How To Replace a Vespa Gear Cable
Before You Get Started
The world is an imperfect place. Screws come loose and cables break all the time. A broken gear cable can be a bummer, but it isn't all that hard to rectify. Here we have a Vespa Rally 200 with a broken gear cable. The procedure will be the same for any 60's to mid-70's Vespa.
First, you'll need to remove the headlight bezel and headlight. Depending on which cable you broke, you may also need to remove the speedometer. In this case, I broke the one that is at the front of the headset, so I didn't need to take out the speedo (see the above picture). Once you have access to the cables, pull the broken one out - either from the top, or the bottom, depending on where it broke.
The tools you will need for this job include all of your basic metric hand tools, including screwdrivers, sockets, and wrenches. In addition, it is very helpful to have a specialzied "third hand tool" for cable adjustment. You'll want to have some sort of pan to catch some case oil as well.
If you need to get to the rear cable, the speedo is held in by one screw, which is located at the bottom center of the headset. It is helpful if you push the speedo cable up from the bottom a bit to give yourself some slack. Before you remove the speedo entirely from the cable, slip a zip-tie around the cable below the top of the cable. That way the top cable nut won't fall down the forks (ask me how I know!).
Here is a close up view of the inside of the headset with the broken cable removed. Note that the top of the cable is held in place by a little aluminum "nubbin", which fits into the bracket on the bottom of the headset. At this point, you want to remove the cable housing from the gear selector box at the bottom of the housing. If you don't, it will be very difficult to get the cable inner through the housing once it reaches the bottom because it will hit the selector box.
Putting in the New Cable
Slip your new cable into the housing, making sure you get it through the nubbin at the top. Once you have it going well into the housing, start to lube up your cable. I use grease, but others use different spray cable lubes. Slide the cable through the housing all the way. You may have to do a bit of jiggling up and down of the cable inner to get it all the way through the housing.
Here we see the cable inner coming out at the bottom of the housing. Once you have it all the way through the end, you want to give yourself ample slack at the top. With a lot of slack in the cable, insert the round cable barrel end into the top handlebar housing. Once the top is in the handlebar, then pull the slack out of the inner cable from the bottom.
Adjusting the Cables
Next, remove the gear selector box from the motor. It comes off by removing the two nuts on either side of the selector box. Make sure to have a tray under the selector, oil will drip out. With the selector box off the scooter, it is much easier to get the cables adjusted. Move the selector to "neutral". Then move the handle on the handlebars to "neutral", so the cable is lined up.
Making sure that your alignment is still at neutral at the top handle, put on the pinchbolt and use the third hand tool to take the slack out of the other cable. This may take awhile, but be patient and get it right. Once the cables are set, move the handle at the headset through the gears to make sure you have it spot on. If there is still a little slack in the cables, you can use the cable adjusters to tighten them up. If it is more than a little slack, loosen the pinchbolt of the offending cable, and re-adjust it.
With the cables in alignment, it is time to put the gear selector box back on the motor. If your gasket is damaged, now is a good time to replace it. The best way to get the selector box back on the motor is to move the selector arm all the way towards the motor. Then, hook it around the end of the gear selector spindle. Once it is hooked on, then push the selector onto the case studs while gently turning the gear handle on the headset. You may have to lightly tap the selector box with a rubber mallet to help it along. Once it is home on the case, simply put the two nuts back on to secure it.
At the headset, you will need to put the headlight, headlight bezel back on. If you removed the speedometer, replace that first, before the headlight. Once that is done, you're ready to roll with your new cable!