Time to kick this build up a notch and bring it into the 21st century.
I mentioned earlier my garage skills are limited, however I do have some others at my disposal that will help me get this car built - the biggest one being that I could theoretically build / mock up the entire car conversion without so much as picking up a screwdriver - by doing it all on the computer.
One of the first things I modelled was the original subframe. This way I could build the new frame 'inside and around' it and see exactly what resulted in what. I then concepted out some new frames.
Initial concept models were rough. I first looked at the ‘traditional’ frame layout, and then concepted an alternate variant out of plate. I showed both of these to my engineer and discussed the pros and cons of each. There was no clear winner over the other, he would’ve been happy to see any of them as long as they weren’t made of cheese and biscuits.
I went away and decided to proceed with the sheet steel frame, like the original mini one, but kept running into the same problem over and over again: the layouts had very poor load paths through the structure into the rear and towers. I could do it, but eventually I accepted defeat in persuit of a stronger layout. On top of that, I wanted to build a frame that looks presentable, and professional, as if I purchased it from someone that’s made a few of them.
The tried and tested RHS spaceframe layout kept coming back as the best suited design.
After many variants and revisions, and a few hundred hours on the computer of design, refinement, and localised area FE model work, this is a near end result:
It’s probably a bit overkill for some, but if I was an automotive engineer, that’s what I’d like to see under the bonnet of a car. I’ve designed it with more than 100hp in mind in case I decide to make the car more interesting later or stick it on a track. I’ve also made allowances for things that may ordinarily be considered unnecessary by some: things like jacking and towing points, integral sump guard, and the ability to change engine mounts without removing the engine.
I should have stopped there really, but like lots of this I have gotten a little carried away.
The (original) front subframe model showed earlier for example is made of the same 29 pieces it is in real life and has an overall accuracy of less than 1mm to the real thing. Tyre treads are accurate to 0.2mm, and the brake calipers and engine block contain internal components even though I have no need to have modelled those because they aren’t of any relevance to the build.
All the steering and suspension parts can be manipulated to check for clearance on frame and engine members too, this way I won’t get it all together only to find out I have no steering!
The biggest advantages to this digital mockup is that at the end I can get all my parts lasercut and bent to minimise the amount of welding to be done (of which there will be a lot). Parts or sub assemblies can be sent out to specialist fabricators in case something is out of my own capabilities, and I play around with different layouts for ancilliary parts.
.. Top stuff!
