The Potts McIntyre story
The beginnings of a wonderful relationship: The early years of Bob Mcintyre with Joe Potts
As detailed in many sources elsewhere, Bob Mcintyre, from Glasgow, started a very successful racing career in 1951 on a friend’s 350cc BSA road bike. After riding it to his first meeting, he went on to win three races and crashed out in the fourth. Bob’s natural talent was easily apparent and therefore it was no surprise that he soon found himself sponsored by Cooper Brothers, of Troon. Success with the Cooper Brothers’ bikes followed, the highlights probably being Bob’s victory in the Junior and second place in the Senior Manx Grand Prix on the same AJS 7R. Joe Potts, from Bellshill, Glasgow, had a reputation as a successful racer and engineer. In the early 1930s he won many sand and grasstrack races on Sunbeam motorcycles. By 1934 his family encouraged him to stop racing and concentrate on his business commitments, which included car and motorcycle sales, a 24-hour garage, engineering work and even funeral directing! However, in 1949 Joe took up car racing in a F3 Cooper, which resulted in further victories and course records at the likes of Bo’ness and the Rest and Be Thankful. Joe’s car dealership, engineering business and personal interest in racing cars, led him to build numerous racing cars, including his own JPS and the highly successful H3 Hopper Special. Through this specialised engineering work Joe acquired the reputation of being Scotland’s ‘high priest of tune’. He was, however, a shy and slightly nervous person who avoided the limelight at every opportunity and it is due to this trait that he never received the recognition he deserved. Joe worked on the cylinder heads and porting for both the Ecurie Ecosse and Lemans winning Aston Martins, but was never happier than when in the workshop with his sleeves rolled up and wearing a brown smock. Always a motorcyclist at heart, in the early 1950s Joe developed a 500cc long-stroke Manx Norton on which he would
enter numerous riders. Joe made his own crankshaft assembly for the machine at Bellshill. The crank was machined from two pieces of NRM3 steel and heat treated to 60 tons tensile strength. The crankshaft had the main shafts formed integrally with their respective flywheels and crankpin formed on the left-hand flywheel. The two-piece crank was designed to be stiffer than the standard Norton item. Joe also made his own connecting rod for the bike. He had been making connecting rods for some time, due to the high compression ratios and hence the high loadings from engines used in JP and Cooper cars that would use methanol fuel. The connecting rods Joe made were machined from a solid billet of Clyde Alloy NRM3 steel. Joe’s connecting rods were shorter than standard items, in order to increase stiffness and for piston acceleration reasons. The big-end bearing for Joe’s engine was supplied by Alpha Bearings, of Dudley. The inner race was pressed onto the crankpin and the outer race pressed into the big-end eye of the connecting rod. Joe also designed the crank assembly to run in two timing side main bearings, instead of the original single journal (standard Manx Nortons went to a double row timing side bearing much later in 1956). These main bearings were housed in a flanged sleeve screwed into the crankcase, in order to prevent the outer races from turning. Joe also modified the cylinder head ports to his own specification and obtained unmachined piston forgings to the pattern he required. He machined the pistons in order to produce a squish combustion chamber. He also manufactured camshafts for the machine, which resulted in both higher rates of valve acceleration and peak lift. All this development work benefitted from Joe’s first-class facilities, which included a Heenan and Froude DXP3 dynamometer. Joe was not a one-man-band and he had a very skilled team of engineers working
with him. Key personnel included Adam Smith (foreman), Joe Woollams (engineer), Alex Crummie (fabricator), Hughie Blair (gas welder), Dick Jones (draughtsman) and David Cooper (apprentice). The engineering shop was second to none, equipped with the very best machines that were available at the time and employed upwards of 20 full-time staff members. It is no coincidence that when Dennis Poore’s ex-scuderia Ferrari Alfa 8C-35 broke a gearbox output shaft at the Bo’ness hill climb, Joe and his team were the only ones trusted and capable of effecting a repair. Riders who had had the chance to ride Joe’s Manx included George Brown (of Nero fame), Alex ‘Eck’ Phillips and Vic Willoughby. Joe’s long-stroke Norton was quick and it was enough to guide George Brown into an excellent seventh position in the 1952 Senior TT. Vic’s eloquent words written about the 1953 TT are perhaps the best illustration of the speed of the Potts Manx and the reputation Joe had built up: “But it was Brown (George) who first gave me a clue as to the sort of performance Potts squeezes out of his engines. George and I were comparing notes in the paddock one morning in June 1953 after practising our Senior mounts, which were both long-stroke Manx Nortons. On standard IOM gearing of 4.23:1 (23 tooth engine sprocket, 44 tooth rear-wheel sprocket), I was getting nearly 6200rpm in top gear (113mph) and was wondering whether I could pull a half-tooth higher successfully. George had no such worries. He assured me he was geared up no less than 1½ teeth above standard (25-tooth engine sprocket, 45-tooth rear-wheel sprocket) and was reaching 6500rpm on the level on his resultant top gear of 3.98:1 (125mph). Brown estimated his speed at the foot of Bray Hill at more than 130mph and told me that he had the legs of factory Nortons during practising. But for my high regard for Brown’s veracity I should have been sceptical of his claims.” Towards the end of the 1953 season both Joe’s tuning reputation and Bob’s riding reputation were extremely high. In the latter’s case he had agreed to become a works rider for the AJS team for 1954. Charlie Bruce, the multiple Scottish 250cc champion and great friend of Joe, had approached Bob to see if he wanted to have a one-off ride on Joe’s long-stroke Manx at the big Charterhall meeting towards the end of September. Bob agreed and travelled up from Scarborough, where on the previous day he had been riding Sam Cooper’s bikes. The competition at Charterhall was stiff with the cream of the Scottish stars, but also present was the experimental short-stroke works Manx Norton that had just won the Manx GP and was to be ridden by Dennis Parkinson. Bob did not need to worry. He won the 500cc event easily on the Potts Manx. This one-off ride left a long-lasting impression on the young Scot as to the speed of a Potts Manx.
Bob spent 1954 as a works AJS rider. It was not a successful or happy time, as he found AMC disorganised and the machines uncompetitive. The season left him pining for more competitive machines and a return to Glasgow. Bob’s memories of the speed of the Potts Manx during his one-off ride ensured that it was on Joe’s door that he came knocking. It was agreed that Bob would ride Joe’s Manx machines and also help run his motorcycle dealership. This was the start of a very special relationship. For the start of the 1955 season Joe and Bob had the 1954 short-stroke 350cc and 500cc machines that had been used the previous year. The 350cc Manx had been used at the 1954 Manx GP in unmodified trim and it had a top speed of 107mph, a figure that would be raised significantly from the development carried out at Bellshill. A simple modification on the Potts Manx machines was the adoption of SU float chambers in order to better control the fuel level. Bob Mac (the shortened name used during his Potts period) had a Bedford van for transport to race meetings and if he wanted to continue racing, he would have to win. Racing in Europe was out of the question due to the large travelling expenses incurred. It soon became apparent that Bob was achieving enough success in racing for Joe to close the motorcycle side of his dealership and concentrate on the more lucrative car side. This left Bob to concentrate on racing. Bob’s 1955 season started at Brough, and what a start it was. On the 500cc Potts machine Bob managed to win the Brough 25 ahead of John Surtees on a works Manx Norton. Success continued with good placings at Snetterton and victory at Oulton Park (beating works machines again). At Snetterton, the 350cc Potts machine retired with bevel gear problems. Joe, however, came up with a solution for this by modifying the timing side main bearing. The 350cc Potts Manx still was not ready for the Silverstone Saturday meeting. Instead, Bob decided to borrow Charlie Bruce’s Velocette MOV special for the 250cc race. Sadly, the MOV was not going at all well and he only managed to compete in the shorter 250cc race, finishing a lowly 16th. This was Bob’s first and only race on a Velocette. On the Senior Potts Manx things improved considerably, with Bob coming home a good third behind Geoff Duke and John Surtees (works Gilera and Norton respectively). Bob was back in winning action at the end of April meeting at Aintree, with victory on his Senior Potts machine in both the 1000cc and Handicap races. Back at last on the Junior Potts machine, Bob finished an excellent second behind Cecil Sandford on a Moto Guzzi. Further wins and good placings continued for Bob on the run up to the TT at venues such as the newly lengthened Oulton Park, Errol, Aberdare Park and Brands Hatch. The Potts team had been busy preparing for the TT. Bob’s Junior machine would be fitted with a home-built aluminium ‘dustbin’ fairing. The fairing was fabricated by Hughie Blair at Joe’s workshop in North Road. To support the fairing, a sub-frame was arc-welded out of small section rectangular steel tubing and this was attached to the machine by quick-release aircraft fasteners. To try to tackle the problem of the front brake overheating, the bike was fitted with a flexible rubber hose that took ‘fresh’ air from an external scoop to the brake plate. In order to try and prevent the footrests from grounding, Mcintyre raised the front forks by half an inch by putting a packer above each fork spring and raised the rear by one inch by making a new sub-frame and replacing the shock absorbers. This resulted in an increase in overall rear wheel movement of 3½in. Bob’s plan for the 350cc bike was that with the new fairing fitted, it would pull 125mph at 7800rpm down the Sulby straight. The senior mount was not fitted with the full ‘dustbin’ fairing, as this caused handling problems at higher speeds. The 500cc was a very new bike and classed as a spare and as such the Potts team had little chance to develop it. The reason why the Potts team could not get the quick 500cc engine ready in time was because the cylinder head casting was found to be porous. For this reason the most hope was with the Junior mount. Bob was also using the latest experimental Dunlop non-directional rear tyres on his machines. Bob was taking the TT seriously and in the first practice session for the Senior, he was second fastest behind Geoff Duke on his Gilera, but ahead of the works Guzzi and Norton riders. Bob had been the fastest privateer for both the 500cc and 350cc classes in practice. The Junior event at the TT was to be the first race to really cement Bob and Joe’s reputation as being the top privateer rider and tuner team in the world. Bob’s main opposition in the Junior race came from the dominant works Guzzis (Bill Lomas, Ken Kavanagh, Duilio Agostini and Cecil Sandford (Taylor tuned Guzzi)) and also from the works Nortons and AJSS. As the Junior race started no one was expecting Bob to challenge the works teams, but at the end of the first lap he was leading with the same lap time as John Surtees on the works Norton. Even better was to come at the end of the second lap, as Bob had pulled into an outright lead on the Potts Manx. He continued to lead the race until the fifth lap. One commentator described his riding by saying: “Through Union Mills and Glen Helen his torso was welded to the tank top. Up Snaefell climb he was brilliance personified”. After the fifth lap Bob had to stop to refuel, which cost him the lead, as Bill Lomas went through into first on his non-stop run. At the end of the seventh lap Bob finished an amazing second behind Bill Lomas, but ahead of Cecil Sandford and John Surtees. The top speed of Bob’s 350 Potts Manx down the Sulby straight had been 123mph at 7600rpm, which was very close to the team’s expected value and remarkable considering that when Potts first got the bike, its top speed was 107mph at The Island. It was noted in The Motor Cycle that even without streamlining it was estimated that the Potts 350cc was as fast as the works Nortons and Joe was described as being “without doubt one of the foremost tuners of the day”. with streamlining, the Potts 350cc Manx was found to be 7mph faster than John Surtees’ works bike. Bob’s second place finish is even more incredible, considering that from half race difference the Potts Manx was overheating badly. The first problem was that as the engine got hot, this lead to a distorted exhaust valve seat that, in turn, lead to a loss of compression. The front fork damping was
also fading badly, as was the front brake. Charlie Bruce said that at the end of the race Bob’s bike had no front brake left! Joe and Bob also won The Motor Cycle Cup, which was awarded to the entrant whose rider improved by the greatest margin upon the average race time for the ffirst 20 riders, in either the 250cc, Junior or Senior classes. At the prizegiving Bob thanked Joe for the machine and “the bits of tin to go round it”. The Motor Cycle commented about the result: “Many years have passed since a lone private-owner seriously challenged three powerful factory teams and emerged from the battle with so much glory.” In the Senior TT on the less modified 500cc Potts Manx Bob came home in fifth position at an average speed of 93.83mph. He was once again the first non-works rider to finish the race. Bob was also part of the BMCRC with Geoff Duke, Cecil Sandford and John Surtees’ team, who won the club team award at the TT
for the Senior and Junior races. Since Bob and Joe had won The Motor Cycle Cup with their Junior performance, Joe would get a free entry for the Manx GP. Joe also got another free entry due to Bob’s Senior performance. These entries would be used in 1956 with great success. The TT had shown the problem of distorted valve seats on the 350cc Potts Manx. Joe, being the sort of person who liked to find a good solution, started testing new valve seat material. Eventually he settled on Hidural 5, which cured the problem. Following the TT, the Potts team were back to short circuit racing. Impressive wins in both the Junior and Senior classes were recorded at Aberdare Park and Errol in June. At the start of July, the Kirkcaldy and District Motorcycle Club ran the Scottish speed championships at Beveridge Park. Bob and the Potts machines won both Junior and Senior races and set new lap records during the process. Such was his dominance that in The Motor Cycle the following was said about Bob’s riding: “Perhaps the most outstanding feature of the Scottish Road Races was the effortless manner in which R Mcintyre (Nortons) demonstrated his complete mastery of the art of short-circuit racing.” At the end of July Bob and the Potts team took an excellent triple victory at Oulton Park (350cc, 500cc and Les Graham Trophy Handicap). The Thruxton International and British Championship meeting followed immediately, where the opposition would include full works backing by the Moto Guzzi, AJS and Norton teams. Bob finished fourth in the Junior and fifth in the Senior final, with Bill Lomas, Dickie Dale (Works Guzzis) and John Surtees (works Norton) in the top three of these races. Motor Cycling magazine commented on Bob by saying: “How that Scottish lad shakes the factory boys!” In mid-august came the Ulster GP, where both Bob’s Junior and Senior machines would be fitted with ‘dustbin fairings’. The Potts team would once again be taking on all the works teams. Bob was the first privateer home in both the Junior and Senior classes by taking fifth and fourth in each class respectively. Back in Scotland, Bob raced at Errol, where he comfortably won the unlimited event from Jimmy Davie and Sandy Bowie, but in a thrilling 350cc race he could only finish second behind Alastair King, who won on an AJS 7R at 69.20mph. Bob was in Alastair’s slipstream for the entire 10-lap race and only managed to take the lead for a short time on the ninth lap. It was Bob’s first defeat in Scotland since 1952, but it was a deserved win by Alastair, who was riding fantastically. For the 1955 Manx GP, the Potts machines would be entrusted to Jimmy Buchan, of Perth. This was to be Jimmy’s first ride in the Manx, however he had experience of the TT from the Junior Clubman’s TT in 1954 and 1955. The machines he was to be riding were the ones that Bob had been using throughout the season. On the first day’s practice (Monday, August 29) Jimmy was immediately topping the timesheets in the Senior class at 86.65mph. In Thursday practice Jimmy had a bit of bother. He intended to do two laps on each of his bikes, but this did not happen. Jimmy went out on the Senior machine first, but the gearbox top fixing nut came loose at Ramsey on his second lap. Jimmy had to tour into the pits and could not make it back in time to take the Junior bike out. In Friday morning practice all went well and Jimmy lapped the fastest on his Senior bike in the wet conditions. On Saturday, he went round third-quickest on the 350 Potts Manx and then in final practice on Monday, under wet conditions, he was third and sixth in the Junior and Senior classes respectively. In the actual races Jimmy finished fourth in the Junior and second in the Senior. Following the Manx GP, the Potts machines were back with Bob. At Snetterton in September the main opposition came from John Surtees. The honours were shared, with Bob winning the 350cc class, but finishing in second place behind Surtees in the 500cc. A third place finish in the 350cc class at the Scarborough International behind the works Nortons of Surtees and Hartle followed. Towards the end of September Bob saw some disappointing results at Aintree; sixth in the 350cc, fifth in the 500cc and fifth in the solo handicap. The following day at Brough, he finished second to Surtees in the 350cc class, but had to retire from the 500cc event. At the International Hutchinson 100 meeting at Silverstone, Bob was back on form against an impressive field of works bikes including Geoff Duke (Gilera) and the factory Nortons of John Hartle, Jack Brett and John Surtees. Bob finished second in both his 350cc and 500cc heats to John Surtees. In the 350cc final, he was involved in a giant battle for second place with Hartle, Brett, Cecil Candford (Moto Guzzi), J Clark and Bob Brown (AJS). Bob’s doggedness prevailed and he was able to pull away from the bunch to finish second behind Surtees. In the 500cc final, Bob finished fourth behind Surtees, Duke and Hartle. The following day at Brands Hatch he finished second on the Potts 350 Manx behind Surtees. Bob did not have his 500 Potts Manx for the 1000cc invitation race, so he rode a BSA to a very good third behind Surtees and Alan Trow (both on Nortons). As the 1955 racing season ended it was apparent that it had been a wonderful success for both Bob and Joe. The success was probably most highlighted by Bob’s meteoric ride in the Junior TT. It was therefore no surprise when the factory racing teams came knocking on Bob’s door. Approaches were made by both Moto Guzzi and Gilera. The continental circus, stardom and world championships beckoned for him – or so it seemed...