21/03/2019
Ensuring your roof box is securely and safely attached to your vehicle is paramount for both your safety and the longevity of your equipment. While roof boxes are designed to be user-friendly, the crucial element that bridges the gap between the box and your car's roof is the fitting kit. Often overlooked or misunderstood, the fitting kit is the unsung hero of your roof box setup. This article will delve into what a replacement roof box fitting kit is, why it's essential, and how to ensure you have the correct one for your needs.
What Exactly is a Roof Box Fitting Kit?
A roof box fitting kit, sometimes referred to as a mounting kit or hardware, is a collection of components specifically designed to attach a particular model of roof box to a specific type of roof bar system. These kits typically include:
- U-bolts or T-bolts: These are the primary fastening components that pass through the base of the roof box and around the roof bar.
- Clamps or Brackets: These secure the U-bolts or T-bolts, ensuring a tight and stable connection to the roof bar.
- Washers and Nuts: Used in conjunction with the bolts to provide even pressure distribution and secure tightening.
- Plastic Covers or Caps: These often cover the fastening mechanisms for a cleaner look and to protect them from the elements.
- Tools: Some kits may include basic tools like a spanner or Allen key, though you may need your own.
The design of these components is critical. They must be robust enough to withstand the forces exerted by the roof box and its contents, as well as wind resistance and vibrations experienced during driving. The materials are usually high-strength steel or durable plastic composites.
Why Do You Need a Specific Fitting Kit?
The reason for specific fitting kits lies in the vast diversity of roof bar designs and roof box bases. Here's why a generic approach won't work:
Roof Bar Profiles
Roof bars come in various shapes and sizes. The most common types include:
- Standard (Square) Bars: These are typically made of steel and have a rectangular cross-section.
- Aero (Wing) Bars: These are designed to be more aerodynamic, usually with an oval or wing-like cross-section to reduce wind noise.
- WingBar Edge: A specific type of aero bar that sits closer to the vehicle roof.
- Specific Manufacturer Systems: Brands like Thule, Cruz, and RoofBox.co.uk have their own proprietary bar designs.
The fitting kit must be compatible with the exact dimensions and profile of your roof bars. For example, a U-bolt designed for a square bar will not properly secure an aero bar, and vice-versa. This is where compatibility is key.
Roof Box Base Designs
Similarly, roof boxes have different base designs with varying channel depths and bolt slot configurations. The fitting kit's bolts need to align correctly with these slots and provide sufficient grip on the roof bar.
Safety and Security
Using the wrong fitting kit can lead to a loose roof box, which is incredibly dangerous. A poorly secured box can shift during transit, affecting your car's handling, or worse, detach entirely, posing a severe risk to other road users. A proper fitting kit ensures that the box is rigidly attached, distributing the load evenly across the roof bars and the vehicle's structure.
When Would You Need a Replacement Fitting Kit?
There are several scenarios where you might need to purchase a replacement fitting kit:
- Lost Components: Small parts like nuts or washers can sometimes go missing, especially during the off-season when the box is stored away.
- Damaged Components: Over time or due to improper handling, bolts or clamps can become damaged, stripped, or corroded.
- Changing Roof Bar System: If you upgrade your roof bars to a different type or brand, your original fitting kit may no longer be compatible.
- Purchasing a Used Roof Box: A second-hand roof box might not come with the correct fitting kit for your car, or the original kit might be worn out.
- Vehicle Change: While the roof box itself might be transferable, the roof bar system might need to change depending on the new vehicle's roof type (e.g., flush rails, raised rails, fixed points, or standard door frame). This often necessitates a new fitting kit for the new roof bar system.
How to Identify the Correct Fitting Kit
Finding the right replacement kit requires careful identification:
1. Identify Your Roof Box Model
The first step is to know the exact make and model of your roof box. This information is usually found on a sticker on the box itself, often on the underside or rear. Look for brand names like Thule, Mont Blanc, Halfords, Cruz, Yakima, etc., and the specific model name or number (e.g., Thule Motion XT, Halfords Exodus, Cruz Pioneer).
2. Identify Your Roof Bar System
Equally important is identifying your roof bar system. Note the brand and the specific profile of the bar. Is it a square bar, an aero bar, or a specific type like a WingBar Edge? Many manufacturers use a naming convention that indicates the bar type.
3. Consult Manufacturer Resources
The most reliable way to find the correct kit is to consult the resources provided by the roof box manufacturer:
- Manufacturer Websites: Most brands have online fitting guides or product finders where you can input your vehicle and roof bar details to find compatible accessories, including fitting kits.
- User Manuals: The original manual for your roof box should specify the type of fitting kit required or provide part numbers.
- Retailer Databases: Reputable online retailers specializing in car accessories and roof boxes often have extensive databases that allow you to search for fitting kits based on your roof box and roof bar combination.
4. Measure if Necessary
If you're unsure, you might need to measure the dimensions of your roof bars (width, height, and any specific groove dimensions) and compare them with the specifications listed for the fitting kits. Also, measure the distance between the mounting points on your roof box.
5. Consider Universal Kits with Adaptors
Some manufacturers offer more universal fitting kits that come with a range of different bolts, clamps, and adaptors to suit various roof bar profiles. While these can be convenient, ensure they explicitly state compatibility with both your roof box and your specific roof bar type.
Table: Common Roof Bar Types and Fitting Kit Considerations
| Roof Bar Type | Typical Profile | Fitting Kit Considerations |
|---|---|---|
| Standard Square Bars | Rectangular (e.g., 32x22mm) | Usually requires U-bolts that fit around the bar. Ensure the U-bolt diameter and spacing match the roof box slots. |
| Aero Bars | T-shaped slot on top, often wing-shaped profile | Requires T-bolts that slide into the bar's T-slot. Ensure the T-bolt dimensions and spacing match the roof box slots and the bar's T-slot. |
| WingBar Edge | Similar to Aero but often a more integrated design | Typically uses specific T-bolts or clamps designed for this bar system. Check compatibility carefully. |
| Other Proprietary Bars | Varies by manufacturer (e.g., specific internal grooves) | Crucially important to use the manufacturer's specified kit. Often uses unique T-bolts or clamp systems. |
Installation Tips
Once you have the correct fitting kit, follow these general installation steps:
- Attach Roof Bars: Ensure your roof bars are correctly fitted to your vehicle according to their manual.
- Position Roof Box: Place the roof box onto the roof bars, ensuring it's centred and aligned correctly.
- Insert Fasteners: Feed the U-bolts or T-bolts through the designated slots on the underside of the roof box.
- Secure to Roof Bars: Loop the bolts around the roof bars and attach the clamps, washers, and nuts.
- Tighten Evenly: Tighten the nuts gradually and evenly on all fixing points. Avoid over-tightening, which could damage the box or bars. Aim for a firm, secure fit where the box doesn't move significantly when pushed.
- Check Regularly: Always check the tightness of the fittings before setting off on a journey and periodically during longer trips, especially after the first few drives with a newly fitted box.
Frequently Asked Questions (FAQs)
Q1: Can I use a fitting kit from a different brand of roof box?
Generally, no. Roof box fitting kits are designed specifically for a particular brand and model of roof box, and their dimensions and compatibility with roof bars are precise. Using a kit from a different brand is highly unlikely to be compatible and could be unsafe.
Q2: My new car has different roof rails. Do I need a new fitting kit?
If you are keeping the same roof box but changing your vehicle, you will likely need a new fitting kit for the roof bars, and potentially new roof bars altogether, to match the new vehicle's roof type (e.g., raised rails, flush rails, or fixed points). The roof box fitting kit attaches to the roof bars, not directly to the car.
Q3: How tight should the fittings be?
The fittings should be snug and secure, preventing any movement of the roof box on the bars. You should not be able to easily rock or shift the box by hand. However, over-tightening can damage the plastic components of the roof box or even the roof bars, so apply firm pressure rather than excessive force.
Q4: What if I can't find a replacement fitting kit for my old roof box?
If your roof box is very old or from a less common manufacturer, finding specific replacement kits can be challenging. In such cases, you might need to contact specialist roof box retailers or accessory suppliers who may stock parts for older models, or consider purchasing a new roof box that is compatible with current roof bar systems.
Q5: Are there universal fitting kits available?
Some brands offer kits described as 'universal' which come with a variety of bolts and clamps to fit different bar types. However, you must ensure the kit is compatible with your *specific roof box model* as well as your roof bars. Always double-check compatibility before purchasing.
In conclusion, a roof box fitting kit is a vital, albeit small, component that ensures the safe and secure transportation of your gear. Understanding what it is and how to obtain the correct one for your setup will give you peace of mind on every journey.
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