With Tales of Triumph Motorcycles & The Meriden Factory (Veloce Publishing, 1996), author Hughie Hancox offers an engrossing memoir of his time working at the Triumph Motorcycles factory. Through his vivid writing, Hancox shares with readers his passion for classic English motorcycles, and his labors in motorcycle restoration. In this excerpt from "(Bad) vibrations", Hancox remembers Triumph’s trials with high frequency vibration in the engines of later Triumph Motorcycles, as well as his encounters with Hollywood stars Steve McQueen and Clint Eastwood.
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Bad Vibrations and the Trials of Motorcycle Repair and Restoration
By this time we were experiencing vibration problems, resulting in the 650 machines cracking brackets, mudguards and petrol tanks. This was vicious, high frequency stuff that we couldn’t seem to cure by altering the balance factors. It wasn’t unusual to have a new bike of only three months usage come into the repair shop, accompanied by its owner to talk to and show the management the problems. One such chap emptied his riding suit pockets of literally dozens of light bulbs he had fitted as the filaments inside kept being vibrated off. One of the bikes I worked on had a split along the length of the rear mudguard, straight down the centre. When I removed the rear number plate and the mudguard mounting bolts, it came off in two halves!
Our only option was to put our trust in the experimental boys and hope that they could tone down this high frequency stuff to a more acceptable level. After all, road speeds were increasing all the while and the Triumph twin engine, as old as it was, had to live in this environment. Most of all the 650cc problems coming in now were to do with vibration and, at one point, we even ran out of the F7004 petrol tank which was the four-gallon, homemarket item fitted to the TR6 and T120. This tank had the single mounting ear at the back and, as a regular as clockwork, off it would come. The stupid thing about it was that you knew the part you were fitting as a replacement under warranty was going to go in just the same way within a few weeks. All we could do was take out the engines, strip the cranks, rebuild them and be ultra-ultra careful in the balancing to get them smack on at an 87 per cent balance factor. The crank had to remain stationary on the knife-edges in any one of the eight positions required. This would at least rule out the crank in any further work should it be necessary. We also ensured that all the nuts, bolts and studs that held the motor and engine steadies could be pushed in by hand, and none of the holes were out of alignment. It’s so often the case when you are trying to put an engine back into the frame that you find the last couple of studs half a hole out, and then the temptation to bang them in with a big hammer becomes too great. You do it, and end up with only threads on one half of the stud or bolt; you can’t start the nut and you’ve forced the thing into the hole, causing stress.
We were always told to take our time and make sure to push all the studs or bolts through with our fingers (you may even have to jiggle the motor about in the frame a bit). If you can’t push a bolt through, open the offending hole out a little with a round file until you can; then and only then, start to tighten everything. I’ve seen so many chaps fit unit motors, put the back engine plates on, but before putting the nuts and bolts through they’ve tightened the front and bottom through studs, which makes life very difficult. We also tried rubber-mounting exhaust systems, but that wasn’t at all popular, because you had to leave the joint at the cylinder head loose, otherwise it would crack the cups off the pipe. Not very good, so we reverted to the normal fitting.
One of the biggest contributing factors to bad vibration was incorrect ignition timing. The Lucas 4CA contact breaker assembly was a fiddly thing to set up properly with a stroboscope, mainly because you could only time one cylinder by moving the back plate on its elongated adjuster holes. Once that cylinder was set correctly and you put the strobe on to the other side and found that that was a few degrees out, you couldn’t alter the second one to correct it otherwise you would end up upsetting the first one. The only way to set the second cylinder, after the first one had been set at the correct degrees of advance at between 1800 and 2000rpm, was to adjust the actual gap on the contact points. It usually equated to 0.001 inch equalling two degrees, so by opening the points gap by an extra 0.002 inch you increased the degrees of advance by four. Conversely, by closing down the point gap you retarded the degrees of advance. Although this method was effective, you had to be pretty exact in your work and, obviously, to be spot on you had to have the kit to do it, and not every bloke who bought a 650 twin had this sort of equipment hanging up in his garage.
After a while, the Joseph Lucas engineers came up with the reliable 6CAcontact breaker assembly, with independently adjustable points. This allowed you to adjust one cylinder dead on, then start on the other set of points without messing up the first side. When you consider we were working to within a single degree, it was pretty exacting stuff. After the motor had been assembled with a nicely balanced flywheel at the new balance factor, the ignition timing set correctly and both carburettors set and balanced, things weren’t too bad!
Later, in 1970 when I was on the service staff, I did actually have a meeting with the UK sales director with a view to replacing under warranty a complete bike for one chap who had been back to the factory so many times with his new 1970 T120 and lost countless days off work keeping his day appointments. We just couldn’t seem to get this thing right; it really buzzed with a bad HF (high frequency) vibration. Alex Scobie, who was the assistant service manager, took it out on test to confirm the service department tester’s findings and, upon his return, told me to go ahead with my request. I did get a new replacement bike for the Oxfordshire gentleman which, in the end, he was very pleased with, together with Triumph service.
Hollywood and Classic English Motorcycles
During 1966/7 the vibration problems continued unabated. We coped as best we could but, once again, it was pretty demoralizing to think that the majority of bikes coming off the track and going to home market dealers were, sooner or later, going to find their way back to Meriden for free-of-charge work under warranty for that damned vibration problem.
One chap who didn’t seem bothered by it was Steve McQueen, the motorcycling film star. He was actually a very good rider, so much so he became a member of the American Vase B team for the International Six Day Trials held in some Eastern European country (where, I can’t remember now). Quite a charismatic character, you could feel McQueen’s magnetism when he was near you. He was intense in most of the things he did and didn’t mind taking chances on the Triumphs he rode; witness this in films like On Any Sunday and The Great Escape. I had the pleasure of working on his 650 TR6 and, whilst it was up on the workbench I discovered, jammed underneath the petrol tank, a pair of his short-wristed chamois leather riding gloves. I offered them back to him and, guess what he said? “You keep ‘em!” I didn’t want to appear grabby so, as graciously as I could I said “Well I shouldn’t, but thanks very much!”
He had done very well in the ISDT but come such an almighty cropper at one stage he’d actually flattened one exhaust pipe to the extent that the engine wouldn’t run properly. Using his noddle, he spied an old forester chap chopping up wood with a long-handled axe, which McQueen used to chop shark gill slots into the offending pipe as gas outlets. Although noisy, the bike at least ran!
When he came to the factory, I was surprised at how small he was (this didn’t seem to bother the office girls, though!) The day after he had gone someone mentioned the gloves I had and I began receiving propositions: you wouldn’t believe the things I was offered for those gloves. I made up my mind not to part with them, however, and used them myself on fine days only, to preserve them as for long as I could. For a long while they were kept with my old riding coat hanging in the garage until my good lady wife decided to have a clear-out. She insists she asked me whether she could get rid of “that old coat hanging on the nail in the garage”; I guess she mentioned it at a time when I wasn’t paying attention. Months later, I had been in the garage for sometime before it dawned on me that the coat was gone and so too, unfortunately, had the gloves. It was with great sorrow that I read of Steve McQueen’s death from cancer in later years. I shall always remember him — and those gloves.
Another famous film star to use Triumph motorcycles was the lanky, laconic Clint Eastwood. Although not such an avid motorcyclist as Steve McQueen, he did ride now and then, especially in some of the films he made, such as Coogan’s Bluff, in which he played a lawman sent out to the big city to collect a prisoner and take him back to stand trial. Ultimately, the prisoner escapes and there follows a frantic motorcycle chase in which Eastwood rides a Triumph Trophy TR6 and the escapee a T100C. Eastwood does actually ride but experienced motorcyclists will detect that certain parts of the chase are speeded up, which does detract from the film somewhat. One of the most glaring examples of Hollywood continuity foul-up occurs in another Eastwood film called Magnum Force. At the end of the film he and David Soul are chasing each other on Moto Guzzi Californians, equipped for highway patrol work, across the flight deck of a mothballed aircraft carrier anchored in San Francisco bay. As David Soul rides off the end of the flightdeck and into the sea, his Moto Guzzi changes in mid-air to a Triumph 650! I suppose that, at the time of making the film, it was more cost-effective to dump an old Triumph into the bay than a Moto Guzzi that in all probability had replaced the older Triumphs in real life service.
Getting back to vibration problems, we found that exact ignition timing helped towards eliminating this condition, so, to enable dealerships to set the new 6CA Lucas contact breaker assemblies accurately, a new stroboscope kit under part number CP207 was introduced around mid-1965. This measure took a lot of pressure off the service repair shop who, up to that time, were the only people equipped with the Suntester stroboscopic timing light.
It was also about this time that the positive oil feed to the exhaust cam followers came into being, due to premature cam lobe wear after only short mileages.
As well as introducing positive cam oiling on the 650cc units in 1966, two years later the sump capacity (oil at any given time in the bottom of the crankcase during normal running) was increased to help and increase splash lubrication of camshafts, followers and lower cylinder walls. The vibration problems experienced on the larger unit 650s, funnily enough, didn’t materialize on the smaller, higher revving 500cc units, which leads me to think that the problems with the larger twins were all to do with rigidity. The earlier pre-unit motors did vibrate but it was liveable with due to the bike’s overall flexibility. Having separate engine, gearbox and transmission, a lot more give — and, indeed, forgiveness — was apparent, but, with the unit construction 650s and even the later 750 twins where the complete engine unit was a stressed member of a very rigid frame, there was no forgiveness at all. I can only think that, to completely eliminate vibration from unit Triumphs, one has to totally rubbermount the engine in a way similar to that system used by Norton motorcycles of the era.
Work on twins under warranty for vibration faults carried on right up to the closure of Meriden in 1973 but the problems were never really overcome.
Read more from Coming Up in the Triumph Motorcycles Repair Shop
Reprinted with permission from Tales of Triumph Motorcycles & The Meriden Factory by Hughie Hancock and published by Vercoce Publishing, 1996. Buy this book from our store: Tales of Triumph Motorcycles & The Meriden Factory.