Mountain driving in a motorhome
What’s the best advice for handling long steep descents such as mountain passes when driving a motorhome or campervan?
The Austrian Alps. Member photo by Anita Sellick
Modern braking systems
Modern vehicles are unlikely to be unduly troubled by lengthy descents, as their braking systems are far more tolerant of sustained use than once would have been the case. It’s still good practice to reduce the need to use the brakes too much by selecting a lower gear and using some engine braking, however. While petrol models naturally produce more engine braking, modern diesels also generate a similar effect, largely due to the turbocharger and various emission control systems incorporated into their exhausts.
With manual gearboxes, just select a lower gear to increase engine braking. With automatics, it may take a little experimentation. Some will automatically change down appropriately, especially the more modern ones, some might need the encouragement of selecting ‘Sport’ mode (less commonly included on vans, to be fair) which tends to increase the willingness to downshift, while others might need manual intervention to select a lower gear.
There are few hybrid vans available yet and very few electric ones which suit motorhome conversion, but we’ll see more of both in coming years. They’ll have regenerative braking which provides a similar effect. However, the amount of regen is often reduced if the battery is nearly fully charged, then disappears when it's full. That’s rarely going to be an issue with an electric van, especially if you’ve just driven up the other side of the mountain! For a hybrid with a small battery, however, it’s quite feasible for lengthy descents to get the battery back up to full charge. You should get a warning message on the dashboard to say that regen is reduced or disabled - you’ll then drive with just conventional friction brakes until the battery is depleted sufficiently.
French Pyrenees, member photo by Helen Laverick
Although braking problems are unlikely, it’s still wise to be aware of the risk of brake performance deteriorating, described as ‘brake fade’.
Fade can arise for a couple of reasons. Firstly, if brake temperature becomes excessive, the friction surfaces can deteriorate and deposit a ‘glaze’ across them which reduces braking effectiveness. Light glazing may wear off over time but heavy glazing can require brake component cleaning or replacement. Second, high temperature can boil the brake fluid, making the pedal feel ‘spongy’ or even go right to the floor. Pumping a spongy brake pedal may restore some braking force. The risk of the fluid boiling increases as it ages, as it absorbs water over time, reducing its boiling point. That’s a good reason to ensure maintenance schedules are followed.
If you sense any braking performance reduction, stop as soon as possible and let the brakes cool. A precautionary pause on a long descent might be a good idea if you’re driving an older model, even if there are no obvious signs of brake distress. There are often ample opportunities on mountain passes to stop, frequently with views which justify a break anyway. On these kinds of roads, why would you not want to prolong the experience a little?
Towing a trailer
A minority of motorhomes tow a trailer of some kind while touring. If that’s a small unbraked trailer, then bear in mind that the additional trailer weight will add to the demands made of your vehicle brakes. If towing a braked trailer, advice is similar to that for those towing caravans. Trailer brakes do less work than the towing vehicle’s, but trailers use drum brakes which are more prone to temperature build-up. They’re controlled by an overrun mechanism which reacts to any significant slowing of the towing vehicle. That can be conventional brake application, engine braking or regenerative braking, any of which especially on a steep descent may trigger the trailer brakes – with experience, you should feel this happening. This risks a situation where the driver protects the towing vehicle brakes by using engine or regenerative braking instead, but with the consequence that the trailer brakes are applied much more frequently – perhaps almost continuously on a long steep descent. That may be despite the driver only occasionally touching the brake pedal.
The Austrian Alps. Member photo by Anita Sellick
Over application of trailer brakes can cause excessive heat build-up (above 300°C or even above 400°C) and consequent damage to brakes and wheel bearings. The recommendation from brake manufacturers, somewhat counter-intuitively, is to brake harder but less often, thus giving the brakes more recovery time. If possible, light acceleration between braking ensures the brakes fully release again. These techniques may be tricky, especially with other traffic around, so stops to allow the brakes to cool again are even more important than for solo vehicles. It’s also worth a precautionary stop because a developing problem with the trailer brakes can be very hard to notice while driving. Once stopped, you can (carefully) check the wheels for excess heat, but even then, it's hard to tell how hot is too hot.
It’s also vital to ensure the trailer brakes and overrun mechanism are in good order, to ensure they only engage when really needed, and release fully and effectively again afterwards. While wear to brake shoes and drums is often modest, periodic adjustment may still be required. A good workshop such as those in the National Trailer and Towing Association's Trusted Workshop Scheme will check this as part of a routine service on any trailer type.
One final point
If you are contemplating a mountain route, take time to check details online first (most mapping sites will show the general conditions and availability of stopping points) or use the excellent listings in the Club’s ‘Touring Europe’ guide, which indicate the minority of passes with vehicle size restrictions which may affect larger motorhomes, along with a wealth of other information. Always abide by restrictions and follow advice on suitability.