On my 97 Scrambler 400 4x4, I noticed when I was cutting donuts, the 4 wheel drive was engaging without the AWD button on. What is the deal?

 

There are thin metal rings that are between the electromagnet and Hilliard clutch in the hubs are supposed to be attracted to the electromagnet when you turn on the 4x4 switch and cause drag on the Hilliard clutch, this drag makes the Hillard rollers climb their ramps and engage the front hubs. On my '99 these metal rings themselves had become magnetized. Not much, they would stick to a screwdriver but it wouldn't hold well enough to pick it up. But it was causing enough drag to engage the front hubs even when the 4x4 was turned off. They are only about $4 each and easy to change.

 

Notes on pulling the hubs:


First I recommend an appropriate shop manual for your quad. – Follow those instructions.

A few tips in removing and reinstalling the front hubs - Put jack stands under the front struts to hold the bike up . Have the weight of the bike on the jack stands under the struts. Without doing this when you remove the axle nut you could over extend the struts and pull the axle CV joint apart. Usually followed by numerous expletives and a trip to the shop to purchase a new CV boot ring because after two hours of unsuccessful attempts to blindly correct the problem inside the boot you succumb to taking it apart to re-assemble the CV joint.

Next - zero sand\contaminants are allowed in the hub\clutch\bearings. A parts washer and pressurized air to blow everything off is highly recommended. A $39 parts washer can save hundreds. I blow WD40 through the strut and inside bearings liberally and then air blow the axle / strut area as best that can be done.

Make sure the armature plate is not bent – even a little bit, and when reassembling ensure that the armature plate is flat against the coil and flat against the roll cage with the tabs correctly engaged in the roll cage. Flat means that the plate comes in contact with both the outer and inner coil lips – as checked at 120 degree angles around the coil. Not having the armature plate in the correct place is the other area most of us mess up and we damage both the armature plate and the magnet coil gap when we torque the axle nut which makes the clutches either not release or not engage for 4WD – there go providing the opportunity to do it all over again. Not having the correct coil gap prevents the energized coil from tightly "grabing" the armature plate slotted to the the roll cage and it not receiving enough resistance to torque around the cam and extend the roll pins – which is the goal to engage the hub to the axle.

Oh – keep in mind that you will have to lift the rear of the bike to facilitate rotating the drive train to assist in properly seating the front axle inner bearings into position.

Proper torque of the axel nut is required – first to 100 inch pounds, then back off and re-torque to 75 + whatever it takes to get to the nearest hole for the cotter pin.

Don’t forget to add fluid. Ford ATF or Polaris Hub Oil.

Again, verify this process and specifications against the appropriete shop manual for your quad.