IM Motors Chassis and Suspension Parts List: Steer-by-Wire Columns, Rear-Wheel Steering and Air Suspension

This list covers the one system where the LS9 departs furthest from convention. It runs steer-by-wire, so the steering gear and the column are separate assemblies joined by wire rather than by a shaft, and it pairs that with rear-wheel steering and air suspension. All three are electrically controlled, which makes the electrical side of each part as important as the mechanical side.

Three systems that talk to each other

The front axle carries a by-wire steering gear and a steering column, listed with its motor and, in one case, with a control box. Because there is no mechanical link, the column's angle sensor and the gear's actuator form a closed loop, and the part number matters because the calibration lives with the pair. The rear axle adds a rear-wheel steering unit, one part number covering both listings, which turns the rear wheels through a small angle to shorten the turning circle. The suspension side is air, with front and rear dampers listed as pairs and a separate listing covering left and right air suspension units, so the spring and the damper appear together in one assembly on this car rather than separately. A second steering item, the S31L column motor with direction stop, shows that the same family of by-wire hardware is shared with another platform.

Why by-wire changes the repair logic

On a conventional car, a steering column and a rack can be replaced almost independently. Here they cannot: the two halves are calibrated to each other, so buying one without the other leaves a system that has to be re-commissioned, and some pairs will not commission at all if the part numbers do not match. The same logic applies to the rear-wheel steering unit, where the actuator and its position sensing are one assembly, and to the air suspension, where the damper, the air spring and the control valve travel together. Practical consequence: this is a group where the correct part number is worth more than a low price, and where a seller who cannot supply the number is not really offering a usable part.

Parts list 9 items

By-wire and air suspension assemblies are photographed as removed and are not electrically tested before dispatch. Air springs are shipped deflated.

What to verify, and what usually fails

Grease is the tell on a by-wire column. Pull back the boot if the listing allows and look for the condition of the grease at the motor pinion, since a column that has been run dry or has ingested water will show emulsion rather than clean grease. On the air suspension, the wear item is the bellows, so check the fold for cracks rather than the outer surface, and check the damper rod for scoring. Air units that have been lying deflated for a long time can take a set, so ask how long the part has been off the car. Rear-wheel steering actuators fail at the ball screw and at the output seal; ask for the actuator to be photographed at the bellows end. With any of these, insist on the part number, since the two rear steering listings here share one number and that is exactly the kind of detail that gets lost in a description.