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April 6, 2014

Half-axle (CV joint) replacement in a 1997 Subaru Outback

Filed under: Uncategorized — Tags: , , , , , , , — admin @ 5:02 am

Our trusty 1997 Subaru Outback AKA “The Nimbus” recently began to exhibit the standard symptoms of CV joint failure: popping/clicking noises when turning, and grease escape. When I first reached under to check it late at night, I got a hand full of black grease from the exposed innards of the CV joint. Closer inspection revealed that the rubber CV boot on the driver’s side was actually torn apart.
Torn CV Boot
The passenger side boots on the other half-axle looked OK, with no leaked grease near them.

Yes, it’s this same Outback, of head gasket replacement fame, but four years later. Now it has about 300,000km on it, and apart from this CV issue and some minor fixes, it has been running fine.

There are several good Youtube videos and other howto blog articles about how to replace a half-axle, so this time, I’m just going to add a few hints onto those from what I found from my own repair. I recommend strongly that you look at that material¬† first before tackling this repair. The Haynes manuals or similar are also pretty helpful:

Note that if you buy either manual by clicking on the links at left, I get a small commission. Even better, if you really want to help support a starving author, you can buy my new book Dog Friends. Dogs often ride in Subaru’s :-) .

The main video that has essentially the sequence and methods that I actually followed in my repair was this one. Also, this post also has some good tips, but in my case, I found that I could get the half axle out by removing the two 19mm strut bolts (but see below about those), without decoupling the ball joint as the person on that post did. Also helps to talk to some experts: my friend Paul C. who has done far more brake/suspension/drivetrain work than I have had some really good hints, some of which appear below -thanks for the help and encouragement, Paul. Finally, if you decide to do this job yourself, good luck and be careful. Cars are big, powerful, and heavy, and I can take no responsibility for any harm that happens to you, other creatures, or to your vehicle, if you follow my instructions.

Some key tools that I needed:
1. A 32mm socket, for the big axle nut. I found this one at Canadian Tire for $15
2. An impact wrench. In this repair, I ran into some tough, rusted fasteners that even a 4ft pipe on a breaker bar would not remove. I got this electrical impact wrench on sale for $100 again at Canadian Tire. It has already been great tool. I likely would not have been able to do this repair without one. Max torque is rated at 350 ft-lbs, but what I think really makes it effective is the intense percussive (as in John Bonham, RIP) action of the thing
3. A 3/16″ punch for driving the CV joint retainer roll pin out. (Unable to find a real one at any nearby hardware stores, out of desperation I actually used an expendable old 3/16 drill bit instead with the butt end against the pin, but that was tricky to hold in place, and I’d recommend getting a real punch instead if you can.)
4. A torque wrench that will do max about 150ft lbs. Torque spec for the axle nut on my Outback is 137ft-lbs.

Parts needed for this repair:

The part I needed was a replacement half-axle. You have a lot of choice here of remanufactured OEM and new units. The remanufactured and new Subaru parts are pricey and this is an old car that doesn’t get hard driving, so I went with a specific new replacement non-Subaru one. After looking around, the most recommended new replacement was made by Empire.¬† I found the part, number 805511, online at Rock Auto for US$52. All in, it was CDN$95 shipped to Vancouver, BC. This is it. Note that the part as supplied came complete with a new axle nut and roll pin.

The repair sequence:
1. Park in a covered workspace sheltered, in my case, from the Vancouver rain. Parking brake on. Back wheels chocked too for safety.
2. Break the wheel nuts free on the work side.
3. Raise the front of the vehicle, on both sides and support with jack stands. I used a Goodyear 2 ton hyrdraulic jack to raise each side, and then put a 2 ton jack stand in place under a lift point near the front, but behind the half axles, one jack each on driver and passenger side. While you probably could work on this repair just by lifting the trouble side, as Paul noted, raising both removes potential load on the sway bar that could make some parts harder to remove. I typically back up the jack stands for jobs like this with a stack of wood 4×4′s just in case.
4. Remove the cover from the axle nut. Bend the blocking detent from the nut, using a hammer and old screwdriver or similar.
5. I used the impact wrench to get the axle nut off, after failed attempts with a long breaker bar. The impact wrench saved me here; took only a few seconds with that to get it free. Note that the weight should be off the wheel when you do this to avoid damage to the wheel bearings.
6. Remove the wheel nuts and the wheel+tire
7. Next you need to remove the two 19mm bolts on the strut, above the hub carrier. First, mark the location of the bolt and the attached metal member with paint, since you will need to put it back in the same place to preserve system alignment.
Then, start by removing the nut from the lower bolt. This was tough even with an impact wrench. Note that you’ll need to hold the bolt head fixed while cranking on the nut. I used a spare 19mm socket and wrench plus a long pipe to hold the bolt head while cranking on the nut with the impact wrench. I had soaked the nut with penetrating oil overnight after initial attempts to free it failed. Finally, after about 5 bursts with the impact wrench of about 20 seconds duration each, the lower nut came free. The upper one removed easily in a few seconds. The bolts came out easily. Note that the upper one has a washer that you’ll need to keep with the bolt and re-install later.

After removing just that pair of bolts, there was enough movement possible with the hub carrier that I could get the half axle out with no need to detach the ball joint nor remove the brake caliper like some folks do for this job.


8. Now crawl under the vehicle and hammer out the roll pin holding the inner side of the half axle onto the transmission. Here is where you should have a 3/16″ punch for this task. I didn’t have one and none of the area hardware stores did, so rather than wait, I used a 3/16 drill bit, butt end on the pin. Desperate measure, and it was tough to hold the bit in place but it worked to free the pin.
9. At this point, the half axle was free to move off the transmission splined spindle, so I moved it and freed that end of the half axle from the car.
10. Remove the other end of the old half axle by moving the freed hub carrier slightly while bending the axle at the CV. Now the old axle is fully removed from the car.

11. Install the new half axle. Mostly the reverse of the uninstall, but be careful to torque the axle nut to spec at the end (137ft-lbs in my case). Before installing it, grease the hub carrier where the axle inserts into it, after checking the bearing seal there. Install the half axle at both ends, and then push the upper hub carrier support into the housing on the strut. Also, be careful when you install the inboard side of the axle that the holes for the roll pin line up with those on the spindle. The axle is not 180 degrees identical because of where the splines are, so only one rotation will work here. I found out which one first, by comparing the spline locations with the original half axle. Re-install the 19mm bolts. Luckily, those parts went back together easily. Be careful to line up that assembly with the strut using your alignment marks before torquing those bolts.
12. Drive the roll pin back in. It should be flush.
13. Check axle nut torque again, then “stake” the nut collar unto the axle detent with a chisel or similar to lock it in place.

14. Put the wheel and wheel nuts back on. Carefully clean up tools from work area underneath, and check around for obstacles before lowering the vehicle. Double check all fasteners before lowering.

After lowering, again, check for forgotten parts, obstacles, etc. Then, try a short test of forward and reverse at low speed. Listen for strange noises. All good at this point in my case. Did a short low speed test drive listening carefully, then checked everything. OK so far. I finally did a longer test drive up to 100km/h, with some steep hill and corners. No problems and the original symptoms are gone. Looks like a successful repair.

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