Can You Drill into Caravan Chassis? Some Tips to Consider Before

The chassis plays an important part as the skeletal backbone of a caravan. As a foundation of the caravan, it supports the body and other attachments or systems mounted on its rails, such as the suspension and running gear, wheels and tires, coupling, stabilizers, and jockey wheel.

Other additions that you might find on a caravan chassis include:

• Water tank mountings
• Extra fuel tank mountings
• Gas bottles or cylinders mountings
• Bike racks
• Stone guards
• Corner jacks or steadies
• Safety chains and shackles

The structure of a Caravan chassis is made of longitudinal Rectangular Hollow Section (RHS) beams and cross Square Hollow Section (SHS) beams. These beams can be timber, aluminum, or galvanized steel material.

Depending on the purpose of your caravan and design, you can either get an off-the-shelf or a bespoke chassis. The style and size of the caravan will determine whether to go for a single (economical tow), tandem (highway speed), or tri-axle (heavy load commercial tow) chassis.

A lightweight on-road caravan chassis is one of the best options in terms of fuel economy. On the other hand, a robust chassis is ideal for off-road or semi-off-road driving. You may have to go for a custom chassis for caravans with specialty roles.

Can You Drill into Caravan Chassis?

The attachments that come with the Caravan chassis may not be enough to give you the experience you want. As you wish to add some accessories and components to the frames, you may be asking yourself, "Can You Drill into Caravan Chassis?". Maybe you are also considering mounting your bike on the rails, adding a checker plate, or installing a new propane line hanger on the caravan chassis.

The question about drilling into a caravan chassis depends on what you ought to consider. You can drill into a caravan chassis if, by doing so, you are not going against the chassis manufacturer. Some producers warn against drilling into the frames as it can compromise the integrity of the structural members.

Guidelines

Before deciding whether to drill your caravan chassis or not, it is best to understand the nature of this solid frame. As an intricate part of a caravan, the chassis is designed and built with strict adherence to structural analysis to best suit the body structure. For instance, the AL-KO chassis is designed and built to precise tolerances.

Therefore, the chassis manufacturer determines the load-bearing capability of the frames and drilling guidelines. As a result, you risk invalidating your insurance by drilling into the caravan chassis. In addition, disturbing the integrity of the frame structure might also deny your claim to the warranty.

Before you can go ahead with the drilling, it is important to get approval from the caravan chassis manufacturer. Otherwise, you risk invalidating all your warranties. Also, in case of failure caused by drilling holes on the chassis, you should be aware that your insurance might be reluctant to pay out if it goes against their modification policies.

Factors To Consider Before You Can Drill into Caravan Chassis

Stress Concentration

Drilling into the caravan chassis will induce stress concentration. Adding an extra load to the chassis may cause that point of distress to either yield (ductile material) or fracture (brittle material). It is recommendable that the drilling process is done in an area not close to bolt holes, welds, or joints to avoid localizing stress and creating fracture points. You may need to consider tensional stresses when the caravan is in motion.

Drilling into a lightweight plain steel chassis can be difficult due to its stiff and hard nature. If not done well, the drilled holes can become a stress point that can become a crack with additional loading. You may need to reinforce the area you are drilling to distribute the load and guarantee that the bolts you intend to use always stay tight. 

Electrolysis

Drilling a rudimental caravan chassis exposes the metal to water or moisture, which can pool the area around the new holes. As a result, corrosion occurs more when you drill on the bottom than on the side of the chassis.

Rust is a silent killer, so after drilling into the caravan chassis, you will need to check for rust from time to time to see if there are cracks. Also, to prevent water ingress when drilling into a caravan chassis, you will have to coat the area with a sealer such as silicon.

Alternatives to Drilling into caravan chassis

If you are not sure about putting a hole on your chassis rails, then you should consider other options such as:

• Using U bolts
• Using adhesives for metallic bonding
• Using worm screw-type hose clamps
• Using a steel backing plate with bolts
• Using weight distributing hitch brackets
• Using angled brackets

The above alternatives for drilling into caravan chassis can work independently or in pairs to provide a firm clamp on the rails.

If you are looking to drill into caravan chassis along the A-frame, you must use a backing plate. As you drill, make sure you use good cutting oil, especially when dealing with tempered steel. The holes you are drilling should be far away from the tubing corners for better results.

After drilling, you may need to treat the holes for rust with good metal paint. At the same time, you will need to check for cracks occasionally so that you can deal with them before the structure fails. If you are not sure about doing it on your own, you can consider having your caravan chassis drilled by a specialist or the main dealers of the caravan chassis.

Structural experts suggest that drilling small holes (less than 5mm diameter) into an RHS section has little to negligible effects on its structural adequacy. However, drilling huge holes can weaken the drawbar. To be on the safer side, you will need to identify the neutral axis, an area where there is neither tension nor compression forces. It is also recommendable to use head screws and some cold galvanizing paint- take good precautions when working with galv.

Types of Drilling

Top Drilling Caravan Chassis

The top surface of the caravan chassis holds dust, dirt, and small stones, which become wet when it rains, creating an area potential for electrolysis and extra weight. In addition, at the top of the chassis, the compression stress is higher. Therefore, the chances of inducing stress concentration are high on this side of the A-frame. The best thing about top drilling is using crush tubes to prevent the bolt from squashing the web when tightening.

Bottom Drilling Caravan Chassis

The bottom of the chassis experiences both tensional and compressional stress due to the caravan loading; hence it could easily cause stress failures. Therefore, the bottom side of the A-frame tubing is not an ideal place to put some holes for any modification.

Side Drilling Caravan Chassis

The caravan chassis sides are considered neutral stress points, hence the most preferable faces to drill. At these locations, the stress is theoretically close to or at zero. Therefore, creating holes into the side of the caravan chassis, not the bottom or top, has less effect on the strength of the structural member material. Most chassis have holes drilled to the side for electrical wiring.

Takeaways

• Always check with the chassis manufacturer before you drill into caravan chassis
• All attachments on the caravan chassis should be mounted on the web of the frame.
• No drilling should be done in flanges of the chassis rails or on the web 40 mm from the corners
• All holes after drilling should be deburred and must not be elongated.
• The holes should be far enough apart (not more than two holes in a vertical line) and from the top and bottom flanges
• All structural bolts used should be of the right grade and correct size; their fitting should include suitable washers (try and avoid spring washers)
• The structural bolts go hand in hand with doubling plates with self-locking plates
• When filling the holes, ensure that the bolts are tight to the right torque.

Conclusion

As it is not advisable to start drilling holes into caravan chassis, you can still do it right. The rule of thumb in drilling into caravan chassis is to ensure that the process does not trap moisture and that it does not cause disturbance to the integrity of the structure. The minimum number and size of the round holes you drill, the less effect it has on your chassis.

It is important to know that the effects of electrolysis might be long-term, but what you need to consider is material failure due to stress concentration. Are you considering drilling into caravan chassis? If so, then you ought to consult a qualified structural expert. On the other hand, you can still buy the tools and do it yourself, at your own risk.