Set-ups

Historical information

Details on how the cars were set up in 1967 is a little sparse.  Some details are given below.  Although the Motorsport articles on the 1967 GPs frequently mention changes to set-up made during practice, other sources suggest setting up was quite rudimentary.  Ron Tauranac (Brabham team designer) reports that other than for the Nurburgring, spring rates and ride heights were not changed between tracks.  Another source reports that Clark only changed the front camber on his Lotus 49 once, and changed it back again.

A contemporary description of the BRM P261 (the predecessor of the P83) states that "A large collection of alternative springs travels with the car, the dampers are adjustable, there are seven different front anti-roll bars, two rear anti-roll bars each having each having seven different positions ... .  There are even four different rack and pinions giving steering reduction ratios between 10:1 (Monaco) and 15:1 for the fastest circuits.

Links

Perhaps the best site for both set-ups and advice on set-ups is Alison Hine's site Eagle Woman's Grand Prix Legends .   Alison's site includes a downloadable set-up program called GPL Race Engineer.  It is a big download (over 4MB) but it is a very useful piece of software.  It does allow you to exceed the limits of the standard GPL set-up screen for both bump stop height and wheel rate.

Another excellent site is Ricardo Nunnini's GPL Foolishness, which includes a great deal of technical information (which as an engineer I love).   His site has influenced others, including Alison Hine.  The information on how GPL "works" is invaluable - his latest insight is on dampers and is definitely worth reading.  His latest set-ups are designed to exploit weaknesses in the GPL physics system, and software which allows you to go outside the boundaries of the standard GPL set-up ranges, using very stiff springs and minimum ride height.  This goes against my rather "purist" approach, but you may feel differently!

Wheel rates

According to books on racing car suspension, wheel rates should be proportional to the car's sprung weight (total weight of the car minus weight of wheels, brakes etc. not supported by the springs).  Allison's and Ricardo's approach to set ups is to set the spring rate in proportion to total weight distribution.  I have not been able to find out the un-sprung weight of cars of the era, but it is likely that un-sprung weight distribution would not be far off the overall weight distribution (typically 40% front 60% rear), as the rear wheels and tyres were bigger and the suspension and drive-shafts heavier too.  Therefore their approach is a reasonable approximation.  I notice that after pioneering the "wheel rate proportional to weight distribution" idea, Ricardo is now advocating slightly softer rear springs than weight distribution would suggest, to improve stability and traction.

The following wheel rates are suggested as starting points - they are all proportional to each car's overall weight and weight distribution, though they err slightly towards a softer rear wheel rate.  The Brabham is reported as having a front wheel rate of 65-75 lb/in and "a little stiffer at the rear". 

Static ride heights

An area of great debate.   From the available evidence it is unlikely that the cars ran lower than 3".   John Cooper is reported as saying 3-4",  Ron Tauranac (Brabham team) is reported as saying 4.5" and 5.5" for Nurburgring.  The 1967 cars in the Donington Motor Museum (Brabham, BRM, Lotus and Eagle) have been measured as 4-5".   Photos indicate the same (though the cars pitch quite a lot so you have to be careful if the car was photographed on the move).  I would recommend 4.00" rear and 3.75" front as a starting point.

Gearing

To help with gearing for each track, here is the maximum speeds reached by the computer cars (AI) at each track.  I hope to translate this to a gear-ratio for each car in the future.