Triumph T100A
‘Looks like it’s standing still when it’s doing 100mph’, rockers sneered. What’s the truth behind Triumph’s first unit sports 500?
Retired garage owner Alex Taylor has often provided us with deliriously distressed, very original classic motorcycles – a typical example was the Francis-Barnett Seagull we sampled in TCM, March 2020. Unrestored cosmetically but wellsorted mechanically and electrically is Alex’s way.
So by those standards his 1960 Triumph T100A Tiger 500cc unit twin is unusually tidy, visually. Just finding a bathtub 500cc Triumph that has complete panelling and an original engine – the numbers match on this one – can be quite a feat, as the tinware was often stripped off (especially in the US, where ‘stamped steel’ was anathema to macho young buyers), or the sports engine was often pulled out and rehoused for scrambling. But Alex has an unusually good network of contacts. He snared the 500 for £3000, and has spent another £4
500 since.
He currently lives at the end of a gravelled drive reached from a rutted single track side-road leading from a narrow village lane, which are all prone to getting water-logged and muddy in the rainy season. So one reason for his buying a pair, 500cc and 350cc, of Triumph’s panelled C-Range unit twins chimed with part of the range’s original intention, ease of cleaning. US publicity had highlighted “conservative and intelligent weather protection.” Another reason related to the fact that Alex is not the tallest rider, so the 17inch wheels and 28.5 inch seat height were plus points. The 350lb weight, 10lb of which was from the panelling, didn’t hurt either; that was 35lb lighter than 1957’s pre-unit T100.
Sparks
“It is easier to clean,” Alex confirmed, “though the sporting T100A doesn’t have the 3TA/5TA’s fully enclosed rear chain. It was complete, as you can see, but the electrics needed totally redoing.” The original 1960 T100A, was aimed, despite the inappropriate panelling,
primarily at US sports riders, and had featured Lucas’ new Energy Transfer ignition, which, though difficult to adjust, allowed battery-less running.
At some point this had been replaced on Alex’s Tiger with the current stock Lucas coil ignition system, as had happened on production T100As from mid-1961. This included an 18D2 distributor, and an original feature on this Triumph is the waterproofing sheath over it, which is clearly visible in contemporary images of the C-Range. These sheaths were usually discarded as they hardened with age, and also, as Alex said, because the low tension lead made them hard to remove when servicing.
“The switches were all broken,” he continued, “and the system had overcharged, boiling the battery and spattering acid about. One thing I retained was a second, spare condenser, sitting down by the base of the distributor in reserve. With the distributor the timing can slip, but only if you bend the clips or don’t put them on properly. The coils should be under the seat, but as found they were under the tank. Coil electrics, and the bigger 6 volt battery I’ve fitted, means the lights are okay when I ride it to evening meetings of the local TOC.”
He’s an all-year, all-weather rider.
Alex, as he does, had also completely stripped the engine. “One thing was that the clutch was very different to the 3TA/5TA.” This was to cope with power increasing from the 5TA’s 27bhp to the 1960 T100A’s 32bhp@7000rpm. The clutch’s driving plates, with Langite friction lining, increased from four to five, and the driven plates from five to six. This meant different dimensions inside the unitised case, with a deeper clutch sprocket, housing and clutch centre, plus longer springs, spring cups, and operating rod. Rebuilder beware. The duplex primary drive chain, for the first time in the 1957-on C-Range’s history, was fitted with an adjustable spring blade tensioner.
Recorded mileage on this T100A was just 12,921, and though that may not be relevant, after stripping, Alex did find the engine “quite clean.” The only major replacement needed due to breakage were the inner valve springs, sourced from Dorset-based Ray Fisher’s BritBits (01202 475327). Alex rebuilt the engine with lower compression 7.0:1 pistons as on the 5TA, not the T100A’s original 9.0:1. The result was a smoother ride, but Alex has found the 500’s 3TA stablemate is sweeter still, and prefers it. “The T100A came with a spare carb,” he said, “but both it and the one fitted were knackered! However I’ve adjusted up the original, with the last tweak just done yesterday, and it’s running well now.” Alex had taken delivery of the Triumph in March 2020, and was riding it by May.
The C-Range cycle parts are another potential problem area today. If Alex had had to play hunt-the-panels, he would have had to remember that the rear panels were half an inch shorter than the identicallooking ones for the 6T Thunderbird and T110 650s, and with different fixings. Luckily the ones on his 500 are original enough to still carry the supplying dealer’s
Unrestored cosmetically but well-sorted mechancially and electricallly is owner Alex Taylor’s way.”
Recorded mileage on the T100A was just 12,921 and on stripping, the engine was found to be quite clean.”
Single inch Monobloc carb 500 engine for 1960 would be developed into 1966 twin carb Daytona winner, and beyond.
Handling with T100A’s ‘gooseneck’ frame could be learned – up
to a point.
name-plate. And the split-prone ‘Fireman’s Helmet’ front mudguard, similar-looking to the 6T’s, carries what John Nelson in his ‘T100/Daytona’ book calls “the oft lost chrome wedge” to accommodate the smaller radius C-Range guard. One thing Alex did find out of order were the stands, which were both bent, along with their pivots and stops. He corrected everything, but found the centrestand “suspiciously easy to straighten – they were weak to begin with.”
The tyres are the ones the bike came with. “17 inch ones can be difficult to come by, and you can’t afford new rubber when you’ve got other things to sort out.” I wasn’t sure I agreed, especially as I was about to put the early unit 500, with its reputation for iffy handling, through its paces. “Yes, for the first couple of miles the handling seems alarming,” said Alex cheerfully, “till you get used to it.” That would have to do.
The T100A story
The genesis tale of the first of Triumph’s C-Range, the 1957 Twenty-One 350, has before been told in TCM.
It was a worthy attempt on Edward Turner’s part to widen motorcycling’s accessibility and appeal to nonenthusiasts.
But it was misjudged, because “designed by a G-Plan committee”, sensible, scooter-inflected styling did not appeal to the young male majority of motorcycle buyers on both sides of the Atlantic, who wanted something butch, sporty-looking, and also more accessible for servicing. They got it with the 1960 T120 Bonneville – but in the same year, Meriden released this first sports unit 500, the T100A, with the cooking 5TA’s panelling and voluminous front mudguard firmly in place.
That first 500cc version, the 5TA Speed Twin, had appeared the previous year, the bored-out, over-square 490cc (69x65.5mm) engine sharing its stroke with the 350cc 3TA. Developed by Frank Baker’s engineering team, it shared overall reliable durability with the 350, and immediately offered competition potential. Right away in May 1959, both East and West Coast US importers sent out detailed bulletins to all dealers, on how to convert the 5TA to Class C road or dirt track racing specs.
The 500 category was significant, as imported machines were largely confined to that capacity in US competition under AMA rules. And as Brooke and Gaylin wrote in “Triumph In America”, “many believe that (the unit 500 twin) was the best engine design Triumph ever produced.” So when the sports T100A
Tiger was released for 1960, there was incredulity that it too came fully swaddled in ‘stamped steel.’
Tuning for the T100A’s iron barrel, alloy head engine was relatively mild, with the raised compression and sports camshafts, but the original cam followers; though the alloy pushrods did feature steel caps to suit the sports cams. (The latter would change to the legendary E3134 profile for 1961, when power rose to 34bhp.
The result was an engine which produced 95mph on test with a wind behind, 10mph more than the 5TA.)
It also shared the 5TA’s frame, the same skinny, single-loop, Cub-derived chassis with its outwardprojecting ‘goose-neck’ steering head, the petrol tank as a stressed member, and what hard-riding journalist Dave Minton called ‘a swinging rear fork no more securely anchored than the traditionally unsatisfactory big twins’. The frame too would be modified for 1961, but only really became what the engine deserved after 1966 and Doug Hele’s race development of the 500s.
Stylistically Americans began to get what they wanted in 1961 too, with the naked TR5A in ‘C’ (Competition) or ‘R’ (Road) variants. Meanwhile Turner’s draughtsman/stylist Jack Wickes visited legendary desert racer, stuntman and Triumph dealer Bud Ekins, in his California workshop. “In the corner,” wrote Wickes, “was this great pile of fairings, and Bud said, ‘Why do you put them on? We don’t want them.’”
Ride The Tiger
With its electrics sorted, Alex’s T100A started first kick. Reliable and easy kick-starting was one of the unit 500’s strong suits, not least for artists and musician owners like Bob Dylan and Janis Joplin. The clutch was light but the gearchange clunky, at least initially as I pottered off apprehensively, waiting for the frame to frighten me. Which it duly did early on, with the front end noticeably imprecise and wandering around offline. The front brake squealed on application too, but there were no rattles from the engine, or the panels.
The riding position with a three inch shorter wheelbase than the pre-units’ plus the 17inch wheels, was a bit compact and jockey-like for a six footer, but you quickly got used to it. The suspension proved hard over bad bumps but otherwise the ride was comfortable.
The seven inch brakes might sing out, but used together they proved effective enough. And the soundtrack from the C-Range’s barrel silencers, which for the T100A had abandoned the range’s aspiration to civilised quietness, with just glass wool and minimal mutes to the straight-through exits, gave a wonderful throaty exhaust note. By the time we’d got to the tight bend we favour thereabouts for photos, I was even getting the hang of gearchanging on the relatively revvy engine, with smooth changes coming, especially down-changes.
Chucking it about for Gary the snapper, I gained further confidence, though cornering always had an edge to it. Once you changed down to third in advance, you could ride through the sharp bend on a throttle rising from 40 towards 50, and the plot held the road well enough for that, as long as you kept twisting the grip to keep the power on the rise.
Putting in a few miles after that, it was the engine, with clean carburation thanks to Alex, which carried the day. A real Triumph, with instant pick-up and bags of acceleration up to 60 and beyond, and smooth enough with it. And as confidence expanded, the whole plot revealed that it appreciated being ridden, if not hard, at least aggressively. Which encouraged you to do so, ride as quickly as possible, use the brakes hard, overtake dawdlers, so forth. I ended up liking it. Overcoming, or rather, learning to live with, the handling limitations of this early unit 500, by driving it on the willing engine, you saw its future, the very excellent late T100
Daytonas. Quite a history lesson!
It’s a real Triumph, with bags of pick-up and acceleration to 60mph and beyond.”