Modern Vespa

Went through the front of my new-to-me S150 about a month ago and found a bunch of things that needed to be replaced/upgraded - brake pads (plates had rusted, knocking the pads loose), brake caliper (discovered corroded and frozen, binding the front wheel), master cylinder (stripped the screw heads while attempting to open, not worth surgery), Stebel horn, BT TPMS, jacked up the pilot jet to size 38, added a few more LEDs...and replaced the speedometer cable (cracked, leaking grease, and not functioning) and worm gear (a little worn, no way that was going back in after all the rest of this had been disassembled).

Note: it IS possible to feed that speedo cable up from the bottom. I loosened the shock nuts, spritzed the area with Teflon, and used a duct-tape "tail" to lead it through the small hole in the fender. It did, eventually, wander through. And the rest was easy...

...almost. Everything is up and running except the speedometer, and the reason is the new cable. The cable turns as the wheel revolves, counterclockwise, as it should. There is a white "keeper" on the speedometer side of the cable, I'll call it a ferrule, intended to guide the cable into the speedometer housing and, I believe, keep the cable from slipping down too far in the sleeve and out of the housing.

It initially did not allow enough of the cable end to poke out to engage the speedometer housing (see the difference in length in the photo below). I was able to adjust it to the old cable's length (green ferrule in photo) with a set of pliers, but that seems to have loosened its grasp on the cable overall somewhat, and it didn't stay put. I cleaned the lubricant off as best I could (ie, not very well) and added a dollop of superglue, to no avail. The cable just wants to slide down too far to stay engaged with the speedo gear.

What have I done wrong, and what should I do to get that darn square bit to stay in the speedo housing?

Unless there's more there than the photo shows, that's an incorrect part, and the one on the left is missing bits also.

[EDIT: Wait, that's just the cable end, not the retaining clip that's part of the cable "outer" housing. Text adjusted to correct this.]

On mine (also an '09) the cable outer housing terminates in a retainer that has two prongs parallel to the cable end, that project into the speedometer housing, and around them an O-ring.

On installation, the prongs go into the housing and the O-ring is slid up against the housing to pull the prongs together so they latch in the housing. (Note: I may have this backwards and the O-ring pushes the prongs apart. It's been a couple of months since had the headset open... but sliding the O-ring up toward the housing is definitely what locks the cable into place.)

I do not recall the part number, only that I once ordered a replacement (before taking the headset apart) and found it was for the LX or LXV when I went to do the task. The "wrong one" had a ferrule with threads on the (inside? pretty sure about that - that was 17,000 miles ago) and was meant to be twisted/screwed into place.

I reinstalled the original, as it had merely slipped out of place. I'm pretty sure it was a dealer-prep fault in not properly positioning the O-ring (not normal dealer prep; they'd swapped out the headlight as it had been cracked in storage or handing).


Edited to add: Wish I'd taken pictures when I had it all apart for doing the Euro-lights mod....

Thanks very much. Yes, there's more to the installation - the "cup" or "retainer" with the two prongs that holds this into the housing is out of the photo. I pulled the inner cable and the ferrule out a bit to show the detail.

Your description of how that O-ring is intended to be slid up and down that pronged retaining cup is helpful, and wasn't obvious when I removed the old cable. I see that the O-ring goes between the prongs and the cup. It is slid down when the cup is snapped into the housing, out of the way of the prongs so they can swing in to engage in the housing, and then gets pushed up towards the housing, sort of locking the prongs in place, interfering with them so they can't easily move in and disengage from the housing.

I'm pretty sure I don't have that O-ring positioned correctly and will look at that again this week. But I don't think that's my problem. The speedo works for about two minutes once the cable length past the ferrule is set, then the ferrule slips up and the inner cable disengages. The retaining cup stays connected just fine regardless of the O-ring situation for these few minutes.

So you noticed the hard way that this is one of the few internal components that differs between the S, and the LX/LXV. I definitely have the part intended for the S. However, there are also two versions of the S cable: the all-plastic new version, and what I guess is the original version with a metal clip at the bottom of the cup. I believe the one I removed is the original version (and you can see from the cable at the very bottom of the photo that it was mightily messed up):

Version 1, $10, all plastic, "model 650836, replaces 649623, 650836"
https://scooterpartsco.com/recambi-scooter/pontedera/vespa-s-50-and-s-150-speedometer-cable

Version 2, $16, a bit of metal on the retaining cup, "model 649623"
https://scooterpartsco.com/recambi-scooter/pontedera/vespa-s-50-and-s-150-speedometer-cable-p-22277

I am not eager to run another one of these cables through that stupid tiny hole in the fender!

Ok, got it, and you do have the correct cable.

Not sure why the ferrule slips on the cable.

You may have to get another cable, but it could be fixable.

The problem is that the ferrule is nylon, and it's really hard to get anything to stick to that. If the ferrule comes all the way off the cable, cut grooves or small notches in the sides of the center hole, put epoxy on the cable where the ferrule will be, then slide the ferrule into place over the epoxy. The idea here is that the epoxy will engage the grooves/notches, since it won't bond to the material of the ferrule itself. Mask off the cable below the ferrule's final position so it doesn't get saturated with glue. You might consider carefully greasing the cable up to the edge of the ferrule's final position to keep the epoxy from wicking down the cable.

These grooves could be made with a paper clip, straightened and heated with a soldering iron.

Otherwise,

My first approach would be to use Plasti-Zap adhesive (clean out any grease first). Saturate the cable with it where the ferrule will be positioned, then slide the ferrule over the glue-soaked section of cable.

It's basically superglue, but it's a hobby-grade formula intended for bonding plastics rather than the mass-market general-purpose stuff. Look for a local hobby shop that specializes in radio-controlled model aircraft and/or drones -- they should carry it

Here's something of the sort on Amazon, as an example. No endorsement intended, though you may want the accelerator spray mentioned at the link as well as the adhesive.

This will probably work, and if it does it will likely hold for a while.

My second approach would be to drill and tap a hole for a very short grub screw, though I'm not sure you could get one small enough.

My third approach (and it's near-desperation, as there's a fair chance it'll ruin the ferrule instead of bonding it to the cable) might be to attempt to melt the ferrule back onto the cable. Use a butane or propane torch, or maybe even a soldering iron, to heat the cable. Be careful that you don't melt so much that the cable shifts sideways and ends up off-center.

Those are CAPITAL ideas, thank you!! The grubscrew in particular, perhaps coupled with the epoxy. I don't think the ferrule is so tiny as to preclude an off-the-shelf grubscrew.

EDIT: or opposing grubscrews; no harder to drill....

Followup: I drilled and tapped a hole, and tried to place a grub screw, but the ferrule walls are too thin and even grinding down the outside of a screw once placed would be ineffective.

So I used a healthy dose of Plasti-Zap, running plenty of it into the hole drilled for the grub screw, and above the ferrule, to make it hard for the cable to slip down through the ferrule and out of the speedo housing.

I gave it all plenty of time to harden, and: IT SEEMS TO BE WORKING. I rode it about six miles at various speeds. Very encouraging.

Not sure if the reason it's working is the higher quality of PlastiZap compared to the homestyle superglue; the additional time I left it to cure before use; the slight extra length I left the cable sticking though the ferrule; or if the grub screw hole allows the PlastiZap to better encompass the ferrule.

Thank you for the suggestions, Rusty J!

Next project will be to test the reported speedo speed against GPS.

There is only one Piaggio cable for the S 150 and S 50, and it fits all of them. No matter what part number you order, you get the same cable. Sometimes Piaggio will change a part or part number, but the listing on a distributor's website doesn't get updated. Or the photo used is a generic part, because the person listing the part will list several different similar parts at once and use the same photo. Make sure the end of the cable is inside the speedometer gear, and not pushing against it, and you should be fine. Now that you've glued it on, what are you going to do if the cable breaks again?

Two entries on the website...multiple part numbers...two different prices...two different pictures...both versions in my hand...most photos online of the old part...please pardon my assumption that there were two versions of the same part. I think I also saw both new and old part numbers offered simultaneously on other websites with different prices but I can't find them now. Perhaps I was mistaken.

I glued the ferrule onto the cable. The ferrule spins along with the cable, allowing the cable to drive the speedo/odo, and their being permanently joined is the way the system is designed. (I did not glue the cable housing into the speedo.) What if it breaks again? Not sure I understand the significance of the question. I'll do the same as I would have done if the glue hadn't worked this time, except with all new swear words developed specifically for this situation: extra crude.

I'll glue it again if it lasted long enough, maybe trying epoxy or superglue-with-baking-soda instead of the straight superglue.

Or I'll tightly run a wrap or two of fine wire around the cable just above the ferrule, like a twistie on a bread bag, to act as a cleat.

Or I'll try to swage or solder a tiny piece of copper around the cable instead of the fine wire, like a small sinker on a fishing line.

Or I'll try to melt the ferrule onto the cable.

Or I'll pull the inner cable entirely out of the outer cable jacket and just replace it with the $13 spare I have coming.

Or I'll rerun the entire inner and outer cable again if the outer is damaged, which was a PITA but will be less so now that I know that it can definitely be done.

I wouldn't have caught it if I didn't see it here. We have over 10K skus, and there are two of us running the place, in addition to a few offsite data entry and website maintenance people. So occasionally something slips through the cracks.
Here's another good example of what happens when Piaggio changes a part... The topbox lock set was changed, and now the keys are square. Most companies are using the old photo with the Vespa shaped keys, because it's more popular, and they will tell you that Piaggio changed it after you get the part. But no matter where you buy it, if it's the OEM Piaggio part, you are getting square keys, because that's what Piaggio supplies now.

One of our accomplishments is that we have the best prices in the US on OEM Piaggio parts. There are companies that charge higher prices than we do, and they have started using tricks like using old part numbers or making up their own part numbers, so you wonder if we are selling the same parts. I don't think that's fair. So, if we catch it, we create a listing of the item with their part number, so people can find it who go to their site first then use google to price compare, and we use the current Piaggio part number in a separate listing, that we put in the different model categories. Somehow the price on our listing using an old part number, that is used to list the item on another site, didn't get changed when we accidently got 120 cables in for the S model, instead of the 12 we ordered, and decided to give them away instead of look at them for the next fifteen years. But no matter where you get it, unless you get a cable that has been sitting in a warehouse for ages, you are getting the same part.