Seeking Opinions on SC Suspension Mod

For my Turbo RoadKing/ Spyder rig I used a Magnum air shock rather than a coil over to upgrade the suspension on the older car. This also allowed ride height adjustment for different loads and roads. (Cheap tilt control).

Lonnie
Northwest Sidecars

Lonnie,
Any chance you could give me a little more information on your set up? I suspect the swing arm on the Spyder is similiar to the Roadster so I would really appreciate it if you could snap a couple shots of where the shock connect to the swing arm. Also, if you could share what compressor and control devices you're using to adjust the shock.
In your opinion, does a "sprung" sidecar ride better than one on a torsion bar?
Thanks

I no longer have this outfit.You can get an idea from the picture where the shock mounts. This particular shock had a maximumPSI of 90 lbs. so a conventional compressor was used with an automotive tire gauge.
A shock controlled suspension offers a much better ride than the old torsion setup and it is adjustable.

Lonnie

Lonnie wrote:
>>A shock controlled suspension offers a much better ride than the old torsion setup and it is adjustable.<<

A torsion bar is a spring. A coil is a spring also of course.
Torsion bars twist and return to their original shape as do coils.This is what makes a suspension do what it does.
Torsion bars due to how they are mounted do exhibit some dampenig on their own. Coils do not.
The idea of running a torsion bar with no shock is doable but they also can work in conjunction with a shock. Adding a shock along with a torsion bar is a good plan and is far from uncommon.
Torsion bars can easily be made to be adjustable as is done on many sidecar setups. We utilze a system where the bike end of the bar can be moved with the use of one bolt which winds up the bar to change ride height. This also will increase effective spring rate to a point. We also have a static adjustment at the active end of the bar that allows it to be set soft or stiffer when the leverage at the torsion arm is changed.
The Spring rate of the torsion bar itself is decided by it's length and diameter. The effective spring rate of the torsion bar system as a whole is decided by the lenght or the arm connecting it to the swingarm of the sidecar. Long efective arm = soft and short effective arm = stiffer.
So, just to set the record straight a torsion bar suspension can be made to be stiff or very strong if allowance for thsi is built into the system. Ride height can be adjusted easily also.
Dampening can be adjusted with a shock if the need is required.
Remember that a shock controls the bounce and rebound of a spring whether it be a coil spring, torsion bar or a leaf spring. A tosion bar and even leaf springs have some damping of their own. A coil spring has little to none. The addition of the right shock can make a lot of difference with any suspension system.

Note that I was referring to the "Old torsion system" on the Motorvation.
Like the "Old torsion system " on the early California sidecars there is much room for improvement.
In the performance field there are those who prefer torsional suspension, some who prefer coils and shocks, some like air ride, some like Blonds, some like all wheel drive.
I'm partial to Redheads and coil over shock suspension with one wheel drive and no sidecar brake.
Haven't tried the Panhard bar yet. But I'll probably like that too.

Happy Birthday America and many more.

Lonnie

Claude,
I appreciate your input, but based on your response, perhaps I wasn't specific enough as to what I was after. I ride the rig empty quite a bit, ignoring the 50 pound bag of sand I have behind the seat. Empty, on our segmented California freeways, it's pretty bad with the sc wheel bouncing all over the place. With my twin boys in the car, about another 100 pounds, it's better, but still pretty bouncy. With a slender adult and my twin boys in the car, now approaching 300 pounds including the sand bag, it's pretty good. What I was thinking was un-attaching the fixed end of the torsion bar and just using it as an axle. Then adding a good quality shock with an air bag to control the height of the car. Empty, I'd have very little air in the bag because there'd be little to no weight on it. Then as the weight in the car increases, I can increase the air pressure in the air bag to compensate.
I guess what my real question is: is this a good idea.
I know very little about sidecars and have only been riding this rig for a few months. The one thing that I am sure of right now is that the sc suspension really sucks the way it is right now. I had considered just adding a shock for dampening, but for the same amount of fabrication time I can put in a shock with an air bag.
I'm asking because I'm sure that there are a lot of things that I don't even know that I don't know. Know what I mean?

Todd,
You may wan tto give Motorvation a call. They are great to talk to and might be able to give you some good advice. It could be that th espring rate of the torsion bar is too stiff or maybe it is binding in it's pivot area.
You idea of converting to a shock is a good one without question though.
I have nothing at all againt shocks and hope I didn;t coem across that way.
Lonnie a panhard bar and an antiswaybar are not the same thing 🙂

So is it a general consensus that a shock and spring type suspension is better than a torsion bar suspension?
I'm asking this question of, and appreciate any and all those experienced riders that are willing to take the time to answer the question.

Originally written by gtoddvp on 7/5/2007 4:36 AM

So is it a general consensus that a shock and spring type suspension is better than a torsion bar suspension?
I'm asking this question of, and appreciate any and all those experienced riders that are willing to take the time to answer the question.

I have owned both and have built sidecars with both. Either will do very well.
The coil over shock suspension is easier to fabricate from a manufacturing standpoint. All there is is a swingarm on the sidecar with a shock mount on it and a shock mount on the sidecar frame at some point. Bolt on the shock and go with it.
The torsion bar suspension ,which is also a spring,works very well also. It is a little more involved to design a sidecar suspension with a torsion bar which indicates that those of us who like them are willing to go a little farther to utilze them.
So what is the good side of a torsion bar ? In the form that Motorvation and we use them they do allow an straight forward means to provide a manual tilt adjustment. They can also be adapted to use an electric tilt pretty easily. The electric tilt does add cost to the assembly where as the manual tilt adjustment is a standard feature on the ones we do.
With a coil over shock suspension some type of linkage must be fabricated to allow the upper shock mount to be moved to adjust the tilt. This is typically an optional upgrade.
Lets look at the torsion bar system we use. The bar is a true torsion bar with splines on each end. It runs through a torsion tube across the sidecar frame with bushings on each end. On the swingarm end of the torsion bar is what is called a a torsion arm. It attaches to the torsion bar's splined end and runs back parallel to the sidecar swingarm and below it. In the swingarm as well as in the torsion arm is a series of holes. There is a link that connects the hole in the swingarm to the hole in the torsion arm. Effective spring rate is related to how long the effective length of the torsion arm is. Short arm = stiff and long arm = softer. So, by moving this connector link farther out on the torsion arm and swingarm we can adjust from a stiff to a soft suspension. If you are droning down the interstate you may want to move the link to curtail the effects of the bump bump bump that joints in the road can cause. If you are going to run the twisites you may want to stiffen things up for better handling with less roll in the turns. You may find a happy medium that is best for you with a passenger on board but you can change it if you want whenever sidecar loads change. If you don't want to play with the adjustment you will find a place that is a good compromse for a plush ride and handling. In essence the effective spring rate can be easily altered as opposed to a typical coil over shocked suspension.
Ride height can also be changed with this type of torsion bar suspenion by moving the torsion arm on the splined end of the bar. This has little to noting to do with any spring rate variations taking place as we are not twisitng the bar up as we would be in compressing a coil spring when it is adjusted.
The manual tilt adjustment with the torsion bar is simply done by a bolt on the bike end of the torsion bar to allow the bar to be wound up when turned. This jacks up the sidecar susupension and tilts the rig left or right. Some have hooked a rachet on this bolt to allow adjustments to be made on the fly. Of course a linear actuator can also be incorporated into the system to provide an electric tilt.
Torsion bars are usually installed on sidecars with no shock as they have some dampening effect due to the way they are mounted. Yes, some have added a shock and felt it was a good thing but we have not seen a huge advantage to that. When adding a shock on a torsioin bar suspension we are speaking of just a shock and no coil spring. I have used conventional shocks and also adjustabel racing shocks where you could opt for different bump and rebound settings. Have also used the old style lever shocks and they

Claude,
Chocolate or vanilla take you pick?
If we add the coil over shock to the torsion bar will we have Neapolitan?

(Just had to break the seriousity for a moment, It's my nature.)

The Panhard bar bit was a favorite subject of the times from my sporty car racing days in the fifties and sixties. Used mainly by the elite "Teabaggers".
I was Morris Garages with Study or Olds V-8 power and most wouldn't even wave as I blew past them in 6th gear (3rd Overdrive).
It was coils and shocks then too (Vanilla).

Lonnie

Claude,
Chocolate or vanilla take you pick?
If we add the coil over shock to the torsion bar will we have Neapolitan?

(Just had to break the seriousity for a moment, It's my nature.)

The Panhard bar bit was a favorite subject of the times from my sporty car racing days in the fifties and sixties. Used mainly by the elite "Teabaggers".
I was Morris Garages with Study or Olds V-8 power and most wouldn't even wave as I blew past them in 6th gear (3rd Overdrive).
It was coils and shocks then too (Vanilla).

Lonnie
......................................................................
A Panhard bar keeps the rear end in place side to side and also provides an adjustment to move the roll center up or down. NASCAR racers refer to these as 'track bars' today. When listening to a race you wil hear the annoncer say " They came in and made a track bar adjustment". What they did was raise or lower the roll center slightly to correct an understeer or oversteer situation. For some time panhard bars were caleld swaybars by many which was really wrong.
Swaybar (actually anti-swaybars) hook one side of the vehicle's suspension to the other side through a torsional spring. This allows for much flatter cornering. The open wheel road racers have used a cockpit adjustment to preload th eswaybar for quite a while for on the go dialing in of the chassis.
Coil overs are popular in most racing today as they do allow less unsprung weith than leaves and springs can be changed easily on the shock itself. Sprint cars, midgets, silver crown cars and the like are pretty much split today between torsion bars and coil overs. I think the current trend is coils with the midgets althoug sprints have come full circle back to the (Neopolitan) torsion bars.
Don't get me started on teabaggers and so called gentlemen drivers..lol. I have seen a few of the sporty car set try the non winged sprint car dirt track world and it was a cross between amusement and out right disaster at best.
Have also seen the revese take place when a good frind of mine who ran midgets for years got a ride in a Bilsten cup car years ago. First time he drove inside the parade going on by the gentleman racers and they had to goof up their precious school learned entry to the apex of the turn they sure cried a lot. He felt that he came to race and they just could not grasp the idea of that...lol.
I won't get into the time we had just finished building a stock car and took it to the local auto cross event for giggles.(We were th eonly ones giggling I think). Of course the small block chevy we stuffed into that austin healy was a cardnal sin too...but that si another story..
Sorry for rambling....hope everyone gets over it 🙂

I used a damper unit from the rear suspension of a car to calm thing's down on the sidecar wheel. This it has done admirably (probably too much when sidecar is empty, but spot on when loaded up), as with anything it's a compromise. I did use quite a heavy damper unit that was lying around in the garage, just because it was at hand.
Safe riding Karl

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?

I think we call it "indispension" over here (GB).Is it a moulded rubber suspension unit as is ussed on trailer's? If so then yes that's what mine's like.
I run the damper off the suspension arm and fixed it to the sidecar frame using a plate and exaust clamp, so that I can alter the length (if and when I decide to put a softer one on). I had to weld a mounting bracket onto the sidecar suspension arm for the damper, that was easy to do.
Safe riding Karl