CV boot replacement               

This is about a 2 hour job if all goes reasonably well

Update:

This procedure was revised in November 04.  I used to split the outer joint with the axel in the car, the rationale being that I didn't want to deal with the high torque of the center hub nut.  Turns out, though, that it's a lot easier to deal with the nut than it is to deal with the snap ring that secures the axel into the outer joint.  This is particularly true of post-92 cars that, for some reason, have extremely tight splines at the axel-to-outer CV joint interface; this can make reassembly extremely challenging.  While most people won't have a torque wrench capable of the 206 to 221 foot pounds of tightening torque specified for the wheel hub nut, I think it can be estimated closely enough.  It's much, MUCH easier to remove the whole axel from the car, remove the inner drive tripod hub and replace the boot from the inner end of the axel than it is to try to split the outer joint while it's installed on the car.

A note on rebuilt axels: They're fine if you can find them AND if they fit.  I can never find them for the Saab 9000.  Other people have found what was claimed to be the right one, but they were too long, too short, too something.  Just be forewarned: They tend to be very scarce and they too often are the wrong part - if you get one, check it carefully against your original for correct length and size.

Special note added 08/20/06: I am damned sick and tired of CV joint boots that only last 30 K miles!!!  From now on I will buy my boots from the Saab dealer; these aftermarket boots just don't last long enough (well, some do, but who knows which ones?!)  I think boots ought to go closer to 100 K miles, although I'm not sure how realistic that is.  I do know that I don't replace CV joint boots for fun, and I'd rather do it as seldom as possible.  The infuriating thing is that if they split, you're looking at a lot of money to replace the joint.  30 K miles is pitiful, and I'm pretty pissed off about it, in case you can't tell.

Materials:

• New outer CV joint boot kit (genuine Saab highly recommended)
  • Boot
  • Boot clamps (one large, one small)
  • Tube of grease
• New axel nut. 
  • I'm not convinced this is an absolute necessity, but it's cheap and it's specified as a replacement item, so order it along with the boot, clamps and grease
• Extra tube of CV joint grease to refill the inner joint
  • because you're going to remove that boot too)
• New clamps for the inner joint (one small, one large)
  • The small one is the same size as the small clamp for the outer joint.  
  • The large inner clamp is an odd size, more like 3" than the more standard 4"-ish one
    • So don't expect your local chain parts store to have it
  • You'll really want a new large inner boot clamp, 'cause it's almost impossible to refit the old one
  • Don't expect a nylon cable tie to be a suitable sub - they usually can't be tightened enough and they usually don't stay in place.
• Paper towels (lots)  Picture of aftermath
• Rags (ditto)
• Degreaser/solvent (brake parts cleaner, acetone, or similar)
• Toothbrush
• Medium sized brush

Tools:

• Wheel removal tools
  • I prefer a breaker bar and deep 19 mm socket, or standard socket and short extension
• 18mm 1/2" drive socket for the bottom strut clamp nuts
  • 19 mm generally will suffice, particularly if it's a six point
• 1/2" breaker bar (preferred)
• 1 1/4 or 32 mm (I think) socket
  • This is for the wheel hub center nut
  • I used a 1 1/4", since it fit - I'm not positive what metric size it should be
• Cheater pipe
  • A 2 to 4 foot length of pipe that will fit over your breaker bar, to provide extra leverage on the hub nut
• Ratchet
• 17 mm  box end wrench
• Various flat screwdrivers
• Hammer
• Expanding snap ring plier
• Needle nose pliers can be helpful with boot clip removal
• CV boot clamp crimping pliers (preferred)
  • And/or the roll-up type, if that's the kind of clamp you have
  • These tools run 6 to 10 dollars, and are worth the money
• A 250 foot-pound torque wrench is needed to do the job by the book, but I make do with a 150 ft-lb one and estimate the final tightening torque of 206 to 220 ft-lbs for the hub nut.  At the very least, you'll want a 150 ft-lb ratcheting torque wrench (very cheap ones - $25 or so - can be had from Harbor freight or Northern Tool).  The reason is that you'll need to tighten the interference-thread-locking-nut at a pretty high torque rate for several turns before it bottoms out.  This would be tedious with a non-ratcheting wrench and would stress a standard ratchet/cheater bar setup, as well as being difficult to control

For the corner you'll be working on:

Remove the center wheel nut

• The torque spec is 206 to 221 foot pounds.  That means you'll have to exert about 150 pounds of force on a standard breaker bar, not taking into account the extra breakaway torque required, which can be considerable.  I was able to break mine loose with just the breaker bar, but it was all I could do (I'm not as young as I used to be - favorite anecdote).  All I can say is, be careful and don't hurt yourself.  It's always much safer to pull a wrench/breaker bar instead of pushing on it.  In this case, it would be nearly impossible to control the wrench while pushing on it anyway.  Best bet is to fit that cheater pipe over the breaker bar, move out another foot or so, then pull steadily and firmly, keeping your back straight and using your legs.  It might be a little tricky controlling it all until you get it loaded up, but once you're got good pressure on everything, it should be easy.
• Then again, if you have an air wrench and a hefty enough compressor (or an electric air hammer), you'll know exactly what to do!

• Once the center hub nut is broken loose, go ahead and use a ratchet to run it out until it loosens up.
• Now loosen the four wheel bolts
• Jack the car up
• Install a jack stand
  • I like to put mine under the rear support plate, just behind the rear bushing of the lower control arm
  • lower the car onto the jack stand.  Leave the jack in place as a backup.
• Remove the wheel

Remove the 18 mm nuts from the two bottom strut bolts.  Picture

• The bolts (17 mm heads) enter from the rear and the 18 mm nuts are on the front side.  A 19 mm socket will generally work on the 18 mm nuts.
• They're pretty tight (57 to 77 foot pounds), so a reasonably long breaker bar is recommended
• Once broken loose, use a 17mm wrench to hold the bolt heads as you ratchet the nuts off
• Drive the top bolt out.
• Drive the bottom bolt out using a hammer and screwdriver/whatever.  There will be some upward pressure exerted by the resistance of the control arm bushings.  It won't be much movement, but it's enough pressure to require driving the bolt out

Pull the hub assembly piece out of the bottom strut clamp.  Picture  

Drive the axel out of the hub splines

• If you have a new hub nut (which you should), it's probably best to remove the original hub nut, then reinstall it backwards to give yourself extra surface to strike with the hammer.  If you do this, run the nut onto the axel until the the end of the axel is about an eighth of an inch shy of the nut (Vice Grips help a lot here).  The idea is to distribute the load on lots of threads while still protecting the end of the axel.  
• It can take a good bit of whacking with the hammer to drive the axel loose
• When it's free, pull the hub/brake rotor assembly outward as far as possible and pry/push the axel free to the front of the assembly.

Loosen the inner boot clamp

• If you have a replacement clamp, you can just pry the old one off.  If not, you'll need to save the original for reinstallation (a new one is vastly preferable!)
• Needle nose pliers work reasonably well for spreading the crimp in the clamp - grasp one side and rotate it toward the center, then repeat for the other side.  A screwdriver can also be driven in to spread the crimp.  Pry the band off the tang when it's loose enough.

Remove the axel

• Grease will flow out of the joint when the boot comes loose, so put a towel on the frame member underneath the inner joint (if you're doing the passenger side, anyway).
  • It's also a good idea to have a plastic baggie handy to slip over the joint to catch most of the grease, and a rubber band to secure it.  Two people make this a whole lot easier.
• Put your fingers under the inner end of the inner boot and pry the boot toward the outside of the car while rotating and pulling on the axel - at some point, the inner boot should pop loose from the hub.  Put the baggie over the drive hub.  Pull the axel assembly out of the car and tilt the inner end up to avoid grease drippage. 
• Carefully clean the dirt from the inside lip of the boot, then drain the excess grease out.

Remove the tripod hub and inner boot

• The hole in the tripod hub is tapered, so it only wants to go on the inner end of the axel one way.  The steel is too damned hard to score with a file or a chisel, so wipe it as clean as possible and mark it with a felt tip pen.
• Using expanding snap ring pliers, spread and remove the snap ring/circlip.  It's light duty, so is pretty easy to remove.
• Use a gear puller to pull the tripod hub off the axel splines (it's a pretty tight press fit)
  • Try to keep it oriented/stored such that you won't have to rely on markings to know which way it goes back on the shaft.  This is with respect to the face of the hub only, not the drive wheels.  Note, though, that if mis-handled, the wheels can pop off the stubs and scatter the needle bearings - you don't want that to happen.
• Slide the inner boot off the axel, bearing in mind that grease will drip out of the small end when you do so

Clean the axel shaft very thoroughly

• It's very, very important that dirt not get inside the boots
• Use brake parts cleaner, engine degreaser, acetone or whatever works best for you
• An old toothbrush works great for cleaning the interface between the small end of the boot and the axel.  You can also push that end of the boot toward the big end a bit to get at the trapped dirt.
• A somewhat larger wire brush works well on the rest of the axel

Remove the outer boot

• Remove the clamps - you can pry the crimp open with a screwdriver
• Spray the axel shaft with silicone spray to allow the boot to slide freely
• While holding the outer end of the axel up, loosen the boot and slide it off the axel, bearing in mind that grease will drip from the small end of the boot when it is removed

Install the new outer boot

• Spray a bit of silicone on the small opening of the new boot
• Install the boot onto the axel, big end first
• Slide it up near the outer joint
• Fill the boot with the contents of a CV boot grease package
• Check the joint and boot for cleanliness, then slide the boot over the joint
• Install the new clamps.  
  • Details
  • The alternate clamp style is a thinner metal band that wraps around the boot, then goes between a couple of vertical tabs.  You pass the end of the clamp through a slot in a wind-up style clamp tool, then wind the tool until the belt is tight, then you bend the tabs over to secure the band.  I think there are a couple of other tabs that allow you to bend the band back and double-secure it.  Then you cut the excess off.  Something like that.  Sorry, but it's been a while since I installed one of those.  It should be evident enough - just make sure you get the right tool for it (ask at the parts store).  This type seems cheaper than the other type, but sometimes it's easier to install (like on the big end of the inner boot on the passenger side, which is almost impossible to get to with the crimp-style boot pliers.

Re-install the original inner boot and tripod hub 

• If your inner boot has any cracks, replace it.  Generally, though, these boots pretty much last forever because they only have to flex vertically, where-as the outer boots have to flex in all directions and with every turn of the steering wheel.
• Slide the small end of the boot onto the axel
• Position the tripod hub with the marked face facing outward (remember, the hole is tapered)
• You'll need to drive the hub onto the axel with a hammer (unless you have a suitable press), but you don't want to pound directly on the hub because you would probably hit the drive rollers, and that's a no-no.  So find a suitably sized socket to use as a driver interface, and hit it with the hammer.  Wrap your hand around the three drive wheels to keep them from popping off and scattering the bearings.  This is an excellent opportunity to smash the bleeding the hell out of your hand with the hammer, so all I can say is, use common sense and be careful.  A good, large vise would be really helpful.  It takes quite a bit of whacking to drive the hub onto the splines.
• When the outer face of the hub is past the groove for the snap ring, spread and install the snap ring
• Fill the inner boot with the contents of a CV joint grease packet, then slide the boot up over the tripod joint until the small end of the boot snaps into its groove on the axel.  Install the small-end clamp.

Re-install the axel 

• Align the tripod drive rollers with the grooves in the driver cup, then push the tripod joint into the drive cup - some axel rotation might help
• Push the big end of the inner boot onto the drive hub - rotating the axel probably will help a lot in this step
• Spray the splines on the outer end of the axel with silicone, then position the end of the axel into the hub splines.  Rotate the hub/rotor assembly to bring the splines into alignment.
• You can swing the front end of the hub assembly in to bang the axel into the splines, but be gentle, to avoid damaging the tripod joint (it's bottoming out in the drive hub when you do this, so do it gently and keep it to a minimum).  Make sure the axel is properly centered before you try to drive it into the hub - rotation helps.
• Use a hammer to drive the hub/rotor assembly onto the axel shaft.  Hut the hub near the center, or the most central part of the brake rotor (NOT the part of the rotor that is acted on by the caliper).  It will take a lot of hammer driving to get the axel to come through the outer end of the hub (late models, anyway).
• When the axel comes through the hub far enough, install the nut and snug it up a turn or two (the axel will want to turn, but quick wrench movements should allow you to overcome the nut resistance enough to get it pulled up a couple of turns).  Leave the final tightening of the nut until the wheel is back on the ground. 
• Clean any grease off the brake rotor

Install the big clamp on the inner boot

• This can be a real bear, as there is very little room to work on the passenger side.  Note as of 09/04/06: Hey, guess what?  There's very little room on the driver's side too!  Certainly not enough for the standard crimping tool.  This time I used a miniature pair of Vice Grip pliers, tightening the screw just a little at a time and crimping several times.  You can also try using diagonal cutting pliers to crimp the clamp, although I think the mini Vice Grips worked better.  It's almost impossible to correctly reinstall an old clamp on the inner boot on the passenger side. 
• You might want to try the wind-up type clamp on the inner boot.

Reconnect the hub to the lower strut clamp

• Push the hub's mounting arm into the lower strut clamp
• Using a screwdriver or such to lever the holes in the hub into alignment with those of the strut clamp, install the lower bolt from the rear and tap it partway home
• Put the top bolt through the antilock cable brace plate, then lever the top holes into alignment and start that bolt.  Wheel position can make a huge difference - try turning the steering wheel a ways toward the opposite side.
• Align the antilock cable brace plate's fingers so that they fit onto the horizontal surface of the strut clamp's sheet metal
• Hammer on a screwdriver or something to drive the bolts into position - to avoid damaging the antilock cable assembly, do not hammer directly on the bolt heads 
• Hold the bolt heads with a 17 mm wrench and tighten the 18 mm nuts to a torque of 75 ft-lbs (????) Y'know, I'm not sure where I got that torque value.  Not sure I believe it, either.  Just tighten 'em good and tight.

Reinstall the wheel and tire

• Position the wheel locating pin at the top or the bottom, whichever works best for you.  I prefer the bottom.  Install the wheel, then install and snug up the four wheel bolts.
• Raise the car, remove the jack stand, then lower the car

Now comes the fun part: Torquing up that big-ass hub nut!  

• Yet another anecdote
• I recommend a 3" extension on the socket.  A 2" one puts your knuckles and the wrench right up against the fender.  Longer than 3" will make the whole assembly want to tilt - makes it too hard to grip the nut and apply good, even torque.
• If you have a 250 ft-lb torque wrench and a strong back, you're in business.  If not, you'll have to estimate 200 to 220 ft-lbs.  First, pull the nut down - this involves a lot of hard quarter-turn pulling of the wrench, and it's pretty exhausting.  The axel will protrude through the nut quite a ways before it bottoms out - more than half an inch.  I used a 150 ft-lb torque wrench set to 150 ft-lb and kept pulling until the nut started to offer serious resistance.  At that point I made sure to pull smoothly but deliberately until the wrench clicked.  I then replaced the wrench with a breaker bar and pulled it another eighth of a turn.  I feel comfortable with that, which is to say that I think that's in the ballpark of how tight it ought to be.  The break-away torque to overcome friction and get the nut moving again is considerable, but it should be done smoothly to get it right.  Or, you could just keep it moving another eighth turn without stopping after the wrench clicks.  
• Worst-case, if you should miss badly enough to cause the nut to some day come loose and the axel manages to work itself out of the hub, you only lose drive.  And probably  mess up the splines on the stub axel.  The wheel won't fall off or anything like that, because it's held in place by the hub-to-strut bolts.  I think you would have to miss the torque by an enormous amount - probably a lot more than 50% - before it would fail.  And, at that, I think it would be more dangerous to drastically over-torque than to drastically under-torque (if the nut breaks, it'll come loose, but as long as it doesn't break, it's going to have a hard time backing off because the threads appear to have designed-in interference to make it a locking-type nut).  Still, the designers obviously set a torque spec for a reason.
• If you have the 250 ft-lb wrench, you can use a cheater pipe to make it easier.  The cheater pipe will help you pull 150 ft-lbs with the 150 ft-lb wrench, but it will still click at 150 ft-lbs, so take it that extra eighth of a turn to finish it off.

Finishing up - tighten the four wheel bolts

• Don't forget to torque the four wheel bolts to 80 ft-lbs
• Install the center cap in the wheel, clean up and put up, and you're done

Check the boot after a couple of days, then after a couple of weeks to make sure everything is going as it should.

• The clamps could slip or break
• Grease could leak
• The clamps could be loose or misaligned and allow the boot to slip off the hub

Inspect the boots every six months, if possible.  I've had cracked ones go for six months without cracking any further, and I've had them split within six months of discovering minute cracks.  Best bet is always to replace them as soon as you see any cracking developing.  Boots are cheap.  CV joints are not.  Rebuilt axels aren't too bad, but they just don't ever seem to be available for Saab 9000's.  And if you can find one, it's often not quite the right part.