Making your own chassis - unique to GT40s?

[Ron Earp]

I've been wondering for some time, is the desire or impetus to design and build a GT40 chassis unique to this type of sports/race car?

I've been around Cobra forums since around 1998 or 1999, and I simply don't recall seeing all that many people hot to build their own Cobra replica chassis. Certainly, of the two, the Cobra would be a much easier chassis to design and build from scratch. However, in the realm of GT40s there are many people who wish to build, are attempting to build, or have completed their own chassis from scratch.

What is it about the GT40 that seems to attract the scratch builder more readily than some of the other cars out there?

Best,
Ron

[Rick Muck- Mark IV]

Ron

Might be.

I have been giving thought to making my own accurate replica chassis with one small difference, I am considering 1/6 scale or so! I plan on using brass sheet and will form the spider over a hardwood form. I don't want to build a complete car, just the mono and suspension....no working 1/6th scale 289 for me!

I can't however, do the machining for the uprights, hubs, etc. I can do the castings but need a hobbiest machinest to do the work, my high school machine skills have long since worn off and I have no equipment. I would even trade formed panels for the work if desired.

Note that I have never really done this and the idea is fueled by looking at Wingrove books and fermented beverages applied internally....I have cut back on my scale plastic work as the eyes aren't what they used to be (neither is anything else but my wife hasn't left me yet..) so this is a long term project.

Any ideas or suggestions are welcome. Also as with several other posts, I would like to find some prints to scale off of.

Rick

[Big_Si]

Having a vague grounding in lotus 7 type cars, I can say ,many of the owners build there own chassis and suspesion parts from scratch. Don't know if you're aware of a book by Ron Champion, "Build you own sports car for £250"? It certainly sparked a craze in the uk. See Locostbuilders.co.uk for more info on us nutters this side of the pond.

[Charlie M]

I don't know. I think few people consider making their own Cobra chassis because there are so many Cobra replica manufacturers out there and some of the prices are very reasonable. Most guys probably figure it's not worth the trouble when they can buy a kit from FFR for around $13k.

Charlie

[Big_Si]

The same is true for 7's. You can buy a Caterham, as one of the most known manufacturers and get a near completet kit for £12,000ish. Or you can
build your own for £2,000. Most do it less for the saving in money nad more to answer the question "Did you build that?" with the something like "yes, I made the entire car, every last bit of it!" To some it's not worth the effort, for some it's the reason for doing it in the first place.

[Russ Noble]

From my perspective Ron, it's a case of being able to build what you want, to your own specification, and not being bound by any unwanted compromises that may have been dictated by someone elses priorities.

If that's the reason for doing it, the sort of car you are going to build is more likely to be a GT40. A Cobra's basic design is that full of compromises that it would not appeal to someone wanting an "ideal" minimum compromise car. Nevertheless a Cobra may well be a more suitable road car and the design limitations may not be so much of a consideration. As a result an existing kit would quite adequately achieve the desired results

It's also a cost thing, a few hundred bucks in steel tube and a grand or so in resin and glassfibre mat etc. A heavy investment in "sweat equity" though. I've been going nearly two years on the project and probably still about another six months before it's complete and on the track.

The whole thing has been quite a learning curve and for every hour actual work on the car there is at least two researching the many different considerations that need to be taken into account. Everything is inter-related, you change or decide on one thing and it affects a whole lot of others. In that respect this forum is a wealth of information and support. There are many things I have found on this forum or have been pointed to by it that I would never ever have been aware of otherwise. In fact without this forum building my own car would be a massive struggle from this side of the world. For reference purposes there are no original cars in NZ and only a handful of completed kits, the closest that I was aware of when I started the build was hundreds of miles away.

I recently did a short write up for my local car club on why I chose to build a GT40. I'll put it on my build thread "Kiwi Scratchbuilt". http://www.gt40s.com/forum/builders-...atchbuilt.html
I need to take some photos and update my thread again too.

Cheers

[BruceLambo]

Well, perhaps not a GT40, but in the same breath I guess. I made the chassis for my Lamborghini Countach replica from scratch. Why? Well, I started looking at the so-called 'kits' in 1987. A trip to the UK and USA to view what was on offer just resulted in seeing some of the worst glassfibre and steel engineering I had ever seen.
So I bought a body shell from someone who couldnt build the thing, then set out to make the chassis.
I copied it off photos of the real chassis. Why? Because it is a proven design and it fits the body shape. I added just a few things here and there for mountings etc but that was about all.
I cast the rear bearing carriers, made my own suspension arms etc and it all works fine. I also made scaled wire models of the chassis and twisted and bent it and added and subtracted peices till I had what I wanted.
As for the suspension geometry, I talked to everyone in the know, read as many books as I could get my hands on then made my own decisions as to what I should do. After a few days driving just the bare chassis on a racetrack, and doing a few changes, it all worked out well.
This was all in 1989-1991. So the only thing that has changed since, is the availability of nice cast carriers and different brake technology, that has been adapted.
I could have bought one of the chassis already on offer from the kit manufacturers, but after seeing the very poor offerings of bad welding, bad design, excessive weight etc - I done my own thing.
Ive attached a few pikkies of my handywork.

[FRPGUY]

Ron, Most of the people that buy my GT40 and Lola T70 MKIIIB Coupe bodies from me are building their own design chassis. The reason I hear the most is ; cost! It's like the kit and homebuilt airplane hobby. Everyone thinks they can build it for less. There is hundreds of unfinished home built airplanes sitting in garages that will never get built. I know of two in my home town.

[Adam C.]

The original reasons for me were cost and accuracy.

After working on it for a few years I have learned that although I have the accuracy thing under control, it certainly won't be any cheaper.

The main driver these days is being able to say "I made that". It is very gratifying.

[jimbo]

I didn't build my own chassis (I'd still be in welding class if I had decided to), but I can offer what I think is an explanation, or part thereof:

The look of a Cobra comes from the external body. It doesn't matter, except in terms of handling and roadworthiness, what the chassis looks like.

But a GT40 IS the chassis, to a large extent. The monocoque, or space frame, locates everything. The body sections are really just there to keep the wind and rain out, and reduce air resistance. The fact that the car is beautiful to look at is an added plus. On a Cobra, the body sections just have to meet each other. On a GT40, they have to fit the monocoque/frame AND each other.

From what I hear from folks who have worked on many of the real ones, they are all custom-fitted to one extent or another. Even the Mark Vs, which were built to a higher standard than any other group of GT40s, are to a large extent individually fitted cars. I don't think you could take a door off one Mark V and put it on another car without a great deal of handwork and fitting.

So the guy who decides to build his own frame is just bowing to reality, in a sense. Might as well create it from scratch.

[Phil]

Ron
Having the tools and equipment was the bonus for me, I was already repairing, tweaking or modifying a lot of chassis, but the deciding point for me was cost and availability of parts. in 1986/87 when I started to look into the project there were only a few cars available in the UK, most with Granada and Merkur parts, and ERA here in the U.S., so the choice was easy in that respect, but as Russ said the hours are there as one picks through the various options and does the trial and error thing on his way through the project. No complaints though..I wouldn't have it any other way.
Phil

[Mike Dozier]

Once again...it's all about the money....

You can bet the ranch 95% of those who read this would buy a GT40 mono
chassis if one were readily available at the price point most Cobras sell at.
Of course as we've beaten to death many times...this ain't gonna happen,
leading to the plethora (love that word) of one-off GT40 chassis being made.

MikeD

[ChrisL]

Ron makes an interesting observation. I read lots of reasons as to why people chose to build a scratch-built car, but not why they chose a GT40 above say a 917 or a P4 or a Lola or any other race car for that matter.

Some of the reasons I would offer is that it is probably the most advanced well known race car that can be “easily” built in the home garage and be legally driven on public roads. The 917 and P4 fall close but I suspect could never be registered for street use, and the Lolas are just not nearly as well known (although I have a strong suspicion that this is all about to change).

I don’t think that I would choose to scratch build a GT40 because there are enough kits out there already, but if had the time I would probably choose to build a replica of the Mazda 787B that won the 1991 LeMans 24Hr. That era holds a special fascination for me and the idea of a 10,000RPM screamer holds even more appeal. A very similar engine (four rotor rotary) is being built by an Aus company so this car is just begging to be built. Mind you it would have to be a space-frame rather than a composite mono as was the original and I would have to concede that it could never be registered. If I can draw a long bow here. Given Fords majority ownership of Mazda, may I suggest that it is the other Ford that won LeMans

Listen to it at full song... music
YouTube - Mazda 787B "The Legend" 4 rotor Le Mans car

[Fran Hall RCR]

You mean a little like this one.....shameless plug there.....sorry

[Mike Dozier]

P4/Lola replicas will never sell in quantity in the US because
they were seldom seen...and are not an American brand.
Yeah I know the Cobras are more A/C than American...
but we Cobra owners can overlook that little ditty.

What surprises me is how few Lolas GTD sold in the UK.
Given all the love Brits seem to have for the Lola,
why did GTD sell 400 + GT40s vs only 12 Lolas ?

MikeD

[Ron Earp]

Originally Posted by MikeDD

P4/Lola replicas will never sell in quantity in the US because
they were seldom seen...and are not an American brand.
Yeah I know the Cobras are more A/C than American...
but we Cobra owners can overlook that little ditty.

.....and the fact that the average "Ian Motorhead" in England knows about road racing, where as the average "Johnny Motorhead" in the US does not know about road racing. Lola doesn't do that roundy roundy stuff......

I still find it interesting that a lot of first time chassis builders will go for a project car and pick the GT40. While maybe not as complicated as modern mid-engine cars, it is definitely more complicated than many other cars.

Ron

[Rick Muck- Mark IV]

Originally Posted by Ron Earp

[COLOR=SeaGreen Lola doesn't do that roundy roundy stuff......
Ron[/color]

Smartarse answer.....
So all the times the won at Indy they were taking extra corners that the rest weren't?


Rick

[Doug Sainlar]

Originally Posted by Ron Earp

I still find it interesting that a lot of first time chassis builders will go for a project car and pick the GT40. While maybe not as complicated as modern mid-engine cars, it is definitely more complicated than many other cars.Ron

Exactly my position, Ron--although not specifically in relation to a self built chassis. I was well on the way to springing for a Cobra replica when I made the decision that I'd rather build a GT40. The big check is still at least a couple of years away, but I started lurking