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Discussion in 'Hacks' started by Pezz_gs, Feb 5, 2008.
This is from a piece of 1980s litrature from "Wasp" in England.
Looks to be an EZS Summit conversion package, possibly with a different engineered front end, with mods to the summit sidecar frame?
HogWild, thanks or that. I was just using the basis of the orginal travel of the R80G/S which is 200mm as a starting point. Allowing 30% Sag would give around 140mm usuable travel.
There is no manual on Leading Link design which suggests a starting point.
Hence the post on what are people running?
What would you suggest? The sidecar will be used for both on & offroad travelling.
Yep, sure does nice work.
The builder of the links had used (say) 50mm od tube. The triple clamp internal diameter was (say) 40mm. all that he'd done was turn down that length of tube that slid into the clamps so that is was now the correct od to fit into the clamps. The top edge of the 50mm od tube was butted up against the lower face of the clamp. Probably looked great when it was all painted etc.
High load point exactly at the weakest point of the tube. The whole assembly, links, shocks, brakes, wheel, guard was flapping around, secured by the brake hoses and speedo cable. Yikes, alright. Shits were trumps, I'd reckon.
I just measured the length between the top or the damper body and the bump stop on the shaft. It's about 70mm.
The polished portion of the shaft is about 55mm. I suppose I could work out the axle travel, but I'm too lazy. BUT
not so lazy as to not go back out and get some rough measurements.
The front pivot to axle is c 290mm
The front pivot to lower shock is c 170.
Simply & very roughly extrapolating a line from the pivot through the shock, 55mm above the shock pivot suggests that I've got about 160mm compression from the static. Got that? So, what does that transfer to in full wheel travel? Stuffed if I know & I'm definitely too lazy to find out today.
All the shocks on mine are custom built. The rear spring is the same type they use on a Group A Commodore. That's where the money goes. By the same token, my XS had XS shocks on the link and a Z1300 air shock on the sidecar. It was okay too.
And bloody hurry up! Stop typing, start bending and drilling and welding. You can make it look pretty after you've got it to work properly.
Remember this? No. And, by just looking at it, there probably doesn't need much further explanation:eek1
So to work out static you just jack the bike up until the forks are off the ground measure, then do the same when it is on it own weight. Then when you are on the bike. Then when you are on the bike drinking a beer
Thanks Ray Appreciate your help no end!
I type when I should be working, not when I should be fabricating
Yeah, but I'm just too lazy to get the jack out.
You type when you should be working? Sounds a bit like Troy, but he's knee deep in snow.
Just been on the phone.
Racetech 650 - 4130 Cromoly Tube - 38.1mm X 4.77mm (or 1-1/2" x .188") is about $70.00 per metre. The 30 degree bends x 2 is about the same $70.00. So $210.00 will get both legs built.
Make sure when welding moly it is done properly. It is best ,when purchasing moly, to get what is called 'condition N'.
It's hard to have TOO MUCH travel on an off-road rig. When I set mine up, I faced a couple of issues:
1) The forks and swingarm were already built (by EML/Belgium) to their motocross specs, but wider for my wide tires, so I worked from there. I set out to complete the setup simply by having shocks (Works Performance) made custom to my specs (max length, min length compressed, spring rate).
2) The bike needed to be near level front to back when sitting on it. That set the maximum shock length (based on the existing shock mounts), considering a bit of sag in the calculation.
3) I wanted as much travel as possible. The limiting factor with my setup is when the front fender hits the radiator. That set the minimum shock length (fully compressed, including compressed rubber bumper). On another bike, the limitation might be when the frame below your motor hits the ground.
4) The spring rate and spring preload was calculated by Works Performance based on their moderate knowledge of leading link suspensions, vehicle and rider weight, and riding conditions (dual sport for you, high-speed desert for me). On our first ride I found the front suspension to be just a bit too soft for my liking, so we changed to stiffer springs.
5) Later I changed to a much taller tire. That increased the trail, which made it very difficult to turn. To fix that I modified the front swingarm to put the axle 25mm further forward. That improved the steering, but made the suspension a bit too soft again, so we again went to stiffer springs.
Now it's all good!
Another goal I had was to try to have the sidecar suspension use the same shock as the front so I had interchangeability. I have a fancy progressive linkage setup on the side suspension, which allows me to adjust the ride height by changing the length of a linkage arm (not while riding). That's really handy for me because I've been constantly testing different tires in all 3 locations, and the height differences mean I'm constantly having to re-adjust the linkage to level out the sidecar. Anyway, by carefully designing the linkage mechanism, I was able to make the side suspension use the same shock as the front uses. That was important for Dakar in case we destroyed the front shocks out on the trail, and had to limp in. We carry one spare shock with spring on the bike all the time. I can take the side shock and the spare shock, and mount them up front if needed. And I have an aluminum strut that's normally used as a "jack", which can be mounted in place of the side shock in a bind. And to top it all off, the spare shock can also mount in the rear in case we break something there (it's happened once already). It's not the best setup, but it will allow is to get moving again in the event of a serious rear (mono shock) suspension failure. Oh, and one more thing, the same spare shock, with the spring removed works as a steering damper. Again, its not ideal, but its better than no steering damper at all.
Wot 'e said....:eek1
Interesting approach. No bending
another on a Gold Wing
Umm, does it look like the stanchions are too long to provide much wheel travel? Damper travel looks like it may be longer than a very hard bump stop.:eek1
Anyone got photos of what I can only call 'duplicate' triple clamps - where the clamps are pushed forward allowing the standard teleforks to be moved 50-60 or more mm forward?
And then there are the ones that just appear to be a pair of plates mounted on the bottom of the teleforks, with an extreme leading axle...
All options, eh.
Just some quick thoughts:
*The shorter the leading link swingarm the more rigidity it has.
*Shorter means less unsprung weight.
*Shorter means that possibly lighter material can be used.
*The shorter it is the more trail varies in bump and rebound (maybe only In theory related directly to the front end itself).
* Some short ones use a bent swingarm to facilitate the use of a longer shock
Curious about the chrome if that is what it is. Google 'hydrogen imbrittlement'.
Is this a picture of what you were looking for?
Utilizing a 145/55R15 front tire/rim assembly from the Mercedes SMART car - the three bolt pattern gives it away.
this is one that has the Triple clamps built with greater offset.
Perry Bushongs work I beleive.
View attachment 151602
Its nice to know where to start looking for this type of thing.
I imagine $$$$$$