Wheel arches

 I've known for a while that I have to add wheel arches for this car to pass IVA and be usable on British roads. But it's taken a while to get to a point where I know what size arches are required. And by the looks of it, they need to be quite sizable;

This pic shows 100mm sticking out from under the arches. Given the tyres are only 185mm wide that's about half the wheel sticking out. It's clear from the photo too, the rule comes down to the centre tread block. 

Now, I'm not worried about suspension geometry or issues around track width, basically because the Haynes roadster chassis was built to spec. But I still need to make up arches.

This is the MK HSR;

The arches are basically huge, but I think I'll need to recreate them. This is a long term task though, I don't know how to make them, what to use, etc. Retasked water butts was one of my first ideas, then maybe aluminium arches. Both come with pros and cons. I did also think about ready made arches, for example of the old Mini. But having done the measurements it's clear that there are no off the shelf options. Well, there are JDM drift options, but they're more than I've paid for the car! 

(later edit)

I came across this Youtube video;

Where they build up some wide body arches using a wireframe. I thought wireframes were what IT people used, turns out they are a real thing. However it gives an excellent process for creating a base shape ready for fibreglass. Using wire shapes with layers of tape on top, they were able to create quite substantial profiles that are very close to the end product. I think I'll give it a go for the arches I need to create. 

I'm going to create them the same for left and right, possibly the same for front and back but I'm not sure yet. They need to meet IVA requirements which are;

1. The wheel guard must extend 30 degrees to the front.
2. The wheel guard must extend 50 degrees to the rear.
3. The wheel guard must cover the full breadth of the tyre between those dimensions.
4. The rear of the wheel guard must not terminate above a horizontal plane of 150mm. (I think this one is redundant on my car, as the 50 degree angle is below 150mm).
5. The distance between the lower edge of the wheel guards and the axis passing through the centre must not exceed 2 * tyre radius (again, a bit redundant, that would be a point higher than the car itself!).

Had item 4 been a thing, I could have tapered the guard but in reality it needs to be full wheel width for the whole distance. I also need to flatten the face so I'm not having to deal with any sharp edges. 

And just to have a different viewpoint, I found the other example of the HSR, the orange and black one;

Unlike the white one, I have no idea whether this was ever completed. These pictures are from a for sale ad back in 2012, and that's all I know of it. But it does give an alternative view of the wheel arches. As with the white one, the fronts reach all the way down to the floor line both ends, and the rears slightly taper inwards again very low to the floor. As mentioned before this wide arch approach never appealed to me, so I'm hoping I can get away with smaller arches. 

I'll start with an inner edge fixed to the car somehow, and an outer edge that matches the wheel curve. Once they're fixed in place I'll tape up between them, then aluminium tape to stop the fibreglass sticking (I'll need to make four of them after all), then sand and fit. I do need to figure out how much mat I need, i have a patch repair kit but I think I'm going to be quite short with only that. I do still have some fibreglass sheet so in theory I would only need some more resin. But it didn't seem that much cheaper on it's own so I might just buy another of the repair packs again, and get some free cloth!