Here's a completely different theory, but one I've read about on 2 or 3 occasions. Being a Polaris rider I didn't buy it right away but after 2 or 3 stories and then witnessing someone do it myself, I do believe this happens more than Polaris wants to admit....

The SINGLE LEVER BRAKING with an inexperienced rider, who may have panicked a little and grabbed the brake lever, is guaranteed a higher risk of "going over" vs. an experienced rider on the same quad who may lean forward a litttle more, not panic, keep the gas steady and make it over the same hill.

This happened when I and 2 other polaris riders were going over the same steep hill. The 2 of us who made it had our ATV's for awhile, they are both liquid cooled (slightly heavier front ends), and we easily crawled over this hill. The other guy's quad was an air/oil cooled 325 Magnum. Sure as $hit he hit the brake and leaned back in a panic, and over it went. No one got hurt, but because of his inexperience, he made this hill a lot harder than it really was.

Personally, I love the SINGLE LEVER BRAKING, but you should be aware of this risk.

 

I think that everybody is missing the point. If the rear tires start to slip and the 4wd kicks in the front can only PULL you up a hill or other obstacle. If the front end is LIGHT then the front end when it engages will lose traction and slip as if you were in 2wd. 4wd engage has nothing to do with a bike flipping over. I think it is driver error or he has no business going up that hill? 2pennies

 

What I'm trying to say is to try it on pavement (on pavement you shouldn't lose any traction), as you start go forward notice that it is harder to turn, that means that the 4-wheel drive is enaged without the rear losing any traction.

 

Interesting you guys havn't pulled a wheel hub apart to look at how the clutch works. I understand the 700 has a single clutch inside the front differential but it works the same -

On a wheel hub clutch - Behind that plastic cap there is a large hex nut looking component that has 4 rollers on each of the flat spots of the hex nut. The axle is always spinning with the drive shaft. If the wheel turns slower then the axle the hex nut is rotated and the rollers are pushed up to lock the hubs - provided the magnets are 1) energized (switch on) and 2) properly aligned

The earlier comment of 1/5 of a turn is half right. The rollers reach maximum extension at half of a 1/5 rotation - or 1/10. But it only takes half of the maximum extension to engage or about 1/20 of a turn.

Do the math - 25 inch tire times PI = outside diameter of the tire = 78.54 inches. A 1/20 rotation is = to the rear tires turning/slipping a maximum of about 4 inches to go from unlocked to locked.

Its a fabulous system to allow for differential tire rpm for turning but true 4 wheel drive traction.

I can address the roll over issue with the polaris. After adding the hi-lifter kit, HD springs, the wife on the back and a half of ton of accessories, it goes over backwards very easily. I'm recovering from the broken bones to prove it.

Never ever ever ever ever ride without a helmet. I got lucky. I should be in a wheel chair or worse.

 

Not that I am doubting your observations, RideRed, but that negates Polaris' own statements about how it works.

 

OK, read this

One of the drawbacks to the Hilliard clutch that Polaris uses for 4x4 is that there is no engine braking on the front tires (only the rear) Here's a little trick.

I copied this from another forum. It is an e-mail straight to hillard corporation who supplys Polaris.

I wrote to Matt Cowen, the Engineering Product Manager at Hilliard Corporation and asked a few questions about the Hilliard Overrunning Clutch used in the Sportsman ATV's. www.hilliardcorp.com/mcdboc2.php3
First my questions, followed by the response from Hilliard with their permission to share the information:
1) I regularly engage the AWD clutch for 4-wheel engine braking by causing the rear wheels to slip in reverse, stopping, then putting the machine in forward before descending the hill. Will this harm the clutch at all?
2) When I perform the above maneuver the clutch remains engaged, even while powering forward, until I switch off the AWD engaging coil. Is this normal operation for the clutch?
3) Is there a way to engage the clutch prior to wheel-spin, allowing me on-demand AWD?
----
Mr. Anderson,
The condition that you are asking about above is called "wedging". What you are doing is locking the rolls in the reverse profile of the clutch (it is a bi-directional clutch set-up) and proceding in the forward direction thus not allowing the clutch to overrun (which is the normal condition). This in turn locks up the drive train and makes the system steer like a fully locked differential. This condition is
advantageous if going down a steep hill becuase it will only allow the front wheels to move as fast as the drive train. This will fully utilize the engine brake because when going downhill the weight distribution of the bike goes to the front end and that is where you want the majority of your traction.

This "wedging" will not hurt the front gearcase, but it could accelerate the wear of the the drive train components (such as the front prop shaft) because it does completely bind up the system and the bike
will be very difficult to steer. Because of the binding and additional steering effort, neither Hilliard nor Polaris will recommend doing this.

You can get the system out of the "wedging" condition without turning the power off to the AWD system, but it is very difficult and
not always repeatable. The only true, 100% way to release the clutch is to turn the power off and put the bike in reverse. This will release the pressure on the clutch and the springs inside the clutch will return
the rollers back to the neutral position.

To answer #3, there is no way to drive the front wheels at the same time as the rear wheels without the rear wheels slipping. The bike is geared to have a 20% speed difference from the back to the front.
This means that it takes the rear wheel to slip or spin 20% (1/5th of a rear tire revolution) before the front wheel to drive the system. This is necessary to give the bike a tight turning radius and to prevent the bike from automatically "wedging". If the front to rear ratio was 1:1, every time you turn the handle bars even slightly, the front wheels would act like they have a fully locked differential and it would take
you 30 feet to turn a 90 degree turn (like driving a new Kawasaki Prarie with the front gearcase locked). Becuase when you turn, all of the wheels on the bike are now moving at different speeds dictated by the ground speed, and the front clutch would not be able to overrun. With the 20% speed difference, the AWD can be on all the time and it will only be there when you need it. You won't get any of the side effects
of all the other systems that don't allow you to turn the 4wd on and off. Basically, having the front wheels driving the same speed as the rear wheels would be like driving a tank and would be hard on the arms
and not very fun.

I hope I have answered all of your questions and not confused you to much. Browse through the overrunning clutch section on the Hilliard web site (www.hilliardcorp.com) for more info on how overrunning clutches work if you have any more questions. Have a good day.

Thanks,
Matt Cowen
Engineering Product Manager
Drive Train Products
Hilliard Corporation

phone: (607) 733-7121 ext. 376
fax: (607) 733-1045

 

Sorry Red, that is not correct. The front hubs don't lock until the rears spin.

 

RedRide,
The system is a bit more complicated than that,,,and It took a little while for me to understand it.
The tight steering is actually the hubs engaging.
The front tires will only turn (on their own) when the rear tires spin 1/5 rotation faster than the front.

 

I do believe the Sportsmans (at least my SP600) are butt heavy. When I jump its great because it flys straight and lands rear first every time. I'm not real experienced so I can only assume the *** weighs more than the front.

John

 

It may be heavier in the rear,,,but dont assume you will land perfect every time.

Landing on the front bumper makes for a bad day. Be careful.