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Performance; Reduction of Load VS Increase in Power

Discussion in 'Performance' started by spaner, Jun 29, 2012.

  1. spaner

    spaner Well-Known Member

    A little revelation to pass along for guys running on ATVs.

    While running in 4WD there should be NO binding of the drive line. I have read more then a few posts where guys are having a hard time getting the "4WD" indicator light to come ON. They recommend rolling the truck back and forth; sometimes report "slight grinding", or a "pop-click".
    This is just not right...:frustration:

    The solution is to monkey with the tire pressures back and front until you get a driveline equalization. This will depend on the type of tire, the width of the tire, the size of the tire, and the weight of the truck, front VS rear, depending on make/model...ie engine in the rear VS the front. Complicated, that's why you have to monkey with it.

    My truck, I have 24x8x12s in the front, and 24x11x12 in the rear. To equalize the driveline with an empty box and one operator, I like having at least 7PSI in the rears so, that means that I need 19PSI in the fronts. Ride's a little stiff in the front. 15PSI in the front is probably perfect but, that means that I have to run 4PSI in the rears, which I don't like for high speed driving.
    Symptoms of a correctly balanced driveline:

    While stopped, pulling up on the 4WD shifter will cause both indicator lights to come on with NO delay.
    While stopped, or in motion (at any speed) and driving in a strait line, shifting out of 4WD takes the pressure of one finger.
    While driving on flat gravel in a strait line, in 4WD and EL gear @ 2TRPM, pressing the clutch in, my truck will continue to roll forward about 30 feet...and slowly roll to a stop. Just like in two wheel drive.
    I don't recommend it but, with the "axle-lock" previously ON, I have shifted into 4WD at 20kph a few times and got only a "click" out of it. If the driveline is not equalized, it WILL grind badly. A final test maybe, I do it regularly but, I don't recommend it.

    While running on street tires, the required difference is much less, perhaps 1 or 2 PSI.

    Moving on,

    There is a lot of information on the site about reducing performance load. Synthetic oils in the driveline, engine load reduction using synthetic 5w weight and a LARGER oil filter has also made a difference for me by increasing flow and, reducing back-pressure (oil pressure..80PSI is bad folks). Look this stuff up, there's lots of it here.

    Recently, I've also noticed a big difference from my front-end work.
    Correct alignment (including camber), new wheel bearings, freshly cut brake rotors, and especially fully serviced front calipers that now float properly and retract the pads to the designed clearance while off the pedal.

    There is a lot more to add (K&N air filter, 2" exhaust etc.) but I really wanted to get that 4WD stuff out there...I really recommend getting a vacuum gauge. I think that it is just as important as an RPM gauge. You can really tell how the changes that you make are affecting things. Like driving on the highway @ 80kph on flat stretches, after every change, the gauge will show a new lower indication, and a small change can make a big difference on the indication. A very helpful tool.
  2. fupabox

    fupabox Well-Known Member

    excellent info...as usual :)

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