Checking for Wear
If you have the right selector box fitted and are still suffering gear selection problems then the chances are that the selector box itself is worn.
You can check for wear on the selector mechanism by pushing on the selector arm, with the wheel in one of the central positions. If you can feel any play or movement in the arm (before you build enough force to select the next position) then the mechanism is worn and needs to be refurbished, or the selector box replaced.
The most common fault is that the sprung roller arm which rests against indents in the gear selector wheel has become worn. On a damaged selector the pivot holes in this roller arm will be worn oval and the pin will have grooves worn into it.
The old method of sorting this problem was with a ‘gear selector box repair kit’ which consisted of a new roller arm, pivot pin and spring. These are still available through VE dealers, but many people now replace the box given the low price of a complete replacement selector box. Repair parts are VE11064 for the selector box arm with roller, VE11065 for the pivot screw for the bracket and VE11032 for the tapered pin for the arm.
Nowadays, given the sometimes dubious quality of replacement parts, refurbishing a used Italian selector box seems like an attractive prospect. You can either try find an original repair kit or use the home repair method described subsequently.
The other occasional problem – particularly on pre-1984 PX models which are more prone to gearbox jumping – is that the tapered pin that locates the gear arm onto its shaft can come loose and even drop completely out. If that is the case then the pin can be given a drop of Loctite and punched back into place to tighten it.
An even rarer occurrence is the gear arm fracturing in two across the hole for the pin. If this happens you really are stuck and a new selector box is your only alternative.
Vespa Gear Selector Box Repair video (full version)
Gear Selector Box Repair
To follow the video instructions above you need access to:
- a pillar drill
- a welder
- a saw
but like Weakest Link, you can also phone a friend…
Assemble the arm, spacer and pin and check the position of the pawl. When the tubular spacer is in the correct position the pawl should be flush with the gasket face (or very slightly raised) on an EFL selector box. On an early selector box the pawl should be raised by approximately 1.5mm.
Weld or braze the spacer into the arm in the desired position. You may need to re-drill the hole through the spacer tube again if the hole distorts during welding.
Apply lots of grease to the pin when you screw it into the gear selector box, then re-fit the spring. The pin is now supported along its length rather than in two small areas. This should significantly slow the progress of wear in the future. It is also important to always use a correct-fitting and well greased gear selector box cover to minimise the ingress of dirt and water.
Thanks to the following for help with this article: Harry Barlow (Pro Porting), Phil (Grand Prix Scooters), Ian (Eddie Bullet), Wolle (Scooter & Service) and the guys at ScooterCenter.com.