Does anyone know whether a taller roof has much effect on off-road stability on a Defender? Clearly it puts weight higher up, but an aluminium roof doesn't weigh a great deal. Obviously if I were to add a roof-rack and then load it right up, that would be a different story - but what about raising the roof on its own?
jamesmartin
Well-Known Member
no but it will have more windage, dormer roofs are quite popular in europe for defenders
Thankyou - that's reassuring. As the only access to the rear is through the back door (will be exported with bench seats) the extra headroom would make quite a difference to the ease of use, particularly for whoever has the furthest forward seat on any given day! It won't be going fast under any circumstances, so hopefully the extra windage won't prove too much of a headache. It'll see bad (really, really bad) roads but I don't think it will be going off-road particularly. I might fit a low-ratio transfer box to help keep the speed down!
jamesmartin
Well-Known Member
you wont notice it all,the weight is on the chassis line
The vehicle is lifted as well. I suppose in the worst case it proves really unstable for any reason, I could create some axle spacers, long half shafts and a longer Panhard rod and increase the track; hopefully it doesn't come to that. I've got a big lathe that would happily handle it all, apart from the splining that I'd have to sub out.
As per usual, I reckon JM is pretty much spot on. If you take the Defender at being 2m tall. (90 is a bit taller and 110 is taller again) If you take the turning force being applied from where the tyres touch the ground then the standard turning moment will be 2m x force applied by the mass of the roof. So, for every 0.1m (10cm of extra roof height) you will be increasing the turning force of the top of the roof by 5%. That's 5% of not a lot of mass up there. Obviously, it does depend on how much you are elevating the roof. Your springs, depending on what you have, will play a part in what's going on.
nobber
Well-Known Member
Your centre of gravity, as James says should be down the chassis or there abouts, it still is but its been lifted so its already a little off where it should be relating to the wheels, making the roof taller shouldn't matter too much, how tall are you going exactly? I wouldn't get too brave if driving sideways across a slope, in any vehicle.
