I have heard this term alot in this forum(true 4-wheel drive), what is the difference in Polaris 4-wheel drive and other 4-wheel drive systems?

 

Polaris calls it true 4-wheel drive because when it is engaged it is indeed sending full power to all 4 wheels all the time irregardless of the traction conditions under the wheels. The system senses differential wheel speed between the front and the rear and then engages within 1/5 wheel revolution. I believe there must be a 20% difference in wheel speed before the system engages.
Other systems use a limited slip type system which does not supply full power to both front wheels in the same way. The way a limited slip system works is that both wheels recieve power under normal conditions, but when one wheel loses traction then both wheels can only recieve as much power as the wheel with the least traction can.
Just like a truck with an open differential, one tire on ice is spinning like crazy while the other tire on pavement is not moving at all. End result is you don't move at all because the tire with traction can only recive as much torque as the tire with the least amount of traction. A limited slip setup is just an improvement on what I described above only they have a torque bias which allows a little bit more torque to go to the wheel with traction.
A locker on the other hand will send equal torque to both front wheels whenever it is engaged whether or not one or both tires has traction. So if one tire loses traction the other front tire still recieves 1/2 of the torque going to the front. End result is you will continue to move.
Polaris system is in essence a locked type system in as that both front wheels have hubs which lock and engage those wheels whenever the system senses the differential wheel speed.

 

That was an outstanding explanation. Good job explaining that system that I myself have often wondered about.

 

I agree,that was a very good explanation.

Some folks really blast Polaris 4x4 system,saying that the 1/5 rear wheel slipage may get you stuck before the front wheels kick in?What a huge misconception.Polaris 4x4 systems works so well that you dont even feel the front wheels kick in.The only real drawback to this system is that the front hub seals do tend to leak alot and there is no 4x3 mode or limited slip,which allows the operator to steer the quad alot easier vs the locked [true 4x4] system.With Polaris 4x4s,you are either in 2wd or you are in true 4x4.Other 4x4 systems,like the underpowered Suzuki King Quad,the new 660 Grizz,Kawi 650 twin,have the option of 2wd,4x3,or locked 4x4.

Bill

 

If you want to make a believer out of non-polaris people who think they have real or true or call it whatever 4wd drive do this, use two garage jacks with the wheels on the bottom, put one under the rear and the other under one of the front a-arms and then drive back and forth on the garage floor and then do the same with one of the other makers 4wd systems.

 

While I think that the models Bill mentioned are leading the industry in overall transmission options (and maybe in practicality); I really like the way you can rip down a loose trail or dirt road on a Polaris and know all four are giving it hell when needed and backing off when you don't. Really gives you a sense of control at 'speed'(even if it's only 45 mph.).

Great thoughts by everyone,

John
'00 SP500

 

Another advantage of the Polaris system, is that it UNlocks when not needed (which is why it is called Demand Drive 4x4 system.
If you don't believe me try this. Lock it in 4wd. Climb a hill, or go through some mud or something. The front wheels will lock, right. Now, leaving it in 4wd mode, get up a little speed, and stomp on the rear brake (rear brake only). Notice that only the rear wheels skid. The fromt are allowed to 'freewheel' yet will lock in again as soon as the rear wheels start to spin.
Hope this helps explain it a little better.
Farmr

 

There are also a couple of disadvantages to this system too. One is when the system is engaged and the wheels start to spin if both front wheels don't lock in right away ( and they don't always)when the wheel finally does engage , the other wheels are spinning quite fast. Guess what happens next. Ever seen an exploded CV joint in a polaris? Also when backing up after disengaging the 4 wheel drive if the wheels don't both disengage ( and they don't always)the machine can take a nice hard lunge to the left or right. Seems strange but if I'm right, the front end was totally re-designed on the 700 to be similar to the other "true 4x4" quads on the market. They now use a servo and lockout in the diff. instead of the axles.Could this be cause they had a problem with replacing a lot of axles under warranty?...... Elroy should be able to verify if this is true.

 

Well!! I now know what true 4-wheel drive means and it sounds good except that last reply from sparkys. Do any of you think the 4-wheel drive system on the Prairie 650 with the posi lever is good also. Thanks for all of the info on Polaris. Pryormountainman
, that was a very good explanation. Thanks.

 

Sparky,
even with all the trouble's I've had with my Pols,I have never had a problem with excessive rear wheel slipage BEFORE my fronts would engage.There is a rev limiter that is set at around 2300 rpms to PREVENT the problem you talk about.If engine rpms EXCEED 2300 rpms,the fronts hubs will NOT engage unless they were allready earlier activated at a lower rpm.Your explaination makes no sense to me.As long as the quad is moving,ALL the CVs on a Polaris 4x4 system are ALLWAYS turning at the SAME speed.Since the CVs are also attached to the front 1/2 shafts,how can damage occur to the CVs if more rear wheel slipage occurs before the front wheels actually engage?I could see damage occuring to the FRONT HUBS if the Rev Limiter was not doing its job,but not the CV joint?If im missing something here,please explain it to me.I dont want to be left out in the dark on this.

On the fronts hubs not disengaging?
This usually occurs by not having your front bearings adjusted correctly and a lack of hub oil.Correct this problem,and it GREATLY decreases the probability of this happening.

Your correct on the 4x4 for the new 700,they did redesign this on that model.

Thank You,
Bill