Aussie in front, TrueTrac in rear
Sorry, it's not TJ-related, but definitely in the scope of this thread.
I recently replaced my stock rear D35 Trac-Lok LSD with a Detroit TrueTrac LSD, u-bolt yoke, and Alloy USA axles. The first thing I noticed on dry pavement was -- nothing. There is no noise and the steering feels the same. However, when it's lifted up on jack stands, you can tell the TrueTrac is different than the stock LSD because the wheels spin opposite directions, like an open diff. The Trac-Lock LSD would spin the tires in the same direction when up on stands, even when you applied a good amount of opposing torque to each wheel. So when there is no power applied to the R&P, the TrueTrac is literally like an open diff.
I tested the TrueTrac on a long strip of fill gravel in the middle of one of the longest streets in town that is under construction. With the left wheel in gravel and the right on pavement, I floored it in 2WH from a dead stop, and the wheel in the gravel did not spin, and the vehicle kept going forward quickly. So the torque biasing aspect seems to work pretty well so far.
Also, I have had an Aussie in the front (Dana 30 HP) since April or so. It is definitely noticeable, even in 2WD, mostly by sound/feel. It doesn't affect the 2WD steering very much, except that I no longer feel it's wise to take relatively quick and tight u-turns like I used to be able to with an open diff. That was one of the things I really loved about my stock XJ. The Aussie ratchets way too loudly when you take a tight u-turn, and I am afraid it's going to frag or something. I double-checked the specs when I installed it -- it was well within the feeler gauge measurements -- so it's not like it was installed incorrectly. Can't really screw up a lunchbox install anyway. And my tires are within 1/4" same diameter and the same air pressure.
The Aussie also will kind of clunk every so often when driving straight on a high camber road. I "know" in my mind that it's normal behavior/sound for the lunchbox locker, but it just doesn't "feel" right to me.
In 4WD, the Aussie pretty much wants you to stay in a straight line, and you know it's there when you try to turn. I will say one thing, it pulls like a son-of-a-gun when in 4WD now. I literally feel it pulling forward much more than when it had the open diff. I have not yet an opportunity to try it on snow/ice, so I can't make any judgement there.
If you install an Aussie in a vehicle with lots of miles, odds are you'll notice that your carrier bearings, axle seals, and pinion seals need replacement (mine did). So by the time you do all the work/pay the money to have the diff rebuilt with new bearings, setup/preload/runout, seals, etc. you aren't that much more ahead by going with the lunchbox instead of a Detroit No-Spin (aka Detroit Locker) or a TrueTrac.
One of the reasons I replaced the Trac-Lok was because it had clutch plates that eventually wear out. From what I've read on other forums, it also sounds like the Aussie will probably wear out. Besides, I can't see how it won't, with all the ratcheting it does while differentiating corners and u-turns.
That said, I am seriously considering replacing the Aussie with a TrueTrac. Since the Aussie was already 1/2 the cost of a TrueTrac, perhaps I should have just done the TrueTrac to begin with? And the Aussie is just a replacement for spider gears. With the TrueTrac, you get a whole new carrier that is probably much stronger than the stock carrier.
If you have the money to do true hardcore wheeling e.g. breaking and replacing parts (JEEP = Just Empty Every Pocket, right?), you might as well go for broke and get the full-on selectable lockers. I've had my Jeep long enough (and am now honest enough with myself) to realize that I'll never use it for rock garden boulder crawling, but will need it for some snow/ice roads, sand, mud, etc. So I think the TrueTracs F/R will be my best bet right now. If I need to keep the front wheels out of the air, I'll just try out the new JK Quicker Disconnects I just installed. Hopefully the combination of TrueTrac and extra articulation will be enough to get through heavily rutted and uneven slippery roads.
So if you don't mind some clickety-clunk noise and want some extra pulling power, the Aussie in a Dana 30 isn't a bad way to go, I suppose. One of the greatest things about Jeeps is there is seemingly no shortage of options, or combinations thereof.
Forest Service Green 1998 Jeep XJ
Last edited by PackDude; 07-07-2010 at 12:58 AM.
Reason: readability, organization