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Polished alloy mudguards and two-tone seat - did this bike leave the factory like this? Not possible to be sure as there was no hard-and-fast rule and the factory would use whatever was available to get bikes out of the gates, if necessary. Difficult to tell, but the mudguards look as though they might be rolled - they would have been razor-edged originally (or so the cognoscenti argue - though perioid photographs suggest otherwise). JR Nelson maintains that East Coast 1966 TT Specials had Alaskan White painted 'guards with Grenadier Red racing stripes while West Coast ones had polished alloy ones. This is the kind of generalisation that the "concours brigade" love! Unfortunately, it is not necessarily true. I'm unconvinced that any 1966 US Bonnevilles had painted mudguards - the parts catalogues specify stainless for the T120R and alloy for the TT Special and TR6C. Every photo I've seen of original 1966 T120Rs and TT Specials shows them with stainless/alloy 'guards.


However, the 1966 TriCor mini brochure (see copy under "Brochures" tab) and another advertising leaflet describe the TT Special as having "Two-tone Alaskan White and Grenadier Red painted steel fenders" while the T120R had "Polished stainless steel" ones. Both share the same factory style re-touched illustration of a TT which appears to have polished guards. It also has the old, shorter kickstart, replaced (according to Gaylin) at engine number DU25497 by a longer, improved version. Since engine number DU25497 precedes any 1966 T120C engines, it stands to reason that all 1966 TT Specials had the longer kickstart.This calls into question the accuracy of the brochures. Maybe the description of the TT Special as having painted fenders is incorrect too? 


David Gaylin maintains in his restoration guide that "sometimes" East Coast '66 TTs had painted 'guards, Alaskan White with a Grenadier Red pinstripe edged in gold (again!). I have to say, I'm not convinced - though I concede it is possible. The only 1966 TT Specials I've seen with painted 'guards are restored ones - and it's quite likely the restorers relied on the information in books and have thus unwittingly changed history. We now have 1966 TT Specials roaming the streets (or, more realistically, cocooned away in collector's hermetically sealed storage units) purporting to be "100% original" with livery in which they never would have left the factory (possibly).

Another debate surrounds the question as to whether the alloy 'guards were razor or rolled edged. Consensus among restorers is that roled-edge guards weren't introduced till 1968. However, I have corresponded with US restorers and owners of 1966 TT Specials from new who are adamant that their's were fitted with rolled-edge alloy fenders. See photo below of Bill Sherman on his brand new 1966 T120TT, the day he bought it, having removed the front 'guard ready for the track. Note the rear fender has a rolled edge. I suspect the matter is not as clear-cut as some might think.

Photo: Bonhams

1966 Triumph T120TT Bonneville TT DU39698 [photo used with kind permission of Bonhams]


Sold by Bonhams at Stafford 18 October 2009 for £8,625.


Engine built 25th April 1966, recorded as "T120TT", cycle assembled 26th April 1966, despatched to TriCor on 28th April 1966 as a "T120TT". One of the last of the final batch of 353 1966 specification TT Specials built in April 1966. Almost all of this batch went to TriCor, with a handful going to Canada, Mexico and Panama.


In my opinion, the 1966 TT Special was the nicest of the TTs - the best looking with a number of useful refinements to engine and frame. While the frame was not popular among TT racers, it was developed by Doug Hele for road racing and is a better frame for use as a street bike. There were 1,306 TT Specials built in 1966 according to factory records, making it the most prolific year for the TT.


Formerly, the accepted production figure for 1966 TT Specials was 798. This figure was provided back in the early 1990s by Harry Woolridge, an ex-Meriden man who had retained the engine assembly records when the factory closed in 1983, to American authors Lindsay Brooke and David Gaylin. The figure was subsequently published in their books and became the accepted figure.


However, Harry had only counted the number of entries with "T120TT" beside them in the engine assembly record. Between the start of the 1966 "B" Range model year, on 14th August 1965 at engine number DU25377, and 9th December 1965, when the first TT Special engine sporting the "T120TT" prefix was built, a total of 512 TTs with the old "T120C" prefix, ET ignition and high compression pistons were produced. The correct figure for 1966 TT Specials is therefore 1,310 - this was confirmed with reference to the assembly and despatch records as well as Harry's engine assembly records. In 1967 1,100 TT Specials were built, making 1966-67 the most common years for this model. This explains why you will always find a '66 or '67 TT for sale on one auction site or another - often at inflated prices and boasting unfounded claims as to their rarity!

[POSTSCRIPT 12 August 2017: David Gaylin contacted me regarding the above figures and asked me to substantiate them. I provided David with lists of the serial numbers and additional evidence sourced from the factory production and accounting records to support my claim that there were many more TT Specials produced in 1966 than the 798 he was advised of by Harry Woolridge. Further review of the figure resulted in a revised figure of 1,304 TT Specials for 1966. Having reviewed my evidence, David replied as follows:

"Congratulations on your research and TT Special production figures.  I find nothing to assail; even the assumptions appear bullet-proof.  Your list has to be the last word on the matter." (David Gaylin, email 9th August 2016).]


The engine assembly record books are believed to have been retained by Harry when the factory closed and he used them for all the production figures in his book "The Trophy Bible". However, the engine assembly records only state what was stamped on the engine, not what model the bike was (the two were not always the same). To count the production figures accurately all three records are required: the engine assembly, (cycle) assembly and despatch books.The production figures in "The Trophy Bible" (which have found their way into Wikipedia and are now accepted as "fact" by many) are highly inaccurate - presumably because only the engine assembly records - sometimes referred to as "Harry's Books" - were used to obtain them. Now all the records are readily available to view at the VMCC library in Burton-upon-Trent it's possible to obtain accurate production figures far more easily than in the past - as I have been fortunate to have been able to do.

The 1966 Bonneville colour scheme for the T120s was stunning: Alaskan White with Grenadier Red stripes edged in Bronze. The sculpted slimline US tank introduced that year was a work of art. Restorers usually edge the stripes in gold, as appears to have been the case with the tank above. I suspect this is not right. Triumph literature describes them as "Grenadier Red, Racing stripe pattern with Bronze lining". However, the "Bronze" turns into "Gold" in some restoration books (most notably, ex-Meriden man John R. Nelson's "Bonnie - The Development History of the Triumph Bonneville", accepted as "gospel" by many because John worked at the factory) and is now  considered "correct" by many experts. 

Photo: Bonhams

Photo: Bonhams

Unipiece air filter - towards the end of the model year, when this bike was built, as a TriCor bike it would almost certainly have been fitted with the individual pancake air filters - a big improvement. The unipiece filters look nice but they're a bit of a struggle to remove/replace. Replacement Parts Catalogue No. 4 lists the pancake filters for TriCor T120s, black unified ones for West Coast ones.

Interesting photo of what seems to be an almost new 1966 model year T120R, taken in Washington State in 1966. This is most likely a JoMo bike (Washington State being on the West Coast), and it's fitted with the seat strap required by Californian law. An interesting feature is the lack of "Triumph" logo on the seat. Purists will tell you this is incorrect and '66 bikes should have the logo. This photo suggests that generalisation is not quite correct - it seems some left the factory without it. Note grips coloured the same as those on Lindsay Brooke's friend's TT. Sometimes bright white ones are fitted on restored bikes - it seems that the original ones - when fitted instead of black - would have been more grey, intended to match the grey of the two-tone seat. Despite the factory intention to fit black seats to the competition models, as David Gaylin points out in his "Bonneville and TR6 Restoration Guide", many left the factory with the two-tone version. Early photos of my own 1966 TT Special, from the second batch built in October 1965, show it with what is believed to have been the original seat cover, which is two-toned.


My guess is the first batches built in August and October 1965 may not have had the logo. In 1966 several changes were introduced part way into the model year - these all seem to have occurred around December 1965. For example, from 9th December 1965 a batch of 473 TT Specials was fitted with a new E3134 Racing profile exhaust camshaft (part number E5047), to match the E3134 inlet. For a short period, the TTs really could claim to have "wilder" cams than their road-going stablemates. However, this was short-lived, for from then on the same cam was fitted to all Trophy and Bonneville models. The same December batch was the first to be stamped with "T120TT" prefixed engine and frame numbers, with the "T120C" prefix being demised.

Around this time too, the "S" was dropped from the frame stamps of TR6s, reverting from the "TR6SC" and "TR6SR" prefixes introduced in September 1964 back to "TR6C" and "TR6R" respectfully. Oddly, a batch of 775 T120Rs built this month received "T120SR" prefixes for the first time, though the records indicate no difference in specification to  T120Rs built before or after. It appears that the "T120SR" prefix was only used for this batch - sparking off excited speculation that these "mystery" bikes have some extra sporty engine spec. Not according to the engine assembly record - which states only that they were fitted with 19T gearbox sprockets and tachos. The factory really did not build such specials - it took JoMo years of persuasion to get them to build them the TT and Trophy Specials - and what they received was really not all that special.


It may be that the "Triumph" logo on the seat was introduced around December 1965, as well as the separate air filters too (TBC), given that this seemed to be a time when several changes were rolled out.

Photo: kind permission Lindsay Brooke

Lindsay Brooke, author of "Triumph Motorcycles in America", on a friend's original paint 1966 TT Special, taken in 2004. Lindsay lives on the East Coast and it's likely this is a TriCor bike. The seat has no safety strap - required by Californian law as I understand it (not sure over what period), and commonly fitted to West Coast TTs, even though there were no passenger footpegs. Greyish-white grips were in common use, though Gaylin suggests black was more common. The lighter coloured grips on this bike may not have been what it left the factory with (they would have been grey) but I have heard that TriCor fitted ones like these. You can just discern the edging to the racing stripes, which is Bronze and not Gold, as commonly found on restorations.


Interesting that the bike is fitted with the unified air filter - if it is a TriCor bike it would have, in theory, left the factory with pancake filters (see above). However, if it was from an early batch, perhaps some were fitted with the unified ones to use up existing stock. It could have been replaced of course - but if it is an original paint bike then I'd expect it to be largely original and unlikely anyone would have replaced the pancake filters with a unified one - though they could have. From this partial photo there's quite a lot of info that can be gleaned regarding the bike's originality: crosshead screws in the cases; nuts and bolts apparently cadmium plated, original-looking rounded TT pipes (compare with the obviously pattern ones on the Bonhams TT); coarse texture on seat looks original (though RK Leighton's covers are indistinguishable from the originals - probably as they made them - all other pattern ones have a smooth finish). 

Bill Sherman on his brand new 1966 T120TT - note rolled edge rear mudguard

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