They look like big money but a top-notch Mustang costs around the same as a Group 4 Escort rally car, thanks to being an arguably simpler device. But more than 400bhp powering a 1200kg coupe guarantees thrills aplenty, and all the parts to build a front-runner are available from suppliers in the US and, increasingly, in the UK.
Though some race series allow more leeway on wheel, tire and brake choice, as well as engine mods, we’ve focused on pre-66 Appendix K cars, for which there is a wealth of events from Masters Top Hat to the Spa Six Hours. And talking of wealth, the men who build them say Appendix K cars hold the best value, with decent used racers changing hands from $80,000 up.
Notchbacks are in vogue, and they’re cheaper than fastbacks. A donor car will be around £8000, and an ‘06’ date code on the left front inner wing top doesn’t seem to matter, as 1966 model-year cars were made from August 1965. Fitting a cage will cost from £1000; nearer £2k if you opt for T45 tubing in an effort to get the car down to its 1180kg homologated weight. ‘Appendix K spec is the only way to keep the residual value of the cars,’ says Westley Harding, whose Falcon Hell Racing builds Nick Whale’s cars. ‘I’ve just built one with the best of everything. It’s yours for £85,000.’
It has to be a period 289, and roller rockers aren’t allowed for Appendix K, though the standard rockers break at 7000rpm so you need to invest $3000 in a hardened set. The standard Hi-Po cast exhaust manifolds must be retained but the exhaust is free from there back. Top-running cars enjoy over 400bhp, but it costs – Steve Smith says the best motors run out at $25,000, while Westley Harding says it’s possible to spend twice that.
The good news is that these V8s only need rebuilding after 30 hours – that’s two seasons. ‘It’ll cost about $10000-14000,’ says Harding.
The choice is four-speed Borg-Warner T10 or Ford top-loader, with the Ford ’box being universally favoured and costing about £2500 reconditioned from the likes of David Kee in the US. McLeod is the name that constantly recurs when talking clutches. The Mustang was listed with a limited-slip diff as an option, and for racing it’s an absolute necessity. Most folk use a Gripper diff, which is both progressive and compact, though Trutrack is an alternative. Decent halfshafts are $750 each.
Suspension and steering
The ‘Shelby drop’ is a given at the front – this means drilling new mounting holes for the top wishbones about an inch lower, which has the effect of slightly shortening the link to induce some negative camber. More camber is available by machining the mounting blocks thinner: ‘You’re aiming for 2½-3°, and if you have more you can work back from there,’ says Harding.
Koni or Öhlins shocks are the popular choice, with Öhlins about $750 a corner. The front anti-roll bar isn’t supposed to be adjustable and Mustangs didn’t have a rear bar so you can’t race with one. Big-spindle uprights are available but they weren’t homologated until ’66.
Steering ratio is supposed to be standard, though Harding says that a faster steering box is acceptable, costing around £$1,000. Wheels are supposed to be 5½x15in, though in practice everyone uses 6in as they are more easily available ‘and some people run 7s’.
Must be the original-type Kelsey-Hayes four-pot calipers up front, and homologated disc size is 11in. ‘Some people use the bigger calipers and 12in discs,’ says Steve Smith, ‘and I wish somebody would stop them.’ Rear brakes must be the standard-size drums, and the best friction material for both ends is a carbon-Kevlar blend from the US, though Smith mentions that some trim the pistons back to fit pads intended for 911s.
Another flavour, sir?
Much of the technology here translates to the Falcon (which sired the Mustang) and its badge-engineered sibling, the Mercury Comet – though they are harder to get down to a competitive weight. So however you like your V8 racers, enjoy.