Re: A better mousetrap!
I'm just posting this article that I wrote for my local car club mag on why I am building a GT40. This is in response to Rons thread "Making your own chassis - Unique to GT40's" Although there is some duplication of what is already in my build thread it does go into the reasons behind the decision to build.
A better mousetrap
The reasons I decided to build a GT40
The story, for me, starts with my TR7V8 which I originally built to be a road car with the idea of doing some competition, in the form of classic racing and Targa, hillclimbs, sprints, etc.
However, any one who has ever done that will know as soon as you put a full cage in a road car, that’s the beginning of the end for streetability. It’s the point of no return!
So over the ensuing couple of years it became virtually a road registered competition car. And it was relatively successful, usually being in the top handful of local cars at classic race meetings. However after a bit of development it rapidly became apparent that the car could not be made a lot faster and yet stay within the classic regs. Realistically, if one wanted to have a chance to consistently beat the local Porsches then it was going to take a Porsche to do that job. Megabucks in comparison to the TR7V8 that was snapping at their heels.
So I need a P car but can’t afford one!
At the end of the 2005 season the TR’s Rover V8 engine was stripped for a precautionary off season check. It had been performing magically and everything seemed OK until the cracktest results came back for the reciprocating assembly. Every rod was cracked, every journal in the crank had two cracks in it except front and rear mains which had only one. Pistons were fine. The whole lot had been cracktested before assembly at the start of the season. Disaster! I reckon the whole motor was only about half a lap away from hand grenading! So, contact Ross Calgher to see about getting something that will hold together. Can do, so I order crank and rods which eventually arrive on special order from Pom Land. No reflection on Ross who actually gave me a good deal, but astronomical price for not even forged stuff, and I’m thinking for less than this sort of money I could get all forged Chev or Ford internals that would deliver twice the power from a Yank motor.
For classic racing I needed a better mousetrap than the TR7!
What about a Cobra replica with some good, cheap, Detroit muscle in it to beat those pesky Porsches? Certainly it would be faster and cheaper than a porker. Once you start looking in that direction it is not a quantum leap from a Cobra to a GT40. Still cheaper than a fast P car. IF you build it yourself. And should also be able to deal to the overseas entries that come over for SFOS and annually dust off us locals.
So a decision was made to scratchbuild a GT40 replica. But what to do about a body? Checked on the internet and found an excellent GT40 site, and started digging around for info. The site is predominantly UK, US and Oz dominated but there is also quite a contingent of NZers there. (Jac Mac a member of this club from Gore is a knowledgeable and prolific poster on that forum) Anyway, contact was made with a fellow NZer who had an uncompleted kit and he generously offered to allow us to take molds from his body. Problem solved! What we didn’t know was the amount of corrective work we would have to do to his car and body before taking off those molds! Maybe he did!!! Still a good deal though.
About this time, enter one Tan Boon Lim a Singaporean Chinese who has been living in NZ for about 20 years. A friend of an employee of mine, Lim has always wanted to build a GT40. Lim is a tool and die-maker of exceptional talent and has access to all the right gear. This could be a marriage made in heaven! I could supply a body, he could do all the tricky machining. It didn’t take long to agree to a mutually beneficial deal J
So we are building two cars. They will be similar but different.
Similar in so far as they will both be Mk1 replica’s, spaceframe construction with fabricated uprights and suspension arms and traditional GT40 type 15” replica BRM pin drive wheels. Power units will be Ford 351W engines with ‘crossover’ exhausts coupled to Porsche 911 Turbo LSD transaxles. (Because anything else that will take the torque is too expensive!) Both cars to be stopped front and rear by 300x32 vented rotors and Wilwood 4 pot calipers And that’s about where the similarity ends!
Lim’s car is being built for predominantly road use with occasional track time. A reasonably powerful, streetable, injected 351W mated to a G50/52 five speed transaxle with 8” front 10” rear width rims and Dunlop GT Qualifier tyres, nolathane suspension bushes, the whole lot all held together by a relatively rugged 35x35x2 tube spaceframe chassis and covered by the Mk1 ‘standard body’.
By contrast my car will see mainly track use though it will be road registered (just in case I want to do any tarmac rallies!). Motor may be a bit more ‘peaky’, dry sumped, forged internals, roller cam and rockers, 825 cfm carb driving through a four speed 930 transaxle which will have a billet side plate and an oil coiler and spraybar added. This is the strongest production 911 trans it’s also cheaper and marginally more readily available than the turbo five speed and has a better range of custom ratios available if I want to go down that track later. There is also a custom dogbox option with the alternative ratios that is not a lot dearer. Wheel widths are 10’’ front, 14” rear running 430/1160x15 and 530/1500x15 Dunlop Post Historic period treaded race tyres. Suspension is fully rose jointed. Shocks will be 8212 series aluminium double adjustable Konis The spaceframe will be different to and somewhat lighter than Lim’s but will incorporate a MSNZ full rollcage. Body will be the Mk1b which has the traditional ‘Gulf flares’ to shroud the wider wheels. Also, borrowed from the Mk2 ‘40’s and fitted also to some Mk1’s, will be twin brake scoops (snorkels) on the rear deck. Horny looking!! And practical.
With all that decided all that remained was to do it. More later.
So that's it. Must get back to work on the car! I need to update this thread soon too, but there's heaps of half finished stuff that depends on something else before it can be finally completed. There's not much excitement in photo's of brackets etc.
Cheers,