Battle

While my rig is a 99, I have a 27 spline 8.25 from a 93 because it has Yukon 4.11 gears. It also has a Spartan lunchbox locker. I want to get rid of the lunchbox and run an aggressive limited slip for better street performance (I have to drive hours to get to trails).

Since the obvious choice is a TrueTrac, I can only get one for 29 spline axle shafts. I don't want to buy a junkyard 29 spline 8.25 because my 27 already has gears set up. So, I've heard some people say you can upgrade to 29 spline by getting the right carrier (i.e. TrueTrac) and axle shafts - is that true? Will all I need to do this is the TrueTrac and some 29 spline shafts?

Please tell me someone has done this and has proof of the success. I thought about going with an Auburn LSD for a 27 spline axle, but the TrueTrac seems to be the ideal LSD on paper.

Fred/N0AZZ

Much of your question depends on use and the tire size you plan on installing as far as what axles to use. In many cases trying to save yourself some money here ends up costing more down the road.

Battle

I'm only running 33x10.5s. No plans to go larger, so really no need for a D44 or other axle. Really, I have no need for chromoly shafts either. I just don't want the lunchbox anymore and want to go for an LSD. Options are sparse for 27 spline shafts and the Yukon gears in my axle now are in great shape. I'm not really trying to save money. If I was, I'd keep what I have.

jedijeb

If you change carrier, you are probably going to need to do a gear setup also. Either LSD will be a new carrier.

Battle

Wait, why? If I'm buying a LSD for a 2.73 and numerically higher gear (which the TrueTrac is), then my current gears (4.11) should be fine - right?

Same with my Dana 30. I plan on running an Eaton E-Locker for 3.73 and numerically higher gears. I'm not going to have to get new ring gears, am I? (Differentials are dark arts).

WyoCherokee

Your ring gear bolts to the carrier(the trutrac is your carrier). Switching to a new carrier may change your backlashing and may not match your pinion shaft depth and pitch.

LACK

^^ That

he might get away with pinion depth but backlash will definitely need to be set.

The 8.25 doesn't use shims for the carrier so its a matter of pressing on new bearings and setting the backlash with the threaded caps.

Battle

Ahhh, okay! That's what I thought. I knew there would have to be backlash set, but my current ring gear should be fine (unless it's damaged of course). I'm not confident enough to set this up. Just want to make sure I'm buying the right parts for my gear and diff guy.

What about the 29 spline axle shaft/carrier swap? Think I would run into any issues there?

LACK

The trutrac is a full carrier diff. It will replace the stock carrier.

You should be able to use the ring gear you have, although id replace the carrier bearings/races as well as the ring gear bolts when you do the trutrac. 29 spline shafts shouldnt be an issue but I doubt they use the same size bearings and seals as the 27 spline shafts.

jedijeb

Sorry, should have said gear setup. Just didn't want you to do as some do and throw the new carrier in there and then burn up a good set of gears.