Lockers

[Eagle]

Quicky tour -- the differential has a cast housing (that's what you see when you look under the back of your Jeep. The axle tubes are press-fitted into that.

Inside the differential housing, you have a pair of bearing caps that are somewhat similar to the main bearing caps in the engine. The carrier is the unit inside that holds the ring gear. The carrier has short legs on it where the bearings are pressed on.

An open diff has a set of spider gears inside the carrier to accomplish the differentiation. Two of the spider gears are splined, and the axle shafts enter into and engage the spider gears. In an 8.25 axle, the shafts have a grove machined into the inner ends, and the shafts are retained by c-clips inside the differential.

A lunchbox locker removes the spider gears and replaces them with some kind of proprietary contraption (specifics vary depending on make) to function as a locker. The carrier, however, remains, and this is why all lunchbox lockers are weaker than a Detroit. The Detroit is a complete unit that replaces the carrier, and thus it can be (and is) made stronger than the OEM carrier. However, because it replaces the stock carrier, you have to be sure the bearings and shims are set up to maintain the OEM backlash. The Detroit can use the OEM axle shafts, which could then function as your "fuse" if you want to think of it that way. I prefer to be a wimp and not break anything, but if I had a choice I'd rather break an axle shaft than blow up a differential.

 

[mdwatkins]

Alright...the decision has been made and I have no choice but to run with either an ARB or OX in the front 30 and since ARB is the only selectable available in the 8.25 rear, I guess that's where I'm heading.

After reading through a pile of articles and information I've decided that for the cost...I might as-well save an extra month or two and just do things once, rather than twice. So when it comes time to regear, in go the selectables

Thanks for all your help and info, it was greatly appreciated

Matt

 

[mikeyl]

quick note about the lunch box lockers. on my D44 the ring gear was too thick to slip the spider shaft out to install the quickloc. i had to remove the carrier completely to install it. and it was a big pain! my reason for the quicloc was that i will be re-gearing in about 1/2 year and i removed my d35 with the factory LS. eagle is correct the LS was a decent traction device when it's intended purpose wasn't overtaxed. been in lots of places with the LS. the d44 csame open diff and i wanted to install something temp to get me by for a short time. so be careful with "the lunch box locker is a breeze to install" talk!

 

[getarpicker]

I have a really bad vibration in the front end of my 98 classic. In reading the above I am seriously thinking of just replacing the front end with a limited slip mainly for the lock out option. I do 90% road driving. I have the front shaft out now just to get rid of the vibration - its already been re-balanced and had all new dana spicer u joints installed. Would anyone suggest which front diff. to go for?

 

[Eagle]

There aren't many choices in limited slip for the Dana 30. TruTrac is the best bet. Trac-Lok isn't available.

 

[Nay]

If you are still looking at this thread...I'd think seriously about replacing the 8.25 if you are going to put new gears and locker in it. It has a tendency towards serious gear whine with lower gear ratios. You can do the locker and alloy shafts and your 29 spline 8.25 will be plenty strong...but even then you still have the crappy drum brakes. Convert to disc brakes (a huge improvement for a '99 XJ that requires no other brake system modifications), as well as alloy shafts plus the locker and gears...and you've spent as much money as a custom built 44, and you are close to a high pinion 9" from Currie.

Think it through - ARB is a great choice for a daily driver...but once you are going with dual lockers and getting a lot more serious about wheeling, you'd ought to consider all of the mods your 8.25 will need, and whether you'd rather spend the money on a custom built axle.

Custom axles can be surprisingly cost effective...you get the labor savings of doing everything at once (gears/lockers/brakes/axles) and this make up for the premium of a custom designed axle that fits your application perfectly.

Nay

 

[basalt51]

Couldn't agreee more. After adding up the cost of everything to improve my 8.25 with alloys, arb, gears, and discs, the price difference compared with currie was about $600 for a HP 9" w/ arb, disc brakes, and 4.56 gears.