cyclopticgaze

bmw 2002

Rear Suspension Teardown

Feb 28, 2010

     So the rear suspension has been dropped and ready for rehab.  It makes a nice winter project, being able to wheel the whole thing inside like that.  

     Time to tear it apart.


The swaybar seems a good place to start.  Its end-links attach to the trailing arms at right (near that hard brake line), and it's braced on the subframe itself at the left.

rear subframe


Both of the subframe mounts are tired.  This is the good one (at bottom), and notice that its rubber is slightly cracked.  Off they come.

rear subframe swaybar


These differential bushings are in a bad way, cracked and broken.

differential bushings


The differential support bracket slides off the diff by loosening the two bolts from below.

differential


The half-shaft CV joints are dirty as hell, and I doubt they've ever been serviced.  Six bolts attach each to the diff on the inboard side. . .

rear CV joint half-shaft


. . . and six more attach the other end to the axle.  This side's even worse, with its rubber boot cracked.  The moly grease inside has been spinning its way out, and dirt is probably worked its way in.

rear CV joint half-shaft


With the half-shafts disconnected, the rear trailing arms come off by unbolting these two forward attachments.

rear trailing arms


     I've got a hunch that the rear bearings haven't seen much love either, so now's a good time to pull the axles.  The only hard part about that is removing the 36mm castellated nut that holds each in place.  That nut is torque spec'd to 289 ft/lbs (!), with as much as 51 ft/lbs more to get the cotter pin in.  


I had to get creative to hold everything still so I could slacken that big nut.  I held the trailing arm by bolting it to a table with two clamps.  But the stub axle still spins, so I put a vise grip on one of the wheel studs, and lodged it against a length of angle iron.  The real secret here is lots of heat, penetrating oil, and an impact wrench.  Lean on the angle iron to keep the axle from spinning, then hit that nut with lots of torque from the impact wrench.  A wrench and a long breaker bar might work, but they didn't for me and I switched to air power.

rear axle


The hubs come off easily with a puller.

hub puller


The stub axle splines are greasy and grody.

axle splines


They push through with some gentle taps.  With the hub out of the way, the drum backing plates can come off, and the brake cylinders can be removed at any time.

axle splines


There's some grunt work to be done now.  The two rubber bushings on the left need to be pulled, and the greasy bearings on the right need to come out, too.

rear bearings


There are two bearings, a spacer, and two dust caps lodged in here.  They have to be pulled out from either direction;  you can't push them in any farther.  Each bearing has a slight ridge inside, so I stuck a drift down in there and pounded on it with a BFH.

rear bearings


Moving the drift around the inside will prevent the bearings from getting lodged in there crooked.  With enough banging, they will come out.  So will the dust cap and spacer.  The other bearing will be easier to get out now.

rear bearings


Pulling the bushings is a royal pain, too.  You could just burn them, but that's messy.  Using a bearing puller got this one moving, but couldn't finish the job.

bushing removal


      You can cheaply build a tool to pull the bushings properly.  I did something very similar with the tension rod bushings up front, but didn't take any good pictures.  There's sometimes some confusion over how to build one of these, so here's a quick description.  Here are the parts you're gonna need:

          —a length of all-thread small enough in diameter to pass through the bushing

          —a short length of PVC tubing for the bushing to slide into as it comes out

          —large washers + a nut to stop up the end of the PVC

          —a smaller washer + a nut to push the bushing through

          —a deep socket to turn the smaller washer + nut and push the bushing

     All total, you'll spend maybe $5 at the hardware store, and it's well worth it.  I'm not giving washer/PVC/etc. sizes because all different sizes will work.  Make measurements before heading to the store.


Here's the setup.  As I turn the small washer + nut with the ratchet, the bushing will get pulled along the all-thread and end up inside the PVC.  

bushing removal tool


A PVC T-joint gives you a nice window to watch the bushing move.  Some hand soap might help to lube it up.  As you crank, the bushing's rubber lip will deform, and trimming it off also helps the bushing squeeze through.

bushing removal tool


Tada.  There's a lot of tension placed on that all-thread, so don't expect the tool to survive the process.  This one managed to do all four bushings, but the last one was its death knell.  When you go to the hardware store, buy a couple extra nuts and extra all-thread.

bushing removal tool


So it's on to the CV joints.  Like all things rubber on this car, the boots need replacement.  I pulled off the metal bands on either end of the boot, then sliced the boot down the middle with a razor blade.  Disposable gloves advised.  And lots of paper towels.

CV joint


     I won't go into too much depth here on CV joint rehab because this post over at my2002tii.com covers the procedure really well;  I relied on it more than once.  After pulling off the rubber boots and removing the CV joints' end caps, I dropped them both in a bucket of gasoline and let them soak for a few days.  I gave the bucket a gentle swirl now and again, and used a wire brush to scrub off the caked-on grime.  When the joints emerged, all that messy moly grease was gone and they looked like this:


CV joint clean


Notice the circlip around the center spline in that picture above.  In order to put new boots on the CV joints, the joint itself has to come off the shaft, so that circlip has to be removed.  Circlip pliers and a small flathead work.  Wear eye protection.  Once the clip is off, a few taps on the half-shaft spline will extract it from the joint.

CV joint circlip removal


Cleaned and ready for paint.  Hopefully I can remember how all this stuff goes back together.

rear suspension parts