Question about Chrysler 8.25 Open vs. Limited

[F0r3stFr3q]

Hey there!
First off, thanks for all the valuable information here. I’m new to posting, but I’ve been reading for a long time.

I’m trying to better understand the difference between an open and limited-slip rear differential, and whether it’s worth converting from an open to a limited-slip.

My current understanding:

• With a limited-slip differential, when the driver’s tire moves forward (while off the ground), the passenger tire moves backward.
• With an open differential, both tires move in the same direction

I’m about to convert a '00 XJ Sport (Chrysler 8.25 open diff) into a daily driver for a college student. We live very rural, near tree line elevation, so the XJ will see about 50% dirt roads and 50% paved roads daily, with winter Colorado snow (mostly powder, wet and heavy in spring). It might also be used for some light overlanding in spring/summer for camping or hunting trips.

XJ details:

• 4.0 with Automatic transmission
• 3.5" suspension lift with 30" BFGs on slightly offset rims (rear chains)
• Considering a detachable front sway bar.
• No rear sway bar

If I were going to put time/money into serious differential work, I’d install an ARB locker on the Dana 30 front (unlikely). However, I’m wondering if there’s a worthwhile performance gain by converting the rear to a limited-slip differential or if riding the brake a bit is about the same?

I am not meaning to rehash age old diff debates, just wondering what is involved in the conversion and if the juice is worth the squeeze?
Thanks for your time and advise!

 

[Paradiddle]

That is not correct. An open differential means when one tire loses traction the power goes to the tire that does NOT have traction - meaning the tire that is spinning. In simple terms - you are stuck.

A limited slip means there is a clutch pack in the diff that does it's best to distribute power as equal as it can to both wheels so you can hopefully drive out of whatever you are stuck in. They work well, but they have their limitation in low traction environments.

A locker means that - you lock both wheels at the diff. You can lift a tire off the ground and the power will still go to the tire that has traction and the tire in the air. It also means that you lose the "differential" part when it's engaged meaning on the road the inner tire will skid because it can't spin faster then the outer tire in a turn (they can be a handful in the front on high traction surfaces like roads). These are obviously the best for more serious off roading conditions that demand it. They can be hard on drivetrains - especially front.

Ms. Vito said it best.

 

[Bent]

These are obviously the best for more serious off roading conditions that demand it.

Only once one learns to drive.

 

[stickandrudder]

I had double trutracs in my jeep before i axle swapped and in deep north idaho snow, I ran into a lot of issues with them on 35s. Even holding the brake, I'd struggle sometimes to get it work. Also doing some rock stuff they'd kinda show their limits. Really nice on icy roads and less extreme wheeling. Huge improvement over an open diff tho, I'd look into a LSD for the 8.25. i'm not sure I'd lock a dirty 30, unless you plan on sticking with the smaller tires. lsd would be nice there too. ARBs are expensive and require a lot extra. That's a lot of dough for a 30.

 

[F0r3stFr3q]

Thanks all!
Thanks for the correction Paradiddle. I jacked the back and know for sure the two tires did not rotate in opposite directions (not a LSD).

Overall I agree with everyone and I am more focused on those worry free evening drives home in winter.

Stick: Is the 8.25 LSD and a "trutrac" the same thing (Chrysler's name for it)?

Are there kits for the conversion? Eaiser to buy a rear axel? I can't seem to find discussion on the topic, but that is because most threads get into true lockers, lunch boxes, etc.
thanks again

 

[RCP Phx]

True tracs are gear driven so they don't wear out. They are a replacement diff made by Eaton. They are a great choice for a non-locker!

 

[Tim_MN]

It also means that you lose the "differential" part when it's engaged meaning on the road the inner tire will skid because it can't spin faster then the outer tire in a turn (they can be a handful in the front on high traction surfaces like roads).

This is also incorrect.

I have a PowerTrax No-Slip automatic locker in my rear Chry 8.25 axle and it behaves about the same in Minnesota winter driving as the factory installed Limited Slip it replaced. Summer and Winter, it unlocks as needed to turn corners on pavement, or rocky trails.

@F0r3stFr3q, What is the budget?

What is commonly called a lunchbox locker ( Lock Right and No-Slip included ) is low cost, simple to install in your driveway, and simple to remove if you do not like how it behaves. A TrueTrac requires some skill and specialized tools and knowledge to install, or paying someone to install it. 32 inch tires would be the max you would want to install with a TrueTrac, but one of the guys in my local Jeep club has one in both axles, and he keeps up with the big boys and their locking differentials.

I would not put an automatic locking differential in the front axle of any 4x4 that is driven on snowy/icy pavement in the winter. Automatic lockers in the front axle have some odd and potentially unsafe pavement driving manners on snowy and icy roads.

Limited Slips and lockers improve traction, and stability.

 

[F0r3stFr3q]

Thanks.
Budget is as little as possible but not more than $500.
I'm comfortable with pulling it part, but wanting to meet the need (daily rural driver and occasional wekend overland). I will look into the Trutrac and Powertrax.
I'll be sure to update this as things go.

 

[Paradiddle]

This is also incorrect.

I have a PowerTrax No-Slip automatic locker in my rear Chry 8.25 axle and it behaves about the same in Minnesota winter driving as the factory installed Limited Slip it replaced. Summer and Winter, it unlocks as needed to turn corners on pavement, or rocky trails.

@F0r3stFr3q, What is the budget?

What is commonly called a lunchbox locker ( Lock Right and No-Slip included ) is low cost, simple to install in your driveway, and simple to remove if you do not like how it behaves. A TrueTrac requires some skill and specialized tools and knowledge to install, or paying someone to install it. 32 inch tires would be the max you would want to install with a TrueTrac, but one of the guys in my local Jeep club has one in both axles, and he keeps up with the big boys and their locking differentials.

I would not put an automatic locking differential in the front axle of a 4x4 that would be driven on pavement the winter.

Limited Slips and lockers improve traction, and stability.

I meant a selectable locker - like an ARB or Eaton. Once those are engaged, they don't slip or disengage until you do it.

Going cheap on lockers is stupid. Buy once and cry once. If you need them, you need them.

 

[Evan03]

I think 105% who have them don't need them.

Grizzly or Detroit the front axle leave rear open and be done with it.

 

[Paradiddle]

I think 105% who have them don't need them.

Grizzly or Detroit the front axle leave rear open and be done with it.

Once you wheel where you need them, you'll know. Why lock the front and not the rear first?

 

[Tim_MN]

Grizzly or Detroit the front axle leave rear open and be done with it.

I would not put an automatic locking differential in the front axle of any 4x4 that is driven on snowy/icy pavement in the winter. Automatic lockers in the front axle have some odd, and potentially unsafe, pavement driving manners on snowy and icy roads.

 

[F0r3stFr3q]

@Evan - I've run a bunch of different wranglers in my day, all over Colorado's and tend to agree with this philosophy.
That said, with a college daily driver I subscript to 'a front locker gets you into trouble that a winch gets you out of' and I wont be funding a winch

I'm leaning toward Trutrac, perhaps front and rear in the future.

 

[Ol Blue]

I would not put an automatic locker or lunchbox locker in the front or rear of a vehicle that is driven on road in the snow. It just gets super sketchy whenever you get on the gas.

Had a Powertrax No Slip in the rear for a few years. I drive my XJ to work when it snows in Colorado so it sees lots of snow on paved roads. Have an ARB now (which acts like an open diff in the snow), and the difference is astonishing. With the lunchbox locker you can only use the gas pedal if you are going in a straight line. You absolutely cannot get on the gas coming out of a turn. If you do, the back end slides out. I made it work and never crashed, but it takes skill and patience. I won't ever do that again.

 

[Tim_MN]

A rear axle automatic locker does necessitate slightly changing your 2wd pavement driving techniques, but that isn't difficult, and the additional traction and stability that the locker adds is worth it. The on-road behavior of the locker isn't that much different than the Limited Slip it replaced.

On a snowy Minnesota day I can drift my XJ sideways down the road for 1/2 a block, shooting twin rooster tails of snow into the ditch. Simply lifting off the gas pedal slightly makes the tail end tuck back in-line with the front.

 

[THE2NDXJ]

This is a bit late to the discussion, but you can check out youtube videos for some great explanations on the differences of all types of differentials and traction control devices. My opinion, its a bit pricey up front, but I love Detroit Lockers. I know lots of people poopoo on them for snow/ice situations, but with a little experience, they work outstanding for traction! They are also not as noticeable or temperamental on pavement as lots of people have perceived them to be.

 

[Tim_MN]

I would not put an automatic locking differential in the front axle of any 4x4 that is driven on snowy/icy pavement in the winter. Automatic lockers in the front axle have some odd and potentially unsafe pavement driving manners on snowy and icy roads. I have first hand experience with that, and never let anyone drive my XJ in the Winter. Some of the guys in my local Jeep club who daily drive their Jeeps remove their lunchbox locker in the fall, and re-install it in the spring.

A selectable locker, or a Detroit Truetrac, would be my recommendation for a traction device in a front axle for winter pavement driving.

For a light duty 4x4 that sees daily driving and/or winter weather driving, I recommend a rear axle locker. A LockRight type lunchbox automatic locker fits that recommendation, is affordable, is a Do-It-Yourself install, and is easily removed.

 

[Evan03]

So what did we decide?

 

[CMNCHE]

For a light duty 4x4 that sees daily driving and/or winter weather driving, I recommend a rear axle locker.

This is almost as dangerous as a front locker on snowy/icy roads.

 

[Evan03]

The xj fad is to lock the rear with gizmos in such but i find the front does the pulling and grunts the rig through stuff a rear locker cant.
Must be easier cheaper quicker or who knows what freaking jeep guys always take the easy way out.
but i find a locked front does the grunt work getting rear locked rig through stuff kinda like a front wheel drive car in the snow.

Snow is some sketch sh!t id just stay home over driving in those conditions.