Modern Vespa

Hey guys,
Mystery:
When I back my scoot out of the garage, the front tire seems to lock up a bit. It isn't constant and doesn't always happen.
There's also a rubbing sound(?) when it binds. This started all of a sudden last week. Nothing rolling forward.
Strange thing is, the wheel spins freely on the center stand in both directions.
Any ideas as far as what to look for?

Speedo gear getting chewed up a little. Check your rubber bushing holding the brass bushing above the speedo gear, and speedo gear. Replace both if the gear is chewed up.

If the rubber bushing is worn, then there is too much play in the speedo gear and when you back up, it allows the gear itself to try to walk out the hole. It then gets caught, jammed and chewed up. Going forward seats it back. This is why it only presents itself going backwards.

Wow, thanks!

Just realized you are on older model. Not sure what the speedo gear parts are on the model you have. I was mentioning rubber and metal bushings for p/Stella speedo gears.

Just pulled the gear. The grease is like clay.
Grease fitting is missing.

I don't think that spacer/washer should be between the nut and the grease sleeve. The fitting should thread farther into the arm to locate the pinion properly.

Deceiving picture. There is no washer there.
Cleaned everything up and put em back in. Never seen grease turn into that. Almost like someone reached for construction adhesive instead of grease.

Still slight binding going backwards, so maybe some spacer/washer should be somewhere there. I see the repair kit comes with one. Funny thing is, now the speedo needle wobble is gone. Thought I was just going to have to live with that.

Yes, I see it now. The collar is not up against the nut. With your front wheel off the ground can you feel the binding just turning the wheel backwards ? You may be able to determine what's binding by the feel. The only thing I can think of that could really drag are the brake shoes. I don't see how that little pinion gear ( even with dry grease ) would be noticeable.

I think you're right. I removed the pinion altogether and there's still that binding while backing up issue. Seems worse now.
Strange though, the wheel spins freely both ways with the bike on the center stand. Binds only when there's weight on the wheel.

Maybe the axle bearings have too much play and when there's weight on the wheel it turns "crooked" so the brake pads rub inside the drum??

Is there any play in the wheel/axle?

Take the weight off the front tire and see is you have any play from side to side. If so, maybe just tightening the axle nut may fix it? Just a thought....

I took a quick video. The speedo is out.
The binding isn't constant or consistent. And rolling forward there is nothing.

https://youtube.com/shorts/BhI0qnOi1rA?feature=share

No play at all.
I'm going to take it apart tomorrow.

You could try just adding a bit of slack to the front brake cable and maybe it will only happen when you apply the brake and may wear itself in.

I can't wait to find out what the root cause of this is, because there's just not that much in there to fail, and what little is in there is inherently bi-directional, e.g. the bearings.

Maybe there's a piece of something that broke off and is sitting such that it only binds in reverse.

Sounds like a brake shoe to me.

Tried slackening the brake cable yesterday. No change.
Today disconnected the cable and now no binding at all.
I have some parts and a proper scissor lift coming tomorrow. I'll pin it down by Friday.
Thanks, guys.

One of the nice features of the Vespa is that the brakes are so accessible. You can just remove the hub nut and pop the drum/wheel off to look.
edit : Does not apply all , like 8" hubs

It'll be interesting to know what it is.
Weak return spring?
Cable with to much friction, maybe a frayed cable?
Brake handle pivot point sticky causing issues?
That little part that rotates to separate or move the brake shoes apart sticky? Maybe old grease?

Maybe a few of the above from a lack of preventative maintenance?

Enquiring minds want to know.

On these brakes, in normal rotation, the upper shoe is the leading shoe and is forced against the pivot pin. The lower shoe is the trailing shoe and is pulled off the pin. They obviously wear in the forward direction. When you roll backwards, the forces are reversed and if there's wear at the pin, for instance, (wouldn't be surprised based on the lack of lube on the speedo pinion) one of the shoes can vibrate. You may be able to just clean the faces of the shoes and the inside of the drum with some 100 grit paper and get any dust off of the parts with some brake cleaner and lube the pin and find it goes away.
You may just need new shoes.

Packages arrived late today. I'll open everything tomorrow.
Few things:
I've been riding with the the SIP brake upgrade kit for about six months. It's been a great improvement, but maybe it has allowed me too much of a razor's edge cable adjustment.
https://www.sip-scootershop.com/en/product/brake-kit-sip-performance-front-vbb-style_23208620?cr=e993ab67-6807-4109-bbed-f6374ebf9f9b&gclid=Cj0KCQjw5uWGBhCTARIsAL70sLJkhq7oZ1vMlGUPp1LOIhs67okcz3cCypf9_eGTgvDNJQy-HDZ8JBsaAjJXEALw_wcB
I suspect there's a binding effect going on with the original (too long) cable housing when weight is applied to the front end. The kit comes with a new cable housing. Still have it. Just got stupid lazy, after just having pulled new cables on the bike.
I think that's the only thing that changes between spinning freely on the center stand and binding with weight on it.
And there's that construction adhesive level old grease.

Okay, opened it up.
First, I was able by hand to duplicate the cable housing bending with weight on the bike. Brakes engaged enough to make trouble. Maybe a clue.
There's a lot of sticky grease filling both bearings. Neither spins without effort.
Nothing like the hard grease on the pinion and the corresponding teeth on the axle. I remember someone telling me that mixing different types of grease can lead to trouble like that.

There is axle play.
https://youtube.com/shorts/hJNFCOR1eLs?feature=share

The axle looks worn where it meets that crusty bearing.

Lever had no grease at all. Dry as a bone.

Another clue(?)
Bearing spacer stuck in there, sideways. Probably been there for years.
Googled effects of mixing different types of grease. Definitely seeing that around the pinion.

It can, also just plain old grease that is old and full of dirt will turn into a crusty mess.

Looks like it has gone years without any preventative maintenance. Then it becomes corrective maintenance. Wonder if there is a checklist for required PM anywhere. Maybe a service station manual?

ok, everyone get ready to laugh or make wise cracks, but when I rebuilt something, can't remember if it was the front end of my p200e, which I did rebuild, or even a machine tool, it could have been an electric motor, I can't remember, I found the bearing was made to turn freely only one way. It wasn't made to prevent it from turning in the opposite direction like a clutch, just that it would sort of lock up. So I called the bearing place in South San Francisco and they told me the problem, brought it back, they swapped it out.

The more I think about it the more I think it was my p200e because I remember sitting on it and trying to back it out of the garage and it was dragging the front tire. I could be mistaken and that was a separate problem, but I do remember going back and swapping the bearing. Old age, lots of repairs, too many machines, etc.

Okay done.
New bearings, pinion, grease. Put in the cable that came with the brake kit. Took 2" off outer, so now 43"
There were several odd things going on there, but I think the biggest one was the missing spacer for where the axle meets the smaller bearing -- the one that was found burred in old grease. Without that spacer the brake pads aligned too closely to the curved edge of the drum. This is a total guess. Anyway, working great now.
That SIP brake kit is an excellent upgrade, btw. A little spendy but worth it!

Glad to hear it's all finally sorted!