Swapping 4-Spke Steering Wheel to 3-Spoke M Sport Steering Wheel

This steering wheel swap is for the E38 & E39 with build dates from 9/96-3/99 that have a single-stage airbag and MLF-CM (multi-function steering wheel control module) that is incorporated into steering wheel and is NOT a separate control module located under the dash.

 

 

From this --> --> --> --> --> --> to this.

 

 

This 4-spoke wheel has a circumference of 124.5 centimeters/49 inches (the seam in the leather is the start/finish point of 360 degrees) and a diameter of 393mm/15.5 inches.

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This 3-spoke wheel has a circumference of 121.5 centimeters/47.8 inches (the seam in the leather is the start/finish point of 360 degrees) and a diameter of 385mm/15.2 inches

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side-by-side comparison of the 3-spoke wheel versus the 4-spoke wheel

 

Tools required/used:

 * 17mm socket for removing  steering wheel hex nut / used 1/4" ratchet wrench w/extension (you'll need at least a 3" extension to clear the rim of the steering wheel unless you have a handle with an adjustable end)

 * 13mm socket for removing negative battery cable (this is a must do to NOT set off the SRS/airbag warning light)

 * 27mm or 30mm torx bit for removing air bag from steering wheel / used 1/8" rachet wrench w/27mm torx bit because of tight space issues (my 30mm torx bit required a 3/8" ractchet which was TOO big to use between the rear of the wheel & stalks on the steering column)

 * phillips head screw driver to remove top & bottom halves (clam shells) of steering column / needed stubby phillips because of space issues between top clamp shell and binnicle of instrument cluster...bottom clam shell used regular phillips

 * flat head screwdriver to help pry electrical connectors apart and also to help pry the clamps that hold the vinyl trim away from the lower clam shell

Step 1:  Adjust seat far enough back for room to work and extend the steering wheel out to its farthest position.  If you want to undo the top clam shell around the steering column adjust the wheel so that your phillips head screw driver can access the screw that holds the top clam shell around the steering column (you may not have to remove this section at all if you move the steering wheel to it's top position).  I loosened both the top & bottom clam shells just in case I needed the room.

 

Top clamshell & the screw that secures it to the steering column

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Bottom clamshell and the screw (hole) that secures it to the steering column

 

At this point undo the NEGATIVE battery cable so that when you pull the electrical connectors for the airbag...you won't set-off the SRS airbag warning light ...DO NOT RECONNECT the negative battery cable until you've completed the install or at least reconnected the airbag's electrical connections!!!

 

Step 2:  Use the 1/8" ratchet and 27mm torx bit to undo (2) screws on rear of steering wheel which will release the airbag from the steering wheel

 

 

Step 3:  Undo the 3 electrical connectors between the 4-spoke steering wheel & the aribag...the 4-wire connector to the RIGHT pod (contains the cruise control buttons) mounted to the airbag, the 1-wire connector for the horn, and the 2-wire connector for the airbag

(FYI: the multi-colored wire loom running from side to side connects the audio/phone controls on the left control pod of the steering wheel to the cruise control button pod on the right side of the steering wheel...there's no need to disconnect these wires)

 

Step 4:  Undo the 17mm hex nut that secures the steering wheel to the steering wheel column

 

 

Step 5:  Before you pull the steering wheel off the column...look beneath the steering wheel column and disconnect the 2 wiring harnesses that connect the steering wheel's SLIP RING to the steering column...once you do that...pull the steering wheel off the column (your half way done). 

 

(you can see the 2 wiring harnesses you need to disconnect in these pics below...look at the wiring harnesses coming from the wheel's slip ring and compare it to the wires running to the connectors below the steering wheel)

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Step 6:  Time to install the new wheel...place the steering wheel on the column and align the hash marks that are engraved into the column's spindle and the wheel's slip ring...then reinstall the 17mm hex nut and torque to 80Nm

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Step 7:  Reconnect the two wiring harnesess from the slip wring to the connectors below the steering column

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Step 8:  Connect the TWO wiring harnesses from the 3-spoke steering wheel to the 3-spoke wheel's airbag (there's only the 1-wire connector (for the horn), and the 2-wire connector (for the aribag)...the left & right button pods are attached & wired directly to the M sport steering wheel (instead of the airbag module like on the 4-spoke wheel

 

(the 1-wire connector for the horn is located at around the 11 o'clock position in the pic below...and the airbag's 2-wire harness has the yellow connector seen at around the 5 o'clock position in the pic below...the 4-wire harness that went from the slip ring to the pods on the 4-spoke's airbag...can be seen running from the slip ring to the pod on the right side of the 3-spoke wheel)

 

Step 9:  Mount the airbag to the 3 spoke wheel using the 27mm torx bit and 1/8" ratchet...there 2 screws...one on each side on the rear of the steering wheel.

 

All done! 

 

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