EZ way to verify 4WD

While in 4wd, make a tight turn. If you're in 4wd, the front end will start to bind up. Make sure you don't have manual hubs.

Good Luck

Put it into 4wd, jack it up, and try rotating the front tires by hand. You'll see the driveshaft rotate.

"Jim Smith" wrote in news:O7qdnTP08Iyw_j_YnZ2dnUVZ snipped-for-privacy@comcast.com:

Thanks for the reply. Exactly what I was looking for. Soon as got it into a tight turn things started binding up & had to reverse \ roll a bit to unbind & get it back into 2WD. Thanks again. dc

Just curious: This is what happens when I want to switch back to 2WD in my (newly acquired) T100, also. In order to get it to come OUT of

4WD, I've got to stop the truck and back up a bit, whereupon it instantly pops out of 4WD.

My owner's manual says nothing about this procedure being required -- yet several people have told me it's "normal". It seems to me that I'm just making excuses for a mechanically impaired system.

Is there anything that should be lubed/adjusted to allow the system to go freely back and forth from 2 to 4WD?

-- Jay Honeck Iowa City, IA '95 T100 4x4 Extended Cab

"Your Aviation Destination"

"Jay Honeck" wrote in news: snipped-for-privacy@p59g2000hsd.googlegroups.com:

My understanding is that they will bind up in 4WD on dry pavements in very tight turns & that it is normal for Toyota's to exhibit this behavior unless they are All Wheel Drive. The key phrase here is "dry pavement" These vehicles are not meant to be operated in 4WD on dry pavement. They need some degree of slippage available to operate smoothly & properly. It should pop in & out of 4WD easily as long as on a slippery surface. dc

Interesting. Thanks for the info!

-- Jay Honeck Iowa City, IA '95 T100 4x4 Extended Cab

"Your Aviation Destination"

Jay,

To clarify, "normal" means "inherent in the mechanical design of a 4WD system without a differentiation mechanism in the transfer case."

This design is a compromise, with the intent being improved traction when in 4WD mode. Some alternatives are open differentiation such as found in AWD vehicles, or limited slip or automatic differentiation (eg Jeep Quadra-track {spelling?}). Although more "user friendly," the latter systems are considered, er, less than desirable by many off road enthusiasts in situations where 4WD is truly needed.

As other posters have pointed out, there is the posibility that you are operating the truck contrary to the owners manual by engaging 4WD on dry pavement, hence why no mention of this "quirk" in that booklet.

If you are engaging 4 low range for traction, you need to either unlock your manual hubs or bypass the ADD system so as not to wind up the drivetrain. You'll want to be gentle on the throttle and/or slip the clutch some, so as to avoid shock that can twist an axle shaft. They aren't made of marshmallows by any means but a little TLC would be a good thing.

No, greasing it won't help.

Thanks for the clarification, Mike.

As the owner of an AWD Subaru, I'm having a hard time understanding any "advantages" of the system in the T100. It would seem to be inferior in every way.

How is the 4-wheel drive system in the truck any better off road?

-- Jay Honeck Iowa City, IA '95 T100 4x4 Extended Cab

"Your Aviation Destination"

As someone else who owns both, I'll point out some differences.

1.) Dual range 4WD. In some situations, only 4WD low will do. Low will allow a reasonable engine RPM while escaping an obstacle or pulling a load at extremely low ground speeds. It also greatly minimizes wheel spin when properly used. 2.) Part time 4WD can save gas and wear and tear while still allowing a locked-up drivetrain when needed. All of the minuses you get when trying to use 4WD on dry pavement are plusses off-road.

Although not technically related to 4WD, most 4WD vehicles have at least some minor thought put into entry/exit clearance angles and center ground clearance. The solid rear axle on the T100 will maintain ground clearance over an obstacle (especially loaded up), while the Subaru's independent rear suspension will give it away attempting to keep the body more level. There are some good off-road independent suspension systems, used on stuff like military HumVees and Oshkosh brand airport fire trucks, that can maintain clearance, but they're different. The T100's solid rear axle won't squat with a heavy load like the Subaru will.

Better 4wd vehicles will also include features that not that useful on an AWD car, like electric or air locking differentials, and the ability to crank the engine in gear, with the clutch engaged (clutch safety switch cancel). A proper 4WD will also be equipped with higher profile tires, possibly with a smaller diameter rim, to allow airing down, better traction, and better rim protection. Next snow storm, watch those 4WD SUV's with the tiny tire sidewalls and 22-24" rims slide all over the place!

That said, I'll take the Outback every time on-road, in snow, on wet roads, etc... I've attempted off-road mud and deep, loose sand with my AWD LSD-equipped Outback, and my Tacoma and Wrangler outshine it every time. ESPECIALLY the Toyota!

Most of the daily drivers would be better served by AWD, but when you need 4WD, you really need 4WD.

Can you expand on this a bit? Why would you ever want to crank the engine with the clutch engaged? (I've wondered what that "clutch safety switch cancel" button is for!)

Thanks,

-- Jay Honeck Iowa City, IA '95 T100 4x4 Extended Cab

"Your Aviation Destination"

Jay,

Barry put it well in his reply. I might point out that the primary difference is in how the 4WD system behaves under the poorest traction conditions, with all wheels intermittently slipping.

A typical AWD system system tends to put the most torque toward the wheel that is slipping. If this happens off road, you get stuck - the wheel with the poorest traction twirls merrily while the rest just sit there.

With a true 4wd system, if a wheel on one axle slips, the other axle will still maintain traction to pull you past the soft spot.

One can run into a situation in truly deep rock where one wheel on each axle is slipping. For that situation, limited slip or locking differentials are the solution. If you think the street manners of a

4WD truck are poor, you ought to try driving a truck with a limited slip rear end.

And of course, as Barry points out, the low range transfer case can make all the difference. Some die-hard off roaders even couple two transfer cases back to back for extra super duper low range.

Again, for situations such as a paved boat ramp where the extra torque of low range might be desired, you can unlock your hubs or modify your automatic locking mechanism (depending on what you have) so that you can use low range without drivetrain windup.

BTW, my own off-road rig is a 1963 Willys wagon, small-block Chevy conversion, with a Warn .75:1 overdrive. Twelve forward speeds, three reverse speeds and a forest of unmarked shift levers coming out of the floor. Guaranteed to give the valet parking guys that "deer in the headlights" look.

If you're sitting on a 60 degree incline with a pile of rocks below you and you stall the engine, the last thing you want to do is mash the clutch pedal.

In a tight spot, you might need to start the truck under one of the following conditions:

- You need to hold the truck on a slope with brake, operate the gas, and don't have a hand available for the hand brake, or a foot for the clutch.

- You need to start the truck from outside with the hand brake on, and the stick out of gear (actually very handy in snow storms )

I meant NEUTRAL, as opposed to in gear. Maybe my brain needs a switch. You wouldn't drive the truck with the starter.

Jay,

I forgot to mention...

Be really careful about engaging the clutch in reverse in 4WD low. I can tell a story about a my wife's pretty face and a Jeep dashboard with matching dents, but I won't.

You are on a REALLY steep hill, and if you roll back five more feet you are going over the edge and 100 feet straight down. The engine stalls. If you push in the clutch to get the engine started the brakes might not be enough to hold you...

You have suddenly decided that you are too young to die.

Leave your right foot planted firmly on the brakes, make sure that you are either in First or Reverse to go in the right direction, hit the override button and engage the starter with the transmission in gear. The starter starts pulling and the engine catches, you ease onto the gas with the right foot and ease off the brakes with the left. And away you go.

And even if it doesn't catch, you can use the starter motor for fifteen seconds to ease yourself out of immediate peril and a ways further from that nasty drop.

You don't want to do it too often, the overload is real hard on the starter motor. But it'll save your ass.

-->--

I always wondered why the switch bypass didn't disarm after starting, or some preset time period. Since I don't do much extreme off-roading, I never thought of your situation.

Now I know why you'd leave it on the whole time. Thanks for the tip.

I get a kick how my "Trail Rated" Jeep needs the switch added aftermarket. Toyota puts it in at the factory.

I don't consider myself an extreme off-roader, but I've been in similar straits. In low range the starter motor has enough torque to both move the rig and start the engine.

ROTFL!

I've only tried 4WD low a couple of times, just to see that it worked. It's pretty amazing -- I suspect I could pull out a few tree trunks with it...

;-)

-- Jay Honeck Iowa City, IA '95 T100 4x4 Extended Cab

"Your Aviation Destination"

Wrangler is best in all conditions IMHO. Enough said.