Hugely robust but cam plate spindle boss in case can be damaged if shifted aggressively (motor must come down and cases split to repair) and gear change can be vague and annoying if linkage not precisely setup.
  • Gears: Gears, shafts and bushings are incredibly robust, short of any obvious damage, replacement/renewal is driven by common sense. Some/all of your focus on this gearbox should be directed to the external/internal shift linkage both through later retrofits, accurate adjustment and assurance than your cam spindle boss/threads are impeccable.

  • Gears (Double Back Lashing): You'll likely read the faster shifts can be executed by cutting every other engagement dog from the faces gears as depicted in MO12 which improves one chances that hastily meshing gears will find the dog roots rather than their faces for more immediate engagement. This should be reserved for racing machinery only as it has no value for the street adding just that - lash - meaning that placing your machine in gear and rocking it back and forth will produce a neutral like feeling as though your chain is slack. Under the same premise a hammer striking a blow from one foot away as opposed to 6 inches can convey more energy, this running gap will just result in you beating your driveline needlessly as the throttle rises and falls.

  • Shifting Underway: This is a large heavy transmission subject to shifting mechanism inertia causing partial engagement/false neutrals. Like a Porsche 930 turbo, be thankful it is bullet proof and work around those shortcomings. Drilling cam plates for lightness and knocking alternate teeth off of dogs sounds racy but is not necessary. Instead, to reduce that shift time, lightly rest your foot on the lever until you feel resistance at the moment you are pulling the clutch in and then ”feel” the selection home. Unlike standard motorcycle sequential transmissions, there is no spring inertia to speed the engagement process so thus no point in booting it. Spare this potential fragile shifting mechanism by just pressing lightly and deliberately and be confident your engagement is really home. After all, when you do let the clutch out....that magnificent motor will take care of any gap lost to those on their noisy, rapidly shifted, high rev’g machines.

  • Cam Spindle Bolt: As mentioned in the header of the Electrical section, the cam plate is retained/positioned by the spindle bolt (MO03 - G34) somewhat tenuously secured into a threaded boss in the roof of the transmission area of your case under the generator. If you are fortunate it will have not loosened, or if so, not enough nor wobbled around to damage the case threads - or worse breaking the casting off - such that it can be retightened after a thorough cleaning and letting a little Blue Loctite soak down into the threads. Engage the flats of a large screw driver and tighten somewhat firmly on one where the bolt does not feel loose in the threads indicating damage but be advised there is minimal thread support for a bolt working under these conditions. Some opt to drill a small hole in between the bolt and case, slotting each wherein a small screw can stake both.

  • Bearings: All the ball/roller bearings in a Vincent are very robust and easily changed by the average hobbyist with the exception of one (MO32 - G15) on the inner end of the lay shaft nesting within a blind hole in the case. This requires a special bearing removal tool (for some, I just spot welded a clip to it in my Red Rap and eased it out) rather than be casually drifted out from warmed cases with whatever you have on hand and is often bypassed by non professional restorers. As this requires the primary and transmission to be disassembled and removed, a sizeable task so mentioned here just so you'll be aware of one of the few failures afflicting this part of your machine.

  • Kickstart Spring: (MO10 - G87/1) Starting technique can render this component vulnerable which though changeable through the transmission cover via the inspection hole is a fiddly and delicate proposition. Better to modify your starting technique. Instead of heaving your weight downward till the kicker swings entirely through and hits home on the stop, With the de-comp pulled give a sharp kick to spin the flywheels, stopping your swing at about 7 O'Clock when viewed from the side which is well before the spring stretched to a vulnerable point.
More info on Vincent transmissions can be found here at