I think one reason I bought a polaris was true all wheel drive and the abilty to turn it off.If honda had a system like that I might have went with them.I do enjoy playing in two wheel drive.And when time for work or rough 4x4 is just a push button away.

 

Sportsman,

Don't you mean a pushbutton AND a wheel spin away, since you are only in 4 wheel drive when the rear wheels spin faster then the front ones?


Just wondering. Mine is one lever pushed forward and NO wheel spin.

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Eric Baatz

1996 Suzuki KING QUAD Remember the KING Lives!!

(Duplicate post deleted.)

[This message has been edited by atvbbs (edited 01-19-2000).]

 

I never notice the wheel spin when going foward but it noticable when backing up.like trying to back up wet loading ramps.It wants to slide to the side have learn to spin a little before starting up to kick in the hubs.

 

Bob,
YES, the Polaris PVT system does shift back if you have an "overgeared" situation. In other words, if you're cruising along at 10 MPH on flat ground... Then you start up a hill, the transmission will "back shift" and allow the engine to return to its power range so that you have maximum torque for continuing on up the hill...

 

Gentlemen,
To be honest I did not care for the belt drive like Polaris for the first ten years because of all the horror stories I heard about water and burning the belt up. About 3 years ago I lost all 4 of my quads in a fire, 86 LT250R, 87 LT500R(my baby), 86230E, and a kawi 300 bayou, anyway I was now in need of a sport utility quad for the approaching hunting season. I came across a 1997 sportsman 500 left over in Detroit for an awesome price, I bought it and I love it. I liked the suzuki king quad but i wanted something that my father could use since he had knee surgery at that time. The best feature is the independant rear, this thing is like a hummer with no rear end to hang up, and I have never had any problem with water entering the belt area, but I do take great care of this machine. I have had her buried up to the seat in mud and still no belt slippage. The automatic is great when we are out exploring, I can use my Gps or talk on the cb with out worring about what gear I am in. I have since built myself a new and improved Zilla fOr when I feel like jamming some gears, and then my girl rides the sportsman and man can she rip on that oversized monster. As for wheel slip, It only takes a 17% difference between the wheels to engage the 4WD and it is hardly noticable on my machine. The king quad's setup is pretty awesome to, and those bikes are damn near bullet proof, but the sportman has work extremly well for me and I will buy another one when it is time to upgrade. See ya



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quadzilla and 500 sportsman

 

Tree Farmer, hope you catch this. I did a search on this subject and found your thread. I would appreciate an explanation of "torque sensing" limited slip front differentials (offered by Honda, Suzuki &?) and their distinction from traditional limited slip, if any. Also, some designs are promoted as "ratcheting cone" type, apparently similar to automotive design; and in one case made by Fuji, maker of differentials for Subaru. Appreciate any info on such as well. Thanks.

p.s. this board's informative value is greatly enhanced by your participation.

 

1/5 of a rear wheelspin isn't that much. It's not like spin for 5 seconds before the front engages. As a matter of fact, you never notice the rear wheels spin. Just my 10 cents.

 

Thanks for the kind words, mtngoat; however, some Forum readers hold opposite opinions!

"Torque-sensing?" Hmmmmm. Does the phrase contain specific meaning, or are ALL limited-slip differentials torque-sensing?

Is the phrase Madison Avenue (advertising) jargon for a generic process, or uniquely meaningful?

I don't know the answer; however, I think ALL limited-slip differentials MUST sense torque difference between their two driven side gears; my limited understanding suggests this process engages whatever torque-biasing mechanism they contain: clutch packs, cones, ratchets, whatever.

In differential action, one side gear rotates faster than the carrier (the spinning wheel's, when one side loses traction), and one gear rotates slower than the carrier (the one belonging to the wheel with better traction). All limited-slip differentials I've looked into attempt to retard the spinning side gear by "mashing" it into a clutch pack/cone/ratchet, connecting the gear to the carrier so the gear can't run away entirely, biasing torque to the gear whose wheel has better traction.

(An alternate technique: a modern automobile's "traction assist" feature automatically pulses the brake of the spinning drive wheel through the on-board ABS computer, thus biasing torque to the wheel with better traction.)

In the case of an automatic or command locker (like Detroit Locker or Suzuki/ARB Lockers, respectively), this lockup with the carrier is solid and positive. With all limited-slip differentials, the lockup is just that--"limited;" some slip between carrier speed and gear rotation is possible. With an "open" differential, or a non-functioning limited-slip diff, the stuck wheel can stop completely while the spinning wheel rotates at twice the carrier velocity.

In my view, limited-slip differentials depend upon sensing torque difference between the side gears for their operation, sometimes using a bevel mechanism to shove the spinning side gear against some friction surface in contact with the carrier. I claim no expertise in the field and look forward to reading additional and contrasting views.

Tree Farmer

 

Tree Farmer, thanks for the reply.
Here's a practical observation I made with a "field test". We put two quads in the same predicament; uphill-off camber-rootbound-uneven front wheel tractability. Sure enough, the "loose" front wheel spun, leaving the other dormant. However, with one quad, "feathering" the front brake caused the dormant wheel to engage, which remained engaged as long as throttle (and I presume the resulting torque) was applied. The other quad wouldn't respond similarly.

Unfortunately, in my quest to understand, the theory and design still escapes me, leaving me to learn and deduce through practical testing. Anyway, I'm babbling. Would appreciate any further insight. Seems if quad makers are going to "puff" their designs, they should back it up with substantive explanations.

 

Long shot, Mtngoat, but I'll try in words sharing my concept of differential action.

Imagine a shaft, maybe 4"-6" long. Some force causes this shaft to turn over, end-for-end, about the midpoint of the shaft. Got it?

O.K. Now the plane of rotation of this shaft is parallel to the planes of the front wheels of your quad when the wheels point straight ahead, located half-way between the two wheels, and shares the centerline of the front wheels when pointed straight.

Visualize this little shaft, turning end for end, right in the middle of your quad, between the two front wheels (right where the diffential is located).

Now, imagine an axle or half-shaft, connected to each wheel, extending inboard to within an inch or so of the little shaft that's turning end for end.

Put a side gear on the end of each half-shaft, parallel with its associated wheel (when pointed straight).

O.K., in the center, we have a couple of side gears with a short shaft turning end for end between the gears, in a plane parallel to the two side gears.

Now, we put a gear on each end of the little shaft, and mesh these two gears with the two side gears.

What happens? The two side gears, and each associated wheel, now turns; the end-for-end rotation of the little shaft is transferred through the two gears on the ends of the shaft to the two side gears, turning the half-shafts and the connected wheels.

Now, imagine the gears on the little shaft are free to rotate on the shaft. What happens if one wheel experiences resistance greater than its mate?

The wheel that experiences resistance slows down, while the other wheel speeds up. This is differential action.

The extreme case is when one wheel is stopped altogether, and the free wheel spins at twice the end-for-end rotation rate of the little shaft.

Limited-slip differentials are designed to connect the spinning wheel's side gear to the thingy (carrier) that rotates the small shaft by friction from clutch packs, cones, or ratchet (remember, the spinning wheel tries to turn at twice the "stick's" rate); this friction biases torque to the stopped wheel's side gear.

When you partially apply the brakes when you have a runaway wheel, you do the same thing, except: the torque biased must overcome the braking force applied if the stuck wheel is going to move. In my own experience, I sometimes can't make this happen.

Well, in the real world, a pinion gear on the driveshaft turns a ring gear that turns the carrier that holds the short shaft described. The gears on the end of the short shaft (pintle) are called differential or spider gears.

A differential is a "zero sum" device; the angular velocity of the carrier (and pintle) always equals half the sum of the angular velocity of the two side gears (or their connected wheels).

Examples: Carrier (pintle) velocity: 100 rpm. Left wheel: 100 rpm. Right wheel: 100 rpm.

Carrier velocity: 100 rpm. Left wheel: 80 rpm. Right wheel: 120 rpm.

Carrier velocity: 100 rpm. Left wheel: 0 rpm. Right wheel: 200 rpm.

Next class, we'll discuss "lockers!"

Tree Farmer