all time 4wd?

[jonheld]

lcool and george couyant, now that is the time before dinos for sure

cheers,
george. (not couyant).

Trying to remember the old email list address that he hosted at SGI.
I'm just f*cking old...

 

[mudgudgeon]

In your tacoma, you had 2 differentials, and a part time transfer case. Your differentials are at the center of your front and rear axles, sometimes referred to as pumpkins. The job of a differential is to allow your tires to turn at different speeds when driving on the street. Every time you drive around a corner, the wheels on the outside of the corner have to cover more ground and therefor turn faster than the wheels on the inside of the turn. A differential allows this to happen.

So under normal circumstances in your taco, you'd be in 2wd, and power would only be sent to your rear axle, where your diff is "open" allowing the wheels to spin at different speeds. This is fine for most driving conditions, but if you've ever driven in snow in a pickup in 2wd, you know how things get really interesting, really fast.

So on a snowy day, you'd put your taco in 4wd high, and lock the manual hubs. By shifting your transfer case from 2wd to 4wd, power is now being sent to your front axle, via the front driveshaft. Your front and rear driveshafts are forced to spin at the exact same speed in this mode. The switches in the center of your front wheels are called manual locking hubs, and they are often confused for differential lockers, which I will cover later. Manual hubs in thier "free" position disconnect the wheels from the axle, allowing the wheels to spin freely, but the axle will remain stationary. This will save wear and tear on front axle parts, and reduce the rolling resistance of the vehicle. Most 4x4's these days don't have manual locking hubs, the are just locked all the time, which wears out your front axle and driveshaft components and wastes gas.

So in order to get 4wd in your tacoma, you shift the transfer case into 4wd high, this will transfer power to your front axle, but not to your front tires until you lock your hubs.

Now say that you are on a washed out steep mountain road, this is where you might use 4wd lo. It works the same as high, but through reduction gears in your transfer case you will be able to drive much slower with more control and available torque. In this scenario, your front and rear diffs are still "open" which will allow your tires to spin at different speeds. This isn't an issue for 99% of truck owners, but when you start doing serious offroading, the limitations of open diffs become very apparent. An open diff by design sends all of the power to the wheel with the least amount of traction.
Imagine you are on the flat ground, with one large rock. You want to drive over that rock with your right front tire, but as you climb up the rock, your left from tire and right rear tire start to lose traction and spin, while the tire on the rock, and the opposite rear tire do nothing. This is the problem with open diffs. Being able to lock your front and rear diffs will force all 4 tires to spin at the same speed, and you will easily climb the rock in a controlled fashion.

Now I'll go over the differences between the taco and a full time 4wd 80.

If you try to drive your tacoma on a dry paved street in 4wd high or low with the hubs locked, you'd have a bad day. Every time you go around a corner, you'd feel the drive train binding, your tires would squeel and you'd have a very real chance of breaking something. This is because of another phenomenon that happens when you drive in a circle, your front tires will make a bigger radius than your rears. Since the front has to cover more ground, your front axle needs to spin fast than the rear, and in your tacoma, the transfer case will force the front and rear axles to spin at the same speed. This isn't a issue on dirt roads, or snowy roads, because your tires can slip a little bit to relieve the stress in the drive train, but on a dry street you can break something.

So how does full time 4wd work? It has an additional differential in the transfer case. This "center diff" will allow the front axle to spin faster around the corner, without binding or damaging anything. But if you remember how open diffs are bad for offroading, you can see why it's necessary to be able to lock the center diff, so that you can evenly split the power between the front and rear axles when you are offroad.

The main benefit of full time 4wd is that most people never have to mess with it or even think about it. A dry summer day, or a snowstorm, full time 4wd just works. Now if the conditions are bad enough, you still need to lock the center diff, or put it into 4lo, but for 99% of people, 99% of the time they never have to mess with it.

The drawbacks are numerous however. The front axle is always spinning, so your front driveshaft, U-joints, gears, bearings, axle seals will all wear out faster. All of those extra rotating parts will also cost you extra fuel, and with a full time system, it becomes important that all of your tires are very close to the same size, especially if you have a viscous coupler.

On to the viscous coupler then. The easiest way to explain a viscous coupler, is to explain a limited slip differential. A limited slip is sort of the half measure between a open diff, and a locker. It allows the tires to spin at a different speed, but it does resist and "try" to spilt the power more evenly. A viscous coupler is the same thing, but it's located in your center diff, inside of your transfer case.

OK, that is long enough.

Great explanation!

If agree with all of that, except in yet to see someone accurately record a difference in fuel use for a change from full time, to part time.
In Australia, fuel efficiency is often touted as a good reason to convert a full time rig to part time, yet no-one ever seems to track fuel use.
My personal experience running a full-time rig daily with front shaft, and drive flanges removed for 6+ months and longer is that there is 2/10 of ****-all difference in fuel use.

In full-time 4wd, I've personally avoided one clear cut, life and death scenario that was milliseconds off being a fatal accident for a stupid woman who pulled out blind into 3 lanes of traffic in the wet, and balked in front of me.

I'll take being able to dodge around stupid women over drifting an 80 everyday. The look on said stupid woman's face when she realized she was about to die from her stupidity well never leave me!

I'll happily pay a minor fuel penalty for the safer handling in my big, tall, heavy beasty, and let's face it, if fuel cost is a concern for you, a landcruiser is the wrong choice of vehicle.

If you want to drift, buy a Silvia, if you want fuel efficiency, buy a prius

 

[mudgudgeon]

Trying to remember the old email list address that he hosted at SGI.
I'm just f*cking old...

Land Cruiser Owners On Line, hence the website is LCOOL

 

[ppc]

The LCOOL website was a later implementation. Originally the mailing list and website were hosted on SGI where George Couyant was once employed. The mailing list was then moved to Yahoo Groups and the web content moved to Lcool.org.

 

[mudgudgeon]

The LCOOL website was a later implementation. Originally the mailing list and website were hosted on SGI where George Couyant was once employed. The mailing list was then moved to Yahoo Groups and the web content moved to Lcool.org.

Ah, ok. You guys ARE old!

 

[ppc]

I do resemble that remark.

 

[george_tlc]

Old email I have (2001) has 80scool@yahoogroups.com so that is after the SGI hosting.

and older email from 2000 has 80_series@sgiblab.sgi.com

Dearie me... I remember joining late 1997 / early 1998 when I bought our 80.

ih8mud was just a few pages of technical writeups... some of my original writeups were on woody's pages as links.

I can hear some of my old bones groaning

cheers,
george.

 

[jonheld]

IIRC, and that's a longshot, the sgiblab was the 2nd SGI list he had. There was another one in the late 90s when I first found it.
I didn't formally join mud until much later, but most of the old Aussie guys are still on 80sCool.

 

[IanB]

Any 80's coming from Canada came from somewhere else.....we never got factory 80's in Canada.

We did get the panty cruiser from Lexus.

Not true, we got ‘91-‘92 FJ80’s and ‘96-‘97 LX450’s sold new in Canada.

 

[george_tlc]

IIRC, and that's a longshot, the sgiblab was the 2nd SGI list he had. There was another one in the late 90s when I first found it.
I didn't formally join mud until much later, but most of the old Aussie guys are still on 80sCool.

Yes, I'm an email packrat of sorts

So, 1999 email list -> 80_series@corp.sgi.com (from) and the reply to -> 80_series@relay2.corp.sgi.com

and my oldest saved email for 1998 -> 80_series@palladium.corp.sgi.com

cheers,
george.

 

[ppc]

George, I think I joined the 80scool mailing list back in 1996. I think there may be only 4 of us from those days here in this forum, Christo Slee, Jon Held, you and myself. Things have really changed over the years as the demographics of the posters changed. When the 100 series came to be the mailing group was split into 100's cool so members moved in those groups. There was 80scool, 80scool_aus, 80scool_usa, 100scool and I think there was a separate 105scool as well.

The Rocky Mountain Land Crusier 4x4 Association still maintains most of the archives for 80scool and 80scool_usa along with other forums and mailings lists...

RMLCA - Rocky Mountain Land Cruiser 4x4 Association

 

[Dave 2000]

I'm going to get a video of me drifting my part timed HDJ around a corner and make you change your mind hahaha

Ah drifting, been BTDT many years ago when I was a lot younger, I used to use a 3.0 CSi BMW, complete with rear wing, very satifying when you get it right.

Regards

Dave

 

[landcruiser3DP]

THANK YOU to all here. i really appreciate the great explanations. going to reprint this and take another run through it. comparing it to the taco is really helpful as well.
once i get my head through this kind of think it usually sticks. that said, sometimes i have to get my hands on something to really get it through my coconut...
/really/ appreciate the information...
- jonathan

 

[sunrk]

Now in 2022 Lcool still exists but the Lcool forums are gone.

 

[Outsane]

My biggest reason to part time is that the steering on the freeway is much easier.

With the hubs locked it feels like a fight on long trips. I drove 1000 miles to Las Vegas with the hub locked and it sucked. Unlocked is way more comfortable. For me

 

[60wag]

Is your center diff permanently locked?

 

[cody c]

My biggest reason to part time is that the steering on the freeway is much easier.

With the hubs locked it feels like a fight on long trips. I drove 1000 miles to Las Vegas with the hub locked and it sucked. Unlocked is way more comfortable. For me

You may need to rebuild your steering pump, and look at camber/alignment etc.

Mine on 42's was not perfect pre hydralic ram mod, but it wasnt squirrely. That mod added firmness as well though.

 

[Outsane]

Pump is Rebuilt, I get regular alignments.

Lifetime at wheelworks..

It's noticeably nicer with the hubs unlocked..

 

[cody c]

Pump is Rebuilt, I get regular alignments.

Lifetime at wheelworks..

It's noticeably nicer with the hubs unlocked..

What size rubber? Checked all TRE's, steer amrs, etc for tightness? How fresh is your steering stabilizer?

I think some people like their steering system tight, others like responsive, some like the steering to turn light and easy without resistance.

My thoughts are that in an AWD scenario where the drivetrain is spinning the front rubber, and if the center of pivot isn't directly in the center of contact patch, then the rubber will want to pull itself inwards (more toe in) just slightly if the pivot point is inwards towards vehicle center, from its neutral position.

Point is, we should consider and maybe aim at more or less toe in for the same vehicle in a AWD vs 2WD configuration, and play around with different settings slightly. Factors like a bit more slack in the wheel bearings can be a factor here too.

If you just want 2WD/4WD then by all means just mod the t-case though. Sounds like your in a warmer climate anyways.

 

[QuackAxel]

All Land Cruisers are made in the Araco factory in Japan.
[/QUOTE


Sort of true. The current Landcruiser is made in the Yoshiwara factory. Not sure if this used to be known as the Araco factory? It is a separate Toyota company called "Toyota Auto Body"