1925 Norton 490cc Special Model 18
Registration no. TR 361
Frame no. 22787
Engine no. 25300
Like the majority of their contemporaries, Norton relied on the sidevalve engine until the 1920s, when the existing and well-tried 490cc unit was used as the basis for the firm's first overhead-valve design. Designed by James Lansdowne Norton himself, and first seen in prototype form in 1922, the overhead-valve Norton made little impact in that year's Senior TT, though at Brooklands D R O'Donovan raised the world 500cc kilometre record to over 89mph using the new motor. A road-going version - the Model 18 - was catalogued for 1923, quickly establishing a reputation for both speed and reliability when a standard engine assembled from parts was used to set a host of records, including a new 12 hours mark. Racing continued to improve the breed, the Model 18 gaining Webb forks and better brakes for 1925 as a direct result of the works team's experiences. The Model 18 retained its essentially vintage characteristics until 1931 when the range was extensively redesigned.
Alec Bennett was Norton's star rider of the early Vintage period, delivering Bracebridge Street's first Senior TT win in 1924, and the engine of the Model 18 offered here incorporates the crankcase of his 1925 Isle of Man TT works machine. Copies of Norton factory records held by the VMCC show that engine number '25300' (in frame '17486') was built for the 1925 TT and intended for 'A Bennett'. (This Norton's current frame - '22787' - formed part of an OHV model that left the factory on 23rd March 1926. The steering damper lug on the top tube is a later addition). Somewhat unusually, Bennett's 1925 TT machine was registered 'TR 361' in Southampton where he had his motorcycle dealership, rather than in Birmingham, home of the Norton factory. No doubt the fact that so little of the original Bennett machine survives reflects the fact that 'TR 361' endured many hard seasons of racing, suffering the inevitable crashes and mechanical failures.
Having hitherto relied on the traditional 'splash' method of lubricating the engine's bottom-end, Norton switched to dry sump lubrication for the 1925 works bikes, which necessitated a redesign of the timing-side crankcase. Leading a race that everyone expected him to win, Bennett slid off at Governor's Bridge and was forced into the pits to make repairs, losing sufficient time to hand victory to Howard Davies on his HRD-JAP. Bennett eventually finished third.
Previous owner Keith Shorrock, from whom the current vendor acquired the Norton, purchased 'TR 361' from the Isle of Man's Murray Motorcycle Museum in the mid-1980s. While in Mr Shorrock's ownership the Model 18 featured in a lengthy article published in The Classic Motor Cycle magazine (July 1991 edition, copy available). Written by Phillip Tooth, the piece included the reminiscences of a previous owner, Joe Diver of Impington, who had bought the machine from a Cambridge undergraduate, Martin Brunt, circa 1952. As purchased the Norton had the front wheel of an International model and later-type Webb forks. Joe Diver raced, sprinted and hill climbed the bike for the best part of the next ten years. The publication of Phillip Tooth's article prompted Norton enthusiast Simon Grigson to write to the magazine (copy letter on file) for it was to him that Joe Diver had sold the Model 18 in 1961. His letter mentions that prior to Martin Brunt, the machine had been owned and raced by the Bovingdon brothers in early Vintage speed events. The engine was already much modified, incorporating 1928/29 ES2 steel flywheels, a later con-rod with ⅞" diameter gudgeon pin, and a modified WD 16H piston. The exhaust cam was a long-dwell item marked 'TTG'. Mr Grigson observed: 'With the TTG cam in the inlet position and a standard W7 cam for the exhaust, it was quite a bit quicker than the almost standard engine I had been using.'
The 1925 engine was installed in a 1929 saddle tank frame and for the next couple of years this hybrid was raced, sprinted and hill climbed. It was during this period that mechanical failure damaged the engine's top-end, though fortunately the special crankcase assembly remained intact. The engine was then set aside, to be reunited with 'TR 361' when Simon Grigson sold the Norton to the Murray Motorcycle Museum in the Isle of Man in 1966.
Restored while in Keith Shorrock's ownership, 'TR 361' was ridden by him on the Isle of Man TT Lap of Honour in 1990. Kept on display in the vendor's house for the past several years, the machine will require re-commissioning and the customary safety checks before further use.