Curbside Tech: 2008 Subaru Outback – Inner CV Joint Boot Replacement Without Full Axle Removal

By
– Posted on July 29, 2022

2008 Subaru Outback

My mother ordered herself a new car earlier this summer.  It arrived this week and she offered to give us her old car, a 2008 Subaru Outback base model that she had also bought new here in Colorado.  Of course we accepted and were then told that the 150,000 mile service was due.  While changing the oil as the first step I looked the car over and quickly realized that both front inner CV (Constant Velocity) joint boots were not just cracked but in two pieces.  Hmm, it seems this gift horse was already spitting its teeth out at me.

Now, my mom may be pushing 75 years of age but uses her cars to the fullest to get to her favorite hikes.  This car usually has seen off-road use three to four times a week since she bought it, either traversing to distant trailheads up in the Rockies, along fire roads or just up the steep, rocky, and barely improved path to her friend’s remote cabin.  It’s been in a few ditches during heavy snowfalls when it’s not clear where the road goes but never any real accidents beyond kissing a guardrail with the front bumper in an icy spin, gets its oil changed every 3,000 miles without fail and apparently has a service binder a few inches thick (that I have not received yet but look forward to perusing).  In short, it gets used properly and everything in the car gets a workout.

Mom decided on a new Crosstrek Sport exactly like the one I reviewed here last year.  She decided that the extra power in the Sport’s larger 2.5liter engine would come in useful at our elevation and the smaller cargo area would mean that not all of her friends’ dogs could join them when she drives them (that’s now a feature, not a bug, Archie was a good hiker but a big shedder).  Here she is having the finer points of its engine explained to her by the very patient man at the dealership at time of delivery on Monday morning.

She’ll be very happy with it I think.  Especially once she gets used to all of the features she never had previously.

But back to the Outback; as I said the inner boots were trashed on both sides.  This often means that the innards of the CV joint are ruined as well as the boot is what keeps dust, dirt, water and whatever else out and the grease in.  I wasn’t looking forward to either replacing or even removing the axles as a similar one had pretty much kicked my arse over the winter in the Jaguar (but I did prevail there, I hasten to add, said story to come eventually).  If the axle nut is at all rusty pulling the axle is better avoided if not necessary as often the shaft fuses with the knuckle and things can start to cascade from there.  Ask me know I know.  Actually, don’t.

As with many things these days, I looked to YouTube for guidance and found my salvation in an excellent video that showed the exact way to replace the inner boots without taking all and sundry off of the car, as a bonus it was done on an identical car to this one and showed the exact part I needed to purchase.  So off to Napa Auto Parts I went, picked up two kits and headed back home.  The beauty of having a Subaru in Colorado is that it almost seems that even 7-11 carries Subaru parts, whatever one may need is usually in stock somewhere nearby.

Wednesday morning came and the car got pulled into the garage.  I had to do both sides, the driver side is easier as the exhaust pipe is not in the way and was the side that was in the video so I started with that one.  It went surprisingly well without any need to go back to the store so here I will chronicle the repair on the passenger side for which removing the airbox in the engine compartment allows remarkably good access from above for a couple of fiddly situations where the exhaust makes things a little more difficult (but still not impossible) from below.  A lift is not needed either.

A decent tool selection is handy but not essential.  Above is everything I used that would be needed.  A Sharpie marker in your favorite color, two 19mm sockets (conveniently the same as the lugnuts use), my impact driver (although a long cheater bar would work fine), a 12mm ratchet and/or wrench, a small pry bar, a screwdriver, snap ring pliers (my one extra purchase for $5.99 while at Napa), torque wrench, and a set of crimping pliers I didn’t think I would need to have but luckily found my PEX crimper when I needed it for the first side.    Some gloves, rags and lots of paper towels are handy as grease seems to get everywhere.

First of course jack the car up and chock the rear wheel(s), securely set it on jackstands while leaving the floor jack in place as an extra measure, and remove the front wheels.  Set those aside after noticing the interesting rust pattern on the steel wheels after fourteen years of driving year round with hubcaps and just swapping the tires every other season.

The brakes are attached to the steering knuckle which is attached to the strut, and the axle shaft’s outer CV joint is slotted into the middle of all of it.  You can see the shaft disappearing under the car towards the inner CV joint’s boot. That’s the target today.

A 12mm wrench takes care of the brake line fastener and an equivalent one on the other side holding the ABS wiring.  Remove those, let the hose and wire dangle (still attached at both ends, just not supported in the middle) and the bolts can be reinserted so they don’t get lost.

The two larger bolts and nuts are all 19mm and are what holds the knuckle to the strut.  Or the strut to the knuckle?

The upper bolt is an eccentric one, meaning it isn’t round like a normal bolt.  This is where the camber adjustment is done on the car.  An eccentric bolt is one that is sort of oblong in cross-section, as it is turned it moves the relative position of what it is affixing.  In order to preserve the camber setting, the Sharpie marker comes in handy to delineate the exact positioning.  An alignment is probably still a good idea but if care is taken, this can get it quite close to perfect (enough).

Loosening these bolts is best done with two large wrenches, sockets, or an impact wrench makes short work of it and makes you sound like a serious professional to the neighbors walking by with their dogs.  Both bolts will stay in place at this point though, they just need to be loosened.

Reaching in from below with the small prybar lets the fastener of the boot be loosened by first prying up the two little tabs and then unfolding the strap part.  This relieves all of the pressure and the fastener can be slid off the boot towards the knuckle to possibly be reused later.  Since this damaged boot is actually split in two it is also possible to slide this portion of the boot down the shaft for now.  If it were still intact it can either be torn the rest of the way or just left until the next step.

Which is to do the same thing to the larger ring on the other end of the boot.  On this side of the car it was far easier to reach over through the back of the engine bay (as in this picture) and loosen it from above, although it’s reachable from below as well.  As I recall it was possible to grasp the boot and slide it around the cup (that cup-looking thing at the end of this shaft) in order to get the clamp mechanism in the correct position to take it apart.  Both the clamp and what’s left of the boot can now also slide down the shaft.

Now we can look into the cup at the joint mechanism.  This one looks quite dirty, far worse than the other side did earlier, however there is absolutely no grease caked on the exhaust below, which it usually would sling itself onto and then bake into a solid mass.  There is some on a shield on the other side though and clearly very little grease is left in the cup.  When CV joints go bad usually you can hear a “clicking” sound, this one was completely quiet so there was hope going into this.

There is no danger of it all falling out as long as the retaining clip is installed, here in the middle of removal.  The prior picture shows it in place, there is a groove just inside the cup that it rides in and then it can be compressed a bit to pull it out.  It’s about the thickness of a large paperclip.

Now it is time to return to the knuckle and strut in order to remove the two big bolts.  Above is the eccentric one, if it is rotated it moves the position of the knuckle relative to the strut and leans (adjusts the camber of) the wheel and tire one way or another (in or out).  By removing both of these the whole knuckle is held in by the lower ball joint and can pivot on that, which gives plenty of room to easily pull the CV joint and axle shaft out of the inner cup while still being completely attached at this end.

By pulling it out, resting it on the exhaust in this case, and reinserting one of the big bolts so it rides a little further up everything is relatively easy to work on.  And as you can see, there is all kinds of nastiness visible here.

But first we have to take this joint apart.  The three little wheel-looking bearings are easy, they literally just fall off their mounts, nothing holds them in place once unconstrained by the cup.

All the way at the far end of the shaft is a small circlip.  Using the new pliers allows it to be spread open and carefully removed from the groove it sits in at the end of the splined shaft.  Then the three-pointed yoke that holds the three bearings just slides off.

Here is that piece cleaned up and in my hand with my gloved finger in the splined center section.  There are three protrusions, and on this piece they all exhibit some wear from the bearings riding around without much if any grease.  The one on the other side of the car had no such markings. Still there was no noise and while there was a little play in the whole thing, it didn’t seem excessively bad.  Or not excessively bad enough to replace it entirely, if later issues develop that is possible to do then now that I know what exactly is going on in here.

Here is everything removed at this point and cleaned up.  The larger clip is from the cup to hold the whole thing in place, the smaller circlip was at the end of the shaft and held the joint in place.  The three bearings just ride on the three points of the yoke and all is normally coated in grease.

Now it’s also easy to remove the boot remnants by just pulling them off the end of the shaft.  Sure, they could have just been cut off earlier as well but that would entail getting another tool dirty.  Normally this would all be one piece of course but then I’d be looking for something else to do instead of writing this.

Here’s the shaft after everything is removed and the cup of course.

Cleaning these pieces is essential as there’s probably all kinds of grit and other stuff in there and on the shaft.  A can of brake cleaner or whatever solvent you prefer works wonders along with a few rags to wipe it all off and then let it dry.

Here are the contents of the kit, same for each side.  One boot, two clamps and a new circlip along with instructions.  While this was a Napa branded part it turns out it is actually manufactured by/for EMPI, the VW parts people that we all likely remember.  $25.88 apiece seemed pretty good for what seem to be well made parts.

Oh, and a bag of grease is included as well, apparently the correct amount to use per unit.  I have no idea what grease this actually is and would probably obsess over it if this were a much newer car, but at 151,000 miles it’ll work well enough without me spending hours at Bob Is The Oil Guy .com or watching a dozen more videos.

So the new boot slides on and down the shaft a bit, then the yoke goes on and the fiddly little circlip holds it in place.  The yoke appears to be tapered a bit as it was difficult to get it to glide on until I rotated it back to front it, then it slid right on.  The positioning of it is somewhat important as when the bearings are on it, they will only slide into the cup if positioned correctly, as you can see the cup is tapered in three places for the bearings.

If off a lot it just won’t go in, if off a little and able to be forced in it creates pressure on the other end (I think?  Perhaps not, it might spin a little to compensate when fully assembled), but putting it in what seemed the sensible orientation and test-fitting via not very critically eyeballing it made it slide in easily and seemed to avoid any binding.   This was done from above rather than below.  On the driver side it was done from below as you can get right under the shaft here, obviously here the exhaust is in the way.

The cup gets the contents of the grease bag squeezed into it.  It may have had a little more, I can’t recall if I took the picture before or after squeezing everything out of the bag.  Care should be taken as it and the old grease can get everywhere.  The boot and shaft can be seen just at the left.  The exhaust is a handy rest for it but I don’t remember not having a handy rest spot being a problem on the driver side.

You may recall that the three bearings were not in place as of two pictures ago.  This is the trickiest part but not difficult.  Working from below (well, in the wheelwell) the three bearings get slotted over the yoke, then that whole assembly needs one hand to hold it together like you’re carrying a six-pack of loose beer bottles without a cardboard carrier.  At the same time it needs to be positioned to go into the cup, and to hold it in place the knuckle with the brake disk and caliper need to be rotated up into the strut mounting area.  Once that is up the CV joint will stay in the cup so the two bolts needs to be inserted to hold it in place.  Two hands and a knee worked well enough, it sounds far more difficult than it actually is.

Once those bolts are in it all sits there by itself, it won’t go anywhere.  The boot could be slid down the shaft a little more if desired but I didn’t want to stretch it at this point, although it’s a pretty thick and sturdy rubber or rubber-like material.

At this point the clip that holds the joint in the cup needs to be reinserted and slotted into the groove.  This picture shows it in place, visible at the right.  The assembly has pushed the grease further into the cup, it’ll end up coating everything with a few rotations as well as the heat softening it up further.

Next the boot needs to be drawn up over the cup.  In this case the cup was painted green where the boot would be covering it making for a handy reference.  Or maybe it was all green and just worn off where it was uncovered over the last decade plus?  Either way it works.  The boot is molded with sort of tabs that help it line up with the scalloped shape of the cup so it’s an odd shape just inside but round on the outside.  Going back a picture makes it kind of obvious how it would be shaped internally.  The smaller end of the boot is not in the correct position yet, it needs to ride in that groove.

Reusing the original clip did not work, it would not fold back to its clamped shape and ended up breaking apart.  The kit came with these universal crimp clamps, so one gets folded around the large portion and hooked into the tabs.

I don’t own crimping pliers but realized I do own a PEX crimper from the plumbing work I do during my remodels, a little experimenting showed that it worked the same for these.  After several attempts it became evident that coming in from above was the ticket, and standing on the removed wheel gave me the leverage to dive into the engine bay, hold a wiring loom aside and operate the rather bulky and somewhat unwieldy PEX crimper until it was tight.

A little futzing with the small end of the boot eventually got it into its groove and the original clamp worked for this end.  Place it, fold the main portion over, then push the little tabs into place and this part is done.  Now is a good time to use some brake cleaner or whatever to get any grease off the exhaust or other parts of the car.

Lining up the eccentric bolt with the marks made at the beginning, torqueing that and the other large bolt to the correct setting, and then reattaching the brake hose and ABS wire supports buttons it up.  More brake cleaner was useful on the brakes as the disk became the hand hold several times and had greasy fingerprints on it.  Reattach wheel, lower the car off the jackstands, final torque the wheel and then a test drive which revealed no new strange noises or odd behaviors.

Here are the remnants of the inner boots from both sides.  I wonder how long they’ve been this way, but am glad I noticed it now.  While the work in the video I referenced took about fifteen minutes with no obvious time edits that I could see, it took me about 75 minutes for the first side and two hours and fifteen minutes for the passenger side working at a quite leisurely pace.  Doing it again on this same exact car would shave maybe 30 minutes off each side for me now that I know how to do it.  It was far easier doing it than I imagined it would be, the video helped tremendously.  Not as simple as an oil change but much easier than swapping out a suspension.  Now the car just needs a few more items along with an Italian Tune Up on my favorite ersatz Alpine Handling Course up by the lake!

Oh, another quick, albeit completely unrelated car-care tip:  If it feels like your AC isn’t keeping up with the temperatures we are experiencing lately and/or the max airflow feels weaker than it should, check to see if there is a cabin air filter that perhaps has never been changed.  The owner’s manual strongly implied that there is not one on the base level Outback, yet after another YouTube video and some glovebox disassembly I found this one…The new one is next to it which improved things tremendously once installed!