The kit includes an OEM steering column, so unlike some other kits that just have a shaft sticking out of the dash with no adjustments and no switches for turn signals, lights, wipers, etc, the SL-C has a pretty refined look to the column.
Until late 2014, all kits came with a column assembly from a Cadillac XLR, a cousin to the later C6 Corvettes (both cars shared a lot of components, including the steering column architecture.) These columns have electrically adjustable tilt and telescope.
When the supply of XLR columns ran out, new columns from the 1999 Oldsmobile Intrigue (part no 26074674) began to appear. These are similar columns but differ in two major respects: they have manual instead of electric tilt (and do not telesscope), and they have a different spline for the steering wheel.
Footroom, and Relocating Column Motors
The early columns have electric motors to manage the tilt and tele functions, and the XLR columns usually have one or both of the motors relocated to gain clearance for driver feet. Unless you have bird-like feet, you will probably end up relocating one or more of the motors. It's easy to do, and gives much more foot room under the column.
Olds Intrigue Steering Column
Below are the pin outs and schematics for the newest style of steering column sold with the SL-C and GT-R. Ken scanned these and he has the factory service manuals in case anyone needs assistance.
The steering wheel nut is torqued to 30 ft/lbs (from the service manual).
If you want to clean up the look of the column and eliminate any redundant wiring, consider removing the #205 (cruise control) harness and the #215 (air bag) harness.
The cruise control on the Olds Intrigue steering column has the cruise switches on the steering wheel. Also the air bag is on the factory steering wheel. Both circuits wiring harnesses leads up to the clock spring. You can just cut all the wires for these two circuits at the clock spring if you don't want to use these circuits. The only other wiring that needs to be saved at the clock spring area is for the horn if you want to keep the horn button located on your aftermarket steering wheel. The horn switch is activated by the wheel depressing a small brass plunger in a white plastic tube as shown below in the photo:
The minimum two connectors and wiring to keep are the #201 connector (headlights, park lights, turn signals and horn) and the #203 connector (wipers).
This steering column has a manual tilt function but no telescoping function.
XLR Steering Column
The following are the pin outs for the XLR steering column.
Olds Steering Column
Wiring diagrams for the Olds column and the XLR column (and most all wiring diagrams in general for an extremely wide range of cars) are available here.
Removable Steering Wheels
Many SL-C owners find it convenient to use a detachable wheel, for reasons of ease of access, and for security (harder to steer a stolen car with no steering wheel). In order to do this, you must have an adapter that has the removable feature, as almost all of them do (as opposed to using an OEM wheel without an adapter, which would mean a semi-permanent installation of the wheel to the column).
Because the two columns differ, you need to target the correct adapter for you specific column. Most adapters are semi-universal, and will fit a wide variety of aftermarket wheels
For the early column, use adapters that are designed to work with 2006 to 2013 Corvettes. These are ubiquitous and available everywhere. The later columns use a conventional Chevy adapter, which are even more common.
There are different kinds of adapters, with different features. For example, some have a much tighter fit, and don't rattle- but are somewhat more fiddly to put on each time. The better ones are machined to higher tolerances, and the price usually reflects that.
The release mechanism differs among adapters, so choose one that you think will work easily, look good, not rattle (if you care about that), and install easily.
Here is a short hub for removable steering wheel from RacingLab (RACINGLAB-67298).
Per Mark B, the correct NRG steering wheel adapter for the new Olds column is SRK-170H.
This adapter is short, and allows the use of a horn button on your selected wheel (if the wheel supports it). Another key advantage is that the adapter can be used without welding or pinning, making it easier to attach to the column than the stock adapter.
Many other adapters are available as well, including this one from Krontec.
The Krontec one has a unique design that makes it impossible to install the wheel offset a spline or two, and also has an option to allow wiring to pass through the wheel/adapter combo for buttons on the wheel. It also eliminates the rattling common in other adapters.
One difference in adapters is the offset (the effective length of the adapter, measured from the face of the column to the face of the steering wheel mount). This has an effect on how the wheel is positioned, and presented to the driver. It's very important to have the wheel positioned correctly for the driver to feel comfortable and effective. The OEMs spend a lot of time on this, and every builder should think about how the wheel will fit in his hands, how and if it clears the other controls, as well as the dash. For that reason, install the dash, and position the shifter where it will be when you are mocking up the steering wheel, and testing the adapter.
Steering Wheel Offset
Like the adapter, the wheel can have an offset. In this context, "offset" means the distance from the base of the wheel hub to the centerline of the wheel rim. A wheel with zero offset would place the rim closer to the dash than a wheel with a positive offset. Use the actual wheel, or a replica, when you are mocking up the steering wheel position. That means you need to understand the actual offset of the steering wheel you are planning to use. Most sites don't list this information, but it is key to getting the position correct.
There is telescoping adjustability in the early XLR column, but not in the newer Olds column. There are some cars that have been built where the owner hasn't taken adequate care here, and the drivers hands foul on the dash, the switches, are too far from the signal stalks, etc. Don't be one of those owners- think this through first, and be sure before you commit to any specific adapter and wheel combination.
Aftermarket Steering Wheels
Almost any aftermarket wheel can be used on the SL-C. The particular wheel you choose should have the correct offset, so that the total offset from the wheel and adapter is correct for your driving position. Your chosen wheel will also need to be consistent with the wheel pattern on the adapter you have chosen. Most adapters will work with one or both of the two popular aftermarket wheel drill patterns, but you must confirm that the wheel you choose will fit on the adapter you have selected. Be sure the wheel you select also has a diameter that makes sense in a car with manual steering.
OEM Steering Wheels
With the XLR column, you can mount an OEM wheel to the unmodified column spline. Certain late-model GM wheels from the 2006+ Corvette, and some other GM cars can be used. These wheels have the advantage of OEM looks and safety, and can have such options as radio and bluetooth controls. These wheels, like aftermarket wheels, can also be modified with a very wide range of options, from specific leather, Alcantara, or other materials, have carbon fiber inserts added, be modified to have a flat bottom, etc. The sky really is the limit here.
One advantage to using an OEM wheel, besides the OEM look and feel, is the fact that an adapter isn't needed (assuming you have a wheel compatible with the column). This adds to the OEM look, and has the further benefit of factory spacing for the wheel and stalk-mounted switches.
<need a table here with the two different adapter styles, and details>
Steering Wheel Size
It turns out that size does matter...in terms of steering wheels, anyway.
More precisely, it's vital to consider the diameter of any steering wheel you select, in addition to all the other parameters. That's because the level of effort from your arms is a function of wheel size. Remember those old school bus steering wheels that were the size of a Hula Hoop? That was to reduce effort and make parking easier for those old buses with unassisted steering. The same principle holds with an SL-C, though: a larger wheel makes a big difference in comfort, especially at parking speeds.
Too many builders pick a small wheel (e.g., 12" or so diameter) because it looks cool. Or racy. Or because it is thought to provide more thigh room.
But they pay a pretty high price in much higher steering effort at low speeds, as well as an impaired view of the tach and speedo. A larger wheel (in the 14" range) solves both of these problems.
If you expect to drive your SL-C on the street, and have manual steering (we don't know of any street-driven SL-Cs with power steering yet, BTW), you should consider a larger wheel, for aesthetics, but more importantly for the reduced effort while parking, as well as improved visibility for the instruments.
The takeaway: Don't select a steering wheel with a diameter of less than 14" (or about 355mm for the metrics folk) unless you have power steering, or arms like Popeye-- or only race the car and have someone else to park and drive at low speeds.
In the end, it's cheaper to buy a larger wheel now, than to decide you need to retrofit power steering later.
For context, the standard Corvette wheel from the C6 model is 14", and that is a car with power steering, unlike the SL-C.
If you feel your thighs mandate a smaller diameter wheel, consider having the wheel modified to have a flat bottom. This is a common mod in places that do this sort of thing, and adds an interesting look as well as yielding a little more room if you need it.
The SL-C ships with a custom steering rack, designed expressly for the car. There is no donor rack, and it doesn't come from an existing car.
The rack is manufactured by Maval Industries to specifications from Superlite.
Some people have wondered why the rack seems to be geared relatively low. The explanation from the factory is that a very quick rack is unstable at high speeds, and the SL-C would then be too darty at the top end of the speed range for many drivers. The current ratio also makes low-speed steering, as in parking, easier as less effort is required. At this time, there is no option for a faster ratio rack from the factory.
However, at least two race cars have implemented a different rack. We don't have details on these, only that they exist and are different than the stock rack.
Some SL-Cs are harder to steer than others. So what gives?
The cars are the same, of course, in terms of hardware, and so the answer in almost every case is that what seem like small differences in the steering wheel diameter and suspension setup make the difference.
Remember that lots of caster tends to keep the car straight, but too much makes steering effort noticeably heavier. And of course, as mentioned elsewhere, steering wheel diameter makes a big differences as well. One builder found that his SL-C had unually high steering effort, to the extent that he was considering adding power steering. IN his car, the problem turned out to be sticking ball joints, that once lubricated, made the car a joy to drive. The takeaway: if your car seems hard to steer, add zerk fittings if they are not present in the joints, and lube the ball joints before you tear the car apart for power steering.
For people of normal size and strength, you don't need power steering in the SL-C. If your car seems to, before you go to an expensive, heavy and complex power steering system, try the car with a bigger steering wheel (14" diameter) and about 4-5 degrees of caster. You'll find that the car is pretty easy to steer, even at parking speeds.
If you really do need power steering because you have a physical problem, the next section discusses that.
The build manual discusses how to convert the SL-C to power steering, for those that need power assistance. This approach works with the factory-provided rack and OEM column.
For race cars, power steering can be added as an order-time option (as some chassis changes have to be made for the power steering motor to clear), but this option is incompatible with the OEM columns.
If any builders have implemented power steering with a different approach, another rack, etc., please update this section and, as you used to hear in school, show your work! :)