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Affordable DIY JK Front Axle Upgrade

Posted in How To: Transmission Drivetrain on September 1, 2012
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Bent front axles in JKs are just about as common as JKs. Get the point? If you add 35s and wheel your late-model Wrangler hard, we’ll guarantee your axle has more shape than Megan Fox. Even mere 33s and daily driving can eventually tweak the Dana 30 and Dana 44 under these vehicles. Naturally, you can buy a complete bulletproof axle assembly to bolt in place, but the price is usually overkill for many JK owners. If you have a stocker that you’re building into a decent off-road machine, however, you can add some beef to the axle under your Jeep without taking out a bank loan.

The stock front axle uses 2.5-inch-diameter, 0.250-wall axletubes. Mount 35s on the ends of this axle and it looks like the first Tinker Toy car you built: a spindly rod connecting two giant tires. Since bending the axlehousing is the primary issue, companies like Synergy Suspension have developed components to reinforce the assembly. The key upgrade is an inner tube sleeve, which increases the strength of the axletubes by almost 60 percent. These slide inside the existing housing and are welded in multiple places to add strength over the lengths of the tubes. In addition to bending, these axles come with weak ball joints and the knuckles deflect where the ball joints mount. Synergy makes an inner C-gusset to reinforce the upper and lower ball joint mounting locations. The company also makes heavy-duty ball joints which are much stronger than stock and are greasable for longer service life.

We started with a Synergy Suspension Jeep JK D30/44 Complete Inner Axle Sleeve Upgrade kit. For $200, you get the inner axletube sleeves, inner C gusset kit, and lower control arm skidplates. The ball joints are another weak point on the JK front axle, so we ordered a set of Synergy heavy-duty upper and lower ball joints (PN PPM-HD-BALL-JOINTS). Even with the cost of the ball joints, we think that our axle upgrade is a steal at $425.

Naturally, there’s a bit of work involved in installing these components. We decided to tackle the task over a weekend in our garage to show exactly what’s involved and what tricks you’ll need to know. The first thing you’ll need is to collect a few special tools, if you don’t already own them. In addition to the normal selection of hand tools, you’ll also need a pickle fork, a ball joint press, and a 35mm socket to fit the spindle nut, all of which we picked up at Harbor Freight. You’ll also need a decent MIG welder capable of welding 1⁄4-inch steel. For this, we used an HTP MIG200.

We sourced all of the Synergy Suspension products through Poly Performance for $425. These upgrades are far easier to do on a front axle that hasn’t been drug over rocks or bent already. If yours is damaged, you’ll need to straighten it before you do these modifications. Also, if you live in the rust belt and have driven your JK through even one road-salted winter, everything will be seized together, making disassembly much, much more challenging.

It may be easier to do some of the welding with the front axle removed from the vehicle, but we opted to leave ours in place in an effort to get everything done within one weekend. You’ll need to support the frame on tall jack stands and remove the tires to let the front axle hang free. If your JK has been treated to a salt bath during the winter, hose down the front end with a strong penetrating oil a day or so in advance.

Torque Specs
There are quite a few pieces that need to be removed and reinstalled on the front axle to do these upgrades. Here are all of the torque specs you’ll need to get things back together.
Unitbearing bolts 75 lb-ft
Axle nuts 100 lb-ft
Brake caliper brackets 120 lb-ft
Lower ball joint 80 lb-ft
Upper ball joint 75 lb-ft
Track bar bolts 125 lb-ft
Tie-rod ends 63 lb-ft
Drag link at axle 63 lb-ft
Swaybar nuts 90 lb-ft
Lower shock bolts 56 lb-ft

PhotosView Slideshow


Poly Performance
San Luis Obispo, CA 93401
HTP America Inc.
Arlington Heights, IL 60005
Synergy Manufacturing
San Luis Obispo, CA 93401

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