How To: Replace a Front Axle on a 2002-03 WRX

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Yes that grease is burned onto the exhaust heat shield… yes it’s going to be a pain to clean.
This is not an uncommon repair on our favorite bugeyed sporty car, and luckily it’s not a difficult one either. The left front axle inboard CV joint sits within inches of the exhaust, so the grease boot experiences excessive thermal stress. The cyclic stresses of constant rotation combined with the heat of the exhaust will cause the boot to tear and eventually split. You can imagine the mess that comes next. Enough time without grease and the bearings in the CV will fail.

If you find that you have an axle with a failed boot, then the best course of action is to replace the axle assembly. It may be tempting to replace the lost grease and the torn boot, but grit and debris can be trapped in the bearings. This will increase the likelihood that the bearing will fail over time. Replacement axles aren’t much more expensive, and remanufactured options are available at great prices. They even come with a replacement axle nut and retaining pin. I got a remanufactured Dorman axle from Autozone, which was nearly identical to the damaged axle that I removed. So here’s how to get it done.

Tools:

  1. 32mm socket (you don’t have to buy this, they can be borrowed or rented from most auto parts stores)
  2. Breaker bar
  3. Penetrating oil
  4. Punch
  5. Hammer
  6. Torque Wrench
  7. Optional: 19mm combination and/or socket wrenches

Process:

  1. Jack up the car, and safely rest it on stands high enough to get under the car
    A jack handle isn’t the most elegant solution, but it gets the job done. Not shown, a hammer and punch for driving out the spring pin that retains the axle on the transmission, as well as wrenches required for pulling the strut mounting bolts.
  2. Remove the wheel at the axle to be replaced
  3. Un-crimp the axle nut from the key slot in the axle
    ** If you get a replacement axle, then it will come with a replacement axle nut. No need to be delicate
  4. Put the car in gear and have a friend stomp on the brakes while you take the 32mm socket and a breaker bar to loosen the axle nut.
  5. Apply penetrating oil to the axle shaft inside of the steering knuckle. The splines have likely rusted and will be difficult to remove without some liquid encouragement
  6. Drive the spring pin out of the axle joint at the transmission
  7. Remove the axle from the car… you have a couple options here:
    1. Mark the position of the camber bolt and unbolt the strut from the knuckle, then pull the top side of the knuckle out in order to disengage the axle from the hub, or
    2. Use the scissor jack that came with the car to spread the engine away from the frame horn on the side of the car at which the axle is being replaced in order to separate the axle from the transmission.
      ** In either case you’re trying to detach one end of the axle from the car. I already had the engine out, so it was easy for my to rock the transmission to the side and slip the axle off the transmission output. This was advantageous because I did not do step 5 and it took a punch and a small sledge to get the axle out of the hub.
  8. Remove whichever end of the axle is in the car, and repeat the process in reverse in order to install the new axle!
    ** If you unbolted the strut from the steering knuckle and forgot to mark your camber bolt position, then be sure to get an alignment afterwards.
  9. Don’t forget to torque the axle nut upon reinstallation. 137ft-lbs is manual torque spec.

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