Why are disc brakes not usually fitted to caravans?

ByTim ScottJuly 17, 2020
4 MINUTE READ
Why are disc brakes not usually fitted to caravans?

They’ve been around for years, but if you’re banging a drum, you might ask, ‘Why are disc brakes not usually fitted to caravans?’

Given the widespread use of disc brakes in our towing vehicles you might wonder why the technology isn’t used widely in caravan hardware. It’s rare to find a van straight from the factory with disc brakes, and as drum brakes have been working fine for most people since the 1970s, why change?

Certainly, disc brakes offer better braking performance, but that comes at a cost, one that’s not readily accepted by the industry, that needs to keep manufacturing costs down and, in general, consumers want cheaper vans.

The drum brakes found in most caravans are electrically operated. Any trailer over 750kg needs brakes, over-ride or electric, and anything over 2000kg needs brakes on each wheel, which is usually electrically operated drums but occasionally more complex hydraulic/air disc brake systems.

The electric drum brakes are simple in design and operation, but they’re also basic in the either fully on or fully off status they deliver. That’s why the operation can be clunky or jerky, and of course, there’s adjustment and maintenance that we’d wager isn’t as thorough as it should be in many cases. Drum brakes may be adjustable, but do many owners set them up correctly with their electric brake controllers, or do they dial up the controller for simply more stopping power?

Essentially, what it comes down to is force. And the force required to operate the hydraulically-operated brake calipers used in disc braking. When cars first appeared on the road and had foot-operated drum brakes, you could push your brake lever and you’d stop. When discs arrived, with a caliper, the force required was beyond that of your average human leg, so the brake booster was born.

Caravan disc brake showing caliper

A brake pad has a much smaller surface area in contact with the brake disc than a brake shoe within a drum, and so when it receives its electrical signal to activate it brake duties it does so well. So does the caliper but it requires a much greater amount of force that is provided by the booster/actuator set-up and that’s the expensive and more complex tech that stops most manufacturers from opting for hydraulic discs on their vans right from the drawing board. Not to mention that the vacuum pressure required to activate a brake booster, runs directly from your vehicle’s engine.

It’s also worth remembering that braking systems are installed in line with prevailing manufacturing design standards, VSB1, so it’s not like you’re relying on technology that’s not up to the job. In any event, if you’re not invested in your braking performance due to lack of knowledge, then its worth finding a skilled brake technician.

AL-KO Drum For Use With Esc

The electric drum brake does work very well in tandem with AL-KO’s ESC which is one area you want seamless integration.

The drum brake also doesn’t enjoy water crossings, and if you’re a full-time off-roader then the maintenance for these terrain-supplied contaminants such as dust, water and mud may direct you to the disc brake option (or a better maintenance program).

AL-KO Disc Brakes on a Sunseeker van

Sunseeker caravan with an AL-KO disc brake option fitted

The electro-hydraulic disc brake set-up is offered as an option from a few van manufacturers that utilise systems from AL-KO and Cruisemaster. As well as off-road-oriented electric drum brake options, AL-KO has two air over hydraulic braking modules for caravans with disc brakes used in dusty conditions. These systems store compressed air in a pressure chamber, allowing instant brake application. The iQ7 Outback and iQ7 Xtreme also incorporate breakaway technology and are designed to “significantly improve stopping performance”. You need to work out whether the cost impost is worth the benefits.

What are the benefits of a disc brake system on your van?

Well, improved brake feel and operation, over what can be a bit harsh drum-brake bite. The disc set-up copes better with off-road use and is definitely a better brake in pure stopping power. Importantly, discs are less prone to brake fade in the way that a drum might on long downhill sections or arduous conditions.

And fade is caused by heat, so heat dissipation, especially on very heavy trailers, is vital and ventilated disc brakes do this very well. If you own a light van or trailer, then the financial considerations mean the heat dissipation from your wallet might outweigh the need for discs on your 1500kg camper-trailer.

And the downsides?

Unless you can buy a second-hand van with disc brakes already installed you’re going to be up for a price penalty. Indicative hardware pricing alone was $2000 for a single axle and $3500 for a twin-axle hydraulic disc brake set-up as part of a full suspension from Cruisemaster. The system is much more complex and requires hydraulics and different electrics, and there are, as with drums, maintenance items and consumable brake pads to consider (don’t forget drums and shoes are consumables too). And of course, there’s the brake fluid that must be flushed every two years.

Cruisemaster ATX Suspension With Disc Brakes

Cruisemaster ATX suspension with disc brakes

Discs at some point will require machining plus you still need a mechanical handbrake, but some disc-brake kits supply this part. Cruisemaster, for instance, mentions its handbrake doesn’t rely on hydraulic pressure as fluid is susceptible to temperature variations.

Another point to mention here, though, is that a disc-brake system will lock on as soon as the Anderson plug is disconnected meaning you have you breakaway component sorted.

Conclusion

Essentially, the bottom line is don’t under-brake your trailer. For the most part (and budgets), the tried and true electric drum brakes will do the job just fine. Make sure your brakes are maintained and adjusted to suit the loads you’re carrying and cleaned after off-road use. If you’re on the very heavy end of caravan models, carry a lot of gear, and do all this off-road a lot then you may want to specify disc brakes from the outset. However, Cruisemaster’s ATX and XT suspension can be swapped out from electric drum brakes to hydraulic disc brakes as an aftermarket option. However, if it’s important to you from the outset, then budgeting for disc brakes to be included on a new van could be off-set by initially doing without an accessory or option that could be added later on.

If discs aren’t for you, keep banging that drum and enjoy your brake!