4x4 newbie questions

[Mister Entropy]

Hi!

My wife and I just leased ourselves a new FJ on Saturday as we've moved to a snowy locale and needed something with 4 wheel drive. Thank goodness the FJ came along to save us from having to get some bland SUV! So far we love it, but I do have some driving questions as we've never spent any time off road, never driven in snow, and never owned a 4x4.

Here's what I've been able to decipher: In 2H the FJ has VSC turned on automatically, but when moved to 4H this turns off. Why does it turn off? Does some other form of traction control turn on or is 4H simply considered enough to keep you on the road? Then there's A-TRAC. I've read that this is only supposed to be used in 4L, is that true? And finally there is the locking rear differential. That seems to be something you only use in serious off-road conditions and even then you probably won't use it unless you are stuck. Again, any of this true?

What it all boils down to is what setting should I be using for driving on-road, in the snow? We had a few inches last night and I used 4H with no problems. Is there ever a time I'll need to use 4L on-road, or is that only for off-road use?

Here's some pics of our Cruiser. It was a bit gloomy that day, but the yellow still makes a statement! Thanks to anyone who has the time to answer my queries.

 

[Riverrock97]

Have you been to toyota.com and looked at any of the animations on the FJ that may answer some of your questions? Also, the owner's manual may help as well.

 

[mustang5]

I sure wish our snowy clime looked like what I see in your pictures. I am waiting for global warming I think it's a wonderful idea.

 

[Mister Entropy]

Well, the photos of the Cruiser are at my in-laws house down in the city where we bought it. This is our driveway a few hours before things got really bad and our Mini was swallowed by the snow.

 

[bulldog-yota]

Ok I'll only try to help here once. I haven't driven the FJC so I'm not fmailiar to all the details, but I know the new 4R/GX very well, especially in terms of all the gizmos and misunderstandings of these.

FIrst of all the auto FJC has a part time 4WD, this means the front and rear axles will run at the same speed when 4WD is engaged (low or high). The manual has a full time 4WD, which means it has a center diff which allows the front and rear axles to run at different speeds. This means you can't run the auto in 4WD on paved surfaces as the driveline will bind in corners, as the rear axles takes a shorter path on a turn than the front axle. SO what does this have to do with VSC??

VSC or vehicle skid control does a number of things to keep the vehicle under control in extreme situations. It sense for wheel spin and slippage, it also detects sliding on a vehicle around corners. It should under no circumstance be confused with ATRAC (will cover it later). SO when it sense slippage/spin or sliding it will throttle the engine back (less power), and also apply the brake to the spinning wheel to limit spinning. During a corner it will apply brake force to the relevant wheels to stop or limit sliding if detected. It works very well and I have tested it on numerous surfaces. VSC is primarily a road tool, but sometimes come in handy at higher speeds on gravel roads too. Because it senses sliding in corners it needs to measure the difference in wheel and axle speeds as well as yaw, steering positiona nd a number of othe rinputs. If you lock the axles together it can't accurately determine slides nor can it appropiately correct it with applying brake force to a certain wheel. Therefor it shuts down when you go into 4WD, as the auto only has part time 4WD similar to locking the center diff on the 80/100/4R/GX/Man FJC.

Before we delve into ATRAC or difflock you need to understand the role of a differential on a truck. It is there to allow us to drive around corners where the outside wheel travels further than the inside wheel. The gear sint he diff allows the 2 wheels on the same axle to run at different speeds and also applies different torque to them pending on the speed they travel at (oversimplified, but the general idea). This is fine and dandy on the road, but offroad you tend have wheels loose traction and/or contact with the surface and hwn that happens the diff sends all the power to the wheel with no traction. This causes the truck to just spin the wheel in the air instead of putting the power to the wheel on the ground. ATRAC is an offroad tool that applies brake force to a slipping wheel in offroad situations to allow torque to be transfered to the wheel with better traction. Since you have an auto you shouldn't worry about locking the center diff. It works real well and is probably better to use than the locker till you understand offroad traction better. From the material I have read the FJC is supposed to have the most aggressive ATRAC of all Toyota vehicles to date.

Here ia a pretty good link covering using ATRAC offroad and some videos
http://www.toyota120.com/forum/showthread.php?t=25

I hope this helps a bit, I can't find all the fancy marketing videos they used to have.

 

[woody]

sharp rig

one GREAT way to learn the system is to get in with a local club....scroll down the main forum page and you'll likely find a club in your state and area....join in for a weekend and they'll show ya all the ropes you need!

 

[saigonsmuggler]

ATRAC is also useful in snow or rain at slow speed.