Axles

[svince1884]

Hey to everyone! NEW-B here. I've got some questions about axles. I've got a 99 Tj with pretty much stock everything. I'll be using my Jeep as a DD, and mudding on the weekends. I'm looking at installing a 8" Skyjacker long arm kit with 2" BL, and running 38" or 40" tires. I know that I have to upgrade my axles but I'm not sure to what exactly. I've seen rigs that are running 37" tires with the same lift with stock axles. They had a truss and axle kit. What is that? What places offer COMPLETELY assembled axles so that I can just order them and bolt them right in?

[zero cool]

Currie and Dynatrac both offer complete axle assemblies with TJ brackets. They're spendy though. Expect to drop a minimum of $5K on a set of fully assembled axles that are ready to bolt in.

[svince1884]

Ok...what about a the 9" rear I hear so much about. Has anybody done a similar swap they want to share or provide some input about there experience?

[tufcj]

38-40" tires are going to require Dana 60 or stronger axles to be bulletproof. I'd say no bigger than 35s with your current axles, even with a truss (keeps the housing from flexing) and upgraded axle shafts (google "super 35 kit"). I think even with 8" of lift, 38s will rub, 40s will require some cutting to get it to flex. For bolt-in ready 60s from the above mentioned companies, be ready to drop nearly $4000 for a front, $3000 for a rear set up with gears, lockers and brakes.

Keep the body lift to 1", any more increases leverage on the bolts, which could fail in an accident. It also causes problems with steering, shift linkage, fuel and brake hoses, and radiator shroud.

Tires that big will require gears in the 4.88-5.38 range, maybe lower (numerically higher). You'll want to think about some type of lockers with that much tire, and you only want to build the axles and set up gears once.

I run 37" tires on my CJ with 7" of lift and 1" body lift, and fenders cut for TJ flares. You can see a pic in the "show us your ride!!" section. I run Dana 44's in both ends. The front is probably OK, the rear is living on borrowed time. I have a rear 60 ready to be built.

Bob
tufcj

[svince1884]

Why the locker? I read some where that lockers really aren't necessary, especially since I'll be running Boggers.

[tufcj]

Without a locker, the tire with the least traction will spin, the other will just sit there, doing nothing. With 2 open diff axles, even in 4WD, you really only have 2 tires pulling. If you cross it up in a ditch, get one front and the opposite rear in the air, forward motion WILL stop.

Most locking diffs require swapping out the diff carrier, which requires professional setup of the gears (even if you're using the same ones). Set them up wrong, and you can ruin your gears. It is a precision process that requires special tools, and can cost a couple of hundred $$ per axle, so you can see why you only want to pay once.

http://auto.howstuffworks.com/differential.htm

Bob
tufcj

[dan58]

Like the above guys said, you'll need 60s to reliably run 38-40" tires, and that's no guarantee. I broke a 35-spline D60 this past weekend.

Any tire of a 36 on a TJ gets VERY tippy, and the wheelbase is much too short. I have a wrangler with 105" wheelbase, versus the TJ's 96.

Going from a relatively stock TJ to one on 38+" tires is HUGE. What is your intended terrain?

Also, Skyjacker absolutely sucks. Look at Rubicon Express or Clayton's Offroad.

For NEW, ready to go D60s from Dynatrac, you are realistically looking at $11K. I fella I know had the wallet to buy a front...it cost him $8300 from Dynatrac.

[mika01]

For NEW, ready to go D60s from Dynatrac, you are realistically looking at $11K. I fella I know had the wallet to buy a front...it cost him $8300 from Dynatrac.

Ouch that hurts!

[svince1884]

Yeah, unfortunately I'm aware of how expensive they are. I've found a place where I can a complete rear D60 practically ready to bolt in for 4000. Terrain, why any terrain of course. Mainly mud for right now though.

[dan58]

$4K is a little steep though.


I'd just go to a shop and ask them to build you something from a junkyard. $3K should do nicely.