What is the Selec Trac advantage?

Clint in KY · **Joined:** Tue Dec 15, 2015 3:28 pm **Posts:** 10

When I bought my '03 Liberty it came with Selec-Trac. At the time I had no idea what it was or did. Reading I find that with Selec-Trac I can lock my Transfer Case (Part Time). Today I used my 4X4 in earnest for the first time. I traversed my 1/4 mile gravel uphill with a 90º turn in the steepest part in 12" deep snow. Going down was easy and going up was a breeze. I did it in Part Time.

So here is the question: What does Part Time do FOR me? I have read what it does TO me, which is bind the drive train if I use in on dry pavement. What advantage did I have using Part Time over Full Time?

flash7210 · **Posted:** Sun Jan 24, 2016 7:03 pm

Use part time when you are in soft sand, mud, and deep snow or ice.
Use full time on wet pavement and well maintained dirt roads.

What it does for you all depends on how you drive it.
Lots of KJs on the road where the transfer case lever has never been moved.

For some folks, part time is not enough. They will install a locking differential in front. That, combined with a locker in the rear and part-time engaged, will give you TRUE 4-wheel-drive.

u2slow · **Joined:** Sun Mar 11, 2012 7:26 pm **Posts:** 160

Where the the Selec-Trac (in fulltime mode) shines is highway speeds when its wet, icy, snowy, etc. This is the one reason I wish our KJ had the Selec-trac.

Part-time forces the front and rear axles to turn at the same speed. Better traction on loose surfaces, also more controlled braking, but has some steering & handling quirks. It's manageable, just not ideal. People say never to use it on dry pavement... but I often do when its freezing out (including highway speeds).

02blue · **Posted:** Sun Jan 24, 2016 8:20 pm

What's been said. I use my FT often even if just wet. Hardly ever use PT. I really like having it but it can be a bit finicky when it comes to tread wear and tire pressure. I've heard the command trac (231) is a bit more robust.

Clint in KY · **Joined:** Tue Dec 15, 2015 3:28 pm **Posts:** 10

u2slow wrote:

Part-time forces the front and rear axles to turn at the same speed. Better traction on loose surfaces, also more controlled braking, but has some steering & handling quirks.

Thanks - this is what I did not know. Now it makes more sense why it is advantageous in the slop and why it would cause binding when the front and rear axles are trying to turn at different speeds as they would in a tight corner.

Thanks again.

bugnout · **Posted:** Mon Jan 25, 2016 10:59 am

I leave the transfer case in Full Time pretty much from Nov to Mar. Love the traction.

bgcarl01 · **Posted:** Mon Jan 25, 2016 3:45 pm

There are a few occasions where I wished I had the selec trac over the command trac that I have. And perhaps will when the current command trac wears out. It works more like an awd vehicle, so I don't have to read what parts of the road are icy and which ones aren't. Although i gotta say, in bad snow storms. the part time is just a straight up monster compared to my friends and wives awd crossovers. Most of those have to spin the front wheels to engage the back ones.

Clint in KY · **Joined:** Tue Dec 15, 2015 3:28 pm **Posts:** 10

The above is why I passed up a bunch of All Wheel Drive vehicles. Once you've spun a wheel you are already starting to be in trouble. I drove 30 miles to look at a Chevy Tahoe that was listed as 4X4 and when I got there is was GMC's version of All-Wheel-Drive where the truck decided when it needed to be in 4wheel. Nope - I wanted a "real" 4X4 and bought the Jeep and learned later it was more than I originally was looking for. I will never be a Hard Core Jeeper with Monster Mudders and lots of lift as that sort of driving scares the p&^%$ out of me. I have a buddy with a Rock Crawler who always wants to take me out to some booney place and I have politely declined. All I want is something that will get up my 1/4 mile + gravel driveway that has a 90 degree turn in the steepest part and will pull my boat out on some of the less than wonderful boat ramps we have around here. I do believe the Liberty will do that.

Thanks to all.

LibertyFever · **Posted:** Mon Jan 25, 2016 7:14 pm

What the lifespan of the Selec Trac?
There must be a clutch pack inside it.
And the transfer case fluid must be specific.

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02blue · **Posted:** Mon Jan 25, 2016 7:53 pm

I've got 174k on mine and no problems. I use the FT mode often. It has a viscous-type coupler so works like some LSDs. Just uses ATF+4.

flash7210 · **Posted:** Mon Jan 25, 2016 8:11 pm

No clutch pack.
Uses ATF+4, same as transmission.

There are a couple things I don't like about it.
1. It's meant to be shift on the fly. If you wait till you are already stuck to put it into part-time you might be too late and not get full engagement. It likes to have all four wheels moving to get fully locked.
2. When shifting from full-time to 2wd it will sometimes get hung up in part-time. You won't notice until you try to make a sharp turn on pavement. Again, it's shift on the fly, it likes to have all four wheels moving (at exactly the same speed) to get unlocked.
Sometimes it takes driving it reverse for a short bit, then forward again to get it to unlock.
And sometimes it will unlock on that sharp turn with a loud pop.

02blue · **Posted:** Mon Jan 25, 2016 9:46 pm

flash7210 wrote:

No clutch pack.
Uses ATF+4, same as transmission.

There are a couple things I don't like about it.
1. It's meant to be shift on the fly. If you wait till you are already stuck to put it into part-time you might be too late and not get full engagement. It likes to have all four wheels moving to get fully locked.
2. When shifting from full-time to 2wd it will sometimes get hung up in part-time. You won't notice until you try to make a sharp turn on pavement. Again, it's shift on the fly, it likes to have all four wheels moving (at exactly the same speed) to get unlocked.
Sometimes it takes driving it reverse for a short bit, then forward again to get it to unlock.
And sometimes it will unlock on that sharp turn with a loud pop.

All true, and it is a bit finicky, so if mine hangs in PT when going from FT to 2wd that means it's time to check my tire pressures. Usually a little pop on the throttle and it shifts fine. Definitely like you to be moving just a bit.

BlueLghtning · **Posted:** Tue Jan 26, 2016 1:34 am

I just got my CRD with Slec Trac and it's the first 4wd vehicle that had a full time 4wd on it. All my other ones only had part time 4wd. I read up so I knew what was what, but it does surprise me that to go from 2wd to 4wd Full time, you have to go through 4wd Part time? It seems it would have been easier to have the 4wd full time first, then the 4wd part time next?

mass-hole · **Posted:** Fri Feb 05, 2016 1:13 pm

My Jeep basically stays in Full-time all winter unless I am drifting. It makes for a much more stable drive on unpredictable roads where it could go from pavement, to snow, and then ice in an instant. The downside is that the full time will allow 1 tire to spin in really slick conditions since its an open differential in the transfer case. So if you are in a really slippery situation its possible to start spinning and then the Full-time will send all the power to one axle. In some cases you could actually have less traction than in 2wd, like if you were to start spinning only the front tires when the rear has better traction. That's where you use Part-time to make sure at least two wheels are getting power because it locks the front and rear axle together, forcing both to spin.

Basically, anytime you think you will be in several inches or more of snow or mud I would go part-time to avoid getting stuck in the first place. If you are just driving to the mall on snowy roads, go full-time.

What is the Selec Trac advantage?

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