I know this topic has been beaten to death. I have spent the last 3 hours searching and reading posts on the subject among the various forums. It is something that I would really like to have for two reasons: 1.) 4 wheel engine braking 2.) Option of having front wheels "pull" rather than only having rear wheels "push" before awd engagement. Just to be clear, I would only want this if I could add it as a third option: 1.)2wd 2.)on demand 4wd and 3.)locked by choice. I have looked at the manual and schematics and read the posts and I am not 100% clear on what role the magnetism plays. W/O the magnetism set up would that mean no 2wd option? I think I understand that the actual engagement is mechanical and not electrical. A fellow who I ride with owns a yamaha wolverine that he modified by installing a polaris front differential (housing or whatever is really is), front axles and hubs. He did all this and still has the twin a-arm set up also (not applicable for the info I need, just FYI at no extra charge). Anyway, he now has selectable 2wd and true 4wd instead of the full-time 3.5wd he had before. In talking to him, I got the impression that when he flipped his switch to engage 4wd that it automatically locked in w/o the need for rear wheel spin. If that is the case, I suppose he could only do this while stopped? I also understood it to stay locked until the switch is turned off. That was then and this is now (after reading posts and service manual). After doing the research, it seems that the polverine has the same set-up as the factory polaris units (i.e., the front axles need to "attempt" to turn faster than the front hubs/wheels. Is there any way possible to keep the hubs engaged until one desires to disengage them? I know the knowledge is here; so, if someone could straighten me out on this I would definitely appreciate it. If it just can't be done, tell me, but please explain why so that I will stop wondering b/c in my opinion if this was added as a third option, the sportsman would be the perfect atv.

 

Their is nothing that can be done without major modification.
From what you've said about your friends quad, I don't see how it truley locks on and stays on. It can't if it is all polaris stuff. Would take some very impressive machine work to put the polaris hubs on a dual a-arm set-up.

 

Another problem that would arise out of a true full-time AWD is that the front and rear differentials have different ratios (3.82:1 for the front, and 3.10:1 for the rear). Your rear wheels would be turning faster than the fronts, which would cause some major tire wear in the least. Not to mention the stress and potential breakage of parts when the machine was running on surfaces with good traction.

-Mark

P.S. These ratios are for the '02 SP700. I'm not sure if they're the same for other models.

 

After reading the preceding replies on here and at the following link,

<http://66.216.19.154/Forums.htm>

I now understand it and that it can't be done. I knew that the front and rear gear ratios were different, but wondered how that was possible. I guess it means that whenever the front wheels are actually pulling that they are turning just a little slower than the rear wheels and when 4wd is not engaged (hubs not locked) the front wheels are traveling the same speed as the rear only b/c the front wheels are actually freewheeling on the hubs. I suppose that also means that quads with conventional front and rear differentials have the same ratio in the front and rear just like in a 4wd truck? Thanks for all the input, I have learned more about my quad in the last two days than the 1.5 years I have owned it.

 

When I changed tires on my Scram I found the fronts to be slightly taller than the stock ones and the rears were exact. This changed when the front wheels engaged and actually started pulling. Instead of engaging after the rears spin 20% (or 1/5 rev.) faster than the front they now engage instantly because the fronts are not rotating with the 20% differential than the rear as designed. This is good and bad no lag time which is not a negligible in mud but is a plus on rocks and a slight turn causing one front to spin faster will engage the awd causing hard steering.

If you want to experiment with tire sizing you can make the Polaris system engage instantly.