To go along with the real world results I posted in May, I have some new results from experiments I did yesterday and today. Keep in mind that if your sportsman is pre 2005 that the results would probably be slightly different for those quads because the front and rear spring and shock rates for 2005 were softened.

Test #1 was to find out the role that the torsion bar plays when one rear tire goes over a small bump or rock.
1. Put a car ramp under the rear tire that raises it 6 inches off the ground.
2. Put a medium size rider on the quad.
3. Use an angle finder to measure changes in suspension angles.
4. Measure the shock compression amount by measuring the amount of rod in middle of shock showing.

Without getting into all the data, the results were that there was only a very small difference in suspension movement between having the sway bar on and off in this situation.
As this was a static test I don't know if the suspension would react differently when the quad goes over the same size bump in a real world ride.

Test #2
This test is a static test to simulate body roll going around a corner or curve at speed.
1. Have a medium size rider stand on one floorboard will all his weight.
3. Use an angle finder to measure changes in suspension angles.
4. Measure the shock compression amount by measuring the amount of rod in middle of shock showing.

Without getting into all the data, the results were that there was a significant difference of the suspension action between having the sway bar connected and disconnected. There was no surprise that the quad had less body roll with the torsion bar connected.
Keep in mind that the torsion bar acts to increase the amount of tension required for the shock to compress.

Test #3
When the front tire of a quad goes over an medium or large obstacle there will be a significant weight transfer to the back of the quad. This puts a large load on the rear suspension. What effect does this have with the sway bar connected and disconnected?
1. Drive the quad up a ramp so that one tire is off the ground 16 inches.
2. NO Rider on the quad
3. Use an angle finder to measure changes in suspension angles.
4. Measure the shock compression amount by measuring the amount of rod in middle of shock showing.

I took pics of this one. They are similar to ones you have seen posted by other people. With the sway bar (torsion bar) connected, the suspension movement was appropriate and desireable.
With the sway bar disconnected there were problems. The one rear shock compressed completely until it hit the bump stop. This was with NO RIDER on the quad. With a rider on the quad it would have hit it sooner before reaching 16 inches on the ramp.
Also, the bushing on the top of the torsion bar was against the muffler. This is not desireable.

My conclusion is the same every time I do these tests, or tests on the trail. For the type of casual riding I do, I'm leaving the sway bar connected. I have a sway bar disconnect kit mounted so that if I want to ride slowly on technical terrain that requires extra articulation, then I have the option, but based on the results above I probably wouldn't disconnect it.

Keep in mind that test #3 may not have had those results with a pre 2005 sportmsman because of what I stated above about the 2005 suspension changes.

Also, as many of you are thinking, I can turn up the suspension preload on the rear springs to compensate for some of the negative results. This is true, but then the ride won't be as soft going over regular terrain. I get the equivalent of the preload by keeping the sway bar connected. This way I have the best of both worlds; the softest ride possible over regular terrain, and extra spring tension when I need it.

Since I don't ride slow technical terrain where extra articulation is preferred, I will keep the sway bar connected. For those of you that do, then you can clearly get a sway bar disconnect kit like I did so you will be prepared.

Have Fun. Ride Safe

 

uhm, would you write my next lab reports for me?[img]i/expressions/face-icon-small-happy.gif[/img]

 

ROFL........


Thanks though Jeff for the results...very interesting

 

In the real world i found a much better ride and traction with the terran i ride in, but there are sure trade offs.

 

Thanks Chris,
I know you have a lot of experience riding with and without the sway bar connected. Would you care to elaborate on the tradeoffs based on your experience?

Thanks.

 

I found that the type of trail riding i do ... under 30mph, 1 to 2 foot high climbs in tight hilly trails, and add mud/sloppy mix. The disconnect allows all four tires to stay on the ground longer, then if it was connected. This increases traction and sure footness (best word i can think of) ... this has over and over shown to allow me to go places others (polaris, honda, etc) get stuck in. During my rides i found many times the others i was riding with get in places were 2 of their wheels are in the air ... when i pass i can get by with only one wheel in the air, add polaris AWD i get past these points without getting stuck, or even slowing down. If you look at my site i have ramp pics with and without the swaybar ... i think the pictures tell the story much better.

[img]i/expressions/face-icon-small-smile.gif[/img]

 

I have those pics saved on my hard drive. The extra articulation afforded by removing the sway bar is very useful in the situations you described. Thanks.

 

Thanks Jeff, i think i'll leave mine connected.
Another thing to note is the extra travel in the '05 shocks and struts over previous models.

I think you need to do some of that testing with another year model back to back [img]i/expressions/face-icon-small-smile.gif[/img] although i don't think there would be much differance.


Jim

 

Are those GNX wheels on your GN?

Steve Lubecki

 

Yes, thanks for the comments.

Anyone else?