2CV Special - Final* CAD Design

[cb11acd]

I suppose I should keep this thread ticking over.

THings are happening, and moving forward. Most of it is in my head at the moment.

I am going ahead with this single-seater-hillclimb-hotrod thing. I am sticking with the 2CV engine (I like the purity, and the price). I have a lot of it designed in my head already and it is onl in the last week I recieved a major PC upgrade, which has allowed me to run decent CAD software (CATIA), and I can now put my ideas in the virtual world.

This is an early layout "sketch". Engine, chassis legs to scale. Wheelbase is correct as is the position of the front and rear axles. Arms are gueswork but that doesn't matter. Wheels are roughly 18inch in diameter.

More updates to come....

[broady]

That is going to feel like a supercar, 2 inch off the floor and the weight of a bicycle!

[cb11acd]

Jan 31, 2020 7:57:22 GMT broady said:

That is going to feel like a supercar, 2 inch off the floor and the weight of a bicycle!

H-point to ground plane is about 200mm. Ride height will be about 150mm. IT will be like sitting on the floor. The height to the top of the wind deflector is about 850mm. so about the height of my hips. Wheelbase will remain 2CV with no overhang at the front and a bit of overhang at the back which will be all gearbox so it should look pretty cool from the rear. Will have under 50hp initially though, so won't be that quick. I am leaving space for the bigger BMW engine though witch is about 90hp. Weight I have no idea. A 2CV weighs 600kg, no idea how much the body weighs but at a guess it would be 150 - 200kg or so. Final weight I hope will be under 400kg which means MSVA rather than IVA (This will eventually be road legal).

[Frankenhealey]

Here's one I made earlier (no I found it on t'internet)

[cb11acd]

I have seen that (on the internet) a few times. I don't think it has front brakes and the engine is the wrong way around. Cool though. Does anyone have decent pictures of the front end?

[metalshapes]

The rear engine on the twin engined 2CV Sahara's were mounted that way ( behind the rear axle).

Supposedly the gearbox design lets you flip the diff so you don't have 4 reverse gears.

That would make the build really easy too.

Turn the chassis backwards, and make what was the rear axle steering...

[cb11acd]

Feb 1, 2020 8:40:33 GMT metalshapes said:

The rear engine on the twin engined 2CV Sahara's were mounted that way ( behind the rear axle).

Supposedly the gearbox design lets you flip the diff so you don't have 4 reverse gears.

That would make the build really easy too.

Turn the chassis backwards, and make what was the rear axle steering...

But that would be easy.

I also want to keep most of the weight between the wheels, and the whole thing would just look neater.

If I was keeping a 2CV body I would probably make it rear engined rather than mid, but the single seater aesthetic just doesn't work.

[cb11acd]

Small update.

This project is still creeping along. I am in a constant battle keeping my garage space tidy and free of parts that arn't needed.

To achieve that, I sold a load of body panels, seats etc that I don't need freeing up space and money. Infact I am a couple of hundred £ off breaking even and I am left with the chassis, engine, gearbox, suspension and a bunch of other smaller parts.

I also built a new workbench and shelf to both store parts and to work on. The table top is made from a part of the chassis.

Before:

After:

2 days later, I had some parts delivered which is for my PhD project. meaning I now have half of a cars interior in my garage stopping me from doing any dirty work (welding, grinding etc). They will shortly be moved but until then serious progress will stop.

I have done some more CAD (Computer Aided Design) though!

ooooo racey.....

I also did some CAD (Cardboard Aided Design)....

I need space for the engine, and I need to either have dodgey angled drive shafts, a shorter engine or to cut the rear axle and re-weld some bracing. The cardboard shows what I am thinking. I might have acecss to a waterjet cutter so making the flat plates, bending and welding should be relatively straight forward.

Once the rear axle is in, I will cut out the front engine mount cross member from the front of the chassis and modify/fit to the rear. I will keep the existing engine mounts and it will be in roughly the same relative position to the gearbox mount. Once the engine is in, I can modify (cut and bend) the rear chassis legs to meet at the gearbox mounting point. Once that is done, I will find places and ways to brace it a bit although I think it will mostly be ok.

The front end is whole other story, which I will get onto once I have actually made my mind up what I am doing...

[Alpina99]

Brilliant work,
A good friend of mine, (sadly no longer with us,) built a Lomax some years ago before progressing to genuine Morgan's,
Looking forward to reading your updates.

[llwynogmon]

I'm following this build with interest, I really like your CAD design for the body, very much in the fashion of post war hilclimb specials, best of luck with your project and your studies.

[Frankenhealey]

Cooling?

[llwynogmon]

Feb 18, 2020 13:12:43 GMT Frankenhealey said:

Cooling?

Intriguing, the CAD drawing appears to incorporate a gap between the body tub / cockpit and the  roll over hoop, that  has the cylinders in the open.  If this is not sufficient cooling with the standard fan, perhaps the oil cooling could be increased  by means of ducting cool air from beneath the car and substituting a larger  oil cooler or adding an extra oil cooler with a thermostat into the system.

[cb11acd]

Feb 18, 2020 13:12:43 GMT Frankenhealey said:

Cooling?

No idea. Maybe.

I the bodywork will have massive side pods that should provide enough air. I will keep the engine fan of there is space for it, if not I will fit electric fans. Increase in oil cooler size is also an option. I have bigger issues to resolve before then like front end suspension geometry and the gear linkage

[cb11acd]

I suppose I have commited to this idea now?

I cut the chassis floor out. Two reasons 1) I want to make it more light weight, and so the floor panel will be replaced with aluminium 2) I want to lower the H-point into the chassis between the two outer chassis rails.

I have also cut the supporting ctrusture for the seats, the remaining piece in the middle is for the seatbelts, but that will also be removed shortly. The structure bing cut out will be replaced/ re-located but for now I need a bit more of a blank canvas.

Next step is to make a cardboard cut-out of me in the driving position and see how it fits. I might make a quick wooden buck to make the key dimensions (backrest angle, width, seat depth etc.)

I hope the progress will accelerate a bit this month as I have booked a week and a half off to work on this. So expect updates a little more regularly

[greencarfritz]

Just remember you need 8 points from the following to not get a Q plate and perhaps more importantly..... for it not to need an SVA..

5 = Chassis, monocoque bodyshell (body and chassis as one unit) or frame - original or new and unmodified (direct from manufacturer)
2 = Suspension (front and back) - original
2 = Axles (both) - original
2 = Transmission - original
2 = Steering assembly - original
1 = Engine - original

Currently you've got
1 = Engine
2 = Steering assembly
2 = transmission

Look like you'll be modifying the rear axle if you plan on driving that - probably with a welded up or locked front axle? So no points for axles.
No points for body shell of course..
I'm presuming you'll be altering the suspension...

You are not allowed to cut the original chassis any members out of the original chassis - which is a funny point on this as it's a galvanised reproduction and not a genuine citroen one so a hard point to make... but I'd be really considering not chopping any members out of this.. especially if you're documenting it all on the inter webs.... just take care eh..

[cb11acd]

I fully expect this to have to go through SVA. I have already crossed that mental bridge.


Structurally I am not worried as it will be re-welded elseware. The steering wheel will also be collapsable rather than a javalin pointed at my chest. feet will remain between the two axles - there won't be much of a crumple zone but there isn't in a 2CV anyway. The rollcages will be put in by somebody else, and should also add some structure. There will be one placed over my head, and one for over my knee area and then braces between them.

[cb11acd]

Now for something a little different.

ERGONOMICS BUCK!

For those that don't know, my PhD is going to be in autonomous vehicle ergonomics. This project is a sort of antidote to the work I do looking into the future. This car is being designed to fit me and me only (unlike my other work) and so I started by sitting on the floor in roughly my driving position and my wife drew my outline on a piece of cardboard sat next to me (high tech I know).

From that I took some dimensions, drew it in CAD and then made it out of wood.

I don't have much space, so I built it ontop of the chassis and clamped it down.

I am also trying to claw back some space, so I have built in this hump that sits underneith my knees to create some volume for a fuel tank. I also wanted to test ingress and egress with this hump (even though I kind of knew the answer).

It needed to go, there is no space to slide your feet back and so that hump was quickly removed.

I continued to modify and test for a couple of day until I had built a more robust mostly wooden buck that includes steering column, gear lever, handbrake, bulkheads etc. Need to figure out pedel position but I am not worried about that right now.

For reference, I measured the backrest angle relative to the seat pan on my daily ford fiesta ST and also the seat pan angle relative to 0 and compared that to my buck.

Fiesta backrest - 101°

Buck backrest - 120°

Fiesta seatpan angle - 17°

Buck seatpan angle - 7°

So torso angle has quite a big difference, with the buck being significantly more reclined and the seatpan more flat.

[crockpot]

Bonkers but excellent (I think!). Needs the BMW conversion for full fear factor.

[Frankenhealey]

Mar 19, 2020 9:23:06 GMT cb11acd said:

Absolutely love the speedo mock-up. Where do you intend to fit the JATO units?

[mylittletony]

I'd imagine you could get away with a smaller diameter steering wheel from a steering effort point of view, that would greatly help your egress issues. You might need to fit a different one for IVA as well thinking about it
Might not fit with the aesthetic though...

Cracking build by the way, been watching with interest