WELL KNOWN CARS
The Story behind Impunity 1 & 2
by John Fack with help from Julian Fack who designed & built the 2 cars
HISTORICAL BACKGROUND
were the cars to beat in Sporting Trials. Sporting they may have been, but trials were very competitive at the time with fields of 40+ cars going out to play at 20 or more events around the country every year, so it was inevitable that one or two people would start to think they could come up with designs still complying with
the National Trial Formula that would spoil the Cannon’s party. Some innovations – Percy Barden’s radical IRS PAB, for example – failed to convince, whereas others like the lovely Nymph that Frank Pryor built for Don Rawlings with its “flat” steering wheel and pivoting front transverse leaf spring system worked pretty well and achieved good results, despite the cable-driven steering needing weekly adjustments, according to Robin Jager who owned the car later. The most significant innovations were to be found, however, in Frank Pryor’s Iris in 1967: here for the first time a fully articulating low roll stiffness front axle was incorporated, to- gether with upright motorcycle spring damper units mounted in the mid- dle, with a steering rack mounted on the cockpit floor. A fabricated tubular axle with Imp stubs – quite possibly another first – located by a Panhard rod and 2 radius rods, with steering activated by a centrally mounted bell- crank, completed the picture. John Benson used a very similar front axle system on the JABS that competes in the Post Historic class today, and the very successful Crossle 80T series from Northern Ireland featured a similar steering system many years later. The Iris was, in my view, a very signifi- cant development and should be considered the father of the modern trials car. It led to the end of the Cannon as the dominant force in Sporting Trials, the heavy front end, the poor lock and most significantly the front roll stiffness contributing to its demise.
For the 1967 season, Ivor Portlock switched back from an Alexis to a new Cannon. Ivor’s dapper demeanour concealed a steely desire to win, and win he certainly did on the 1960s. Not quite at the same win rate as Rex Chappell or Lol Hurt mind you, but very deft use of his right foot meant that he could out-trickle the best to rack up a load of victories. I sus- pect it did not take long to dawn on him that some of the newer machinery gave drivers an advantage that would elude him in the asthmatic old Cannon, so he tasked Bill Warr, a farmer and talented engineer who was building himself a modern Renault engine car, to convert the Cannon in to something more competitive. Bill removed the Y type front axle and fabricated a new tubular axle with Imp stubs, rack & pinion steering, rose jointed mounted A-frame and lower radius rods, 2 centrally mounted motorcycle spring damper units and motorcycle wheels and brakes – in other words, exactly the sort of front end set-up you will see on any post-historic today; it would remove around one hundredweight (50kgs) from the front end . He also removed the A8 drums and cables, grafted some B Series 9” brakes on the back and attached the master cylinders to the original Cannon fiddle system. But he went further and – I believe for the first time in a trials car– disconnected the Ford gearbox from the engine moved it back a foot or so and turned it on its side. This in turn meant a much shorter A-frame; at the time there was much debate about the benefits or not to traction afforded by short A-frames. Whether it actually made a difference or not is unproven, but Impunity 1&2 and all the Facksimiles followed suit. What we do know is that it moved the weight back in the chassis, albeit only a small amount, which can only be a good thing. Later Jack Pearce (Kincraft) and Ken Harrison (Ibex) would do the same thing but they took the concept a stage further by mounting the gearbox on the A-frame. Finally the venerable E93A motor was bored and stroked to a capacity of over 1350cc in a last ditch attempt to make it competitive with the A Series and Renault engines that were starting to appear at this stage; it had terrific pulling power low down but had no appetite for revs whatsoever.
This was the car that Julian Fack bought in January 1972, although he did not take delivery until September that year. Ivor, ever ambitious, moved on to a BMC powered Dryad (one of a group of 3 cars featuring all the recent mod cons, the other 2 being Bill Warr’s Bilbo and Bill Evans’ Beva) after its owner Bob Pardoe was killed in a car crash. Julian, who had spent the previous couple of seasons following Jerome & myself around as a mechanic to our moderately successful Cannon and our desperately unsuccessful PAB, finally had his first trials car. He cut his trials teeth on the much-mod- ified Cannon from September till the following April. During the Summer & Autumn of 1973 it magically morphed in to Impunity 1…and a new era in trials was set to begin.
