4:1 Rock-Trac Part Time 4wd system?

[White Eagle]

Yeah but it mentions the terms, Rock-Track, Tru-Lock….At least you get an idea for those with a mechanical aptitude what the fancy names are referring to.

I’m still hoping Jeep introduces the Hummer traction system, the one they invented, maybe they can call it “Magic-Trac”

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[Badunit]

You would be better served by just reading the manual for what it is. If you are unfamiliar with 4wd systems, I recommend reading the manual thoroughly. You can do some major damage if you use 4wd when you shouldn't. The manual tells you everything you need to know about operating the 4wd system. The important distinction for operating the transfer case is whether it is a four-position or five-position transfer case, not the marketing names Jeep gave them. The manual shows how to tell the difference.

I think the manual does not stress highly enough that a part-time transfer case (four-position, like Rock-Trac) should only be used on very slick surfaces. People who have AWD vehicles might think part-time 4wd can be used on dry roads or in the rain or on patchy roads with some snow but it can cause some major damage if you do.

 

[White Eagle]

But it is important.

The manual can only “Show a diff” or similarly by using the proper name compared to what it is or does.

Otherwise it ain’t showing jack.

If my window sticker says it was equipped with a magic butterfly then I want to know what that is I paid for and there danged well ought to be a reference to the term in the document.

Life is so much easier with my YJ

 

[ShadowsPapa]

You would be better served by forgetting the marketing nomenclature and just reading the manual for what it is. The manual tells you everything you need to know about operating the 4wd system. The important distinction for the transfer case is whether it is a four-position or five-position transfer case, not the marketing name Jeep gave it. The manual shows you the difference.

And I'd hope most buyers go into it understanding that the difference as far as Rubicon is concerned is the low ratio, crawl ratio.
It's all in the brochures which you can download online.

More confusing is the RockTrac name is used for the part time and full time transfer cases in the Rubicon!

But it is important

Why?
It's a 4 wheel drive transfer case, not really anything special, especially considering what's out there today. All you need to know is how to operate it, and I'd hope anyone buying any 4x4 would either already know that, or have it figured out on day 1, or at least read the manual. There's nothing important about these transfer cases - just what's in the owners manual.

 

[White Eagle]

I have already splained myself, I have a different view than you.

 

[White Eagle]

If its important enough for a brand, a multi kabillion dollar conglomerate, to coin and market a term then it would reasonable to expect a written description or breakdown of the term.

 

[White Eagle]

BadUnit, I concur about not stressing enough the 4 position part time case, -vs- fulltime, but there is no such thing as Rock-Trac, not listed in the manual

 

[Badunit]

This was in the 2023 marketing brochure. Is nothing like this in the 2025 brochure?

 

[White Eagle]

Thats only marketing

 

[ShadowsPapa]

This was in the 2023 marketing brochure. Is nothing like this in the 2025 brochure?

It's laid out a lot differently in the 2025 brochure, they aren't listed side-by-side but are only listed with the models they come in -

 

[Zachanadandy]

Do you read the manual before you drive any vehicle or do you just get in and drive a they all function the same? Same question for the trigger analogy? Do firearms even come with manuals? Or is it a timeless, intuitive design that you pick up, point and shoot? Like shifting a transfer case. I don't care if the manual was written by an 8 year old and it's called the 4wd stick thingy, I still know what it is and how to use it.

 

[White Eagle]

Good for you

 

[rubicon4wheeler]

This video (and many similar ones) incorrectly describe torque distribution percentages in the various drive modes. It drives me nuts.

The 50%/50% torque distribution f/r is only under ideal circumstances where all 4 tires have equal traction. Same with the 25%/25%/25%/25% torque distribution described when 4WD with diff locks engaged. This is only when moving in a straight line where all 4 tires have equal traction.

In slippery surfaces, the 50%/50% torque distribution f/r is variable from 0%-100%, with power going to whichever axle has the most traction. Same thing l/r with differential lockers. In the real world of off-roading, up to 100% of the driveline's torque can be routed with diff locks to any 1 tire that has the most traction.

This is what separates true 4WD systems like our Jeeps' from the AWD or faux-4WD systems of most vehicles, whereby clutch packs, viscous couplers, and open differentials do not lock and cannot distribute a meaningful percentage of the engine's power to the tires with traction. This is why traction control systems are used in conjunction, as a Band-Aid to a subpar system. They're helpful for snowy roads, but usually pretty worthless on a trail. This is why you'll still see faux-by-four crossovers stuck in a driveway with 1 front tire stopped on asphalt while its other tires spin helplessly on ice.

Think of it this way: when your Jeep is in 2WD, it's really just 1-wheel drive. Put it into 4WD, and it becomes a true 2-wheel-drive. Engage the rear locker, and it becomes 3-wheel-drive. Engage front and rear lockers, and now it's a true 4-wheel-drive. Brake Lock Differentials (traction control) can supplement open differentials, but they're not a replacement for diff locks. Traction control systems work best in conjunction with a high-bias mechanical limited-slip differential, preferably a Torsen worm-gear style, but most manufacturers are too cheap to put a proper LSD into non-performance vehicles. The HMMWV used Torsen diffs front and rear. The problem with limited-slip diffs and traction control-based systems is that they require wheelspin before they start working, which means wear and tear on the driveline, the tires, and (most critically) the trail. A vehicle with traction control or limited-slip diffs may be able to scramble up a difficult section of trail, but it will take wild wheelspin and higher-than-necessary speed to do so. Conversely, a vehicle like a Jeep Rubicon will effortlessly idle up the same section in 4WD with diffs locked, without spinning a tire. No trail damage, no drivetrain shocks, no brakes wearing and overheating.

 

[Zachanadandy]

This video (and many similar ones) incorrectly describe torque distribution percentages in the various drive modes. It drives me nuts.

The 50%/50% torque distribution f/r is only under ideal circumstances where all 4 tires have equal traction. Same with the 25%/25%/25%/25% torque distribution described when 4WD with diff locks engaged. This is only when moving in a straight line where all 4 tires have equal traction.

In slippery surfaces, the 50%/50% torque distribution f/r is variable from 0%-100%, with power going to whichever axle has the most traction. Same thing l/r with differential lockers. In the real world of off-roading, up to 100% of the driveline's torque can be routed with diff locks to any 1 tire that has the most traction.

This is what separates true 4WD systems like our Jeeps' from the AWD or faux-4WD systems of most vehicles, whereby clutch packs, viscous couplers, and open differentials do not lock and cannot distribute a meaningful percentage of the engine's power to the tires with traction. This is why traction control systems are used in conjunction, as a Band-Aid to a subpar system. They're helpful for snowy roads, but usually pretty worthless on a trail. This is why you'll still see faux-by-four crossovers stuck in a driveway with 1 front tire stopped on asphalt while its other tires spin helplessly on ice.

Think of it this way: when your Jeep is in 2WD, it's really just 1-wheel drive. Put it into 4WD, and it becomes a true 2-wheel-drive. Engage the rear locker, and it becomes 3-wheel-drive. Engage front and rear lockers, and now it's a true 4-wheel-drive. Brake Lock Differentials (traction control) can supplement open differentials, but they're not a replacement for diff locks. Traction control systems work best in conjunction with a high-bias mechanical limited-slip differential, preferably a Torsen worm-gear style, but most manufacturers are too cheap to put a proper LSD into non-performance vehicles. The HMMWV used Torsen diffs front and rear. The problem with limited-slip diffs and traction control-based systems is that they require wheelspin before they start working, which means wear and tear on the driveline, the tires, and (most critically) the trail. A vehicle with traction control or limited-slip diffs may be able to scramble up a difficult section of trail, but it will take wild wheelspin and higher-than-necessary speed to do so. Conversely, a vehicle like a Jeep Rubicon will effortlessly idle up the same section in 4WD with diffs locked, without spinning a tire. No trail damage, no drivetrain shocks, no brakes wearing and overheating.

You realize that none of that is true? Think about being stuck in 2wd where 1 tire has 0 traction or is hanging in the air. Pre-BLD/traction control what happened? The tire with 0 traction just spun and the other tire did nothing. Was 100% of the power going to the spinning tire? Nope, equal power was going to each rear tire but because there was no resistance there was almost no power being made. There's a reason a dyno is also known as a load cell. Without resistance power simply can't be made. In 2wd is always 100% of the power to the rear axle and 50/50 split. BLD works not by magically rerouting power to the tire with traction but by braking the free spinning wheel and increasing resistance thereby increasing power output... to both wheels equally. In 4wd without an active center dif is always 50% front and 50% rear. With lockers and 4wd you can have 1 tire with traction doing all of the work, but it's doing it with 25% of the power as the other 3 tires are are obviously powered as everything is locked. The hard part for me to wrap my head around in the 1 tire free spinning scenario was how is the engine only producing a few ftlbs of force that it trashed to spin a tire while revving to 6k rpms. The answer is resistance.

 

[ChrisNLA]

Occasionally I feel like I am greatly overthinking various problems in my life.

Then I log onto the forum.

Nah - I think I'm alright.

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