The MAC was a popular commuter and touring motorcycle that needs very little introduction, so lets delve into the history of the iconic machine produced by Velocette.
A MAC with attitude! Credit: Steve Lainson
The Velocette MAC made its entrance in the depths of the depression. The overhead cam bikes that Velocette had spent a considerable time developing were proving too expensive for the average Joe in uncertain times. Skilled workers on the production line had to hand-assemble the tricky shaft-and-bevel camshaft drive, and this resulted in a rather pricey machine. Velocette looked to the respected and talented engineer Charles Udall to solve the issue and take the company through to better times. The simple answer was a move to an overhead valve configuration, which would be quicker to produce and would require less high-skilled labour to assemble.
A 1937 MAC. Credit: Stuart Woods.
It started with the M series and the first step was the development of a 250cc OHV single, dubbed the MOV. The tiddler packed a punch thanks to a high-level camshaft. This allowed for shorter push rods, and more revolutions – up to 5000 per minute to be precise…. for a 250cc motor that was quite something! It was an immediate hit and proved to be an able performer, capable of 78mph – a spectacular speed at the time.
A 1946 MAC resting up in Japan. Credit: Hideya Goto
The next year (1934), the motor was tweaked and the stroke increased to 349cc, enough to propel the newly unveiled 127 kilo MAC to a very respectable 75mph – plenty of speed for the rickety roads of the 1930s. The MAC soon became a popular utilitarian motorcycle, carrying thousands of men back and forth to work each day.
A 1946 MAC. Credit: Hans Bramberger.
In October 1939 a MAC was purchased by the British War Office Army Mechanisation Experimental Establishment to test its suitability for military use. The tests were successful albeit a number of modifications were recommended, and in 1940 the Velocette MAC was modified into a military specification to support the war effort. The bike was designated the MAC (WD) – the WD coming from “War Department”, although it was often referred to as the MDD as this was the prefix for the serial numbers. The MDD had an upgraded clutch and the pressed-steel front brake drum was replaced by cast iron fittings which became standard for the later MAC models due to the shortage of aluminium which was needed for aircraft manufacture. The MDD included a protective shield bolted to the frame over the crankcase, a rack replaced the rear pillion seat, and the headlamp was masked to comply with blackout regulations.
Velocette’s first order for the military MAC was from the French Government, however the contract for 1,200 motorcycles was cancelled and only a few were delivered before the French were overrun by the advancing German Army. The British War Department took over the contract in June 1940. The WD MAC spec was improved in 1941 and became the MAF (“AF” denotes Army Forces). The key updates were a stronger frame, front fork refinements, revised cam profiles and a lower bottom gear. The WD MACs were capable bikes on the battlefield, however the factory was only capable of a relatively small output, and by September 1942 the MDD order was cancelled. Rumour has it that a bunch of WD MACs were lost in transit somewhere in the English Channel.
A test rider putting a 350 WDD to the test.
Civilian MAC production restarted after the war. The bike coped well with the low-grade post war fuel and this added to its appeal as a reliable commuter… some would say that the Velo was a cut above the average thumper and for this reason it cost a bit more than the equivalent BSA or Matchless 350cc bike. The most dramatic change was in 1948 when the trusted girder forks were replaced with innovative air-sprung Dowty Oleomatic forks (and in 1951 these were upgraded to Veloce ‘tele forks’ which were developed for the Velocette LE). The seals on the Oleomatic air forks were somewhat problematic and word had that many would fail before a MAC had even rolled off the production line (oh for technology!). A 1950-era MAC was said to return a cheery 80mpg at an average speed of 30mph, and this was a key reason that they continued to live on for many years.
A rigid MAC with telescopics. Credit: Ed Gilkison.
Velocette also introduced a unique system for altering the preload on the rear shocks. The frame featured a slotted track for the upper mounts, enabling the shock angle to be altered by sliding the top mounts back and forth through a short arc. This enabled the rider to tweak the preload to his or her liking.
A 1956 MAC with Tele Forks. Credit: Ross Moorhouse.
The MAC had been a staple in the Velocette line-up for almost a quarter of the century, however the market for practical motorcycles began to dwindle through the 50s. The simplistic, trusty bike was removed from brochures in 1960. In total, more than 25,000 MACs were made during the production run. They always a cut above the average thumper, and the spirit of the MAC continues to live on with plenty of the dependable old machines still gracing the roads today.
an article by The Girder Club
If you would like to be kept up-to-date with the latest news and information on vintage motorcycles, feel free to sign up to our newsletter, which we aim to ping out each month.
Leave a Reply