One regular issue with Lambrettas is stripping of the M3 threads that hold the headlight rims onto Series 3 headsets. Over the years there have been many different solutions offered including:

  • Fitting an M3 helicoil.
  • Tapping the hole to M3.5 and using the screws from household electrical sockets.
  • Fixing M3 nuts to the back of the aluminium headset lugs using glue or chemical metal.
  • Drilling out the hole, fitting a long rivet and then cutting a thread through the rivet with an M3 tap.
  • Temporary bodges include putting the plastic end of a cable tie down one side of the stripped thread and using it as a ‘Rawlplug’ or using a wing-nut behind the headset lug.
  • Probably most effective is simply to have the holes aluminium welded, drilled and re-tapped to M3, but this will require the headset to be repainted.

A pack of 10 M3 rivet nuts only costs around £2.50 including delivery from www.memfast.co.uk
A pack of 10 M3 rivet nuts only costs around £2.50 including delivery from www.memfast.co.uk

Sadly most of these methods require either some skill or special tools, however thanks to the members of the LCGB forum (www.ilambretta.com) we’ve tested a simpler method that only requires a drill, some epoxy glue (e.g. Araldite) and the purchase of some special rivet nuts (‘rivnuts’). These can be purchased in the correct M3 thread size in small quantities by mail order.

If you have any good scooter repair tips or bodges, please send them in.

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Thread the rivet nut onto a headlight screw as shown, apply glue and pull into position in the hole. The flange on the rivet nut ensures that it can never pull through the lug.

Assemble the headlight and rim and screw assembly together to hold the rivet nuts firmly in position while the glue sets.
Assemble the headlight and rim and screw assembly together to hold the rivet nuts firmly in position while the glue sets.
Once the glue has set you end up with a stainless steel thread in the hole which is stronger and more durable than the original aluminium one.
Once the glue has set you end up with a stainless steel thread in the hole which is stronger and more durable than the original aluminium one.
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