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Thread: HowTo->Pull the steering box

  1. #1
    Join Date
    Jun 2010
    My Cars
    '97 840CI

    HowTo->Pull the steering box

    Following some repairs on the hydraulic lines, I discovered my steering and brake assist was gone.
    DejaVu way back to my work diagnosing hydraulics.
    We know that if the steering box passes high volume, then it pulls the entire system down the volume-pressure curve, eventually taking out the brake assist also.
    The fastest, surest way to determine if it IS the steering box that is messing up is to swap it out for a know good unit.

    This writeup is my most recent, cleanest path for accomplishing a pull of the steering box.
    This updates and replaces the "pull" preamble previously found in the thread HowTo->Overhaul a ZF steering box.
    Here, more comprehensive with better pics.

    My estimate would be 2-3 hours for a first time novice, 1.5 hours for an organized talented owner, and no more than 45 minutes for a professional tech on game day.
    Same numbers again for putting the box back.

    The vehicle shown herein is a 1997 840, with X-frame and servotronic.
    The 850 and other years may differ slightly in steering box and hydraulic lines.
    Very early years will not have the X-frame.

    Tools, assuming no commercial garage lift
    Floor jack
    Lifting pad
    2 jack stands for vehicle
    1 jack stand for engine support
    2 wheel dollies, optional
    Balljoint popper, for the steering linkage
    22 mm socket, for banjo at box,
    15" of ratchet extension
    8mm allen, at vane pump
    Bucket, perhaps 2 quart / liter
    Drip pan
    Misc flat and philips screwdrivers
    Hammer and long metal rod, for protection in rough neighborhoods
    Misc open-end wrenches
    Misc close-end wrenches

    Jack vehicle
    This to gain access on this low clearance vehicle and because we will be removing control arms making the front suspension incapable of supporting the front end.
    Although the front wheels can be left on, and that is how it is shown herein, it is suggested that they come off, to eliminate the weight as the struts get pushed around.
    Not shown, jackstands. You will use them.

    Rock / wind screen
    4 screws, probably 4.2 aka #8
    Inspect body nuts

    Fluid drain at pump
    Takes 8mm allen. And a bucket.

    Inspect seal

    Pressure line at regulator
    Takes 17mm open-end.

    Banjo bolt, cooler line at steering box
    Takes 22mm socket and 15" minimum of extension.

    You didn't forget the pan, did you?
    Shop tip: Whenever opening ANY connection, assume fluids will come out.
    Same applies when you even slightly move an open line.
    Same applies when you overturn the steering box.

    Sway bar links
    Immobilize using a 17mm open end, or 5/8 as shown
    That might be (?) a 15mm socket

    X-frame, except on very early model years
    Support X-frame, jackstand option shown. With sway bar, if weighs about 25 lbs.
    On the way back in, and knowing the weight, I was able to bench press it into position and get bolts started.

    Bolts, each side...
    - 2, relatively short, like 15mm
    - 1, really long
    - 1, relatively thick, probably M14

    Hardware survey, disorganized and not complete. Each side...

    Shield(s). Each side.
    Do not disassemble halves.
    Left side shield has a notch, when the servotronic is present.
    3 fasteners each side @...
    - Body, with relatively large washer.
    - Engine cradle, under cap. Relatively long, like 12mm
    - X-frame. Relatively short, like 8mm.

    Column yoke
    Remove the yoke bolt. 13mm wrenches.
    It is not sufficient to merely loosen as there is an interference notch on the shaft.

    Slide the yoke off the steering box input shaft.
    It is not necessary to make any arrangements in the cabin.
    DO NOT pry between the yoke end and the delicate plastic pointer on the box.
    Here we are using a 1-1/2 in wide crow bar wedged between the yoke's upper U and a set of bolts on the steering box.
    It may help to LIGHTLY tap a thick, flat screwdriver into the clamp gap.
    DO NOT hammer the yoke directly as it is aluminum and will deform.

    Engine mounts, engine support
    Disconnect mounts from engine cradle by removing 2 nuts each side.
    Support the engine. Here we have lifted the engine perhaps a half inch, then set it back down on a jackstand with a wood board across the entire front edge of the steel oil pan.
    This support will see approximately half the engine weight, about 220 lbs.

    Engine cradle, aka subframe
    Remove bolt from control arm at the engine cradle.
    The control arm can swing out of the way to the rear.
    Engine cradle fasteners...
    - Long bolt at rear but should have been removed already with X-frame
    - 2 relatively short, up front

    Dang, engine cradle is stuck
    A dowel locates the engine cradle to the vehicle chassis.
    A heavy hammer on a long rod got it unstuck.

    Lower the engine cradle, balanced on the floor jack.

    Steering arm
    Common balljoint tool. Requires very little effort.

    Unbolt box from cradle. Two bolts plus associated washers and nut.

    1) During assembly, follow the factory manual for bolt torque values.

    Quote Originally Posted by toomanyparts View Post
    ... suggest 17mm flare wrench for the regulator lines as they are easy to mangle if not delicate in technique...

    3) As you are returning the steering box into place, manage the pressure line so that it doesn't get jammed up into the engine heads.

    4) Line up the column yoke with the pointer on the box so that the steering wheel in the cabin is clocked properly.

    5) The suspension must be fully compressed when tightening the control arm bushings.
    Since we still require access to the wrenching zone in this low clearance vehicle, this means the tire patch must be elevated.
    Here I've gotten paranoid about suspension deflection and binding, and so have used dollies to give the tire patch freedom of movement.

    6) This spot marks the X, except on very early years.
    Oooooh, is that an LED strip, used as shop light?

  2. #2
    Join Date
    Mar 2011
    Liberal Loontown, CA
    My Cars
    Cool Volvo, Ugly BMW
    Amazing documentation as usual. Only note I would make is that you might suggest 17mm flare wrench for the regulator lines as they are easy to mangle if not delicate in technique.

    Very helpful for future reference. Thank you.
    What "thumbs up" really means

  3. #3
    Join Date
    Jun 2010
    My Cars
    '97 840CI
    Quote Originally Posted by toomanyparts View Post might suggest 17mm flare wrench...
    Or you might, as now quoted in the footnote section.

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