Smaller Steering Wheel for a Z3- Published in BMWCC Magazine

[Mike Fishwick]

As my original article seems to have vanished into cyberspace, here is a repeat. (This also contains guidance on removal and replacement of a standard airbag)

A SMALLER STEERING WHEEL FOR THE Z3 Mike Fishwick

I have always found that manufacturers tend to fit their sportier models with steering wheels which are larger than necessary, apparently believing that customers are all would-be truck drivers, and BMW is no exception. Worse still, the M-Technic wheel fitted to my Z3 had a hard rim of a peculiar shape, with hard pieces of plastic designed to cut into one’s thumbs. After two hundred miles my fingers were sore, and a four hundred mile day left my hands in pain; a replacement was necessary – but where from?

While not an enthusiast of the passive safety devices foisted upon us by the American market, it seemed sensible to retain the airbag, unless there was no other option but to fit a bag-less wheel. Small airbag wheels did not, however, seem to be available.

I finally discovered RDI of Herdecke, near Dortmund, manufacturers of TUV-approved RAID steering wheels. A visit to their factory confirmed that one of their small airbag steering wheels would be the answer to my problems, and on return I spoke with the UK dealer for RAID. I found that their price was some 50% higher than in Germany, and that delivery for the specification I wanted was ‘unknown.’ I eventually contacted Chrom-Design of Troisdorf, near Koln, finding that delivery was ex-stock, at a sensible price. (www.Chromdesign.de)

The RAID airbag steering wheel is available in three sizes – 320, 340, and 360 mm, covered in various combinations of plain and perforated black or silver leather, and is mounted on an adapter boss to suit the steering column and wiring of the vehicle in question. The full-size air bag container is roughly the same size as that used on the E36 Compact, with twin horn pushes concealed under the leather at each side of the carefully-shaped rim.

I eventually decided on a 340 mm (13¼ inches) diameter, this being 30 mm (1¼ inches) smaller than the original, without being so small as to obscure the instruments. Black leather was the material of choice, with perforated sections at each side to enhance grip.

Fitting presented no real problems, which was a good thing, as the instructions were all in German! Access to a good BMW manual, such as the TIS disc is, however, quite adequate.

Before starting work, engage the steering lock, in order to provide a good reference position for the steering wheel.

The original wheel was removed by first disconnecting the battery (make sure the cables cannot touch!) and then removing the lower shroud from the steering column. By this time the specified (post-’93) waiting period of five seconds – for the airbag system to drain itself of electricity – will have expired. Now unplug the orange (airbag) and horn (white) connectors which will be seen beneath the steering column.

Using a Torx key, release the air bag by removing the two screws at the back of the steering wheel. The airbag unit can now be drawn out, and the wiring disconnected. This involves one standard push-on connector (brown wire) which is part of the horn circuit, and the yellow airbag connector. This connector is a tight push-in fit, but can easily be levered out with a small screwdriver. Always place the airbag with the ‘driver’s side’ facing upwards, or in an accidental deployment the metal support frame will take to the air!

The centre bolt can now be removed (plenty of leverage is required) and the steering wheel slid off its splines.

The airbag and horn circuits are carried from the column to the steering wheel by means of a connector unit containing a spiral printed circuit – rather like a watch spring – with four conducting tracks deposited upon it. This is either wound up or expanded, depending on the direction in which the wheel is rotated, and must be set to its mid position when bolted to the steering wheel with the front wheels in the ‘straight ahead’ position.
This relationship is normally maintained on removal of the steering wheel by the plastic clip which is released when the centre bolt is removed, locking the connector unit to the wheel. As the connector unit will be removed, its position must be maintained by locking the unit’s rim to its body with tape.

Remove the small Torx screws holding the blue horn wire and the plastic locking clip, before removal of the screws securing the connector unit in position.

Bolt the adapter boss onto the RAID steering wheel, then fit the plastic clip and the connector unit to the boss. The original horn wires (brown and blue) are connected to the terminal block at the base of the wheel, using the black adapter wires supplied.

I find self-cancelling indicators to be a nuisance, as I always cancel the indicators manually (probably due to forty years of motorcycling) and often find that they self-cancel too early. I therefore cut off the curved vane from the back of the connector unit, which is responsible for tripping the indicator switch. To remind others who may also drive the Z3 I will later fit a small audible alarm, connected to the indicators.

Fit the boss to the column splines, noting the white pin at the eleven o’clock position, which locates the connector unit in position relative to the column. Carefully check the exact location of the wheel. Once you are sure of its location, fit the centre bolt and fully tighten.

Insert the yellow airbag connector, and carefully fit the bag into the wheel, securing it by the two Torx screws. Reconnect the orange (airbag) and white (horn) connectors below the column, making sure that everything is neat and secure before replacing the lower column shroud. Reconnect the battery, check the horn, and reset the various memory functions on the radio, which will have returned to the maker’s default settings.

Criticisms? Only one – the holes in the boss for the small Torx screws securing the connector unit were not threaded, which could give a non-engineer some problems (I understand that this was an isolated case) my solution being to drill the holes, and tap with M4 threads to suit some small cap screws which were handy.

The price from Chrom-Design, including the BMW adaptor boss and delivery charges, was 531.90 Euros, or about £360, which has totally transformed both steering response and driver comfort on long runs. From an aesthetic point of view it also looks like a sports car steering wheel, rather than something found in BMW’s corporate parts bin. The wheel is made in Hungary, and the quality of finish is something which BMW (or Alpina!) would be proud of.

Make no mistake – the steering wheel is a major part of the tactile relationship between a car and its driver, and I have the feeling that the Red Zed and I are now entering into an even closer affair than before.