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Unread 07-22-2002, 07:49 PM   #1
Quebecman
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Trac-Lock Differential

I'm from Quebec, Canada, Kingdom of snow (french snow) and I'm looking to purchase a Liberty Limited with Select-Trac. I've never have a Jeep before (sorry) and I don't understand what is the benefit of the Trac-Lock option. I understand (...) that when I'm in Full-Time 4WD, the differential is locked in the center so I will get stuck if 2 wheels spin like the front left and the rear right, is that right or I'm a idiot?

Can somebody tell me what can happen if I don't have the Trac-Lock? Is it true that even with 4WD I can get stuck in the mud or snow because one wheel can spin? Is it true that Trac-Lock can prevent this?

Thanks!

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Unread 07-22-2002, 08:28 PM   #2
gonz165
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Basically, Jeep offers two four-wheel drive systems: part-time Command-TracŪ and full-time Selec-TracŪ. Selec-TracŪ has the added feature of a full-time mode that can be used year-round over any surface, whereas Command-TracŪ has to be manually disengaged if you're on regular street surfaces.

For a much better summary of various 4WD systems available, see here: http://www.cars.com/carsapp/national...ied/index.tmpl
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Unread 07-22-2002, 08:36 PM   #3
Liberty-4-All
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Re: Trac-Lock Differential

When in 4WD Full-Time ( for the road ), your transfer case is not locked. You KJ will be using one of the 4 wheels to propel you forward. If one starts to lose traction the power will be trasferred to one that has traction.

When in 4WD Part-Time ( for off-raod ), your trasfer case is locked so that one front and one rear wheel will turn at all times. With open diffs ( no trac-lok or locker ), if a wheel gets light and spins you do not get added traction on the other wheel ( same axle ).

With Trac-Lok it will sense that a wheel is loosing traction and transfer " some " power to the opposite wheel. This means that the two rear tires will both be working ( 2WD or 4WD ). When off-road the Trac-Lok will sense this loss of traction and " try " to compensate for it. If one rear wheel gets off the ground the Trac-Lok will not transfer power because it is receiving no input. You can " fool " the Trac-Lok by touching your brakes ( left foot while applying gas-much easier with an automatic ). This makes the Trac-Lok work even if the axle has one wheel off the ground.

This trick also works with open diffs but does not hook up as solidly as with a Trac-Lok. If you are going to attempt a steep climb that has some ruts, it is a good idea to pull the e-brake up three clicks before you attempt the climb ( just make sure you release the e-brake after you finish the climb ). If the e-brake is not enough you can give the foot brake a try with the left foot and it will engage both front wheels ( to a point ). Wiggling the front steering wheel will also help get both front wheels turning ( great for mud ).
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Last edited by Liberty-4-All; 07-22-2002 at 08:39 PM..
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Unread 07-23-2002, 08:26 AM   #4
Quebecman
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OK I understand. Great explications.

Another question : does the Trac-Lock is ready to work all the time or only in Part-Time 4WD (Command-Trac)? What I mean is if I drive on Full-Time 4WD in winter and 1 wheel begin to spin on ice, does the Track-Lock will transfer some power to the 3 other wheels?
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Unread 07-23-2002, 08:36 AM   #5
Liberty-4-All
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Quote:
Originally posted by Quebecman
OK I understand. Great explications.

Another question : does the Trac-Lock is ready to work all the time or only in Part-Time 4WD (Command-Trac)? What I mean is if I drive on Full-Time 4WD in winter and 1 wheel begin to spin on ice, does the Track-Lock will transfer some power to the 3 other wheels?
Trac-Lok is a LSD ( limited slip differential ). It resides in your "rear" axle so it only affects your two rear tires. Since it resides in your rear axle, it always has power applied to it and works in all settings ( 2WD,4WD Part-Time, 4WD Full-Time ). An LSD in the rear can make driving on ice kind of tricky. It sometimes tends to make you spin out. It is not as big an issue with a KJ as with other short wheelbase vehicles in the Jeep line. With Selec-Trac engaged in Full-Time 4WD, you should have no problems. I have a Powertrax No Slip Locker in the rear and it works great with Full-Time 4WD in the wet.
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Unread 07-24-2002, 12:40 PM   #6
MrEmoto
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Quote:
Originally posted by Liberty-4-All
I have a Powertrax No Slip Locker in the rear and it works great with Full-Time 4WD in the wet.
If you don't mind my asking, how much would I expect to pay to add a rear diff like that?

Thanks!
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Unread 07-24-2002, 12:49 PM   #7
Liberty-4-All
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Quote:
Originally posted by MrEmoto


If you don't mind my asking, how much would I expect to pay to add a rear diff like that?

Thanks!
You can order them thru RockyRoadOutfitters or Rustys. They are about $350.00 plus shipping. Be sure to tell them if you have an open carrier or a limited slip ( different part numbers ). It is a "lunch box locker " so you will not need to set the backlash. With some mechanical skill you can install yourself in about 2-3 hours.
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Unread 09-12-2014, 07:33 PM   #8
mmortiz9
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Command Trac-Track lok rear axle

I have Jeep Grand Cherokee 1993.This has Command Trac transfer case. I want to know if this grand cherokee has "trac-lok rear axle ?
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Unread 09-12-2014, 09:15 PM   #9
RockRollin
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As mentioned, trac-loc is only a LSD. It can be paired with select or command trac. The best option in snow is part time 4wd. Part time gives you a center LSD. The center LSD is what Jeeps outstanding traction legend is based on. Full time, or locked center diff can cause a break in traction on its own (why its not recommended for dry pavement). Honestly any 4wd Liberty is going to take good care of you in the snow, provided you have decent tires. My first KJ had the trac-loc and it was very squirrley if I got on the gas in the snow. I do miss it on the trails though.
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Unread 09-14-2014, 03:57 AM   #10
Billwill
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Quote:
Originally Posted by mmortiz9 View Post
I have Jeep Grand Cherokee 1993.This has Command Trac transfer case. I want to know if this grand cherokee has "trac-lok rear axle ?
You can look for a label on the rear axle...may tell you if it has Trac Lock....don't know if it was even invented by 1993!

Trac Lock needs a fair amount of attention as special Mopar Friction Modifier has to be added to the diff at the time of a diff oil change so if this has not been done for some years now then your Trac Loc is now a "Trashed Loc" as many people call it.....it does not have a very good reputation...I have it on my 2002 Export CRD and have changed the rear diff oil and added the Mopar Friction Modifier and have had no problems though!

As stated...Trac Lock is in the rear diff and has nothing to do with the transfer case being Command Trac or Select Trac!
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Unread 09-14-2014, 06:27 AM   #11
tjkj2002
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Quote:
Originally Posted by RockRollin View Post
As mentioned, trac-loc is only a LSD. It can be paired with select or command trac. The best option in snow is part time 4wd. Part time gives you a center LSD. The center LSD is what Jeeps outstanding traction legend is based on. Full time, or locked center diff can cause a break in traction on its own (why its not recommended for dry pavement). Honestly any 4wd Liberty is going to take good care of you in the snow, provided you have decent tires. My first KJ had the trac-loc and it was very squirrley if I got on the gas in the snow. I do miss it on the trails though.
Got it backwards,part time 4wd "locks" the t=case so the front and rear driveshafts spin at the same speed so a no-go on pavement.Full time 4wd is the one you can use on pavement since it's a "open" diff inside the t-case allowing the F/R driveshafts to spin at different speeds.
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Unread 09-14-2014, 07:01 AM   #12
RockRollin
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Yea, dangit. I constantly get that backwards. Full time you can RUN full time, not locked full time.
Something about my old Dodge with 4hi/4hi-loc has tainted my brain. Thanks for clarification tjkj.
Anyway, the option using the center LSD "Full Time" proves better in snow personally.
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