Audi GT40 Bastard Plan [Archive]

11-09-11, 09:34 PM

Ok, ive been tooling around with a few ideas for several months, started collecting a few little bits and pieces as they popped up, and now figure ive got enough parts together, and a solid enough plan, that i figured it was time to put pen to paper...

so in a nutshell... im going to build a simple, rather quick, track day toy for not too many dollars (apprx 15,000euro)... this is the idea...

http://www.vintage-venom.com/GT40/GT40_web_pics/011.JPG

scratch built spacefame chasis - nothing fancy now, but imho a shit-ton better than half the 'kit' designs available (which seem to try and focus on some semi-resemblence to original monocoque design, rather than make use of the whole idea of triangulated space frame design). Ive got napkin sketches so far, and have started to CAD things out, but the idea is A) safety/cage central design, B) light (800kg) and rigid C) cheap

suspension, brakes and steering stolen of a ma70 supra, and cloned onto said spaceframe with tweaks to geometry to pull the wheels around. will need new coilovers, and depending on space might go with inboard shocks running on a bellcrank. TBA.

Engine will be a 2.7 Audi TT motor out of an A6, unopened engine bolted up to a 01E 6sp box out of a 2.5L deisel FWD. funnily enough that 01E box (getrag?) holds its own over 450hp behind NA V8s. Plan is a pair of 993 KKK K16 turbos, and about a bar of boost through 2 std RS6 coolers, should make about 350-400hp @ wheels. the 2.7 has a really neat VVTi system which should be had to control with a simple aftermarket, so hopefully management will be nice and easy

nothing really GT40 about any of the above, but i figured if i can pick and choose whatever i like to design, then why not make the package externally sized to slip under a std GT40 body. body parts are cheap (ish) and readily availble from multiple sources here in europe land, so fuck it, why not. I was considering a super7 along the same lines of thinkin, but the enclosed roof, and capability to cage the cabin better on something with a roof made the decision easier.

goal is under 2 years. Im currently as design stage, and parts collection stage. Im trying to nail down suspension and wheel components, including buying a set of wheels, so that theres something fixed to design around... starting from the bottom up. chassis start, donor car, and GT40 body parts will come once Ive got a workshop again (hopefully soon!)

heres some pics of something that looks at least externally similar to what i have in mind. you might have seen Iains around, I wont be building anything as 'complete' as that in terms of a race package. Something cheap and cheerful, unopened, off the shelf available engine with fasts, and some basic, reliable unbreakable bits to complement the package.

cheers
ed

garvice

11-09-11, 09:43 PM

Subscribed.

11-09-11, 09:44 PM

no better place like the present to dump some internets information...

FRONT
A - distance between upper A-arm mounting points 845mm
B - distance between lower control arm mounting points 640mm

REAR
C - distance between upper A-arm mounting points 830mm
D - width of diff across the flanges 260mm
E - distance between lower control arm mounting points 415mm

http://www.v-eight.com/images/Images_Forum/both_crossmembers_question.JPG

http://www.v-eight.com/images/Images_Forum/front_crossmembers_question.JPG

http://www.v-eight.com/images/Images_Forum/rear_crossmembers_question.JPG

11-09-11, 09:55 PM

now just for interest...
D - width of diff across the flanges 260mm

compares to 01E diff flange spacing of 270mm. so allowing for say 25mm CV adapters, means the spacing will go up to about 320mm, pushing suspension out 30mm per side.

conveniently enough that leaves enough space under the rear arches of the GT40 body im looking at (1820wide at the arches - outside measurement) to slip a set of 280 wide porsche cup slicks onto about +40mm 10" rims...

front offset i havent figured out 100% yet, but should be between +25 and +40 offset on a 9" rim, say a 250 tyre. the wider i can push the pront suspension the better, as it opens up the space avaiable for a pedal box between the suspension pickup points.

anyways... on the very verge of heamorrhaging cash on these wheels (fuckin most expensive single piece of the project plan so far!)

peal

11-09-11, 10:02 PM

Can hardly wait, sounds awesome!

11-09-11, 10:09 PM

:h5:

Monk

11-09-11, 10:49 PM

This should be good...

And by good I mean awesome.

msmola2002

12-09-11, 01:03 AM

http://www.stickergiant.com/Merchant2/imgs/450/ssim51_450.jpeg

waiting for updates and possible kit package :p

12-09-11, 01:17 AM

plan-o-gram #1

wheelbase 2415mm
front track 1510mm
rear track 1530mm
max width 1820mm

260 front tyre, 280 rear

supra suspension:
-front moved 15mm out per side
-rear moved 30mm out per side

give or take...

12-09-11, 02:09 AM

ATL Savercell FIA FT3
Length x Width x Height = 505 x 305 x 224mm

http://h007.pat00.de/2084c04ee248/p/1287747788-2187.jpg

waiting for updates and possible kit package :p

lol... kit
anyone wants the CADs though, thats easy enough :)
(although my 3D CAD sucks, so 2D only!)

and fuck! just missed an auction on these fuckers... only went for 100eur for the pair. shit. ah well there will be more, im in no rush. but yeah, really nice oem cooler set up (RS6) and its not too hard to imagine where these will sit ;)

12-09-11, 03:24 AM

plan-o-gram #2

working on 100m ground cleranace

EAGER to hear input on floorpan-to-ground distance in terms of setting things up right, to later implement a good ground-effects system... whole floor will be panelled front to rear, with provision in the rear to sweep up.

thoughts?

cheers
ed

Marv

12-09-11, 07:54 AM

By the tangled beard of Zeus! Subscription to your newsletter/RRS/carrier pigeon service is required.

I will look forward to the point where you'll get bored of the V6 and buy a TT V8 out of a previous shape RS6 (as the TTV10 is probably going to be a bit big... and expensive)

farmsci

12-09-11, 09:02 AM

I wholeheartedly approve, please carry on!

rob_2JZA61

12-09-11, 09:08 AM

awesome

Greg Rust

12-09-11, 11:12 AM

Woohoo, this is going to be awesome!!!11GT40

takai

12-09-11, 03:26 PM

Why the JZA70 subframes?

From memory (of Oskar) the JZA80 ones have a much nicer geometry:
http://www.v-eight.com/images/Images_Forum/jza80_subframe_0002.jpg

12-09-11, 03:47 PM

MA70 is cheap and available here in krautland. also in LHD (unlike most JZA supras which are RHD) so i can steal the steering setup

i think the arm pivots are still all balljointed (just look like bushes externally) and i can tweak the pickup points anyway to dial it in more specifically

anyway, main point being i can get a MA70 complete car, running for under 1000eur, and having the whole car will be beneficial in terms of cloning things over.

also the MA70 rear end has the spring/shock in a slightly different poisiton, which suits a simpler chassis design

edit:

oh and i forgot, the MA70 doesnt run assymetrical diff flanges (JZA80 does) so the CVs drive shafts are equal length either side... makes life easy for adapting to the audi box (whioch is also a symmetrically flanged box)

takai

12-09-11, 04:35 PM

Ahh, point taken. Sounds good :)

Gammaboy

12-09-11, 06:02 PM

I have no love for the supra bits, but love the general concept - been plotting something vaguely similar for a long time.

Uncle

12-09-11, 06:17 PM

Win.
Subscribed.

12-09-11, 06:19 PM

simplicity, cost and familiarity with the parts i guess

i could pick something newer (eg Z05/06 as suggested previously elsewhere) but relistically that adds to the cost substantially, and for a total budget under 15k eur, i need to draw the line somewhere.

what specific objections do you have to the supra parts?

and alternative suggestions?

cheers
ed

Gammaboy

12-09-11, 06:47 PM

No big objection really - just that they're a mid 80's designed mass produced cheap-ish thing, and there's better bits around, and associated cost savings involved - starting with a better front end might mean not having to fuck around with brake upgrades, they're a fairly short upright designed to fit under a 15" wheel... how do they do caster/camber adjustment on them? Are there tubular bits available for that gen Supra available as an upgrade path later on? Having said that, the upper arms look to be pretty good alloy forging.

C5/C6 vette stuff was my suggestion - but yeah, not so viable in Germany I guess.

12-09-11, 07:26 PM

Corvette is viable, but i just decided to draw a budget line in the sand. not that im trying to be a total cheap ass, but just making a conscious descision not to get totally carried away. its a project, and a toy. trying to keep things simple and serviceable, and not get fancy and expensive.

caber caster is usually done through cam-headed bolts on the lower control arm. id be planning to install the same deal on the mounts i make for the chassis

the one thing to keep in mind too tho, is the ability to tweak the pick-up points a little before welding mounts to the chassis. thatll leave me the flexibility to chose basic camber caster range. plus i can determin the stuff like dynamic camber, and similarly tweak mount position, and base position of the arms at normal ride height to suit.

not that much available in terms of aftermarket arms. brakes are easily upgraded. though theyd be pretty big (if not ugly and a little heavy) and with some pagids/ebc greens etc, should pull 800kg up pretty quick. PS 16" wheel std

if anyones got a better idea as a no-frills donor, im all ears. ive looked at BMWs, and Audis etc, and no joy there. keep budget in mind :)

cheers
ed

spiller

12-09-11, 07:28 PM

The MA70 set up is ok, and im sure you'll be solid mounting the rear sub-frame to your space frame as the floating rear SF is a downside to the MA70s handling but can be easily fixed. The stock steering system is pretty god awful though, very vague and un-responsive so i'd suggest either sourcing a manual rack or working out some way to quicken up the steering rack. Also, there are good options for both front and rear brakes for the MA70 (rear involving near straight bolt up brembo gear off STi/Evo) so that will be useful for you. No question that the JZA80 geometry is far better but availabilty/budget is part of any build!

oh and subscribed.

gat5rodeo

12-09-11, 07:32 PM

This should be good if your balloon experiment was anything to go by :yup:

takai

12-09-11, 07:43 PM

Look at using a Cortina rack for the front, easy and cheap to obtain out of the UK, and tons of racks available from people like Quaife.

spiller

12-09-11, 07:45 PM

yep, they dont make any off the shelf items for the MA70 so its custom or go home if you go down that path.

HoonBoy

12-09-11, 07:58 PM

Are the front subframes for LHD or RHD? They look very similar to RHD MX5 which could give you a manual rack.

12-09-11, 08:09 PM

PS - not planning on bolting in the wholoe subframe - just using the arms, uprights, brakes, swaybars etc, and cloning (+- a little customisation) mounts onto my own chassis and subframe

PPS - even aftermarket JZA80 parts arent exactly good, and the good stuff is stupid expensive. might as well just make my own if going down that path

Gammaboy

12-09-11, 09:43 PM

The supra is a front rack, and with where the footbox winds up, you'd probably want to stay front rack - you could go a rhd escort quick rack flipped upside down to work as a front rack - Panteras did this but using Austin allegro racks from memory - hence a "rhd" pantera rack is a rare thing as only a handfull of lhd allegros were built...

12-09-11, 10:21 PM

def determined to stay front rack - need all the space possible there for pedal box, and prob a fuel cell

whats with the std steering?

TBH id be tempted to keep the std rack, and see what its ilke first. with the altered geometry, and 1/2 the weight, it could be entirely different to std.

spiller

12-09-11, 11:13 PM

standard steering is progressive power steering (but you probably arent going to use this?). Its just very light and poorly weighted IMO. Might be okay if you loop the lines and run it as a "manual" rack, or just source a manual rack anyway as some did come without PS, not sure about euro specs though. If you are aiming for 800kg, manual rack should be sufficient with some good quality steering arms.

12-09-11, 11:26 PM

looped lines and manual rack is the plan

i tried to fuck with the progressive steering in the jza80, and it never really felt good

and like you say for the MA70, it was way too light, and no feedback.

i eneded up running the jza80 rack un-assisted and looped on itself for 2 years. never had an issue

200MPH

12-09-11, 11:38 PM

Ah, so this explains your rant on why you thought GT40 replica chassis were rubbish etc and also your thread on camber.
Well, you're clearly mad, but many others have gone mad going down the same path... So you won't be the only one. Been snooping around GT40s.com? Do that, it's all been done before, but perhaps not with old supra as a starting point.
Why don't you just fabricate up a rear 5 link rear end similar to original gt40? If you're fabricating the chassis you obviously should have the skills? Adapting a production double wishbone front is generally a decent plan however.
As for 800 kg, I think you realistically are looking at more like 1000 kg wet weight as a minimum. The body and windscreen weight is not quite featherweight. Pretty sure a TT Audi V6 is not that much lighter than a Windsor V8 either.
Keen to see how it all goes anyway, good luck.

13-09-11, 12:20 AM

yep, sponging lots of info off gt40s. a few quite helpful guys doing scratchbuilt chassis whove been very happy to lend a couple of critical dimensions, plus ive hooked up a deal on the body

2 things: 5 link rear requires custom uprights, or most of the 5 link uprights you can buy are meant for knock-on spinner wheels. then theres the issue of CVs hubs and flanges, what hubs, brakes etc etc. much easier just to carry over a complete rear assembly.

the other thing, a lot of the scratch built chassis have an absolute TON of redundant tubes. then they panel EVERYTHING in sight. i really dont think theyre that well designed. and no offence to the guys at gt40's, but lets just say id like to steer my design in another direction. locostbuilders have a far better selection of chassis.

i reckon chassis complete should come in around 200-250kg. im not putting in a lot of extras, and as im not going for the full 'look' outside the shell, its easy to keep things minimal. i reckon 800 will be doable :)

eg of a chassis, just picked randomly from a guys buld thread, very typical in style... an absolute heap of tubes, lots doing nothing structural, and any sense of torsional rigidity comes from the paneling. generally speaking gt40 guys seem to go for the 'look' of the old monocoque, rather than a sensible chassis, and they must weigh a ton as a consequence

http://farm4.static.flickr.com/3434/5727843642_12b6fee80a.jpg

"a good design has 1 part doing two things, not 2 parts doing one"

Gammaboy

13-09-11, 08:58 AM

Sure is alot of box section steel in that thing! I agree, doesn't look to be a particularly efficient chassis design.

Justengt4

13-09-11, 12:17 PM

That chassis looks bloody horrible. Less is more should be the approach.

So you aren't waiting for Cheapracers kit? ;)

The A70 suspension is capable enough so that's a reasonable basis i reckon. Simplifies having to design your own geometry which is always fraught with issues.

Greg Rust

13-09-11, 12:27 PM

Could half of those vertical boxes in the front end just be replaced with a triangulation?

13-09-11, 01:24 PM

Could more than half of those tubes generally speaking just be replaced with a triangulation?

fixed

Greg Rust

13-09-11, 03:03 PM

Ah cheers, so I'm glad it wasn't me just thinking that.

13-09-11, 10:22 PM

MS paint-o-rama

first pic (RED) is whats NEEDED to mount body panels too. theres more pickup points here and there, but these are the key locations. theres pivots front and rear that the shells hinge on, but they can be mounted on simple outriggers, doesnt need to be chassis proper

second pic, with BLUE (tying in the red parts too), is kinda my idea... i suck at 3d CAD, but its clear in my head. im slowly putting several 2D versions together. but this si kinda the idea.

profi

14-09-11, 04:47 PM

I still don't think you should base your chassis of that thing, you don't want to start with compromises, they come naturally.

14-09-11, 06:48 PM

well, im kind constrained within external limits of the body and suspension, plus those red marked tubes have to be there as thats the body mounting location (and top of the roll hoop).

if youve got any ideas, feel free to ms paint your heart out :)

i want to keep with simple square tube for the most part, but the cage (windscreen roll hoop, rear hoop, floor horizontals, and side intrusion ill do in CDS)

200MPH

14-09-11, 10:31 PM

Here's some ideas for you Ed. Below you'll find pics of a GT40 chassis, DRB to be precise. They're the ones I've had the most to do with, though I've also had exposure to RF and Tornado (RF being a Tornado derivative).

Now, a DRB built to race with no added weight (no interior, a/c, lightweight battery etc) weighs about 1110 kg wet, with half full tanks (about 40 L of fuel). That's with a CAMS compliant half cage. So, looking at the chassis photos, you can immediately see a DRB has an over engineered chassis. The rear main rails are 75 x 50 RHS! But is is a stiff chassis (7200 NM/deg when tested to the Aussie way in NCOP - originally the QLD Transport test method) and I can't see it ever having an issue with dealing with many years of service. But it is a bit overkill for track use.

So, say you save 50 kg of chassis steel. Not that easy when you do an audit of the weight of every bit of steel you have. The are paneled using zinc coated steel in the main. But a RF uses sheet ali, which you have to drill umpteen holes, trim and bend to size and then rivet in. Lots of work! And not much lighter in fact. And you do need to panel a car, ever a racer. Firewalls, floor, front rear wheel arch etc.
OK, so your trans is about the same weight and the TT V6 quad cam will weigh similar to an alloy headed small block Ford Windsor V8. Maybe you can run one fuel tank instead of two. 40L capacity instead of 80 ish, but say save 15 kg. Delete GT40 fibreglass dashboard and save say 5 kg. So far you've saved 70 kg. Add heavier production based suspension arms and uprights. But I won't penalise you additional weight for that to be generous. DRB runs Alloy front A arms and uprights, quite light. Pretty sure old Supra stuff ain't alloy.
So you still have 230 kg to go to get to your 800 kg. And that's not including the extra you want to add via a full cage.

Your idea of a front mounted fuel cell has been done before also (got a picture if of one you like), but I'd have thought you'd just run a single tank on the left side behind the tank covers. Keeps weight low as possible, centralised so it don't affect F-R balance as it empties and other side of car to driver. Perfect!

Anyways, enjoy the challenge, but you'll be finding out soon enough why GT40 chassis are made like they are: cause they work and you'll be gravitating to similar conclusions as you fabricate the fill in the space between the suspension.

profi

14-09-11, 10:43 PM

What thickness material is used on that chassis?

14-09-11, 11:03 PM

key is in the chassis i guess. i think the std tube chassis designs are bad, and realistically if you can make any shape i like hiding under that shell, as long as the body mounts up, why should it be so complex? maybe theres some issues i havent found yet preventing that? but i think most chassis are stuck with a level of historical design, where poele have wanted to fabricate a spaceframe chassis, that when paneled up, have the 'look' of the original gt40 monocoques. i give no fuck for such things, so really, it could looke like a tubular sand rail under there and if it fit, id be happy. lol, even imagine an ariel atom exo type fram under there :)

(ps i dont like the idea of fuel cell in the side rails. sure balance might be better, but in the even of crash, id prefer not to have a fuel cell with a target painted on it. id like to mount it up the front and keep it out of harms way :)

weight, well, ill guess well see :) 800 was my optimistic lower limit i admit, but really if i say 800, and aim at something in that area, and end up somewhere nearer 900, id be happy. id be a bit miffed much over 900 tho, and dont see why that would be particularly hard to acheive.

takai

14-09-11, 11:05 PM

Looks like 1.6 or 2mm.

200MPH

14-09-11, 11:38 PM

Profi - dunno what thickness DRB chassis is. Would vary between tubes I guess. Never bothered to measure one. Takai's guess seems about right though.

Like I said Ed, you'll find out why most GT40 replica spaceframe chassis look like they do. Each of those chassis members - they do something, and similar for other proven designs. Though yours will be different if you try the supra rear suspension trick. Have you any experience with FEA modelling of chassis or practical torsion testing experience? Of course this is not absolutely required to fabricate something, but to get it lightish, stiff and strong enough & you'll have to have some idea of the path to take. Anyways, get your body and start filling in the space underneath...

14-09-11, 11:39 PM

spitballing

14-09-11, 11:47 PM

FEA i can do, but realistically i think FEA is worth dogs balls without a back up source of actual eperic information to tie it to. its too finicky, and 99% the results are rubbish

practical torsinal rigidity testing. nope, i have none.

but i can tie-wire a smashed pelvis together and know what a stable construct is when i see one.

well see i guess. im sure ive got a lot to learn with respect to this thing, and no disrespect to how things have been done in the past, but it just doesnt float my boat. if you can point out things along the way, im all ears, and always open to suggestion :)

200MPH

14-09-11, 11:49 PM

How do you propose to get in the car? Remember a GT40 has massive cut-outs for the doors, which makes a full cage difficult. Also makes getting decent torsional stiffness reliant on the side chassis memebers, which is why they are typically well cross braced. Especially so in the DRB design!

200MPH

14-09-11, 11:56 PM

FEA is fine, you just need to know what the limitations are and how to use it. Having the ability to discern right from wrong is the tricky part with it. Practical measurements to verify FEA is very handy too. On some chassis designs I've seen good correlation to modifications made to increase stiffness, but other designs didn't respond in real life anywhere near that modelled. Never did work out why...but if it was easy everyone would be a F1 designer!

15-09-11, 12:01 AM

yup, as i said tho, just spitaballing in ms paint whislt bored at work

ANY proper cage design is going to suck balls if you expect a roof member to pass over where the roof line is... especially if it intersects the door opening at the roof. though how that is any different to a regular sedan full cage with side intrusion X member and windscreen vertical, i dont know. the cages ive seen in GT40s that have the windscreen hoop ending mid-air, with only that centre brace connecting it to the rear hoop - me no like. any impact to the top corner of the screen is going to instantly push the cage straight into driver/passenger occupancy area.

its not a road car, convenience is not the question. safety at 200kmh into trees is

takai

15-09-11, 08:50 AM

http://i532.photobucket.com/albums/ee327/profi_2008/Cage004.jpg

Thats probably a good reference point.

Greg Rust

15-09-11, 10:31 AM

That DRB chassis is miles ahead of the horse cart on post #35

15-09-11, 12:59 PM

balsa wood has been bought

fuck 3D CAD for quickly eyeballing multiple different tube configurations!

profi

15-09-11, 02:17 PM

http://i532.photobucket.com/albums/ee327/profi_2008/Cage004.jpg

Thats probably a good reference point.

Ah no, don't put that beast up as a reference!

This car will come in at around 850-900kg (still has chassis to go in).

http://a8.sphotos.ak.fbcdn.net/hphotos-ak-ash4/254737_259043030775350_100000089663831_1080684_289 8639_n.jpg

http://a5.sphotos.ak.fbcdn.net/hphotos-ak-ash4/262416_259042627442057_100000089663831_1080683_697 7422_n.jpg

200MPH

15-09-11, 03:10 PM

Yeah, profi's SS is nice, but nowhere near what will fit under a gt40 shell.

I'll post up a pic or two of a DRB with a full cage tonight when I get back to computa. There is a way to get a bar between the top of a and b pillars, hinged at one end and quick release pinned at the other. That way you can get in and out of the thing. It will still be an absolute bastard to get in and out of with the cage design I will post! They are hard enough as is with no cage in cockpit.
How tall and fat are you BTW? You may want to think about a diet / amputation if on he generous size...

rorz

15-09-11, 03:34 PM

Cool project!

200MPH

15-09-11, 09:19 PM

So, here are pics of DRB with full cage. Like I said earlier, you could add a hinged/removable bar between the top of the A and B pillar if you were concerned about lack of roof level outer bar. Don't think you could get in with a fixed bar there though. Not unless you were small and some sort of contortionist!

333pg333

15-09-11, 10:12 PM

Can't imagine that you couldn't pickup some Corvette suspension out of the U.S. pretty cheap, even if you forgo those BBS wheels for now?

15-09-11, 10:15 PM

excellent pics, cheers :)

ive got something in mind with the side intrusion bars, basically taking them to the level of the true floor, rather than the fuel tank sill. that would a) make them a stressed member front to rear, reducing the need for such reinforcing in the tank pod. linking the A and B pillar hoops would complete the chain.

if those side intrusion bars werent so intrusive to the dioorway, you might get away with the roof bar, and still have an accesible cabin.

ill post some pics later this eveining when im home from work...

ive got some balsa/superglue/6pack beer...

200MPH

15-09-11, 10:49 PM

So, side intrusion bars at floor level, some 100 mm off the deck eh? What are you trying to stop intruding on you exactly? A sideways approaching speed bump maybe? No, the whole point of side intrusion protection is that it needs to be up high enough to absorb energy from something more your height, say the front end of another car hitting you after you've spun in front of them. Rule of thumb : if it don't make it difficult to get in and out of, then there's not much point to it. That's why there is an ADR for side impact protection that requires reinforcing in the door, not the sill panel below the door, which is analagous to what you're suggesting.

Corvette front suspension is a winner. DRB uses C4 setup. Later C5 better bet now for all the aftermarket bits you can easily get for brakes etc, but both are dirt cheap ex US. See pic of C4 setup in DRB. Far nicer than old Poopra stuff. Unless you already have poopra stuff and are really cheap. And you still need to go a proper 5 link rear you know. Getting the chassis to fit around motor/trans and supra mounting points might suck a bit...or a lot.

16-09-11, 01:22 AM

So, side intrusion bars at floor level, some 100 mm off the deck eh?

yeah, nah :knock:

more like 450m, the depth of the middle of the X simply giving a deep point maximizing the opening window for ingress/egress. basically identical to the intrusion bars in profi's last post. that would put the height of the access window at around 700-750mm. i dont see the need for such architechtural sidepod fuel tank frames/sills if a) there are no fuel tanks there and its simply a body mounting point, and b) structural strength can be found with the cage construction

Greg Rust

16-09-11, 01:07 PM

So has the Corvette front suspension been modified to allow the use of a coil over rather than the typical transverse leaf?

16-09-11, 01:21 PM

does anyone know any quick and dirty 3d CAD soaftware, that uses a simple 3D co-ordinate approach to line drawing ??

defining planes and doing extrusions through space based on planes, just to create simple tubes, is VERY time consuming... especially when youve got a lot, they all lie on different planes, and you want to quickly keep changing them just to eyeball the effect??

200MPH

16-09-11, 03:56 PM

Xw - correct. Just needed to fabricate a lower coilover mount, drill holes in lower arm and bolt together. Not difficult. You can actually make a mid engined supercar type thing using a C5 vette donor. FFR gtm. Very clever people FFR are with their kits; good value plus well thought out designs that maximize use of donor car parts.

Greg Rust

16-09-11, 03:58 PM

Cool cheers 200, Maybe I should have done that instead of putting a Mac strut in the front of mine

Ed, we use Solidworks for 3D stuff and also Polyworks for our laser scanned data.

XFJET

17-09-11, 08:00 PM

17-09-11, 11:44 PM

pity i hate solidworks! blasphemy i know, but it just rubs me the wrong way :)

i dont have it on my laptop where im working at present though. will wait to give it a crack when i get home in a couple of weeks. pity a simple coordinate based standalone platform wont do it. i understand autocad can do it, but havent tried yet...

...mainly because ive been sticking my fingers together with twigs and supergle

ran out of wood... more triangles to come :)

http://www.v-eight.com/images/Images_Forum/GT40/Picture008.jpg

http://www.v-eight.com/images/Images_Forum/GT40/Picture009.jpg

http://www.v-eight.com/images/Images_Forum/GT40/Picture010.jpg

http://www.v-eight.com/images/Images_Forum/GT40/Picture012.jpg

http://www.v-eight.com/images/Images_Forum/GT40/Picture013.jpg

Greg Rust

17-09-11, 11:50 PM

GT40mm

Ben Wilson

18-09-11, 09:14 AM

ran out of wood... more triangles to come :)

That will never work, how are you supposed to fit in there? :)

18-09-11, 10:07 AM

http://images.cheezburger.com/completestore/2009/8/22/128954314330155943.jpg

333pg333

19-09-11, 03:02 AM

Wood will burn and break.

Momus

19-09-11, 04:16 AM

Set it up for 40 to 60 mm of ground clearance. Design around 50 mm

In my experience you will struggle with the road car based suspension layout.

You need at least sphericals for your top and bottom upright joints to facilitate ready adjustment of ride height and arm angles. You will not be able to get the car low enough with acceptable geometry without dropping the lower outer ball joint a fair way.

Don't laugh but a Torana rack is probably worth a look. They are strong, easy to modify, front mount and manual.
Perhaps a little slow.

Check the fit up of the Porker BBS's to your front end. Swapping from Mac strut offset wheels to wishbone set up may involve steering and suspension geometry compromises and expensive disapointment. If you are running 18" slicks your wheels will be around 12" front and rear. At the front with deep inner rim sections you may be forced to use special wishbones to allow sufficient lock.

Greg Rust

19-09-11, 11:24 AM

http://i174.photobucket.com/albums/w85/xwgasaxe/zoolander-school1.jpg

19-09-11, 11:08 PM

^^ lol

http://iruntheinternet.com/lulzdump/images/mini%20me-pimping-car-money-verne%20troyer-12918589199.png

20-09-11, 12:14 AM

Set it up for 40 to 60 mm of ground clearance. Design around 50 mm

In my experience you will struggle with the road car based suspension layout.

You need at least sphericals for your top and bottom upright joints to facilitate ready adjustment of ride height and arm angles. You will not be able to get the car low enough with acceptable geometry without dropping the lower outer ball joint a fair way.

the only problem is the alternative to setting up road car suspension, is cost. stepping away from oem equipment means fabricated uprights and hubs, aftermarket brakes, etc etc. not that i couldnt design the arm geometry and fabricate it, but its getting away from my KISS philosphy with this.

40-60mm ground clearance is doable, though not what i planned (was thinking more 80mm) and to my napkin maths, was doable in terms of simply shifting suspension pickup position on the chassis. no?

not sure what you mean about needing to get the lower ball joint low? figured id just locate the lower control arm chasis mount 120mm or so up the chassis

Momus

20-09-11, 02:19 PM

If you use the Toyota stuff and lay it out carefully I can see you will get what you want for the least amount of expense and effort.

The front end will have to be mounted high to get the chassis low.

Carry on.

20-09-11, 11:59 PM

apparently stress testing the superglued wood model was not smart...

farmsci

21-09-11, 04:31 PM

apparently stress testing the superglued wood model was not smart...

I LOL'd... Have you worked out what the equivelant force on a full size version your fingers exerted?

21-09-11, 05:40 PM

approxiately equivalent to a loaded coal train based on the damage :knock:

edit: actually it was pretty funny, i was talking to the missus on the phone, telling her how i busted it, and needed to put it all back togther, and she just calmly mumbles something about "oh like every other car youve ever built"... fuck it made me laugh

anyway, ive got it back together today, and will be doing the front and rear sections this evening...

once its done, ill drop a few pics up, id appreciate some feedback on the overall design :)

cheers
ed

23-09-11, 01:34 AM

heights in the front end not 100% but thats easily fine tuned. plus i need to add the steering rack mounts. still undecided on upright vs inboard front shocks. design should accommodate both (give or take). but... thats the basic idea.

ingress/egress opening looks doable, legroom and pedal box looks doable. minimal windscreen obstruction, good front-rear load distribution, torsionally rigid. (and keep in mind theres a little paneling to add, especially around the front bulkhead)

200MPH

23-09-11, 10:04 AM

Assuming you've built it to some sort of scale, have you made some scale front wishbone mount locations? Cause that is where all the loads enter for the front section you've built.
Have you ever tried to get into a (full scale) 40? Give it a go before you get too far down the track.
So far it looks plausible at least, getting in/out excepted.

Greg Rust

23-09-11, 12:31 PM

That main front to rear roof area cage brace isn't going to work, the doors have the large cut out that takes in most of the roof, so you will have to rejig that area as 200MPH said

thechuckster

23-09-11, 12:38 PM

Was going to suggest a brace between the front legs @ dash height (and hide it behind the dash)?

And am assuming there's more bracing/structure to go in at the front to support both attachment points of the upper wishbones? Sort-of like this:
http://ajden.se/bentley/merror.jpg

rob_2JZA61

23-09-11, 01:34 PM

That main front to rear roof area cage brace isn't going to work, the doors have the large cut out that takes in most of the roof, so you will have to rejig that area as 200MPH said

the only factor with that is if there is room to get in and out of the car, as long as that part of the cage fits under the body it doesnt matter what shape the doors are the bar will run below them.

Greg Rust

23-09-11, 02:05 PM

Yea but there is bugger all room to start with,

http://marcval.com/autoshow/03/GT40_3.jpg

23-09-11, 03:13 PM

yeah, there is more triangles to go in up the front (ran out of wood again) but its going to come down to the specifics of suspension pick-up points, and whether i go for upright direct-action shocks, or inboard on a bellcrank. it will probably look a little different up there eventually, but i wanted to get the main load-bearing tubes in, make sure the loads can go back and forth into the main cage correctly, and get the basic shape to make sure it fits under the clam.

getting the suspension mounting points to line up will be easy enough now, as so far everything is easily within ballpark of final position, and it will all easily fit under the body. theres enough room for the fuel cell, legs and a pedal box. so im happy.

regarding roof... yeah, its a shitty compromise. ideally, id like to leave it as is, and just crawl in and out of the car. the longitudinal flexion rigidity depends on that cage front to rear.

but yes, i will test run how fucked up access is once its jigged up and tacked, and i can change plans if required. maybe look at how wide the doors can open, and how far inboard those tubes can sit whilst remaining effective, and not getting in head space.

i dont mind a bit of comedy getting in and out, if once in, the driving position is perfect, the cage is safe, and the chassis rigid. where comedy become simply impossible, ill definitely test run :)

Greg Rust

23-09-11, 03:24 PM

Yea I guess you may end up finding it easier now that steering wheels have been made removable with detachable bosses, also those massive wheels back in the day would have made it a pain to get out.

200MPH

23-09-11, 04:06 PM

I've yet to see a pic of a 40 with upper outer cage bars like you want to use to tie top of a and b pillars together. Well, not a fixed one at least. There is a reason for that, and it ain't comedy! Like I said, find a 40 and try get in it. How's your back and knees? Better hope they're sort of flexible!
So the front is relatively easy to get double wishbones mounted with a good load path. What about the supra 5 link rear mounts, plus eng/ trans mounts?

23-09-11, 04:21 PM

rear end i havent figured out yet. havent even looked at it honestly. also waiting on basic block dimensions off Seb.

yes im flexible ;) unfortunately havent fund a local fourty to try and squeeze in to find out specifics. been a few years since i sat in one, and cant remember much. not much that i need to remember anyway.

head-first crawl seems like an option...

also like your idea of the quick release bar, but need to figure a coupling method that is structural, and firm in compression and tension once tightened.

takai

23-09-11, 06:39 PM

I reckon with the A-B pillar bar the monkey bar feet first into the cabin would be the go. You can then use the bar to pull yourself out again.

Local guy here has a TVR with a very similar aperture for getting in and out of. Seems doable though.

garvice

23-09-11, 08:25 PM

Does the A-B pillar bars need to be straight? What I mean is can you tie the A and B roll bars with an X member like you have done on the vertical of the B roll bar? Would that maintain ridgity between the A and B roll bars whilst still giving you a little more access room?

23-09-11, 09:14 PM

headspace is at a bit of a premium, so in need to preserve the area directly above, and unfortuatley cant put any X or curved bars etc into that region. its either directly between A-B pillar corners, or a single (or narrow double-bar) in the middle of the roof.

28-09-11, 06:37 AM

note to self
cool resource link... http://www.flyingfoam.com/launch.html

02-10-11, 10:42 AM

looking for some feedback on a chassis design ive been playing with.

mixed round CDS for the main cage sections, and plain box everywhere else. outrigger side sills are for body support only, and rear aero tunnels i put in so i could look at clearances for what size tunnel widths and tapers. front windscreen is bloody wide, and doesnt match the rear hoop, hence the slightly funky A pillar upright region. theres 2 small tubes to add there to tie things together, but i admit its a bit ugly.

there's obviously a bit of paneling to go in plus a few small tubes (ran out of glue again) 30L fai fuel tank goes up the front, and at present, looks like it will be a single seater with a large halo'd sparco. if theres room for a jump seat, i might try it, but for now priority is driver seat position and pedal box clearance, and thats consuming space. otherwise, ill have lots of space for fire supression gear, gear shifter linkages etc etc. access aperture is about 70cm tall by about 100cm wide.

overall dimensions are 1:10 scale, and id say good to a few cms on a 1:1. chassis is 50mm lower in the base than standard, but with body fitment staying at near standard height... that way it maximises cabin space, and get the ground clearance into the 60-80mm region without making the body looking totally dumped on its guts.

sorry for the lack of sexy 3d .pdf to spin and twirl with your mouse, but fast eyeballing with balsa and superglue was a little more entertaining than learning how to do multiple tube extrusions in solidworks. for now anyway.

any suggestions, criticisms, or other feedback appreciated :)

cheers
ed

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00001.jpg

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00002.jpg

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00003.jpg

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00004.jpg

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00005.jpg

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00006.jpg

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00007.jpg

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00008.jpg

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00009.jpg

http://www.v-eight.com/images/Images_Forum/GT40/chassis_v101_oct11_00010.jpg

SLO78U

02-10-11, 06:14 PM

looks good.

going on the daytona and cobra chassis that i used to make there are a few bars you could drop. and a few that can be moved to make it stronger.

EDIT - the top side bars wont work on a 40. you need the space there to get in. it's pretty much impossible to get over the sill and under that bar in a 40. unless your only 2 foot tall.
Also you will struggle to put a normal seat into it. in a 40 you lay down more than sitting up. it's really weird. go and sit in one before you get to keen on making one. I cant stand it. you feel like your going to slide under the wheel.

not to sure on the rear set of bars. I think you could take out 4 bars. the 2 rear most vertical ones and the triangle ones that connect them. also maybe add a removable 'X' bar between the rear down tubes. makes it easier to put the engine in and out and will add a lot of beam and torsional strength to the rear part of the chassis.

in the front section you could straighten the two going from the bottom of the screen to the front of the chassis.

also keen to see what your going to do with suspension mounting points. these are important points of the chassis design to make sure that suspension loads are accounted for in the chassis design. Maybe look at your suspension geometry now and then modify the chassis to fit your suspension.

guessing you will be running a simple uneven dual 'A' arm front and an 'A' arm top with trailing arm rear. get the size and length of the suspension and make sure they will fit. you will probably have to change length from perfect to acceptable to make it fit in the constraints of the chassis.

02-10-11, 10:42 PM

see highlights

looks good.

cheers

going on the daytona and cobra chassis that i used to make there are a few bars you could drop. and a few that can be moved to make it stronger.

EDIT - the top side bars wont work on a 40. you need the space there to get in. it's pretty much impossible to get over the sill and under that bar in a 40. unless your only 2 foot tall.

top bars between A and B pillars will be a PITA. problem is theyre a pretty essential load bearing member front/rear. once idea is to run a quick release bolt, and make the bar hingable to aid getting in and out. just need to figure out exactly what kind of quick release system will work, and be good in tension/compression/bending when secured. ill tack stuff up obviously and be trying a few ideas based on my physical felxibility

Also you will struggle to put a normal seat into it. in a 40 you lay down more than sitting up. it's really weird. go and sit in one before you get to keen on making one. I cant stand it. you feel like your going to slide under the wheel.

as ive lowered the floor 50mm, keeping the roof line at the same position, im hoping to improve taht a little. iv modelled a sparco in there, and it does manage to sit reasonably upright given that extra 50mm. but again itll come down to tacking up basic dimensions in real life, and trying stuff out. Ive sat in one a few years ago, and also found it weird, but wasnt that bad. and with a proper bucket like the sparco (rather than the std trampoline based seats) im hoping itll be snug and secure

not to sure on the rear set of bars. I think you could take out 4 bars. the 2 rear most vertical ones and the triangle ones that connect them. also maybe add a removable 'X' bar between the rear down tubes. makes it easier to put the engine in and out and will add a lot of beam and torsional strength to the rear part of the chassis.

in the front section you could straighten the two going from the bottom of the screen to the front of the chassis.

reckon you could ms-pain your ideas on one of the pics?

also keen to see what your going to do with suspension mounting points. these are important points of the chassis design to make sure that suspension loads are accounted for in the chassis design. Maybe look at your suspension geometry now and then modify the chassis to fit your suspension.

ive modelled the suspension geometry in CAD (2D) and the chassis dimensiosn were made to correspond with those points, plus with a wheel offset and tyre choice in mind, all to fit in the body limits. you can see the horizontal bars front and rear where the upper A arms will sit

SHARPIE01

03-10-11, 04:27 AM

great project
that looks alot like the shower room in cell block A max security
long bay gaol
"just another bare bum in the shower":fgay:
only joeking

03-10-11, 04:32 AM

its the shower room of my cell in the nurses quaters at bathurst hospital. only location with some glimpse of natural light :gay:

Datto-Zed

03-10-11, 07:01 AM

Last weekend I tried to get into Willy's GT40. I'm 6' 1" and I've come to the conclusion I will never drive that car......I just don't fit. Left knee is pressed into the dash so can't push the clutch, right knee is on top of the shifter. Fark these things are tight! :eek:

With a bar across that entrance you're going to need to be a pretty good contortionist. I'm sure it would be doable though.

Edit: Oh and my head has to be cocked side ways to close the door. With the door open I look at the roof. With a seat that was a bare aluminium shell I reckon I might just fit.

sv_i

03-10-11, 08:08 AM

I like this project.
If you haven't read it yet, read this:
http://www.amazon.com/Racing-Rain-Brilliant-Legendary-Dedicated/dp/1893618714/ref=sr_1_3?ie=UTF8&qid=1317592980&sr=8-3

Not much technical stuff in it, but it gives you an idea of some of the headaches that John Wyer/Horsman went through with their GT40s.

03-10-11, 02:25 PM

cheers for the link, ill have a look :)

re: seating room, yeah, my oath its squishy, hence the single seater appraoch. i figure ill have about 75, maybe even 100mm more headroom than what you sat in. floor is 50mm lower to start with, sparco will be riding on its ass on the floor (plus minimal ass padding) and the seat will be inboard slightly, towards the highest point in the roof. plus im not running a dash, and im allowing LOTS of space into the footwell area to prevent issues with leg movements and pedals etc.

my first consideration with this whole thing is driver position, its got to feel right, and everything layed out the way i want from a drivers perspective, otherwise itll go on the scrap heap. im picky with driving position :)

cheers
ed

Datto-Zed

03-10-11, 03:13 PM

Ahhh you'll be right then! Compressed seat height in Willy's is probably ~50mm off the floor, so your estimate 75 - 100 mm more will be about right.
The other problem for me in Willy's is the driving position is quite upright. So seeing as you can move the pedals further forward and have a slightly more reclined driving position, that will help heaps with the head room and knee room.

04-10-11, 11:52 PM

shit just got real

:D

cheers to Aaron at import monster for the awesome yahoo.jp service

BBS LM 18x9 and 18x10 now acquired

52233

Fondles

05-10-11, 12:03 AM

Sexy sexy looking rims mate.

Justengt4

05-10-11, 08:13 AM

Not wide enough for a GT40 proj :P

05-10-11, 12:46 PM

i cant afford rubber bigger than that!

Justengt4

05-10-11, 08:05 PM

I hear you on that one...300+mm is killer and makes you think twice about baggin them up ;)

msmola2002

06-10-11, 10:37 AM

FYI tried to open this page and chrome blocked me

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hope this helps