Out-rigger Tires, Turning, Highway Speeds and Tire wear
My Pulse # 199 has air-shocks front and rear. I have an onboard air pump, pressure gage and switching valve to monitor and or adjust front or rear shock pressure while driving.
I have been driving my Pulse for over several months and racked up almost three thousand miles driving back and forth to work. I commute twenty-five miles one way. Eighteen miles of that commute is driving at speeds from 70 to 80 miles an hour. After becoming very confident driving this vehicle at highway speeds I have been playing with raising and lowering the air-shock in which rises or lowers the body/out-riggers. I have found the Pulse is best driven with the out-riggers just touching the ground. When making a normal ninety-degree or more turn in a Pulse with air-shocks, the out-rigger will lift six inches or more depending on the speed and pressure in the air-shocks. After completing the turn the body/out-riggers stay high until the load comes back on the shocks and has time to settle. During this time the Pulse will teeter-totter from out-rigger to out-rigger, creating an annoying, unwanted and possibly dangerous situation. What causes this is the air-shocks (mainly the rears) unloading/extending from the side G loads in the turn. This is also confirmed by watching the air-shock pressure gage drop drastically. Once the air-shocks are unloaded/extended it takes a few seconds for them to settle back to normal ride position. The air-shocks being under pressure are actually helping (pushing) to assist the excessive roll problem. Bob Cervero has Pulse #61 with coil shocks and it does not exhibit this problem. One way I have found to help over come this problem is to lower the air pressure in the shocks. This has the major draw back of increasing the load and friction on the out-rigger tires. My first set of out-rigger tires lasted less than four hundred miles which is another problem in its self.
So how do we fix this over roll problem? Bob and I were discussing the problem and he came up with and idea of limiting the swing-arm travel. With that in mind the ideas starting flying. One idea would be to attach a right-angled rod by the upper shock mount and provide sliding blocks on swing-arm that the rods would travel through. The very ends of the rods would be threaded for adjustment and have rubber bumpers to soften the end limit of the extension. The adjustment would allow you to set the total ride height and control the lift of the out-rigger tire. This is another project I plan on doing on the Pulse.
Ok now Iím going to start some controversy about the Pulse. My personal finding with owning a Pulse is this vehicle was never designed to drive on two wheels down the highway. The geometry of the production LiteStars/Pulses front ends are not set up to do this. There is no way you can get feed back from countering steering like you do from driving a motorcycle. The Pulse uses a gearbox with reduction for steering, which completely eliminates any counter-steering feed back. To learn more about counter-steering go to this link and look for counter steering. http://www.msgroup.org/DISCUSS.asp
I have tried many times at highway speeds to do this and found it to be dangerous. If you have ever ridden a motorcycle and left the kickstand down and tried to make a turn you would understand. I have been able to keep the Pulse on two wheels for a short time. Itís very hard to do this because of wind conditions, your body weight changing slightly to one side or other cars passing and creating wind turbulence. Riding on two wheels means at sometime the out-rigger tire is going to touch. When this happens at highway speeds things become very dangerous, the teeter-totter from out-rigger to out-rigger can become very rapid and excessive. Over controlling when this happens would result in a disaster at this speed.
This also brings me to why the out-rigger tire wear is high. When driving with the out-rigger tires just touching at highway speeds creates excessive wear on them. Even the very slightest turn scuffs the out-rigger tire from side to side. Because of the outrigger tire location the tires will always scuff sideways when you turn. This can best demonstrated by just pushing the Pulse while turning and hearing the outrigger tire scuffing. Air pressure had made a major difference in tire wear so far. I have tried several tire pressures with the current set of tires and hope to get about 1200 miles before I have to replace them again. I am currently this set of tires at 13psi and will try 10psi on the next set of out-rigger tires. The first set of tire I was running 65psi and got less than 400 miles on them.
Coil-over springs kits and
standard automotive shocks would not allow for the major differences in
loads (passenger, gas, carried items) but does help in the rebound as the
standard coiled shocks installed on some production units. By using my onboard
adjustable air-shocks I have found the best shock position to be with as little
load as possible on the out-riggers tires. This is hard to judge unless you
raise the shock height while driving until you can teeter-totter then just lower
the shocks until both out-rigger tires just touch. With the on board air-shock
pressure gage this allows you to preset your normal load setting with out having
to do this each time. The only time I have found more load on the out-rigger
tires helps is when there is a heavy cross-wind driving at highway speeds. Also
I have found Pulse handles better with a passenger load driving at highway
speeds. One other plus for having air-shocks is when backing up by pushing or
using the electric reverse unit. Itís much easier to move the Pulse backwards
when one out-rigger tire is lifted. This is especially noticed when making even
a slight turn in reverse. Using coiled shocks and changing loads does not allow
you to adjust the delicate load requirements to minimize the out-rigger tire
wear. I have also found that the front air-shocks require only an initial
adjustment for an loaded or unloaded passenger load. I run the front wheel
height between 10 and 11 inches. This height is measured using a ruler from the
ground level to the front body edge of the front wheel cavity, taken at the
center of this opening. The rear shocks do the most for load adjustment because
of the loaded position of the passenger and storage compartment.
I have never checked the toe-in because there is no adjustment to correct it, but you can control the camber of the out-riggers to help decrease the wear at the center of the tire.
The U.S. DOT defines motorcycles as "any vehicle that maintains not more than three wheels in contact with the ground and has a saddle seat for the rider. Is the LiteStar/Pulse a motorcycle? I find the LiteStar/Pulse design runs mainly on four wheels and sometimes rides on three when you are turning. This is why the out-rigger tire wear is so high they are almost always in contact with the road. I have a demonstration video that was made for marketing the Pulse and you can see that it rides on all fours when going down the highway and lifts a tire in a turn.
I am also in the process of building a high point tire balancer for the eight-inch out-rigger tires. Automotive tire balancers were never designed for this small of a tire and they do a poor job of balancing them. I will post more on this when it is completed.
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