Originally written by gtoddvp on 7/16/2007 1:23 PM
Claude,
I contacted Motorvation and there is really no adjustment. What Gary told me was that if I wanted it to ride softer that I could pull the bar out, chuck it up in a lathe, and turn off about 0.010" between where it rides in the bearings. He says that will let it twist a little easier, resulting in a softer ride. The down side is that when I have a lot of weight in the car it will pull to the right unless I also install the electric lean.
I think maybe I should decrease the front end trail and build and install a sway bar before I re-invent Motorvation's suspension.Karl,
Did you add that damper to a torsion bar car?
.......................................................................
So the issue seems to be that your suspension is simply too stiff fopr you. I woudl at least take the torsion bar system apart and make sure it is not binding for any reason as it very well could be. It needs to be abel to twist under bump and recover under rebound.
Yes some have added a shock (just a shock) to a torsion bar suspension such as yours and maybe that too could be a good experiment.
I also see no reason why you could nto add a coilover shock to the rig if you wish and get rid of the torsion bar.
Personally I would be wary of turning down a solid torsion bar to decrease th espring rate. Many reasons for this and I am not saying it may not work but if it doesn't it coudl be a bad day for sure.A new smaller diameter bar woudl be a better choice for many reasons.
Let me say one more thing just as a food for thought thing. When a rig has a soft suspension on teh bike and a stiff suspension on the sidecar many times when on a road that has cross jopints that are not smppth and run 90 degrees or so to the direction of travel a rocking motion can begin to develope as th ejoints are crossed.
The sidecar wheel hits the joint and transfers weight to the rear wheel of the bike which compresses a little..then immediatley the softly sprung rear wheel hits the joint and the rocking motion between the sidecar wheel and the rear wheel of the bike begins. Thsi can be quite troublesome and aggrivating on a long straight stetch of road. It can also be felt through the bars on some rigs.
Claude,
I appreciate your input. I do believe that the rear suspension is a little soft. I have the pre-load nut tightened all the way up and it is still pretty bouncy compared to before I put the sidecar on. I put the rig on a couple scales to assess the load and with me on the bike and my boys in the car there's 625 pounds on the rear tire. The torsion arm is all good. When I disconnected the fixed end, it rotates freely. I think I'll see about stiffening up the rear suspension perhaps fabricate a sway bar before I start re-engineering Motorvations's suspension.
The reason I put a damper on, was because I changed the sidecar wheel from a 13inch Mini wheel to a 15inch Citreon wheel rim (similar looking to EML wheel's), to match the 15inch wheel's I have on the bike. To do this and have the sidecar sitting as low down as is practical and to get the sidecar wheel lead, I had to modify the swingarm which made it heavier. The sidecar now bounced quite a bit and grounded on right hander's (G.B.). I decided that the rubber in the torsion bar was acting as a spring would without damping, hence I added the damper and "hey presto" the hole rig sharpened up. I now have very little "low-down" in a right hander. I have those Italian shocker's on the bike (Maza-somthingy) which are rock hard in solo use, but pretty darn good on my outfit.
Safe riding Karl
Safe riding Karl
Originally written by outfit on 7/18/2007 5:56 PM
The reason I put a damper on, was because I changed the sidecar wheel from a 13inch Mini wheel to a 15inch Citreon wheel rim (similar looking to EML wheel's), to match the 15inch wheel's I have on the bike. To do this and have the sidecar sitting as low down as is practical and to get the sidecar wheel lead, I had to modify the swingarm which made it heavier. The sidecar now bounced quite a bit and grounded on right hander's (G.B.). I decided that the rubber in the torsion bar was acting as a spring would without damping, hence I added the damper and "hey presto" the hole rig sharpened up. I now have very little "low-down" in a right hander. I have those Italian shocker's on the bike (Maza-somthingy) which are rock hard in solo use, but pretty darn good on my outfit.
Safe riding Karl
Safe riding Karl
Motorvation has no rubber in the torsion bar mounting.
Claude
Please explain torsion bar suspension. I'm under the wrong impression here.
Safe riding Karl
Originally written by outfit on 7/18/2007 8:21 PM
Claude
Please explain torsion bar suspension. I'm under the wrong impression here.
Safe riding Karl
The torsion bars spoken of here consist of a full length steel bar that is in essence a torsional spring which works in a twisting motion. It is attached to the sidecar swingarm in various fashions and as the swingarm moves up and down it twists the torsion bar. The torsion bar by design wants to return to it former state so a spring motion takes place. The torsion bar runs in bushings of some type so it will rotate as it twists.
The types of suspensions many times referred to as torsion suspensions may come in various forms but may or may not include an actual 'torsion bar'. Some consist of a swingarm whose pivot point is captured in rubber. As the swingarm moves through it's arc motion the pivot point area twists the rubber in a circular motion. The properties of the rubber make it want to return to it's original shape and a spring action takes place. This is common on many trailer axle assemblies and some have bene adapted to sidecar usage. Over time it is said that due to the rubber actually being a part of the pivot itself fatigue within the rubber takes place and adjustments like toe in can go out the window as consitancy can no longer be maintained.
With a true torsion bar supension this is not a typical issue as the pivot bearing is unrelated to the direct action of the torsion bar itself.
The ones we do have a sidecar swingarm that is totally seperate of the torsion bar. The bar runs in its own bushings across the sidecar frame and has a 'torsion arm' running parallel to the sidecar swingarm that is linked to the swingarm with a vertical link consisting of heim ends. The torsion arm is simialr to a swingarm but runs below it and basically parallel to it.
Effective spring rate can be easily adjusted from stiff to soft by changing the leverage working on the bar by moving the link closer to or farther away from the pivot points.
This suspension can also be adapted to utilize a coil over shock in lieu of a torsion bar by the use of different suspension mounts.It also allows the addition of a simple shock absorber in conjunction with the torsion bar if desired when additional mounts for a shock are added.
Amazingly the torsion bar works quite well with no shock on it as there is a dampning effect in place due to the torsion bar action and mounting system itself.
How well any sidecar suspension works is dependant upon many things. To say a certain spring rate, whether it be in the form of a torsion bar , a coil over shock or even a leaf spring, is the best is simply to say that it is an okay compromise for what we are working with.
Spring rates (effective spring rates) if they are to work best shoudl be dialed in to what a given sidecar and bike combination consists of.
Universal shocks may work okay but improvemnts can usually be had. Adjustability is a good thing although we see little of it as far as effective spring rates go in the sidecar world. In other words a spring that may work on a sidecar attached to a large touring machine may be far too stiff for a sidecar on a lighter bike...or...maybe more commonly, a spring that works okay on a lighter bike combination may be far too soft if the same sidecar were mounted onto a large bike.
Everything is a compromise of course. The fact is that sidecar manufaturers do a great job of providing what is a very good compromise for all bikes that a given sidecar may be mounted to as far as supension go.
Can a suspension be dialed in better for a certain rig? Sure it can, but whether it is worth it in many cases depends on the rig, the riding style and how much the effort is worth.
Ease of adjustability is a good thing but is diffcult to obtain in some cases.
It sould be said also that in the case of some sidecar , Harley being the number one most common example, no suspension at all works quite well. Rigid sidecar supspensions with sprung bodies are noting new
Thank's for clearing that one up Claude. Mine has the rubber in and I suppose after 18yrs the rubber has gotten old. I'm not overly keen on this set-up anyway, as there's no room for adjustment.
Safe riding Karl
