I've always drooled over Lotus / Caterham 7's. As soon as it was published I bought one of the first copies of Ron Champion's book. I've even got a Anson 7 model !
At a show I managed to get a sit in a Caterham - and salesmen had to pull me out. Same with a pre litigation Westfield I went to view at the factory (they are only 1.5 miles away from where I was born and still have relatives so visit regulary).
Basically I have leg problems (registered disabled) that means getting in and out of a 7 is virtually impossible
Doors therefore are a essential requirement so the dream of a 7 has been put to the back of my mind - until recently !

Please bear with me whilst I try to explain my idea.
What I'm thinking is using a backbone chassis from a Lotus Elite, Excel, Eclat etc . Even a Spitfire chassis could be a possibility.
The body then would would be build as per the plans around the chassis, adapting , altering as necessary. Doors could be incorporated into the design and probably the whole profile raised sightly. ie the lower section below the bonnet higher to provide more interior room.
Of course that would completley change the look of the vehicle but would at least suit my needs. The nose cone would need cutting in half and additional material added to extend it's height.

This is just a theoretical dream idea at present but any input appreciated.

Cheers.

Paul H

Hmm, interesting idea! However I think you could do it a lot more easily (well perhaps not easy, but stick with me)
The strength of a 7 is in the tunnel and high sides, but what if you replaced the high sides with a full roll cage, putting rigidity up high.
The chassis may have to be built specially to include the cage being designed in specially, rather than many where they are welded in, kind of like a later addition.
The full cage will also give you something to grab hold of to help yourself in and out the car.
That way you've got a proper looking 7 that meets your needs, rather than taking a full bodied car like an elite excel etc, and trying to make it look like a 7

I'd expect it to be simple if you chuck in a roll cage to add strength and modify the side rails to be much lower. But why don't you get a replica or a kit of a more suitable car? Lacia Stratos, GT40, T70, Cobra, Porsche speedster.

One thing you may have to work around is side impact strength - are there any IVA regs on side impact strength? Obviously it would just mean some more detailed door engineering but it's worth knowing before you start. I'm thinking full cage route too.

I seem to recall that MK Sportscars helped build an Indy for a disabled driver. Not sure it had doors as such, but I'm sure it had a cage and was adapted for easier entry and exit. Might be worth speaking to them (and other manufacturers) to see what's been achieved in the past.

My dad wears a caliper on one leg and has carried out various mods over the years to make cars work for him. These have included fitting hand operated clutch mechanisms, extra grab handles and rising seats.

Where there's a will there's usually a way

I wondered about doors for my build, mainly because I wanted to fit wet weather gear and doors would make things easier. But it was pointed out to me that the edge of the chassis is not that much higher than the edge of most bucket seats, so I wouldn't gain much by having doors.

The one thing I found, even as an able bodied person, was the distance from the seat back to the dashboard seemed very short, with the steering wheel a few inches off the dash. Would you benefit from having the dashboard closer to the front of the car, to open up the cockpit a bit more? You'd still need the wheel to be fairly close but at least it would give you a bit more space to get in and out. As mentioned a roll cage would also give a bit more assistance for entry and exit.

I used to have a chassis torsional strength paper from somewhere on the internet. It compared the benefits of space frame and ladder type chassis regarding tortional strength and weight for a 7 type car. If I remember correctly a ladder chassis made from 75*50*3 box had 85+% of the strength of the space frame design for a book 7. So I guess substituting the lower outer rails and cross rails for 75*50 box would provice almost standard tortional rigidity if you keep the rest of the space fram as is), and increase the weight by ( at 5kg/m) about 60kg? You would get some of that weight back as you will obviously have lost the weight of the tubes you have replaced, and since the rest of the space frame chassis has less relevance for the overall chassis strength you could probably reduce some of the 25*25 tubes in the book design to 20*20, but obviously this would need to be carefully considered. If you have difficulty with your legs I'd second moving the scuttle forward a bit, and also look at some way to have a tilt adjustment to lift the steering wheel for getting in and out.
Best of luck anyway!
Regards
Hugh

quote:

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Originally posted by hughpinder
I used to have a chassis torsional strength paper from somewhere on the internet. It compared the benefits of space frame and ladder type chassis regarding tortional strength and weight for a 7 type car. If I remember correctly a ladder chassis made from 75*50*3 box had 85+% of the strength of the space frame design for a book 7. So I guess substituting the lower outer rails and cross rails for 75*50 box would provice almost standard tortional rigidity if you keep the rest of the space fram as is), and increase the weight by ( at 5kg/m) about 60kg? You would get some of that weight back as you will obviously have lost the weight of the tubes you have replaced, and since the rest of the space frame chassis has less relevance for the overall chassis strength you could probably reduce some of the 25*25 tubes in the book design to 20*20, but obviously this would need to be carefully considered. If you have difficulty with your legs I'd second moving the scuttle forward a bit, and also look at some way to have a tilt adjustment to lift the steering wheel for getting in and out.
Best of luck anyway!
Regards
Hugh

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+ 1 for the Locust idea as it is based on a ladder chassis and would be straightforward to modify the sides without damaging the structural integrity. http://www.locust.org.uk/
There aren't many Locusts being built at the moment but there is a strong owners club and it would be practical to pickup one that has already been through the IVA (or earlier SVA or has the correct 'grandfather' rights V5) and that needs some work- and do that at the same time as the modifications to the sides to provide access.

Though a space frame Locost/ Haynes etc chassis will be more the weapon of choice for trackdays the fact there are still so many keen Locust owners about suggets they are probably quite ok as a road car.

quote:

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Originally posted by nick205
I seem to recall that MK Sportscars helped build an Indy for a disabled driver. Not sure it had doors as such, but I'm sure it had a cage and was adapted for easier entry and exit. Might be worth speaking to them (and other manufacturers) to see what's been achieved in the past.

My dad wears a caliper on one leg and has carried out various mods over the years to make cars work for him. These have included fitting hand operated clutch mechanisms, extra grab handles and rising seats.

Where there's a will there's usually a way

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It could be worth also having a word with someone like Phil Eagle of Talon. I know he has produced some special one off chassis for people at very much the same cost as a bog standard one.

Food for thought:
http://www.hotrodders.com/scratch-built/Cover

Somone on here designed a car and almost got it produced. He was the son of user 907 if i remember correctly. His car had doors. Could be worth looking at that.

Look at an austin Maxi for inspiration as it had great torsional rigidity - I read recently this was attributed mostly to the high sills.

I'd be looking at doing something like 3" side out of two standard 1" tubes an inch apart. Fully welded on the outside with 1.6mm steel sheet. On the inside I'd fully weld BUT weld it to the floor 2" in from the outside (therefore making a triangle section). I'd also fully weld the transmission tunnel as per cymetrics analysis. Add in a cage and you may end up with a stronger car than standard.

I've currently got a 1972 Austin Sprite (one of the 82 still known to exist out of the 1022 made after agreement with Healey finished). Once in it's comfy but with hardtop on getting through the door is difficult for me. I need long doors like, say, a Marlin and preferably suicide ! Actually sucide doors are perfectly legal as long as they have the appropriate latching mechanism (black cab rears car provide). In the past I've have 3 MGB's and not serious difficulty getting in and out of them.
The idea of using a Lotus as a basis is many fold. They can be bought relativley cheap - especially if no engine, it'd be a rebody so no BIVA test as long as chassis 100% original, no wishbones to buy or fabricate, brakes, suspension already matched to the chassis, neat pedal box, etc.
As I say just an idea at present - but no harm in dreaming.
Got my Ron Champion book out for inspiration. It's a 1996 issue and pre SVA - good old says
This picture from Alistair McGranaghan's web site http://www.alt-media.co.uk/v6_locost/ gives you an idea of what my idea could look like with the extra height in the sides -




Paul H