Car roof box.

[Chris1985uk]

hi everyone,

I'm always concerned about the weight in the caravan, I put clothes, drinks and everything I can in the car to the point where there isn't much in the caravan besides a gas bottle, aqua rolls etc.

I have recently purchased an air awning which Im putting in the roof box. Is there any reason why using a roof box is a bad idea when towing? Or am I just being too cautious?

Thanks.

Chris

 

[Buckman]

We have a roof box which we used frequently and it had no ill effect on the handling of the vehicle towing or not. Most roof boxes are limited to about 50-60kg, but you need to check the maximum load the roof of the vehicle can handle.

 

[ProfJohnL]

Hello Chris,

Most car manufacturers do set a maximum limit for the weight to be carried on the roof so do watch out for that.

Obviously adding any more weight high up (in a roof box ) will cause the car to lean more when cornering, but how much depends on the car and speed at which you drive it. It also depends on your sensitivity to the sensation.

Adding anything to the outside of the car will affect the cars aerodynamics adversely, But when towing I suspect the difference will be swamped by the drag of the caravan in tow. However when you have unhitched the caravan, I would suggest you also remove the roof box for two reasons. Firstly is teh fuel economy, but secondly many holiday locations have carparks' with height restrictions.

 

[otherclive]

Never had any problems towing or solo with a roofbox mounted. I use a Hapro Traxer which has been TUV crash tested and can be accessed from both sides.

 

[Buckman]

Never had any problems towing or solo with a roofbox mounted. I use a Hapro Traxer which has been TUV crash tested and can be accessed from both sides.

Ditto. When towing the roofbox is loaded however your speed is limited. When on site the roof box is empty so makes no real difference to stability as roof boxes are very streamlined. Empty a large one like ours weighs less than 20kg.
If the maximum load on the roof is i.e. 60kg this means you can only load the roof box with 40kg of goods. The load is spread over 4 points so not a big deal.
We have never removed when out and about as it is not practical as no where to safely store the box. The only area that we have had an issue accessing car parks was in Dorset where the height barrier was 2.1m so we simply parked on the road, but yoiu need to be aware of the height. We have never had an issue with car parks on the continent as most seem to have no or higher barriers.

 

[JTQ]

Adding anything to the outside of the car will affect the cars aerodynamics adversely,

I believe "adversely" is not necessarily so, or the F1 boys have got it seriously wrong.

There were of course, car roof mounted deflectors that caravanners used in the late 1900s, and many lorries now integrate into the tractor design. They without doubt need to be correctly designed, to be a greater asset than disadvantage, but not all have an adverse effect.

Returning to roof boxes i had an interesting conversation on these with a fellow D3 user, and fellow engineer and similar anorak. He using the then available LR, somewhat dumpy top box mounted as far back on his Disco as it could be. If he was to be believed, he had found on his treks into Spain, with hours of motorway use the top box significantly lowered his fuel consumption on type of route.

 

[Buckman]

Returning to roof boxes i had an interesting conversation on these with a fellow D3 user, and fellow engineer and similar anorak. He using the then available LR, somewhat dumpy top box mounted as far back on his Disco as it could be. If he was to be believed, he had found on his treks into Spain, with hours of motorway use the top box significantly lowered his fuel consumption on type of route.

I think a lot depends on the shape of the roof box. My consumption did not change very much so that it was noticeable and being a sad person I keep records. All I was doing was moving weight from inside the vehicle to the outside so weight was about the same.

 

[Bluetonic]

I've used a roof box whilst towing for several years, we put the bodyboards/wetsuits etc in there, keeps the car a bit cleaner. Usually have 2 surfboards on the other side of the roof bars.
Never had any issues towing or solo, mpg little change, maybe slightly better as the roof box is probably better aerodynamically than the wobble box and stops from air hitting the van ?

 

[Beachball]

Cannot comment never used a roof box so far so i let other members on this forum answer the question .

 

[Thingy]

I used to use a large Thule on the xc70, which carried awning, poles and our maggots, boots and windbreak. Didnt seem to affect fuel ecomomy, didnt cause any handling problems either. I only got rid of it because it was too high a stretch on the Shogun for me.

 

[Gozza2]

My roof box has lived on the car since the start of the year (temporarily left with nowhere else to keep it!). Can't say I've noticed any difference in the handling, and it's fairly aerodynamically shaped so I don't think it'll affect fuel consumption much, but I haven't checked.

It takes the car to just over two metres high so it just fits the multi-storey at work, there are some car parks in town I can't use, but none that bother me that much.

On site we use it to store things like the dirty washing bag that we don't want to keep in the van, a spare sleeping bag that we carry just in case, and anything else light enough that can save us a bit of space in the 'van!

I can't say I've ever noticed any effect when towing with or without the roof box - it will undoubtedly change the aerodynamics of the outfit one way or the other, but unless you're driving on the very limits of handling I can't see it mattering.

 

[Buckman]

In both cases the roof box is empty so no noticeable difference in fuel consumption as box is very aerodynamic. As we no longer need the roof box will probably be looking at selling it sometime.

 

[Beachball]

In both cases the roof box is empty so no noticeable difference in fuel consumption as box is very aerodynamic. As we no longer need the roof box will probably be looking at selling it sometime.
View attachment 2158

View attachment 2159

Looks nice

 

[ProfJohnL]

Several contributors have made vague claims that a roof box has not dented their fuel economy on a solo car.
I can assure you the effect is there and if you were to do the test scientifically you would see a difference. It may not be much, but it's there. It will be more noticeable on smaller engined cars and EV's and when traveling at higher speeds.

 

[Thingy]

Prof, no doubt there is an effect. However, with my tug, the fuel economy is so poor that the roof box effect makes so little difference its not really noticeable. My claim though was whilst towing, not solo.

 

[Buckman]

Prof, no doubt there is an effect. However, with my tug, the fuel economy is so poor that the roof box effect makes so little difference its not really noticeable. My claim though was whilst towing, not solo.

We never used the same roof box on our Shogun, but at 17mpg when towing I doubt if it woudl have made much of a difference to consumption over 100 miles.
Same applies to our current Jeep. Extra fuel used when towing is minimal and nothing to worry about. Same when not towing and roof box is empty. Now if it was a couple of litres difference for 100 miles I would be concerned. LOL!

 

[Beachball]

We never used the same roof box on our Shogun, but at 17mpg when towing I doubt if it woudl have made much of a difference to consumption over 100 miles.
Same applies to our current Jeep. Extra fuel used when towing is minimal and nothing to worry about. Same when not towing and roof box is empty. Now if it was a couple of litres difference for 100 miles I would be concerned. LOL!

17 mpg when towing with a roof box that not a lot i was thinking the same about my car but i get over 30 mpg when towing without a roof box and now i am very happy

 

[Buckman]

17 mpg when towing with a roof box that not a lot i was thinking the same about my car but i get over 30 mpg when towing without a roof box and now i am very happy

Does your car have a 3.2l lump for an engine?

 

[Beachball]

Does your car have a 3.2l lump for an engine?

Your choice but prefer this 2.0 4motion DSG 190 bhp diesel

 

[Buckman]

Your choice but prefer this 2.0 4motion DSG 190 bhp diesel

Which is why we dumped the 3.2 lump after only 3 months for a more economical car when towing! Now get 22-23mpg towing even with roof box so happy chappy!

 

[Hutch]

I had the Isuzzu, Diesel, 3.0 litre V6 engine in the Vauxhall Vectra. A wonderful power unit 30 mpg towing a 1600 kg caravan. And solo at 70 mph around 45 to 50 mpg. A real long distance car.

Fit that engine into the Sante Fe or the Sorento, that would be great.

 

[Fraseb01]

My roof box is on the motor permanently and its full as i leave the chairs ,windbreak etc in there permanently also.

I don't worry about fuel , fill it up when it needs it lol.

Even my golf clubs and trolly live in the motor🙈

Yes i do think i need a van 🤣🤣🤣

 

[Beachball]

Which is why we dumped the 3.2 lump after only 3 months for a more economical car when towing! Now get 22-23mpg towing even with roof box so happy chappy!

I hope you are very happy with your choice

 

[Buckman]

My roof box is on the motor permanently and its full as i leave the chairs ,windbreak etc in there permanently also.

I don't worry about fuel , fill it up when it needs it lol.

Even my golf clubs and trolly live in the motor🙈

Yes i do think i need a van 🤣🤣🤣

Why do you carry the chairs, windbreak etc if you never use them?

 

[Fraseb01]

Storage to be honest , i could store them in the caravan i suppose 🤔

Next house move will have a nice large double garage, 🤣👍