A potentially dumb question

[Lx450inNC]

I'm new to off roading and have been trying to learn as much as possible about my LX, exactly how the 4WD functions work, and what it's capable of. (no lockers)

I've been researching online and reading the forum, but a lot of the threads here descend into madness and infighting. Here are my questions:

1. What's the point of the full time 4WD in high? Other than bad gas mileage? If the full time 4WD is open differential and can be made useless by one wheel spinning, why would Toyota set that as the 'all time' position?

2. What is the best example of real world scenarios for when I will use open diffs / locked center diff / 4hi / 4lo? i have the cdl switch mod.

 

[mct75]

Not dumb.

AWD is useful on pavement, for traction. Driving dynamics folks can chime in about the benefits of AWD in cornering, launching, etc. Your LX has a device called a viscous coupler that acts as a limited slip device. If you're in some snow and the rear end starts spinning, it will lock up and force the front axle to turn as well. An open diff in the center puts you ahead of any part-time truck that has a "locked" center (with no differential) on pavement. A part-time truck in 4WD will always have a tire slipping when it's making a turn. In mud this is fine, in snow it's dangerous, and on pavement you're stressing driveline components. AWD is objectively better.

 

[voodu3]

This has a ton of good info along with the other FAQ’s

differences in 4WD, AWD, full time 4WD

forum.ih8mud.com

 

[Lx450inNC]

Not dumb.
If you're in some snow and the rear end starts spinning, it will lock up and force the front axle to turn as well.

Isn't this what the center diff lock does? It splits the power evenly between both axles? If the viscous coupler does this automaticaly, what's the need for the center diff lock?

 

[mct75]

The VC only provides some lockup (the diff can still slip a tad). This is good on snow and whatnot, but if you're off-roading you'd want full lockup.

The VC also operates by heating up when it slips, and periods of lots of slip have been known to burn the thing up.

It's no replacement for true traction control on paved roads, but it's a very simple and reliable TC solution from the 1990's.

 

[CarolinaBlue]

If I might suggest, you've got a great local resource with @Izzyandsue and the offroad classes right up the road from you at Uwharrie. I highly suggest you check him and the offroad safety classes out. Very informative and will likely let you test your vehicle out in situations you rarely would seek out yourself, but in a controlled environment with expert instruction. There is a classroom section that will teach you about 4wd systems with physical examples you can pickup and handle yourself, as well as technical driving and recovery sections.

 

[Rusty Marlin]

With out lockers, its still a more capable vehicle than any 4x4 I've ever owned, dodge, chevy, ford, big and small. There's simply no drama with the LC, you point it where you want to go, apply throttle, and it goes there.

 

[ZackR]

One major advantage (at least in my opinion) of all wheel drive (or 4 wheel if CDL is locked) in high range is how the cruiser feels when driving. There's much less rear squat when accelerating and when decelerating engine braking is applied to all four wheels.

In addition; there's no need to decide when to use all wheel drive since its always there. For example when transitioning from pavement to a dirt road and then from a dirt road into a rutted muddy road, or a snow covered road, etc. With the CDL (center diff lock) switch you can activate true four wheel drive (50% power to front and 50% to rear) on the fly (while moving) and there's no need to get out to lock the hubs, etc. I use this feature very frequently.

Think back to the original intent of the 80 series landcruiser, it's a solid A to B transportation device that can cover any and all roads in relative comfort without much drama.

 

[ZackR]

2. What is the best example of real world scenarios for when I will use open diffs / locked center diff / 4hi / 4lo? i have the cdl switch mod.

1. CDL unlocked with open diffs cover about 90% of my driving needs, including offroad use.
2. CDL locked with open diffs cover another 5%, mostly in deeper snow (6"-12") on forest service roads but at 20mph speeds. Also on some steep or muddy trails I'll lock the CDL but put the transmission in 1st gear.
3. Low range with CDL locked covers the last 5%. Steep climbs and steep declines offroad for the most part. Low range is sometimes necessary to have enough engine braking and enough torque to sustain a long rough climb. I also use low range when recovering a stuck vehicle (going forward only, avoid recovering in reverse to preserve the front diff).

 

[ZackR]

Isn't this what the center diff lock does? It splits the power evenly between both axles? If the viscous coupler does this automaticaly, what's the need for the center diff lock?

The difference is that the viscous coupler is intended for intermittent use to minimize wheelspin whereas the locked CDL stays locked to prevent wheelspin in the first place.

 

[Cruzerman]

1. CDL unlocked with open diffs cover about 90% of my driving needs, including offroad use.
2. CDL locked with open diffs cover another 5%, mostly in deeper snow (6"-12") on forest service roads but at 20mph speeds. Also on some steep or muddy trails I'll lock the CDL but put the transmission in 1st gear.
3. Low range with CDL locked covers the last 5%. Steep climbs and steep declines offroad for the most part. Low range is sometimes necessary to have enough engine braking and enough torque to sustain a long rough climb. I also use low range when recovering a stuck vehicle (going forward only, avoid recovering in reverse to preserve the front diff).

This completely depends on what you are doing. These numbers may match your wheeling areas & conditions, but not necessarily correct for everyone else. Lots of folks use low and lockers all the time for their type of wheeling.

 

[ZackR]

This completely depends on what you are doing. These numbers may match your wheeling areas & conditions, but not necessarily correct for everyone else. Lots of folks use low and lockers all the time for their type of wheeling.

Point taken... my rig is stock and most of my wheeling is pretty mild compared to some.

 

[baldilocks]

The main thing is that you knew enough to buy the best. When I first got into 80’s five years ago I was a reading and researching maniac here on Mud. There is A LOT of good, accurate info here. Buy a hard copy of the factory service manual and put it beside the toilet, it’s ’s good reading.

 

[Rusty Marlin]

If I might suggest, you've got a great local resource with @Izzyandsue and the offroad classes right up the road from you at Uwharrie. I highly suggest you check him and the offroad safety classes out. Very informative and will likely let you test your vehicle out in situations you rarely would seek out yourself, but in a controlled environment with expert instruction. There is a classroom section that will teach you about 4wd systems with physical examples you can pickup and handle yourself, as well as technical driving and recovery sections.

I took one of Izzy's classes at the 2019 Logan's run, can't say enough good things about it! Excellent instruction, and was able to apply it the next day.

 

[graham5david]

Running in 4 hi with an open diff doesn't waste that much gas because it doesn't place a ton of power demand on the engine. Its equivalent to turning the alternator. The additional power required to turn wheels that are already turning is far outweighed by the additional traction you get by distributing that power to 4 wheels instead of two in normal conditions. Its also adequate for most offroad situations until you get a tire off the ground. In those situations locking the center diff sends equal power to the front and back so you can still turn the wheels with traction on the end that doesn't have a tire off the ground. if you have diagonal tires off the ground then you need a rear or front locker. Or just pick a new line.

 

[EvanD]

Point taken... my rig is stock and most of my wheeling is pretty mild compared to some.

I don't mean any offense, people drive what they like, but it does sound a bit like a high percent of your driving could be handled in pretty much any AWD vehicle with okay clearance. I plowed 6-12 inches of snow in my STi plenty of times without issue. It also handled most forest roads I'd thrown at it. s***, when I was 16 my mom's FWD Toyota Sienna plowed 6+ inches of snow to and from the ski hill without issue.

I cut my moderate-serious wheeling teeth in a slightly modded 2005 4runner (3 inch lift, 33s then later 35s, no lockers). Cut my moderate wheeling teeth years before in a stock Oldsmobile Bravada (). Compared to those the 80 feels like cheating most of the time.

These days, I seldom use my rear locker even on some of the higher rated trails in Moab (there's also some trails I won't run, mostly because I always have to get it back to Idaho even when stuff goes wrong).

Granted, I don't always take the most extreme line either.

The front has only been used a handful of times and mostly because I'm stubborn and didn't want to find a new line.

Most moderate-harder trails ill throw it in 4lo which locks the center diff (I don't have the magic button). I'm hard pressed to think of a scenario when I'd use it even if I did. 4 high with a locked center diff just doesn't even compute in my small brain.

The unlocked and 4 hi 80 has taken me everywhere I've asked it in normal/snow/class 4 road driving.

I guess my point is 80s are amazing but serious overkill in learning proper line choice and wheeling techniques. I'd def suggest either a course like the one mentioned and/or finding a local club with experienced members.

I'll also add that in my limited reading of people with 2wd mods and/or driving without the front driveshaft it doesn't make a big difference on MPG. 80 gassers just suck at it. No two ways about it.

 

[Lx450inNC]

Its also adequate for most offroad situations until you get a tire off the ground. In those situations locking the center diff sends equal power to the front and back so you can still turn the wheels with traction on the end that doesn't have a tire off the ground. if you have diagonal tires off the ground then you need a rear or front locker. Or just pick a new line.

This makes sense to me. The ice analogies always threw me off. This is easier to visualize.

 

[ZackR]

I don't mean any offense, people drive what they like, but it does sound a bit like a high percent of your driving could be handled in pretty much any AWD vehicle with okay clearance.

None taken, I chose the 80 because when I do encounter difficult trails it handles them without breaking a sweat and it'll always get me home. I might not be out wheeling very extreme trails but I do spend about 40% of my driving offroad and on forest roads which is much higher than most folks. I also haul a lot of firewood with a trailer, trudge through deep snow offroad (usually 2 feet or less), both of which are a bit much for a crossover type SUV. I also work from home and have several other vehicles so it's easy to maintain the 80 myself when needed.

 

[pawnthatdude]

1. What's the point of the full time 4WD in high? Other than bad gas mileage? If the full time 4WD is open differential and can be made useless by one wheel spinning, why would Toyota set that as the 'all time' position?

Full time 4WD is very useful on snowy roads, where traction varies greatly. In some places it's plowed and dryish, other places packed snow and ice. If you had a part time setup, with a locked center, you'd constantly have to think about when to be in 2WD and 4WD.

 

[Cruzerman]

I personally would not take a "jeep" class but instead seek out a 4WD club in your area. Most clubs are anxious to welcome new members, even ones that have no experience. I have found the experienced folks love to mentor newbies. Not only will you learn 4 wheeling skills, you will meet some nice folks, make new friends, find local places to go, have people to go with, and you'll get to hear endless 4 wheeling stories.