This last weekend I saw another Sportsman roll down a hill. Like the two previous times I've witnessed this, the machine was going up hill when the front end came over. In every case the riders were mostly ok (this last guy cut his eye up pretty bad though). Now, I've been writing this off to rider inexperiance, but this third event has me wondering...

I remember reading somewhere that Polaris' 4wd set up is such that the front tires don't actually engage unless the rear tires lose traction. Perhaps I read that wrong, but proceeding on that premise, isn't this a little dangerous for hill climbing? In the situations above the riders were in a gravel pit and there was plenty of traction for the rear tires to hook up in. Assuming the drivers were in 4wd mode and what I think I read is correct, there would never be a loss of traction at the rear.

Perhaps it's something else, though, like weight bias. Are sportsman's "butt heavy?"

But then, maybe it really is rider inexperiance. Or maybe I just see more Polaris roll overs because there's just more of them around.

Polaris riders, please don't take this as a slam on your machines, I think Polaris makes fine machines, though I'd not chose one for myself. I've even recommended them to others. I am just wondering if there is something to the design of the machines that would make them more prone to these types of roll overs.

 

On Demand True 4-wheel drive. not no 3.5 wd crap. all four wheels pull on demand flip the switch and what the sportsman throw mud and dig in. unlike other models all 4 wheels are pulling not the 3.5 wd (when one front wheel spins the other will THEN start pulling) rider inexperience and steep hills may be the problem

 

I am not questioning the 4wd vs 3.5wd issue. What I read was...

"Polaris’s On-Demand 4WD system features a thumb switch to choose between rear drive or “traction-sensing” all-wheel-drive, which engages both front wheels with full torque (no limited-slip differential) when the rear wheels lose grip." (emphasis mine)

In the situation I described, the rear wheels would NOT lose grip so, by extrapolation, the "traction-sensing" would NOT engage the front wheels and this would encourage the flip.

I've no doubts about the performance of the sytem in general, they seem to be excellent in mud, for instance, perhaps second to none, but if what I've read above is true, couldn't that be dangerous in some up-hill situations?

 

it is on demand true 4-wheel. the tires are going to pull not matter what. traction sensing or NO traction sensing

 

With all due respect, dbass, that's not what I understand it to be. From what I understand, pressing the 4wd button engages the system but 4 wheels are not driving unless the torque sensor senses slip in the rear wheels. When it does, THEN all four wheels are engaged. True four wheel locking is excellent in mud and this system would excel there as well, but in the hill climb I mentioned the rear wheels would NOT slip so the torque sensor would NOT engage the front wheels even if the 4wd button was pressed. When the rider (and there probably was some inexperiance involved here) applied throttle because he didn't think he was going fast enough to make it up the hill this system wouldn't help him.

Again, I am not trying to bash these machines, but I would like to know what people think on this issue. I've had no problem climbing these same hills on my cat and I am by no means an expert. The cat, however, has a weight bias towards the front (helps keep it down) and when in 4wd mode (which I use on these hills) there is always power going to at least ONE of the front tires (no sensing system to engage). I'm not touting the Cat's advantage over the Polaris here, there are other situations where the Cat would be left behind, I am sure.

 

Pechmial,you are right the rear wheels must loose traction or spin before the front wheels will engage.When I say loose traction I mean you probably wont even feel it spin before it will engage the front wheels it takes just a few seconds.

 

I'm going by memory here, but I think it only takes like 1/5 of a wheel turn (slipping) to engage the front hubs for 4 wheel drive. I've rolled my SP500 over going up a steep hill in W.V. while riding. I think it had a lot to do with my inexperience and that the rear shocks were set to the softest setting. I'm only guessing here. But since then I've increased the shock setting up 2 notches, the rear doesn't squat as much going up hills now. Of course this is in Florida where most of the hills I ride up are actually pits and we're riding up out of them. When I bought my SP500 the rear shocks were set to the softest setting for a great smooth ride over rough terrain. But for hills I think you should increase the setting up at least 2 notches. I've read about this setting online here and it seems to work for me.

 

Pechmial
You are right it does take the wheels too spin before the front kicks in , And you are right it can be missleading if you do not understand it I myself have had my scram almost come over on me because I was going up a steep rock face with all kinds of traction so that the front did not engage to hold the bike down I am not goin to sugar coat it , it can be dangerous.I think when you lock them in they should stay until switched off but yhey do not come that way right now so I guess I will just have to live with it , But the advantages of the system surley out do the negatives.

Just my 3 cents

 

The front wheels will engage as soon as the rear slip (when the switch is on) but not before.
Is it dangerous hillclimbing??? I personally don't think so. Here are my reasons why:

If the front end comes up & over, it would flip anyway, in my opinion. For example, a 2wd machine with the same weight bias will flip or spin out, right? If it can't spin, it will flip. Same deal with the Sportsman, when the rears have enough bite that the front don't engage. A flip occurs when the center of gravity is higher than the balance point (rear wheels). This will happen regardless of the machine.
Around here the Sportsmans are pretty much the kings of the hillclimb, but they do require an experienced rider. They have more ground clearance than most machines. This gives them an advantage for clearing obstacles, but the driver must lean forward more/sooner than with a competetive machine. The soft, independans suspension allows all 4 wheels to remain in contact with the ground more than most any machine without IRS, but can squat more, particularly when set up too soft. Think about it this way. The guy has the suspension set up for 'average' riding. Then he adds all his gear, which makes the rear end sag down some. Then he starts going up the hill, causing even more weight to transfer to the rear, which makes the rear end sag more. This has the effect of making the hill 'steeper' than it really is. Add to that the fact that the machine is taller than most, and you have a recipe for a flip. However, in almost every case I have seen where a Sportsman flipped, it was with an inexperienced rider, and more often than not, an inexperienced rider with the rear suspension set too soft.

I can think of one instance where the Polaris 4wd system would be worse than full time, though. Climbing up a hill with excellent traction, and with a 'shelf' somewhere in the slope (I find them fairly often right at the top). If you are crawling up the hill, without enough momentum to 'bounce' over it, you can flip. The front tires hit the ledge, and the rears have to slip 1/5 of a turn or so for the front to grab. This is only about 6 inches or so, BUT, if you are already at an extreme hill, that just may be enough to kick the front end up in the air. If it were already engaged, the front wheels could help climb over it gently enough to avoid a rollover.

Farmr

 

That was some awesome explaining!!! Lost1, what do you think?