Helmetrock
Guest
Does anyone know what stress I should calculate with if I should make my own adjustable paralever arm?
stress
About five years worth of it..
About five years worth of it..
Helmetrock
Guest
Hehe but I mean mechanical stress to the paralever arm, not mental stress to my parents
I believe that the pushing forces at braking is worse than the pulling force at accelleration, and that the forces from the suspension working are very weak, am I totally wrong?
I planned to use a 20 x 1.6 mm stainless steel pipe 23-43 (316) and a stainless thing in each end, and an M16 thread for the adjustments!
I'll translate the measures to your strange systems later
I believe that the pushing forces at braking is worse than the pulling force at accelleration, and that the forces from the suspension working are very weak, am I totally wrong?
I planned to use a 20 x 1.6 mm stainless steel pipe 23-43 (316) and a stainless thing in each end, and an M16 thread for the adjustments!
I'll translate the measures to your strange systems later
We use these measurements now It's the Merkins that still use Inches and eigths and sixteenths!I'll translate the measures to your strange systems later
Helmetrock
Guest
Noone who knows at all?
If I'm right, there is only stretch force to count with, no force that pushes it together is possible to get? Or am I totally lost?
All info is of interest!
If I'm right, there is only stretch force to count with, no force that pushes it together is possible to get? Or am I totally lost?
All info is of interest!
I'd expect the major forces to be push/pull, based on acceleration & braking. There will also be shock loading in normal suspension travel as the rear shock is mounted to the swingarm. The paralever bearings & arm will take a lot of punishment when the rear wheel hits things like rocks & potholes. Torsional & sideways forces should be fairly low, but will increase if bearings in the swingarm & paralever mounts wear & possibly when the bike is leaned over in corners. As for the values to be placed on these forces, that's for someone with much greater knowledge than me...
I'd simply match the cross section of the OEM lever, correcting for material property differences. You'd have to make sure that the member section gives the same properties in compression.
As the lever is pinned at both ends, you don't have any bending moments / shear forces.
I'm sure I've just stated the bleeding obvious
As the lever is pinned at both ends, you don't have any bending moments / shear forces.
I'm sure I've just stated the bleeding obvious
Paralever
Why bother?, these things are sold in the states used to be advertised in the American club magazine. I would be worried about stressing the u/js in the swinging arm. Think the American idea was to lower the rear of the bike.
dave gs.
Why bother?, these things are sold in the states used to be advertised in the American club magazine. I would be worried about stressing the u/js in the swinging arm. Think the American idea was to lower the rear of the bike.
dave gs.
Helmetrock
Guest
Now I'm a pipe fitter/welder, not an egnineer, but I can't see at what point the push force would be?
As I see it, both braking and accelerating gives pulling force, and only when the rear wheel is pushed down by the suspension, any noticeable pushing force could be, but probabely I'm wrong...
The reason I want to build it myself, it because then nobody else has built it
A shorter arm raises the rear end of the bike, so that the steering angle gets smaller, and then giving the bike quicker steering!
The GS has a 365 mm original, and the other 1150 has a 385 mm arm, and my arm will be adjustable between those lengths for sports/touring
As I see it, both braking and accelerating gives pulling force, and only when the rear wheel is pushed down by the suspension, any noticeable pushing force could be, but probabely I'm wrong...
The reason I want to build it myself, it because then nobody else has built it
A shorter arm raises the rear end of the bike, so that the steering angle gets smaller, and then giving the bike quicker steering!
The GS has a 365 mm original, and the other 1150 has a 385 mm arm, and my arm will be adjustable between those lengths for sports/touring
Now I'm a pipe fitter/welder, not an egnineer, but I can't see at what point the push force would be?
As I see it, both braking and accelerating gives pulling force, and only when the rear wheel is pushed down by the suspension, any noticeable pushing force could be, but probabely I'm wrong...
The reason I want to build it myself, it because then nobody else has built it
A shorter arm raises the rear end of the bike, so that the steering angle gets smaller, and then giving the bike quicker steering!
The GS has a 365 mm original, and the other 1150 has a 385 mm arm, and my arm will be adjustable between those lengths for sports/touring
I don't think you really need the stress figures to do what your thinking.
What you do need to do is basically copy the OE part, building in your adjuster.
Use bar or tubing that is of similar size and thickness and your half way there.
Your biggest problem will be making the adjustable section with anchor points that will not have any movement where they connect to the rest of the link arm.
Bear in mind the adjustable section will have both push and pull forces at both ends.
Helmetrock
Guest
For the adjusting part I planned to weld a M16 or M18 outer thread into the arm itself, and then make an internal thread on the small piece on the gearbox, and put a contra nut(?) to stop any play in the threads.
What do you think guys?
I've made som drawings, but in swedish.
What do you think guys?
I've made som drawings, but in swedish.
Helmetrock
Guest
Could you please explain this a little clearer?
I planned to use either a stainless 16 mm bar or a stainless 22 x 3 mm tube, since that is what I can get my hands on at work! They are the same area as the the original, is that all it takes?
And then I will make a fork in one end, and a piece that fits the original bushing in the other end with an internal thread for the adjustment
Remember that anything you use in the construction will have to be able to withstand the constant push-pull forces of the movement applied to it by the wheel's and the weight of the bike etc.
In other words:
Make dam sure there is no freeplay in the adjustable parts of the arm and minimal lateral movement in the locating joints/ends of the arm, in a way much as you previously describe.
If you are planning to utilise the tube by threading it internally and then using a lock nut to hold it in place (note also the 3mm tube thickness will probably not be enough), it would be wise to use a finely pitched thread (more threads per cm). Similar to that found in a track rod on a car steering rack.
D6
Registered user
i recon its twice as strong as u need it
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