RS Framed Evolution |
Dates of detail changes to Velocette models can be confusing as changes were announced for the model year in September / October of the previous year. More than likely these changes would have already been put into production even before they were announced. Occasionally some changes were phased in by model to use existing stock. Therefore this information can only be used as a guide.
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Date |
Model / Engine Number |
Event |
| 1952 Dec |
Spring framed MAC introduced | |
| 1953 Mar | New top gasket for the oil filter housing introduced | |
| MAC chain case modified | ||
| MAC number of clutch springs increased to 16 | ||
| July | "O" ring fitted to exhaust valve lifter cam | |
| July | M17/4 cam superseded by M17/5 on MAC | |
| Sept | Oil pump feed gears reduced to 3/16" on MAC | |
| Sept | Minor change to rear suspension units | |
| Sept | New oil tank transfer A 134/4 replaces simple line transfer A 134/2 | |
| Dec | MSS introduced, originally fitted with prefix 12 gearbox | |
| Dec | Panniers available for MAC / MSS | |
| 1954 Feb |
Carb setting changes on MAC | |
| Mar | 16 T gearbox sprocket and stiffer front fork springs available for MSS when pulling sidecars | |
| May | Primary chain covers modified to accept felt ring - note MAC and MSS primary covers have different part numbers | |
| June | Spacer added between inner and outer primary chain covers | |
| June | Miller headlight 79CV now standard on MAC / MSS, this requires different bulbs | |
| June | MAC now uses MSS silencer MAS30/2 | |
| MSS Scrambler introduced | ||
| MSS Endurance introduced US market | ||
| June | MAC22659 RS3709 |
Prefix 11 gearbox replaced by heavyweight prefix 14 gearbox. MAC now uses 12 clutch springs compared to the MSS 16 |
| Sept | MAC 23142 | K87 ball main bearing superseded by roller bearing K87/2 |
| Sept | 12 - 2195 14 - 1604 |
First gear wheel, now fitted with two bushes rather than the one full length bush |
| Nov | MAC 23193 | M17/7 cam and followers M9/5 fitted to MAC |
| 1955 | MAC | Now available in green as well as black |
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Loch Ness monster seat replaced by seat with pointed front |
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| April | Veloce ordered first Monobloc carbs from Amal to replace 276 range | |
| May | Gaiters added to front forks and two way damping added to Scrambler | |
| July | Scrambler rear fork torque tubs now doweled | |
| Aug | All fibre washers replaced by soft alloy washers | |
|
MSS |
Solid skirt piston replaced by split skirt piston |
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|
MSS11786 |
Engine studs increased from 5/16” to 3/8” Crankcase MAS 29/3 |
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Rear number plate now changed to enclosed two piece |
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MSS 11889 |
Prefix 14 gearbox made standard, rather than previous prefix 12 |
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Petrol Cap moved from left hand side to right hand side of tank |
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| MAC also available in green | ||
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Dec |
Venom and Viper introduced |
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| 1956 | Endurance available in the UK | |
| Apr | MAC 24630 | Stem diameter of exhaust valve increased |
|
Squarer type rear light introduced to MSS |
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| MSS, pillion footrests, steering damper, stoplight and air cleaner no longer standard but available as optional extras | ||
| Mar | VR Scrambler introduced | |
| May |
MSS 11970 (RS6818) MAC 24284 (RS7535) |
V belt replaces flat belt and new dynamo belt covers fitted |
| MSS 12078 | Band primary chain case changed to screw type | |
|
May |
MAC |
Headlamp nacelle carrying switch ammeter and speedo. Speedo changed from 80 to 120MPH. Diacon tank badges |
|
MSS 12303, VR 1144, VM1114 |
Flywheels reduced in size, 0.0625" narrower, 0.75" less in diameter |
|
| May | Lower selector fork rod superseded by one 1/16" longer | |
| May | Engine crash bars available | |
| June | MAC24677 (RS8480) |
Cast iron cylinder replaces Alfin type |
|
June |
VM1227 (RS8488) VR1222 (RS8323) |
VM inlet tract diameter increased from 1.125” to 1.1875”, consequently carburettor changed from Monobloc 389/14 to 389/15. VR inlet tract increased from 1.0” to 1.0625” consequently carburettor changed from Monobloc 376/56 to 376/61 |
| June |
VR1262 |
M17/7 cam replaced by M17/8 on Viper |
|
MSS |
Drive side bearing boss diameter increased, crankcase MAS 29/4 |
|
| Petrol tank knee grips moved further back | ||
| Oct | Reinforced rocker box gasket specified | |
| Oct | Stronger atd springs fitted (possibly to Viper only), however these were replaced with the original types in August 58 | |
| Nov | VM1503 (RS9136) |
Modified oil tank and breather arrangement for Venom, MSS and Viper |
| 1957 | Light alloy rims, close ratio gears, racing seat, clubman pipe and silencer, two way damped forks and other items were first catalogued to comply with certain racing regulations | |
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Sept |
Modified oil tank and breather arrangement for MAC |
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1958 |
Flatter seat used |
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|
Regulator moved to rear mudguard under the seat |
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| May | MSS 12542 (RS10906) VM 2206 VR 1720 (RS10917) |
Valve retaining collar and associated components strengthened |
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Oil tank lugs strengthened |
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Silencer now made with heavier gauge material |
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June |
MSS 12561 |
Extra drive side plate added |
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Nimonic 80 exhaust valve used on Venom and Viper |
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| Aug | VR 1837 (RS11314) |
Extra drive side plate on Viper standardised. Previously an extra |
| Sept | MSS12585S (1001/35) |
MSS Scramblers fitted with triangulated frame |
| Sept | Glassfibre engine covers available | |
| Dec | VR1922 (1003/35) |
Viper Scrambler introduced |
|
1959 |
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Froth tower added to oil tank, and breather vented to rear chain |
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Timing cover with casting for rev counter drive now fitted as standard |
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| Sept | MkI Venom and Viper Clubman listed for 1960 season | |
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1960 |
Cylinder head changed from sand cast to die cast |
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Change to frame lower tubes now welded - engine / mudguard mounting changed from original casting |
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|
14/4916 12/7081 |
Gear change linkage changed from a well-engineered component to a piece of bent scrap iron! |
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|
Lubrication of the big end revised |
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|
Oil scavenging tube lowered in crankcase |
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| Aug | MAC discontinued | |
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Sept |
Miller dynamo uprated from 36 watts to 60 watts |
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| Sept | Venom and Viper Clubman fitted with 41/4 gallon tank with badges and aluminium trim. | |
| Sept | Venom and Viper Veeline and Veeline Clubmans introduced with Dolphin fairings | |
| Deepening ratchet on kick-starter to prevent slippage | ||
| Some machines fitted with Girling rear dampers | ||
| Cast iron cylinders replaced Alfin barrels | ||
| Dec | Veeline fairing available to order for retrofitting | |
| Dec | TT ratios now not fitted as standard to Clubman machines | |
|
MSS 12915, VM 5049, VR 3605 |
Dynamo pulley increased in size |
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1961 |
Veeline fairings introduced |
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1962 |
VM 5551 | Rear of petrol 4.25 gall tank mounted on rubber block |
| Nov |
VR4121 |
4.25 gallon tank introduced on standard models |
| Nov | Venom and Viper Specials introduced with non chrome three gallon tank, pressed steel full width hub, MSS/MAC rear hub (later changes again) 60mm, 100 MPH speedo in modified nacelle | |
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TT carb optional on Viper |
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1963 |
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Woodhead Munroe suspension units replaced by Girlings on MSS, Venom, Viper - Specials still Woodhead Munroes |
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Crankcase includes timing chest drain rib MAS 29/4 |
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| Sept | VR, VM Clubman | Clubmans fitted with Monobloc as standard rather than the previous TT carb |
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Sept |
VR4372 |
Crankcase suction filter replaced by blanking plugs, Oilways increased in section, crankcase halves now located by dowels MAS 29/5, crankcases heat treated on Thruxton |
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1964 |
Chronometric Speedos and rev counters replaced by magnetic |
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Sept |
"Thruxton" head now optional on Venom as part of a production racing kit including petrol and oil tanks |
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1965 |
Thruxton introduced |
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1966 |
Miller electric's phased out, Lucas gradually introduced |
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| Sept | VMT421 (RS18889) |
Rear tyre reduced in width to 19 X 3.25 and cast lloy brake and gear change levers replaced the earlier items |
|
Oct |
VR4542 |
Engine breather changed requiring modification to oil tank, crankcase MAS 29/6 Deeper skirted dual seat fitted |
| Oct | VR4541 (RS19079) VM6289 (RS19020) |
MKII Clubman introduced |
|
1967 |
VM 6362 / VMT 506 |
Fork stanchion diameter and bushes increased in diameters |
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Exhaust pipes reduced from 1.75" to 1.5" on Venom Clubman and Thruxton |
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One piece push rod tube introduced |
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New seat with skirt that follows frame introduced |
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Amal Concentrics fitted as standard |
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Battery box fitted as standard on all models |
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Venom, Viper fitted with Thruxton mudguard stays |
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Rear wheel speedo drive and associated components changed |
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| Pressed steel rear brake peddle replaced with aluminium components on Clubman's and Thruxton's. | ||
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1968 |
VM 6488C |
Coil ignition replaces Magnetos |
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Viper and MSS discontinued |
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Thruxton barrels now fitted to Venom with extra spacers |
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All bands and badges replaced on petrol tanks by transfers and gold lining |
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| 1969 Jan |
VM6459 (RS19636) VR4579 (RS19498) |
Venom and Viper Specials discontinued |
| Viper Clubman, Veeline and Scrambler discontinued | ||
| MSS scrambler discontinued in the UK - for export only | ||
| Some bikes fitted with plain bearing in the chain wheel to replace the ball race | ||
|
1970 |
Last Thruxtons fitted with 36mm Amal Concentrics |
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| 1971 | Feb | All production ceased |