Sim-Lab Cap Washers: What They Do and When to Use Them

Quick answer

Cap washers are dome-shaped covers that sit over bolt heads to protect your rig's finish and keep the bolt head from snagging. Use them anywhere a bolt head is exposed on your sim rig, especially on aluminum profiles where bare metal can scratch or look unfinished. They are not load-bearing, so never use them as a substitute for a flat washer under a bolt head.

If you have ever assembled a sim racing cockpit, you know the small parts matter as much as the big ones. Cap washers are one of those tiny components that can make your build look cleaner and last longer, but they are often misunderstood. This FAQ answers the most common questions about Sim-Lab cap washers so you can decide if they belong in your toolbox.

We will cover what cap washers actually do, when they are worth using, and how to install them without causing problems. Whether you are finishing a new rig or upgrading an existing one, these answers will help you get the details right.

What are cap washers used for?

Cap washers, sometimes called finishing washers or dome washers, are placed over the head of a bolt after it is tightened. Their primary job is cosmetic: they hide the raw bolt head and give your rig a more polished, finished look. On a sim rig made from aluminum extrusion, exposed bolt heads can look industrial and unfinished, so cap washers are a quick way to clean up the appearance.

Beyond looks, cap washers also provide a smooth, rounded surface that is less likely to snag clothing or skin than a bare hex bolt. They can also offer mild protection against scratches if you frequently move or adjust your rig. However, they are not designed to distribute load or prevent bolts from loosening, so do not rely on them for structural security.

• Use cap washers on visible bolt heads for a cleaner look.
• They are not a replacement for flat washers under load-bearing bolts.

When should I use cap washers on my sim rig?

Use cap washers whenever a bolt head is exposed and you want a finished appearance. This is especially common on wheel decks, pedal plates, and seat brackets where bolts are visible from the driver's seat or from the front of the rig. If you have a black anodized or powder-coated profile, a black cap washer blends in nicely and protects the finish from the bolt head's sharp edges.

They are also useful on bolts that you might occasionally adjust, such as those on a sliding pedal deck or a seat slider. The smooth cap reduces the chance of scraping your knuckles or snagging a glove. Avoid using them in areas where the bolt head needs to sit flush against another component, as the cap adds a few millimeters of height.

• Ideal for visible bolts on wheel decks, pedal plates, and seat brackets.
• Skip them where a flush bolt head is required for clearance.

How do I install cap washers correctly?

Installation is straightforward: tighten the bolt to the manufacturer's recommended torque first, then press the cap washer over the bolt head until it snaps into place. Most cap washers are made of plastic or rubber and rely on a friction fit, so no tools are needed. Make sure the bolt head is clean and free of grease so the cap stays put.

If you need to remove the bolt later, simply pry the cap washer off with a small flathead screwdriver or your fingernail. They are reusable if you are careful. For a secure fit, choose a cap washer size that matches your bolt head diameter; too large and it will wobble, too small and it will not cover the head.

• Tighten bolts first, then push the cap washer on by hand.
• Match the cap washer size to your bolt head diameter for a snug fit.

Do cap washers come in sets, and what sizes are available?

Yes, cap washers are commonly sold in sets. Sim-Lab offers a cap washers set of 6, which is handy for covering the most visible bolts on a typical rig. The set includes six washers in a standard size that fits the M8 bolts used throughout many Sim-Lab cockpits. If you need more, you can buy multiple sets.

Size compatibility is key: these washers are designed for M8 bolt heads, which are standard on most sim racing hardware. If your rig uses M6 or M10 bolts, check the bolt head diameter before ordering. The Sim-Lab cap washers are not adjustable, so they will only fit the intended bolt size.

• Sim-Lab cap washers come in a set of 6, sized for M8 bolts.
• Verify your bolt size before ordering to ensure a proper fit.

Are cap washers necessary for a sim racing rig?

No, cap washers are entirely optional. They do not affect the performance or structural integrity of your rig. If you are on a tight budget or prefer a raw, industrial look, you can skip them without any downside. Many sim racers never use them and their rigs perform perfectly well.

That said, if you care about aesthetics or want to protect your investment from minor scratches, they are a cheap and easy upgrade. They also make the rig look more professional if you stream or show it off. Think of them as a finishing touch rather than a functional necessity.

• Optional for performance; purely cosmetic and protective.
• Worth it if you value a clean, finished look or stream your races.

Cap washer quick reference

What they do

Cover exposed bolt heads for a clean look and protect against snags and scratches. Cosmetic and protective, not structural.

When to use

On visible bolts like wheel deck, pedal plate, and seat brackets. Skip where a flush bolt head is needed for clearance.

Installation

Tighten bolt to torque, then press cap washer on by hand. Match size to bolt head diameter for a snug fit.

Product facts

• Sim-Lab Cap: Designed for comfort and style, this classic curved-brim cap features an embroidered Sim-Lab logo and an adjustable, one-size-fits-all design. If you are already buying cap washers for your rig, the Sim-Lab Cap is a natural companion for showing your brand loyalty at events or on stream, and its adjustable fit means it works for most head sizes.
• Simucube 2 Quick Release Adapter: This adapter allows you to remove the original SC2 quick release and install your hub, extension, or quick release. Includes all hardware and is compatible with all 3 common mounting patterns: 6 x 50.8 mm, 6 x 50.2 mm, 6 x 70 mm. If you are swapping wheels or upgrading your steering column, this adapter gives you flexibility without buying a new base, and the included hardware means you will not need to source extra bolts.
• Sim Pedal Heel Rest: The Sim Pedal Heel Rest provides support for the back of your feet, enhancing comfort and stability while operating the pedals. It is made from 4 mm thick aluminium and includes spacers for installation. A heel rest can reduce fatigue during long stints and help you apply consistent brake pressure, which is especially useful if you race endurance events or practice for hours.

Cap washers are a small detail that can make a big difference in how your sim rig looks and feels. They are affordable, easy to install, and reversible if you change your mind. If you want a polished finish and a bit of extra protection, pick up a set of 6 and see the difference for yourself.