Fitting Aftermarket Steering Wheels: The Definitive Guide
Steering wheel fitting guide
Swapping the standard steering wheel for a Sparco, OMP or MOMO wheel is one of the most popular interior changes we help with. It is not a case of unbolting one wheel and bolting on another, though. You need a boss kit made for the car, you may want a quick release, and on most modern cars you have an airbag to think about.
This guide covers the whole job: which parts you need, how they fit together, the fitting steps, the checks afterwards, and what removing the airbag means for the MOT and your insurance.
- You need a boss kit made for the car; the wheel bolts to that
- MOMO, Sparco, OMP and Sabelt wheels use a 6 x 70mm pattern; Nardi and Personal use 6 x 74mm
- A quick release fits between the boss kit and the wheel, and adds depth
- Removing the standard wheel removes the driver airbag
- An original equipment airbag that is obviously missing is a major MOT defect
- Tell your insurer about the change
The parts you need
There are up to three parts in the stack. The boss kit, also called a hub adapter, fits the car’s steering column. An optional quick release bolts to the boss kit. The wheel bolts to whichever is on top.
The boss kit is the only part that is specific to the car. Columns vary in their splines and fixings from model to model, and often change part way through a model’s life, so check the year range on the listing matches your car. Our hub guides list the kits by make, for example the B-G and MOMO Ford hub guide.
Bolt patterns: which wheels fit which hubs
The wheel side of the stack is where brands can mix. MOMO, Sparco, OMP and Sabelt wheels all use six bolts on a 70mm pitch circle, so a MOMO boss kit will take an OMP or Sparco wheel. Nardi and Personal use six bolts on 74mm. The B-G boss kits we list are drilled for both, so they take either.
Older British wheels from Mountney and Moto-Lita use larger patterns, and there are adaptors to put a 70mm or 74mm wheel onto one of those bosses. Garreth’s advice is to look at the back of your wheel and measure before you order anything, especially with a second hand or older wheel.
| Wheel brand | Bolt pattern |
|---|---|
| MOMO, Sparco, OMP, Sabelt | 6 x 70mm |
| Nardi, Personal | 6 x 74mm |
| Classic Mountney and Moto-Lita bosses | 6 x 101mm or 9 x 101.6mm |
Adding a quick release
A quick release lets the wheel come off by hand, with no tools. One half bolts to the boss kit and stays on the car, and the other half bolts to the wheel. The two lock together with a collar or catch.
It makes getting in and out much easier in a car with a bucket seat and a cage, and taking the wheel with you is a good deterrent. Some quick releases use a master spline so the wheel always goes back on straight.
A quick release adds depth, so the wheel ends up closer to you than it would on the boss kit alone. If your seating position is already close, a flatter wheel or a slimmer release makes up for it. Our guide to steering wheel dish explains how dish and depth change the driving position.
Check the release now and then: that the bolts are tight, that there is no play when it is locked, and that the mechanism is clean.
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Fitting it, step by step
This is a general order of work. Always follow the instructions that come with your boss kit, and if you are not confident with airbags or steering parts, have it fitted by someone who is. The steering wheel is not a part you want to come loose.
- Disconnect the battery. On a car with an airbag, leave the system to discharge for the time the car maker gives before you touch it.
- Centre the road wheels and mark the column so the new wheel goes back on straight.
- Remove the airbag, if fitted, by undoing its fixings behind the wheel and unplugging it. Store it face up somewhere safe.
- Loosen the centre nut but leave it on a few turns until the wheel is free of the splines, so the wheel cannot come off into your face. Use a puller if it is tight.
- Fit the boss kit to the splines, lined up with your mark, feed the horn wire through, and tighten the centre nut to the car maker’s torque.
- Fit the quick release, if you are using one, to the boss kit and to the wheel, tightening the bolts evenly in a cross pattern.
- Bolt the wheel on with the six screws supplied, with the top of the wheel centred.
- Connect the horn before you close everything up.
With the standard wheel off you can see what the boss kit has to work with: the splined shaft, the clock spring behind it, and the indicator stalks either side.
Features built into the standard wheel, such as audio or cruise control buttons, will not carry over to a plain aftermarket wheel.
Checks before you drive
Reconnect the battery and go through the basics. Is the wheel straight with the road wheels pointing ahead? Does the horn work? Do the indicators cancel as you straighten up? If you have a quick release, does it lock fully and come off cleanly?
Then turn the wheel from lock to lock and check nothing catches on the stalks or trim, and that you have clearance for your knees. Take a slow first drive before you trust it.
Airbags, the MOT and insurance
On any car with a driver airbag, the airbag is in the standard wheel, and it does not transfer to an aftermarket wheel. Taking the wheel off means the car loses that protection.
That matters for the MOT. The MOT inspection manual lists an airbag fitted as original equipment that is obviously missing as a major defect, and an SRS warning lamp showing a system malfunction as a major defect too. For a car that was built with a driver airbag, a road going MOT is a real consideration before you fit a wheel.
Removing the airbag is also a modification your insurer needs to know about. For a car used on the road, keep the standard wheel and airbag so they can go back on. For a dedicated track or competition car, an aftermarket wheel is the normal choice.
Choosing the wheel
Once the hub is sorted, the choice is about diameter, dish and grip. A smaller diameter quickens the steering feel but takes more effort without power steering. A flat wheel suits a road car where the driving position is already right, and a deeper dish brings the wheel closer in a car with a fixed seat.
If you want to check whether a MOMO boss kit will take the wheel you like, our guide on fitting a wheel and quick release covers it.
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Do I need a boss kit to fit an aftermarket steering wheel?
Yes. The boss kit is made for your car’s column, and the wheel bolts to it.
Will an OMP wheel fit a MOMO boss kit?
Yes. MOMO, OMP, Sparco and Sabelt wheels share the 6 x 70mm pattern.
Where does a quick release go?
Between the boss kit and the wheel. It adds depth, so the wheel sits closer to you.
Will my car pass the MOT without its airbag?
An original equipment airbag that is obviously missing is listed as a major defect in the MOT inspection manual.
Do I need to tell my insurer?
Yes. Removing the airbag and changing the wheel is a modification your insurer should know about.
Match the boss kit to the car, check the bolt pattern, and think about the airbag before you start.
Give us the make, model and year and we will match the boss kit, quick release and wheel for you.
