Modern Vespa

I just got this bike up and running after 4 years sitting. When I rolled it out, the speedometer cable mangled itself...so I just replaced it.

As I was rolling around testing it (it seems to be working), I noticed a knocking sound coming from the dashboard.

It's not the engine, it's not the front wheel...it's not in time with any of that. I gather that it's something connected to the speedometer cable.

Is this something that's commonly related to speedometer cable replacement, or could it just be another problem I've found (this scooter is a snowball disaster)

I've had to replace the:

Headlight
Hoses / Fuel Line
Fuel Tap
Brake Pads
Variator rollers
Drive Belt
Tires
Battery
Intake manifold gasket
Speedometer cable...

...and now... ga-dunk, ga-dunk, ga-dunk from the dash.

*sigh*. I just want to sell this thing already.

Did you replace the entire speedo cable and housing or just the inner cable part. If you replaced only the inner cable part it is probably busy eating itself rotating inside the dry housing, especially if the cable makes a sharp bend. Take the inner cable out and w/ good brg grease ( put grease in your hand), rotate the inner cable through your closed hand w/the grease while feeding the inner cable back inside. Thin spray aerosol is not very good, grease is. Also -if the old cable was rusted inside, there is probably some still in there. Bad,bad,bad. If you have the money, just replace the entire inner and outter speedo cable. The noise is probably the inner cable in a bind trying to rotate, jump,rotate,jump,etc.

I replaced the entire cable and I greased the inner cable thoroughly. I also replaced the gear at the wheel.

What I'm wondering at this point is if there's resistance inside of the dash where the cable connects that's causing the square pin to slip, and which led to the original cable failing. If there was, I would think that the speedometer wouldn't read correctly at all, but it does read when it rolls. It could be something else in side of the dash that's failing, no?

At this point, I'm going to need to manually turn and test the mechanical connections independently.

Another thing that I did while I was rolling at about 10mph was to feel along the cable (the column is still exposed) to see if there was any abnormal vibration that matched the sound frequency...but the cable feels smooth and isn't ticking along with it.

Well ,you eliminated what I though was the issue, sorry. Just a thought- if you unhook the speedo cable from the speedo head, go for short ride, does noise go away ? That would eliminate the possibility of the speedo cable causing the noise IMO. Therefore more searching is required. Also if you do that and no change, can you disconnect speedo cable at the drive end and spin with a drill to see if it is related to the speedo head ? If all else- consult Yoda.

I'm about to transition to the dark side, which could put Yoda on the defensive. So...there's that.

I think it's actually ticking down at the wheel, which means I need to jack it up and find a way to spin the wheel while I futz with the cable connection. It's definitely not in the dash.

It could be something else altogether. Who knows at this point?!

I don't know if this works on an ET4, but on an LX or GTS you can upturn the pet carrier and rest the frame on that while you deal with the front wheel.

I just put a jack under the footrest and lifted it about 1/2". Seems that the sound is coming from where the cable inserts into the wheely thing. I pulled that out and pulled out the gear in there and rolled around and had no symptoms.

I did replace the gear, but I'm going to clean and put the old one back in.

For clarification sake, is the speedometer cable basically held in place by the springy metal hook attached to the 6mm bolt on the caliper and the rubber gasket around the cable sheath?

My guess is that the cable is turning, but it's wobbling a bit because it's not secured...or the gear isn't the right size. I'm comparing the two as soon as the old one is cleaned off.

20 years old and stood for 4 years in Arizona Is it not super hot for 300 days of the year there I'd expect some problems, In with your list of replacements hope you have changed the gear box/engine oils and fluids.

If you still have the inner of the old cable try this test cut around 150mm or what you can off the speedo end and put it in a variable speed drill and insert it in the speedo and slowly rotate this will tell you if its the speedo, then the same with the other end rotate the wheel while holding the cable if you feel resistance or grinding in your fingers that's your starting point to the problem, if its worm drive it may just need lubrication 😉👍

Success! Turns out the cable just wasn't seated perfectly at the wheel and it was slightly angled, causing a clunky clunk.

In Arizona, to get this bike back up and running I had to completely overhaul all of the lines, the fluids, new variator rollers, new drive belt, some new wires, a new intake manifold gasket, new oil, new oil filter, new fuel tap...

and thanks a lot Walbro...I couldn't find a new float bowl gasket so it has a new carburetor (so dumb), new fuses, brakes, air filter, blah blah on and on.

I greased the new speedometer cable inner springy thingy, the new speedo gear, etc., and greased everywhere grease is needed.

New battery too, and new tires.

Now I just need a seat cover to replace the vinyl that's no longer there. Foam is still good...but it seems seat covers are in short supply.

As of this moment, I have a healthy bike that's running like a champ.

Is 8000 miles low mileage for a 20 year old bike? Wondering what this thing is worth on the open market. I paid $2500 for it 10 years ago when it had less than 500 miles on it.

Check out Cheeky Seats for a seat cover, they are very good.

Thanks for the tip. I had found them before but they didn't have any black seat covers available. I think the blue one might suffice.