gearr swap and carriers
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I'm changing my gears from 3.21 to 4.88s. They said I don't need to change the carriers. Is that true I heard you did?
Last edited by jaybrown; 03-20-2012 at 11:56 AM.
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All rear JK 44 aftermarket gears are what is known as 'thick' gears. Usually Dana 44 gears use 2 different carriers and the carrier you need will be determined by your gear ratio. 3.73 and down gears use one carrier and 3.92 and up gears use another. JKs, and their earlier TJ Rubicon brothers, changed that. The TJ Rubicon, like the JK Rubicon, has a standard 4.10 ratio. However, they were built on the 3.73 down carrier, not the common 3.92 and up carrier. The aftermarket mfgrs knew that Rubi users would want to change ratios and produced a full line of desirable ratios (4.56, 4.88 etc) in the 'thick' design so Rubicon owners would not have to change to a different locker when they needed a gear swap. Since the Rubicon requires a 'Thick' gear, the replacement gears also fit non-Rubi models that would have the 3.73 and down carriers anyway due to ratios used on the Jeeps- 3.21, 3.73.
Now the confusing part- JK rear 44 open carriers are slightly different, internally, than previous open differentials and common lunch box lockers, like an Aussie, won't fit. To install an Aussie in the rear of a JK you need an open Dana 44 carrier from a TJ or earlier model, also 3.73 down. You need to re-drill the ring gear bolt holes for the larger bolts used in JKs but that not a difficult job.
FWIW- I don't usually recommend a lunch box for rear applications, especially for DD use. Unlike a Detroit Locker, which provides very similar performance, lunch box lockers wear over time and have a tendency to shear pins making them useless. A Detroit Locker is a far better option if you want auto-locker perfomance. One of the big advantages of a lunch box is the ability to install it yourself without a back lash/shim change to your carrier. With a JK you need to replace the carrier anyway so spending a couple of extra $$ for a Detroit is well worth the cash.
#10
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I bugged them again and they questioned the supplier and turns out everybody here is right. You need a front carrier. Thanks for the info or else I would have had a jeep with the front end apart for a couple days waiting for parts or paying extra to put it back once they noticed it wouldn't work. Thanks everyone