4x4 systems

[MikeJ06]

Hello,

I'm having some trouble understanding the command-trac 4-wheel drive system on my 06 liberty. It says that the front and rear axles are locked together when 4hi is engaged but what does that mean exactly? Are there locking hubs on the front axle and the rear diff remains open? Or are both axles locked? If that is the case then why would there be a need to upgrade with lockers? And if both axles are open, then why couldn't I use 4hi on normal pavement conditions? I know this is an elementary question(s), but I've only ever driven front wheel drive cars except for an AWD Talon - and the differentials where never a major concern of mine. Thanks in advance to anyone who can help make me understand.

 

[Atrus]

I tried to have this explained to me. This is what I got out of it...I could be wrong.

Command Trac:
Without the LSD option, or an aftermarket locker, yes, both axels are open. The transfer case, however, locks the front and rear axles together. When you turn, the front axle is at a different speed than the rear. That's where the binding comes in.

Select Trac:
Without the LSD option, or an aftermarket locker, yes, both axels are open. The transfer case, however, does not lock the front and rear axles together in 4FT. In 4PT, it locks them just as command trac. When you turn, the front axle is at a different speed than the rear. 4FT runs as an open diff, 4PT runs locked.

 

[MikeJ06]

So in 4PT the front and rear axles are running at the same speed? That makes sense considering the rear axle has a shorter travel distance when turning and having the front and rear locked would cause slip and drag. Thanks for your input!

I never gave any time to try and understand the different types of systems. But I want to get into off-roading and it would be nice to know what needs to be done not to get stuck.

 

[Atrus]

Yup, that's what I understand -4PT, f/r axles are at the same speed.

Kind of a bummer...I thought I got a 4x4....I actually got a 2wd Better than a 1wd though!

I looked at my build sheet and it doesn't look like I have the LSD

 

[_UnLiMiTeD_]

can you request a build sheet online for free or do you have to go into the dealer

 

[Atrus]

either or. I guess you can e-mail them from the customer support link, or just go into the dealer.

I had my buddy at Chrysler pull mine for me. He e-mailed it to me.

 

[Tline155]

LSD should be easily noticed by looking at the rear axle. A green band should be around it. Mine is right nest to driver hub.

 

[o8k]

Yup, that's what I understand -4PT, f/r axles are at the same speed.

Kind of a bummer...I thought I got a 4x4....I actually got a 2wd Better than a 1wd though!

I looked at my build sheet and it doesn't look like I have the LSD

Does your Vehicle have the ESP thingy? if so, that helps traction in some cases, not in others.... Also, if you have an automatic, you could always just jam on the breaks and the gas at the same time, and vualla! your slippy wheels will slip less and it may get you out of a jam!!!!

 

[Ry' N Jen]

Swap

Good day,

I was also uncertain as to how Command Trac and Select Trac worked.
Good explanation! Thanks!
I would like to ask a question.
Can I swap out my Command Trac transfer case for a Select Trac transfer case?
I am going to make an educated guess here as to what I need in addition to the transfer case.
Select Trac T/C lever and linkages, related hardware.
Some sort of wiring harness with bulbs and sockets for gauge cluster indicator 4F/T - 4 P/T
Does anything computer wise require re-programing???

Thank you.

Ryan Heibloem

 

[sevenhelmet]

Good day,

I was also uncertain as to how Command Trac and Select Trac worked.
Good explanation! Thanks!
I would like to ask a question.
Can I swap out my Command Trac transfer case for a Select Trac transfer case?
I am going to make an educated guess here as to what I need in addition to the transfer case.
Select Trac T/C lever and linkages, related hardware.
Some sort of wiring harness with bulbs and sockets for gauge cluster indicator 4F/T - 4 P/T
Does anything computer wise require re-programing???

Thank you.

Ryan Heibloem

That's a big job- one not commonly done. However, I don't believe it requires any reprogramming, unless you have Electronic Stability Control. ABS should be unaffected. Essentially all you add with full-time 4-wheel drive is a lockable center differential (part of the selec-trac Tcase) which allows the front and rear axles to spin at different speeds so you can use your 4wd when you're on a dry, solid surface. Are you wanting to mod this yourself?

I personally like the Command-trac just fine, it's a tough, reliable transfer case which does everything I need and then some. The only mod I'd consider for my drivetrain is an ARB locker for the rear.

 

[Atrus]

Does your Vehicle have the ESP thingy? if so, that helps traction in some cases, not in others.... Also, if you have an automatic, you could always just jam on the breaks and the gas at the same time, and vualla! your slippy wheels will slip less and it may get you out of a jam!!!!

Yup, I have ESP - standard on '07

How does the brake trick work? I don't understand how that would help.

 

[MikeJ06]

The command-trac transfer case does not utilize a true differential. It merely locks the front and rear axles together while I would assume the selec-trac transfer case uses an open center differential to allow the separate axles spin at different speeds.

Don't quote me, I'm just learning this stuff for the first time myself.

 

[sevenhelmet]

Command Trac = No differential in the T-case

Select-trac = Lockable differential in the T-case. Unlocked (open) diff during 4WD full time, locked during 4wd part time (locking axles together like the command-trac.)