4-Wheel Lock Issue on 2006 Nissan Murano

Recently I slid off the road during a snowstorm. After engaging the "4-wheel lock" I noted that the rear-left wheel was spinning while the left-front wheel wasn't turning! (I couldn't see what was going on on the other side.) With the lock engaged, I expected that all four wheels should be engaged and turning? If 4-wheel drive isn't supposed to work this way, what good is it? I had to do huge amounts of shoveling and get a board to place under the rear wheel before I could get out.. According to specs, this vehicle has a "locking center differential." I bought this vehicle assuming I could get all four wheels to turn at the same time!! Help much appreciated! Thanks. frank

Reply to
frank1492
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Ok, I'll bite....

I would first highly recommend you read your owners manual, the part about driving in 4x4.

You have a 'part time' 4x4 system that locks the front driveshaft to the rear driveshaft so both see power, 'but' you obviously have open differentials on the axles.

An open differential send 'equal' power to both wheels on the same axle at the same time. This is fine with even traction, goose it and you get

4 rooster tails in 4x4.

However, as you found out, when you have one wheel spinning on ice, it needs very 'little' power to turn so the wheel on the other side also sees this very little power and just stays put.

There are mechanical ways to get around this. One is to buy a locker or a limited slip unit for the differentials. This allows both wheels to spin when the traction is uneven side to side.

The other way should be listed in your owners manual, it is in both of my Jeep manuals. This other way is to load up the spinning wheel with the brake. When the pressure from the brake causes the power to increase to keep the wheel spinning, the other stopped wheel also sees this increase. If you hit the brake pedal hard while giving it gas, it can give enough resistance to match the power needed to break the stopped wheel free and away you go!

My owners manuals say you can use the emergency brake to load up the spinning wheel to get both moving, but I have much better luck pounding on the brake pedal in shots. That can get all 4 tires shooting rooster tails from a stop.

I have used this method 'many' times to avoid being winched or strapped out of places when my Jeep is just sitting there calmly spinning one rear and one front tire on ice.

It takes practice and properly adjusted brakes, but it does work.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > Recently I slid off the road during a snowstorm. After engaging
Reply to
Mike Romain

Just because the center differential locks doesn't mean the front and rear ones do.

--scott

Reply to
Scott Dorsey

The Nissan manual seems to offer very little on this. Thanks particularly to Mike for your most complete reply. You say "buy a locker." Can these be installed on any vehicle? How do they work and what kind of control is available from the driver's seat (if any?) I will look again, but I saw no extensive discussion of the "lock" capability or any procedure for "fooling" the differentials by braking. I guess we "refined" Murano owners are never supposed to need these things. One question still remains: Under what conditions does "locking" the center differential help? The capability seems rather useless to me. And name me an "off the shelf" vehicle in which I can lock *all* the differentials when needed without any "tricks.". Thanks again. (Printing Mike's reply for reference.) Frank

Reply to
frank1492

The (some) new Jeeps offer a front and rear locker that you can manually engage from the cab when you need them. Several companies make lockers. Some are air controls and some are cable and some are electronic and some are limited slip automatic ones.

You can get a limited slip or locker for just about any 4x4.

The front and rear locked together means all the tires see equal power which 'really really' increases the pulling power of the wheels. It should only be used on dirt or snow covered roads. Heavy rain is ok for most too, but never use it on dry. That is why it is called 'part time' mode.

It locks the front and rear together so when you turn, one wheel has to scuff. On dry roads, this can break things if you have too much traction.

Because of this, you might find it is better to use 2 wheel drive when say at a long left turn intersection in the snow. In part time 4x4 the tires can scuff which gets them up on top of the snow and makes it want to go straight. I shift to 2 wheel just before the turn and back to 4x4 after. I find it is better.

Braking is also totally different in 4x4 and the Jeep manuals specifically say to 'stay off the brakes' when in 4x4, to use the steering and gears. Folks think about not using brakes in 4x4 off road because it is too easy to lose it, well it is the same on road in 4x4. You can stop amazingly fas when gearing down right. Takes practice!

The brakes in part time 4x4 have one more gotcha too. When in 2 WD and you hit the brakes, you just loose the steering because the front wheels lock up. The rears have a proportioning valve to stop them from locking too so you track straight.

When you hit the brakes in part time 4x4 though, if the fronts lock up, 'so do the rears' and you will slide sideways off the road faster than you can blink!

I recommend everyone find an empty parking lot come first snow to try out their 4x4 to see just what does happen. Keeping on the gas when you start to slide can be hard to get used to.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > The Nissan manual seems to offer very little on this. Thanks
Reply to
Mike Romain

Equal an open differential provides equal TORQUE to each side, not equal power. The wheel that is not turning receives exactly zero power, but is pushing forward with exactly the same force (torque divided by wheel radius) as the one that is spinning. So the limited force of the wheel that spins also limits the force the non-spinning wheel can apply.

Reply to
Steve

Thanks Mike. I think I have everything I need now. I will check the Murano in a parking lot next winter. Of course the minute I started to slide off the road I did exactly what you said not to do- applied the brakes hard. I realize now that that was the worst thing to do. It will be hard to overcome that habit, whatever drive arrangement I end up with, but I will try. Frank

Reply to
frank1492

I have used the word 'torque' in the past for this, but far too many people nit picked the definition as it applies to pieces to make 'any' sense at all for the average person so I just say power to the wheels and most people understand.

If you are an engineer with more education than brains, well fine, nit pick away...

I guess I could say 'power to the wheels in the form of torque', but...

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
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Reply to
Mike Romain

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