cyclopticgaze

bmw 2002

Front Struts and Springs — Teardown and Buildup!

Jan 22, 2012

     Over the past year or so, I've been slowly working to rebuild the 2002's front suspension the same way I recently did the rear.  It obviously took a lot longer than expected or hoped, but the car's finally back on four tires.  I replaced the front springs and shocks, and did a lot of rehab along the way.


Here's a stance shot to start.  Stock (but tired) suspension in front.  Ireland Sport springs and Bilstein Sport shocks in rear.  This was taken right after the rear was done, so the rear hadn't settled at all yet.  Dammit, Mojo!  Move!

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There we go.

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After getting the car chocked and on stands, the front wheels come off and you gotta unbolt the swaybar end links so the suspension will fall.

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I want to take the struts out completely, so off come these three bolts that attach the top of the strut to the car.

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These spring compressors are a pain in the ass to use, but with the spring compressed, you can stand on the suspension and drop it enough to swing the whole strut out like this.

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     If you clamp onto the strut with some vice grips, you can remove the top nut easily.  Then, the strut bearing and spring slide off.  Keep all those washers and shit;  you'll need 'em for the rebuild.


I waited to disconnect the brake hoses, so the strut dangles by them.  Careful about that.  Look at all that crap in the lower spring perch!

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Scraped a bunch out, and look, there was a drain hole there.  Not doing much draining.  I guess that's what happens when the car's in Arizona its whole life and there's no water for drainage.

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This big gland nut on top of the strut has to come off so you can remove the shock.  You can use a tool that locks into those four dimples, but a plain ol' monkey wrench works, too.

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I tried hammering on the handle of the monkey wrench, but it just wasn't budging that gland nut.  When I broke out the big breaker and torqued it hard, it came off.  Mind the dogs.

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Gland nut removed.  I pulled on the insert pretty hard, but it was stuck in the strut tube.  In the end, I extended the insert all the way out, grabbed the end of it as tight as I could with some vice grips, and hammered the grips' handles.  That dislodged it.  Buy good tools;  they withstand (ab)use.

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Once it got moving, the insert pulled out easily.

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Looks like the passenger side shock's been sitting in its own oil for a while.  The stain looks old, too.  These are trash;  good thing I planned to replace them.

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Not all of the brake lines came off cleanly.  This connector was so rounded and stuck that it pissed me off a smidge too much, so I took a hack saw to it.  I'll buy new hard lines for the calipers.

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Since the whole strut is coming off, I disconnected the three bolts that join it to the pitman arm at the bottom end.  Those bolts are held with safety wire, so I clipped the wire, loosened the bolts, and off falls the strut.  The caliper comes off easily, too.

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     I de-gunked the struts using my fancy new soda blaster.  You hook it up to an air compressor to blast powdered Sodium biacarbonate (a.k.a.: baking soda).  The soda was a nice medium;  it ate the crap away and even paint if you hit it hard, and because it's pretty innocuous, it's ok when it gets everywhere.  My 3.5 HP compressor couldn't keep it moving at 100 CFPM for long, so it was a little slow going.  I went through probably 30 pounds of soda on this project and made a big mess of the driveway.


Left:  old and dirty.  Right:  blasted and clean.

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To the basement!  Tapping off the hub's cover cap, there's a cotter pin to remove, then off comes a big castelated nut.  Then the rotor will come off revealing the nasty, old grease that's been "lubricating" the bearings.

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Degreased and masked, the strut tubes get POR-15'd.  I tried not to get any on the spindles (where it would affect the bearings) or inside the tubes (where it would make it hard to drop in the shocks).

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No reason to re-use the bearings and races what with their questionable past, so I used a drift (not pictured) and hammer to knock them out.  Purchasing a new set of bearings, they come with inner and outer bearings plus races and a bearing seal for the inside of the rotor.  These all tapped in pretty easily with a bearing installer.  In this picture, the bottom rotor has the inner bearing+race installed, but the seal isn't tapped all the way in yet.

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     Moving to the top of the strut, I got some new strut bearings.  I also got some fixed camber plates from Ireland Engineering.  These can be installed with everything in the car by just compressing the spring and dropping the strut bearing, but it'll be way easier right now where everything is out of the car.  Thing is, new strut bearings come with bolts riveted into them.  You have to bang them out in order to bolt the camber plate to the bearing.


Here's the fixed camber plate on top of the new bearing.  You gotta take a hammer to those three bolts sticking up on the bearing (the ones with the plastic covers on their threads).

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With those bolts banged out, the camber plate will drop in place and you can bolt it to the bearing.

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     The strut insert should drop right into the tube.  (One of my strut tubes must have been bent imperceptibly because the new shock wouldn't fall all the way down into it.  Maybe that explains the shock that was leaking oil.)  On goes the spring, then the top spring perch.  Now things get more complicated:  there's a series of washers that have to be reinstalled in the correct order.  I told you to keep all those washers and shit!  Here's a good diagram showing their placement with respect to the strut bearing.


The shock will just spin in the strut tube, so in order to tighten the top lock nut, you have to hold it still with a hex wrench.

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     I didn't re-use the worn out spring pads because . . . they were worn out.  Well, also, I think it's easy for 2002s to get a "sagging ass" look where the back end looks lower than the front.  That's probably because the rear fenders don't arch as high as the front ones (see that top picture).  Anyway, what I did was leave out the front spring pads, lowering the front a little, while leaving the rear stock spring pads in place.  You can't see it in the next picture, but I cut some small lengths of rubber hose and put them on the ends of the spring to prevent the springs from being metal-on-metal with the spring perches.

     Something else you can't see below is that these Ireland springs are short.  So short that you won't need spring compressors to put the whole thing back on the car.  Also, when you drop the car back on the ground, you have to make sure the springs set correctly in the perches.  One way to avoid this is to drill holes in the perches and wire the springs to them.


Happy days when the parts start to get heavy again.  On goes the brake backing plate.

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Provided that the new bearings are seated properly, the rotor will slide onto the spindle and leave plenty of room for the flat washer and castelated nut that bolt it on.  Don't torque the nut too tight or the bearings will get compressed and stressed.  A cotter pin keeps the nut in place and a metal cover keep road grime out.

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Before reassembly into the car, I did some soda blasting in the fenders, focusing on the seams and crevices, and then I POR-15'd everything I could.  You can see that baking soda will go down to bare metal, but you have to blast hard;  it's best at just removing the road grime.  I took off more than is shown here, then scrubbed it all with degreaser.

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Hopefully that coat of POR-15 will keep the rust at bay.  Now that the car is parked outside, surface rust is starting to form.

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     Now it's that wonderful time when all the new parts go back on the car.  Always faster and easier than the rusty, dirty teardown.  As the Haynes Manual is fond of saying: "Installation is a reverse of removal".  I started with the three bolts at the bottom of the strut, then the three strut bearing bolts on top, then reconnected the swaybar.


The three bottom bolts are held with safety wire.  They're actually kind of tricky:  it's a tight spot, the bolts are shallow so it's easy to round them off, you don't want to over-torque them because they might break off inside their blind endings (that would be a pain), and when it's all over you have to wire 'em up.  This picture's from a while back, when I first started tackling all the bushings and such of the front suspension.

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I bolted the calipers back on and positioned the flexible brake hoses.  Now I had to replace the hard brake lines;  their fittings were all rounded off and I had hacksawed that one anyway.

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After a trip to the auto parts store, I had four new brake lines.  Only problem was, they were longer than they needed to be, but not so long that I could just put a loop in them.  I hand-bent them and used this el-cheapo bender to shape them.  This got tricky because I had to give them clearance for the wheels, but also clearance for steering.  This wacky sigmoid shape turned out to work — put the key in the ignition to unlock the steering, then spin the strut through its steering range to make sure the lines clear everything.

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     After that, things get easy:  bleed the brake system and slap the rubber back on.


     Even after a year of sitting, the car fired right up with a little starter fluid sprayed down the carb.  Sounds like a banshee with nothing but the exhaust header.


One of the rear drums is locked up.  Maybe it just needs adjusted, maybe the parking brake is locked up after sitting for a year.  Either way, lay into that gas enough and you can drag it around.  Guess I need a limited slip diff!

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And here's an "after" stance shot next to the "before".  Looks like the front and back both dropped maybe an inch.  The "before" shot has the Ireland sport springs and Bilstein Sports installed in the back, so you can see how much a year of holding weight matters.  Maybe the front will settle accordingly.  I haven't driven it around yet, either, but it looks better already.

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Here's a better comparison.  For a side-by-side, I flipped the after pic, scaled the pictures to the same size, and rotated them slightly so the hubs are level in both pics.  Makes it really clear how tall the original suspension was and how stout and sporty the new suspension looks.  A nice improvement, and even better if the front settles a little over time.

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     Suspension:  DONE!  Now I gotta do something about that exhaust because, right now, I'll get pulled over for a noise violation.  Hopefully it won't be a year 'till that next post!