Finishing up the fork assembly
Most of the work I’ve done on the scoot so far has been aesthetic, other than Robbie’s once-over at Scooter Bottega, so while I’m in the weeds I’m going to replace the cables throughout the bike.

I’m using a pack of Prima scooter cables available at most online retailers. They come with everything you need for both a small or large frame vintage scooter minus one thing, a speedometer cable that is actually more of a worm-gear. It threads up from a geared cog on the front hub, up through the fork and into the speedo. Given it’s not a brake or other cable it’s one of the least likely to need replacing, but while I’m at it with the cables I figure I might as well give it some new love.

So, the task: replace the speedometer and front brake cables in the fork assembly. Following Richard Hoar’s advice at VespaMaintenance.com I bought some braided picture wire at Home Depot for the task of running a guide wire through the existing cable outers.

Replacing the front brake cable
The idea is to remove the existing cable, but only the inner cable, leaving the outer cable sheath in place through which to run a guide-wire. This wire is then used to run through the cable outer, and out into the new cable outer. You then tie a knot, and pull the whole thing back through the bike: the old cable outer, followed by the new cable outer until the new cable outer has completely replaced the old inside the scoot.

If you’re just replacing the cable inner, it’s an even simpler task: once the old inner is removed, you don’t need a guide-wire: just grease up a new inner and thread it through.

The picture wire is your guide. Most picture frame wires are only available in a nine-foot length, and this wouldn’t be long enough so I bought some by the foot, which was only available in one gauge (thickness.) I eyeballed it to be thick enough to bear some tugging but thin enough to go through the existing cable outer. I was wrong.

The wire was too thick to thread through the existing cable outer. Given the cable runs through just the fork I chanced my luck. Starting with the front brake cable, I decided to pull the old cable (inner and outer) completely out of the bike and pray I could feed a new one back in without the old cable to guide it.

I took a length of the picture wire, and wrapped some electrical tape around the end so it wouldn’t fray as I pushed it. I then fed it into the bottom of the fork and it slid easily through appearing at the top of the fork.

Feeding the guide-wire into the bottom of the fork.

The guide-wire has made it all the way through the fork and out the top.

Now the tricky part. Using more electrical tape, I tightly bound the end of the wire that had just poked out of the top of the fork to the new cable outer. I then pulled the wire back through the bike the way it had come (pulling out of the bottom) while feeding the new cable outer through the top so as to not stress the tape joint just by pulling.

Tightly joining the new cable outer to the guide-wire with tape.

Fortunately it worked like a charm, given that thankfully the fork is relatively straightforward with only one gentle S curve. The new cable outer came out through the bottom of the fork.

Before greasing up and threading through the new cable inner, one task specific to the front brake cable remains. About three inches from the top of the old cable there’s a break in the cable where the front-brake switch runs in-line. The front brake switch contains a small pressure plate that detects tension on the cable when you apply the brake caliper. This switch in turn lights the rear brake light. Neat, huh? Not all Vespas work in this manner, but it’s there on my PX.

Using another piece of electrical tape (handy stuff) I marked a length of the new cable from the top that matched the length of the old break in the cable. Using a hack saw I cut the cable at this point, and then to prevent wear on the cable ends, added a little of the tape to each end. Then it’s just a matter of running the switch in-line and threading the new cable through the whole thing.

Marking the correct cutting position for the in-line switch on the new cable outer (remember not to cut the inner!)

I’ll need some play in the brake cable to hook it up to the front brake caliper, so for now I’m not going to connect it at the hub. I’ll do that once the fork is back in the bike.

The speedo cable
The speedometer cable is threaded through in an identical manner, and is held in place at the base of the fork where it enters the hub by a small metal plate. This plate bites down on the cable by way of a small rubber grommet which grips the cable as the plate is tightened down.

It’s a little tricky to get to, but with an 8mm wrench I could slowly but surely loosen it a quarter-turn at a time. I cleaned up the bolt and plate with a little sandpaper and set them aside.

This is the bolt you need to loosen to free the old speedometer cable.

After removing the old cable in its entirety, I threaded the new cable outer through in exactly the same manner as the front brake and it went without a hitch. It was then just a matter of inserting the worm gear inside the cable deep into the hub as far as it would go and tighten down the metal plate to lock it in place. Getting at the bolt and plate in the small place is fiddly but doable.

The new cables in place at the top of the fork with the switch in-line. The top of the speedo cable has a plastic plug that plugs into the underside of the speedometer.

Finishing up
With the cables in place, it’s time to complete the front fork by adding the new front fender. This simply feeds over the top of the fork and is secured with three bolts on the top and one on the side. Nice to see the first part of my bike come back together.

The new front fender (and my inspection sticker) back in place.

Conclusion
The cables look good, but I’ll only know for sure once I hook them back up to the headset. Some scooterists have suggested that it can be a little tricky getting the worm-gear inside the front hub to line up exactly so I might need to play with that if it’s clear that the speedo isn’t clocking new mileage when the scoot is back on the road.

The only other point of concern I have is the brake-light switch, which took a bit of abuse as I disassembled the fork prior. It had caught on the upper bearing race. I’m also hoping that the way I cut the cable to insert the switch is adequate. The one I removed was a specific cable for the job that had neat metal end caps where the cable lengths met the switch. I’m not sure if these are necessary for correct operation. Again, I won’t know for sure until I have the fork back in the bike and the headset hooked up.

As far as threading the remaining cables is concerned. I’ll do that once the forks are back in the scoot. Given the cable lengths are longer and run through the body of the scoot, these are undoubtedly going to be tougher given my guide-wire is too thick. The Haynes manual suggests soldering the end of your new cable inner to the end of the old cable inner and pulling the two through the existing outer. Perhaps I’ll try this with the new cable inside its outer cable and then try and tug the whole thing through, old and new. We’ll see.

’til next time.

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