The 1972 Castrol 6 Hour Race
Recollections by Joe Eastmure
These are my recollections of the 1972 Castrol 6 Hour Race; but to do justice to the story I need to set the scene for the race first.
The late 1960's and 1970's were good times for motorcyclists keen on riding road bikes fast. The bikes of the era were comparatively simple compared with 1990's roadbikes but they went reasonably fast and handled well enough. My road bikes routinely cruised at 100 MPH without incident.
The best thing about the era for a motorcyclist was the relative freedom of the roads in terms of traffic volume, the absence of boring freeways, unrestricted speed limits outside built up areas and the fact that police radar hadn't been developed yet. Road racing to me was always an extension of my road riding and it's no coincidence that the hard core of touring riders in Willoughby Club, of which I was a member, were riders of the calibre of Paul Giles, Tony Hatton, Dave Burgess and Blair Harley, so it was natural that the 6 Hour concept was revived by Willoughby Club in 1970. In the inaugural race I not only partnered the winning 250 class Suzuki with Dave Burgess but as honorary Treasurer of the Club went home with about $20,000 in gate takings! Not to keep of course.
I had drifted into road racing using first my R60 and later my R75/5 BMW's as well as a 250 Suzuki specially bought for production racing. As a junior Customs officer production racing suited both my limited pocket and interest.
Leading up to the 1972 6 Hour I had the experience gained from some hundreds of thousands of road riding miles, a few years production racing and the lessons of the 2 preceding 6 Hours. Following the 1970 win Dave Burgess and I shared a 315 Suzuki for the 1971 race and this race was important for my subsequent 6 Hour rides.
In the 1971 race I was riding the bike at about the 3 hour mark and leading the 500 class, when the chain broke (luckily) at the pit entrance. Chains were a problem for the 315 as it ran a 525 size and we were unable to obtain a racing quality chain for the 1971 race. Compounding the problem was the fact that we used a 31 tooth countershaft sprocket which, while giving absolutely perfect gearing for Amaroo, meant that the standard chain had a very hard time. By the time the chain broke it was very loose and breakage came as no surprise.
For some reason fitting a new chain took forever and as the chance of winning the 500 class slipped away I grew steadily more upset so that by the time I got going again I was very angry. The spur of that anger seemed to tip me into a new approach to determination and calculated aggression which completely changed my approach to riding in the 6 Hour race. The 315 was blessed with virtually unlimited ground clearance and I simply threw the Suzuki past other bikes at every opportunity. In the following 2 odd hours I found that as my anger cooled off I could maintain the pace as a calculated tactic and while other riders seemed to be tiring or their bikes went off I could thread the Suzuki past most of them.
After reflecting on my experience in the latter part of the 71 race, for 1972 I elected to ride the whole six hours myself on a new (but now superseded) J model 315 Suzuki provided by NSW distributors Hazell & Moore. Dave Burgess had taken the 315 we raced in 1971 and converted it to a racing machine and had teamed up with Mike Steele on a 750 H2 Kawasaki for the 1972 race.
I was having trouble finding enough time to run in the Suzuki properly so I lent it to a mate who promptly ran it short of oil and lightly seized the pistons. Bob Burgess from Pittwater Motorcycles was preparing the bike and after boring the barrels had the bottom skirts of the new pistons chamfered by 1mm to bring the port timing up to full standard specification because of barrel liner/port misalignment. This turned out to be a disastrous move because it was the real reason why I was subsequently disqualified from the race results.
The 1972 race started with me in mid field as bikes were lined up according to capacity. The Suzuki was away quickly and I settled down with my only ambition to win the 500 class. Despite lapping in practice within 1 second of the unlimited bikes I had given no thought to an outright win.
After about half an hour the Suzuki began to settle into its racing stride characterised by a peculiar whining yowl which developed as the induction and exhaust harmonics stabilised at racing temperature. For a mere 315 cc the Suzuki really did go well at Amaroo Park when settled into racing pace because the gearing options allowed every bit of power to be used to the full. It was nowhere near as quick as the 750s or the full 500s in a straight line but as a total package of power, handling and braking it was perfect for Amaroo where the emphasis was on cornering.
Starting from the hairpin exiting in second gear I would go up to fourth for the right hander onto the straight, changing to fifth at the control tower and sixth at the kink going up the hill. At the left hander over the top of the hill the bike was absolutely screaming at around 8000 - 8500 RPM and if I had a clear run and set up the apex right I could just get through without having to feather the throttle. Coming out of the loop in 5th gear I would go to 6th and if everything was right I could get through the next fast right hand bend with only a faint easing of the throttle. Down a few gears at the tight left hander against the inside concrete wall and after a short sprint beside the lake, late braking for the hairpin again.
My technique for the race was simple - head down, throttle against the stop and never get slowed down by traffic. I think the secret of riding the Suzuki fast was to avoid delay as much as possible to maximise the bike's high cornering speed potential. No other bike in the race could stay with the Suzuki around corners and I simply rushed inside or outside other bikes to maintain corner speed on every possible occasion. Any check to follow another rider through a corner, especially a larger capacity bike with better acceleration, meant that the Suzuki's comparatively poor acceleration trapped me until they either went away up the straight or I got past at the next corner.
After the race settled into a pattern I tried to offset the Suzuki's straight line speed disadvantage by trying to slipstream the bigger bikes at every opportunity and slipping past at the next corner. If they went past again I would repeat the tactic until either I cleared away or they did. Then I would wait for another big bike and repeat the process.
Because I did not do a lot of road racing during the year it took an hour or so to really get into the groove and in that first hour I was racing for the 500 class lead with Les Kenny (H1 Kawasaki) and Peter Stronach (RD350 Yamaha). The outright lead was being fought over by H2 Kawasaki riders Geoff Lucas, Gregg Hansford and Mike Steele and Yamaha 750 riders like Ron Toombs and Brian Hindle.
The H2 Kawasaki's were handicapped by having to stop 5 times for fuel while all the serious 750 Yamahas had time bombs ticking away in their engines which would put all of the serious contenders out of the race.
After a couple of hours I was in the groove and started to lap consistently in the low 62 second mark which was right on the Unlimited bike's pace. My fastest lap when everything must have clicked was 61.4 which was within a fraction of the outright production lap record.
My favourite passing spots were:
I never made contact during the race but sometimes the speed difference at this point was so great I worried about the rider in front making a sudden change of line, unaware that I was fully committed to passing. I was left with fleeting impressions a number of times of riders wrestling with a bike trying to tie itself in knots because I had forced them to make a sudden direction change or braking manoeuvre.
Exiting the back loop became a personal test to progressively nail the throttle earlier and harder on leaving the second apex and still just stay on the road as the track curved right around to the fast loop at the back of the circuit. It took about 1 hour of racing to gradually increase my confidence to the point where I could exit the second apex at my own limit.
The fast curve around the back of the circuit was another good spot for me to pass because with a good run out of the loop and up the short back straight I could just about take this corner flat out. I found that riders of H2 Kawasaki's and similar bikes ridden by good riders could out accelerate me in the short connecting straight but because they would have to brake and I didn't, I could achieve a higher apex speed and pass them coming out of the corner on the run down to the tight left hander. The Suzuki had quite good drum brakes (provided green Ferodo racing linings were used) and I could outbrake the bigger bikes leading into the tight left hander before the run along the dam to the hairpin.
The mental and physical effort of keeping at this race pace was substantial and I had to do a lot of physical conditioning in the previous months including road running, weights and using a spring loaded hand squeezer at every opportunity. I spent many hours at work using the squeezer while working on Customs import entries.
The ability to never fall off the pace was essential for a good six hour place and showed up after about 2 hours when many riders began to tire. I had the capacity to keep my concentration pretty well focussed for the whole 6 hours whereas I noted that many riders would begin to visibly slow after an hour or so. Riders like Kenny Blake and Tony Hatton had the same approach as me but there were not too many others who could keep up full race pace from start to finish. Strangely, keeping focussed was difficult despite the high level of risk and I would have to constantly tell myself to keep alert and concentrate on the race. However, I often found my mind kept drifting away onto other matters and it would show on your lap times.
To keep alert I would note each lap time displayed by my crew and if it showed I had slowed and I could not blame slower riders or an error, I would screw up my concentration to attack each corner as best I could until the lap time came down to the low 62's.
At around 1.30pm I was presented with some very unexpected news when my pit signalled I was in the lead outright! Now I knew I was going pretty well from the race pattern because so few bikes were passing me, but to be in the lead was not in the race plan. I can remember doing a double take and wondering if my pit was playing a joke after reading this news, but as I had also been given my best lap speed of 61.4 around this time I realised I must be doing OK.
The news certainly gave me plenty to think about and I began to redo fuel consumption figures in my head as this would be very important from here on. The 315 had a big 3.7 gallon tank and could just last one and a half hours at full race speed, but with the reserve tap set on there was no second chance if we misjudged things. I had made the first stop at 11.30, the next stop at 1 pm and was scheduled to make my last stop at 2.30pm. Having to make only 3 pit stops obviously helped me keep up with the Kawasakis while the top 750 Yamahas were steadily destroying themselves.
With the race some 23 years in the past I find it hard to remember the ebb and flow of the whole race but the memory of the sheer effort of the thing is still clear. At 3pm I was looking forward to the race ending and at the 3.30pm mark when I was quite tired, I really needed the pit signals telling me I was in the lead again to spur me on as Mike Steele on the H2 Kawasaki closed in with about 10 minutes or so to go.
When Mike caught me I was determined to fight it out by slipstreaming as much as possible up the straights and retake him around the corners so that we changed positions a number of times. With about 5 minutes to go I finally pressured him into a mistake and he dropped the H2 around the loop. While Mike was on the deck I lapped him about 3 times and was happy to finish the race absolutely knackered but feeling pretty pleased with the effort.
Of course it was all for nothing in the end because of my disqualification.
Why was I disqualified? The missing horn became the accepted reason but it really was because the scrutineers considered the barrels and pistons had been doctored beyond acceptable limits.
However, remember that for 1972 Willoughby adopted more stringent standards than in previous years, perhaps spurred on by the outrageous oversized Ducati that was also disqualified, but I think marketing reasons had a big role in the decision. The previous year's Chief Scrutineer, Blair Harley, stated he would have passed the Suzuki and my belief is that a win by a discontinued 315 Suzuki did not fit the new marketing image for the 6 Hour race as a race for "superbikes".
I later learned that one of the placing bikes also did not have a horn and Dave Burgess,
who was my best mate, later confided to me that because of chronic pinging on the winning H2 Kawasaki, his crew took a punt the evening before the race and put in extra head gaskets to try and control it. The vigilant scrutineers somehow failed to notice this.
One of the scrutineers later earnestly told me he had conducted tests on a 315 and had found that the horn interfered with cooling air and caused a noticeable drop in power. What bunkum as proved in the following year's 6 Hour race.
In the 1973 6 Hour race I rode the same 315 Suzuki after taking over engine preparation myself to avoid any further trouble. After a precautionary crankshaft rebuild, new barrels and pistons AND a horn, I won the 500 class completing 234 laps - the same lap total that won the 1972 race!
The 1973 win came despite race regulation changes which required using the Suzuki's standard 3.00 size front tyre and the fitting of new footrests and rubbers for the start of the race. In the 1972 race I used a 3.50 front tyre for extra ground clearance and the footrests for the race were mere pegs after practice wear.
The 1973 changes meant I lost time in the first hour grinding the footrests away to achieve reasonable racing clearance plus I had an unscheduled pit stop in the first quarter hour to let off a rear brake which began to bind because the cable had not been properly secured. Despite these extra handicaps, especially the reduction of ground clearance caused by the smaller front tyre, I still did the same number of laps as in 1972 when the bike was supposed to be illegal.
It's all ancient history now but you can see that the episode still irritates me. Hazell & Moore gave me the bike and I continued to use it as my road bike until 1984 when I bought my Honda CX500EC.
I've always ridden a bike to work every day and the old 315 had notched up about 150,000 km by the time I retired it. The Suzuki sits in my garage today in very good condition just waiting for the dollars to restore it to concourse condition. I must dust it off one day and give it a fling on a club run.
Muzza - 2001