GT40 Car

GT40 Replica Construction Article
Design and Construction.
by: R.C. Sundt

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The cars that you grow up with are the ones that stay in your imagination throughout your life. Such is my feeling for GT40's. Not only do I have fond memories of their heady days of success in the sixties, but they still can hold their heads high when compared to the styling and performance of modern "supercars". In fact a GT40 will cause a major stir when a Ferrari is hardly given a second glance.

For years I have wanted to build a GT40 but little things like family, career and money kept getting in the way. Finally, at the beginning of 1992, I acquired a 1970 351 Cleveland 4V "Off the floor" and spent a happy year slowly rebuilding it as time allowed.

When I had finished, about the only original parts were the block, crank and inlet manifold. It has been bored out, balanced fitted with roller rockers and a new cam that was considered a hot street cam here in England, but rather tame by my American friends. As this project came to an end towards the end of 1992, 1 started looking around for something to put it in.

As finance is still a major consideration, - I eventually acquired a second hand KVA body-chassis unit complete with all suspension items and a lot of other extras. Despite the danger of taking over someone's else's problems, I was persuaded to go ahead because not a lot had been done to the chassis other than to bolt the suspension on and install a dummy 351 Cleveland block.

The car arrived just after Christmas and I started work. I rapidly found out tha everything was not as it seemed.

I have mucked around with cars all my life, but I have always started off with a complete car (which you take to pieces and restore) or with a substantially complete kit like a Marcos or a Lotus. When you do this, you know that everything is where it should be and there is a "right" place for it to go. Not so with a GT40. Every one is different.

I keep a book of reference photos of different cars and the different ways they find of doing everything. Very useful when trying to work out a clever way to get part A to mate with part B while still leaving room for C, D and E.

The first thing that I found was a number of brackets had been brazed onto the chassis. I actually pulled the front anti-roll bar mounts off with my hand, so all the brazing had to be removed and every weld checked. The next problem was that the suspension geometry seemed, to say the least, unusual, with massive amounts of bump steering by the rear wheels particularly under any conditions of roll.

Also, although the basic chassis structure was square and symmetrical, the upper part of the chassis seemed to have been welded by eye. There was a 10mm difference in height of the suspension mounts on each side of the car and a 10mm difference in the front door pillar heights The only answer was to strip the chassis right back to the bare bones and start again.

A solution was made doubly necessary because of the size of the 351 Cleveland engine. It is a bit longer and deeper than a standard 302 and required suspension mounts to be moved to allow it to squeeze in. Again I ran into the problem of where was the right place to put things like the suspension mounts.

I live in Surrey, but I work in Bristol for most of the week, so I am building the car down there as I have plenty of time in the evenings with nothing else to do. Richard Lewellyn owns the garage in Bristol where I am working on the car - he builds and races hot rods in his spare time and he came to my rescue.

With his knowledge and some basic trigonometry, I wrote a small computer program (in Excel) that shows on a graph the roll centres for different suspension set-ups as the car bounces and rolls on the suspension. With the aid of this program I was able to reposition the suspension mounts while marginally improving the handling of the car --- in theory. Now it looks right and it feels right But the proof of the pudding --- Ah well! I guess I'll just have to wait and see how it works in practice.

Calculating where the roll centres are is not difficult. What is much more difficult is finding out how much movement is acceptable or disirable in Practice. Any suggestions?

GT40 Car One other little problem is getting the flywheel and clutch (from a Ford transit) to talk to the gearbox which is a Renault 21 T in a Renault 30 casing with a Renault 5th gear.

I solved this by mounting a Ford Transit clutch thrust bearing inside a Renault 30 thrust bearing carrier. I was surprised to find that it fits with the minimum of modification. The only question I haven't decided is what driven plate to use. The obvious choice would seem to be a Renault 21 T (it fits) but does anyone have any suggestions?

Now the chassis is almost complete with almost all of the brackets welded on and most of the major components in place on a trial basis. I was delighted to find that not everything has to be expensive. The pedal box is from a Skoda and cost just 10! It has now been modified for dual brake cylinders with a balance bar and remote reservoirs.

Within the next month the chassis will be stripped back again and sand blasted and sprayed. Then I can start to put the car together for real.

In last month's Fortification, some pretty unkind things were said about Ken Attwell and KVA. Initially I was not sure that I agreed because I phoned Ken Attwell in January and spoke to him and he was very helpful. However, since then, he has gone underground and has not responded to phone or fax despite his promises to help.

One person:who has been a great help, however, is Andy Sheldon of Tornado. I have bought quite a few bits from him and he has always taken the time to explain how things work and to be helpful . He even took the time to go through his parts list and mark the items that would fit the KVA chassis. . Now that's service! Thank you Andy.

When the GT40 arrived, I joined the Replica Owners Club and I attended my first meeting at Tim Martin's house on March 27th. It was an excellent evening and enjoyed myself immensely. My thanks to Tim and his family for their hospitality and to Tim for allowing me to crawl all over his beautiful Forty with a tape measure.

As Tim said in the last newsletter, I have a lovely village green outside my house in Surrey, which would be a beautiful site for a Forty get together one summer afternoon. It would be nice to have my own Forty there but perhaps we should do it sooner than later, it could be some time...

Last year I read an article about people who build champion home-built aircraft. They said that friends of the builder of the grand champion home-build at Oshkosh in America last year had built two perfectly good airplanes from the bits that he had thrown away as not good enough.

I am beginning to understand what they meant. It usually takes three attempts at anything before I get it right. - The process of learning and building is - hard work but rewarding and fun. The prospect of driving my own Forty is a pleasure awaited with some impatience, But already I am starting to think I could do it better next time ---- I think I'm hooked!


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