Simon, I've been signing off with Druid online for ~15 years but fwiw I'm David.
Anyway after more considering and reading up of race car construction I've begin to consider a second approach instead of a spaceframe. Glued aluminium honeycomb similar to the J-car/Mk IV, (although for me its got to be a Mk I body).
Not that I'm particularly interested in authenticity. I'd *love* an original (or one of the 'to original plans' replica's) but as I can't afford either I'm going to have my interpretation of it. It'll look like a Mk I and it'll have a V8 but beyond that I'm going to make it as modern as possible.
Has anyone ever duplicated the Mk IV honeycomb chassis? Or got any pictures of the chassis itself? I've got a few but they seem to be at odds with the description of it being a glued chassis as it appears riveted. Of course it could still be glued and the glued joints reinforced by riveted plates...
Thanks for the links and pics, I'd not previously considered the J-cars/Mk IV as I prefer the look of the Mk I so while I knew it was aluminium I didn't really 'twig' as to it being honeycomb so I have few pics of it.
I read the thread on honeycomb core after I'd posted my response. It was actually that same book mentioned "How to Build Motorcycle-engined Racing Cars." that piqued my interest in honeycomb in the first place.
The main advantage I see is that it can be prototyped, first in styrene at 1/10 (very easy to divide every measurement by 10) and then full scale in MDF *very* cheaply and relatively easily, a router is really all you need. Reinforcement, bobbins, mounting points can all be designed and trialled long before the expensive part. As I see it *everything* should sorted before you have to commit to making it and by that point you shouldn't need to redesign or modify. Even up to that commit point of buying the sheets a space frame is *still* an option as with a bit of planning everything can just be fitted to that instead.
Down side is that it has to be very *very* carefully planned and built otherwise it will just fall apart. Reading more on the subject I've realised that the J-cars/Mk IV's are bonded with the edging strips and reinforcements riveted to prevent peel.
I'm pretty much decided that I'm going to do it, rather than wait years until I have the cash for the larger bits or a kit I can start small *now*, knowing that I can adjust easily before I have to commit. As it stands I already have the front hubs/arms/brakes/rack, I know what wheels and have a set I can borrow, I think I know what I want for the rear suspension (I'm just waiting for the uprights to come up for a decent price on ebay), how I want to do the suspension, I have a pretty good idea on the engine (4l 32v V8) and transaxle (6sp Audi), I know track and wheelbase so now it boils down to do I buy bodywork or make it.
Back onto the original subject however plans would still be very handy, I'm very roughly basing my plan on the (poor) autocad plans that have been floating around since 2004 (based I believe on an ERA GT40) with various other measurements gained from various sources over time.
 I estimate 6 sheets at ~£10ea, in comparison honeycomb sheet is £200+ea, Technical Resin Bonders says £203+ which is for 13.70mm/0.5mm facing, "How to Build Motorcycle-engined Racing Cars." suggests 15m with 1mm facing which given that the J-cars/MK IV used 1/2inch seems a good suggestion.
 Up to the point of having a drivable car that you can't drive because it'd fall apart if you did!
 I figured seeing as its GT40 'inspired' rather than a replica I may as well upgrade to modern suspension so inboard shocks.
 Going to make it 'stock', shorter than the (wider tracked) frontend donor so given that this makes it less Ackerman and the donor is already a pretty good handler this should make it rather direct on the steering and faster reacting!
Well for those still after plans I've come across these, not had a full look yet but seems at the very least to be the autocad originals for the jpeg's that are floating around, sectional body plans and some plt files.
No promises of any accuracy (in fact I believe others have already commented that these are far from accurate).
I had a look at those plans last night and they really are poor. At first glance they look ok but zoom in and it all goes to hell. The 'sections' are flattened (slightly) variable width 'slices' (about 1/4inch) rather than zero width, spaced (slightly) irregularly and too far apart IMO (about 8.5inch). It looks to me to be copied (badly) from a 3d model. Still, something could be based on them but would take a lot of work.
Hi guys, have only recently come across this GT40 thread, hence this is my first post, I too got the AutoCAD file discussed earlier, it was several years ago and indeed it is the Tornado plans. Back around 2005 or 2006 I drew it up using an older version of Solidworks, since then I have not updated it, but have saved an E-drawing version that can be viewed in 3D for free by anybody even if they do not have the Solidworks program. If necessary you might have to download the free Edrawings viewer if it doesnt work, found easily on the net. In order to see it rename the file extension that it reads GT40.easm instead of:
GT40 OVERALL rename file extension to easm .pdf
If anybody has difficulty opening, renaming or viewing let me know and i can email it directly to you, and if anyone would like the original Solidworks files also i can oblige.