low( not much suspension then) but there's plenty of room under frame and sidecar .
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  7. propforward

    propforward PIE!romaniac

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    Yeah that's quite the load. I'll be interested to see what ground clearance I end up with on my rig with a fully laden sidecar and my fat ass sat on it. Probably be dragging the bottom of the sump on the ground.
    #7
  8. FLYING EYEBALL

    FLYING EYEBALL out of step

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    fork tube extensions
    stiffer straight rate springs (maybe heavier oil)
    longer stiffer shocks
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  9. JustKip

    JustKip Long timer

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    I think this is my next move. I've already added the stiffest springs they make for it, but the 36mm longer tubes are now ordered. Not sure about heavier oil, though. It's 10w now. Thinking of mixing 50/50 with 15w when I get the new fork tubes. I have a pair of OEM Scrambler shocks (38mm longer), but I think I should order new ones with stiffer springs, rather than try to make up for the extra 100 lbs on the back with pre-load.
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  10. JustKip

    JustKip Long timer

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    Contacting Klaus for a set of rear shocks is next on the list!
    It's the sidecar's subframe, attached where the center stand used to mount, that hits the ground. But it's only the lowest point by a little bit. I'm pretty envious of all the ground clearance that Vernon has on his Scrambler outfit.
    #10
  11. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    The amount of “sag” is important.

    Where in the travel range the rig sits at and how much travel is available from that point also has to be considered.

    In off road racing you want to bottom out at least once every race. If you don’t you’ve got waisted travel. Like pilots say about landing with runway behind you.

    If your longer suspension has longer travel, depending on your set up, you could very easily end up bottoming out more.

    Your springs determine where in the range of travel your rig sits, not the different oil viscosity which only determines the dampening.
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  12. JustKip

    JustKip Long timer

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    My rear shocks can almost bottom out while parked in the garage :wink:

    I gave the guy at RaceTech my front weight when I was shopping new springs. He calculated the appropriate spring rate at 105% of the heaviest spring available. So that's the springs I bought, and it's close enough. Bonneville rear shocks have 3.9" of travel, and I can use it all in driveways and intersections in a sedate ride around town. I wasn't really looking for more travel, just taller. The 4.7" of fork travel actually feels pretty plush. I know it could bottom out if I was pushing hard on rough roads, but the rear shocks won't allow that kind of riding. But the real issue is bottoming out, even when easing over parking lot speed bumps, or through easy ruts on dirt roads. The oil filter is somewhat protected between frame rails, but it would only take one protruding rock, and a skid plate would take up ground clearance that I don't have to spare. Adding a skid plate is part of my motivation for wanting more air under the bike. I'm going to drag this thing around behind the RV, and beat it like a rented mule.
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  13. steam powered

    steam powered just a regular punk

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    When you get to the point that the only parts you are planning on keeping are the engine, gearbox and enough of the chassis to keep your vin number, you will think you are near the bottom. Then it will occur to you that it would be cheaper to start with a 1200 scrambler and a set of raked triple clamps, but a leading link would be nicer, and so the descent starts again.

    Lift the bike enough so as to not scrape hard parts, any more than that is counter productive. Stiffen the suspension as much as you can bear, comfort will be the limiting factor before you start having problems with the wheels not staying on the road unless you are a real hardass. Make sure you have enough damping to handle the stronger springs. This is based on the premise that this is a road rig (including dirt roads) rather than trying to emulate a sidecarcross outfit. And as Dave points out, clearance under the sidecar is more important than under the bike. If you think about 4 wheelers, they measure ramp over angle (aka breakover angle) when viewed from the side vs distance to the lowest point when viewed from the front because, hopefully, you are travelling forwards rather than sideways.
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  14. JustKip

    JustKip Long timer

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    Really not looking to be extremely tall. Just stock height of a stock Scrambler 865, instead stock Bonneville height. Scrambler is still very much a street bike.
    But I also need to change the rear spring rate to handle the extra 120 lbs.
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  15. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    The internet is just fucking brilliant as that is where I was able to find the solution to your suspension woes, the picture was labeled "Lift Kit"

    Lift kit.jpg
    #15
  16. JustKip

    JustKip Long timer

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    :photog :lol3 :lol3 :lol3
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  17. davebig

    davebig Another Angry Hun !

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    Whilst fooling with the Black GS I ended up using a Q1 racing shock and I bought at least 4 different springs from various places all car or street rod springs till I got what I wanted.

    https://www.qa1.net/circle-track/suspension1/shocks
    I don't remember if we used a 62 or 82 series it was the smallest body size with threading for adjustable spring preload or ride height.

    All sorts of 1 7/8" springs and rates https://www.jegs.com/webapp/wcs/sto...&submodel=&engine=&Nrpp=&No=&persistYmm=false

    This guy helped me http://www.esssuspension.com/
    as Q1 doesn't sell to the public.
    The question is of course what will fit on the back of the Triumph and do you like enough to spend time and money ?

    Motor cycle shocks cost 30-40 % more cause they are motorcycle shocks
    Here's my post https://advrider.com/f/threads/custom-shocks.1121240/ I think elite shock services became ESS Suspension.
    This stuff is much more robust and rebuildable if you can get them on the Tri :-)
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  18. JustKip

    JustKip Long timer

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    Klaus has recommended the Hyperpro model 360 TS, at $1009 for the pair, sprung to my weights. I got the email too late to order yesterday, so I'll call him on monday. He said they'll take a week to build, then about another week for shipping to the west coast.
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  19. davebig

    davebig Another Angry Hun !

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    I forgot the axiom from people smarter than I "springs hold the rig up, shocks damp the spring" The damping adjustment decides how big a hit it takes to make the spring move.

    That's allot of money said I, who currently has 3 shocks at EPM and have to call them first thing Monday.

    You could get by cheaper at Q1 but it won't be easy or plug and play :-)
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  20. FLYING EYEBALL

    FLYING EYEBALL out of step

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    Thats what I did for fork oil when I did my Trees, had a partial of 10 and 15 and it's been fine.

    For Shocks I've been running the budget Progressive 412s in a longer stiffer(o gosh)setup and they have been great.
    #20
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