Modern Vespa

Greetings from the central mediterranean.

I was wondering if anyone had any problems with the rear brakes in a Vespa300 GTS. I use the scooter daily till I garaged it for a month. When using it again the rear brake handle was stuck. I took it to the local mechanic and he applied pressure and it gave way. However now it's gets stuck frequently even when driving making it dangerous to drive. The scooter is practically new (bought 2019) and the handle gives way only when I stop the bike and apply pressure using two hands.

Anyone had a similar experience ? I'm asking before going to my local mechanic so that I'll sort of know what he's doing, if you get the drift?

Has this model been recalled in the USA because of similar problems?

Thank you all and great site.

You apply pressure to the rear brake lever with two hands? Hmm...

Either way, this sounds like a master cylinder fault.

Or the caliper is stuck. That could happen to any bike.

But would that make the lever itself stuck in position?

I'd say there's such a possibility. But of course you're right that the master cylinder is more common.

Also it reminds me a silly thing which I found by my own dumbness this summer. But it is related to warmth of the brake fluid. Here's how it happened and what exactly:

1. A year ago I've changed the brake fluid in my Big Beo's front brake. I've topped up the reservoir up to the correct level and probably slightly more.
2. Some months after I've changed the brake pads. All was fine.
3. When the air temp became REALLY HOT, my front lever got stuck too. It was very hard to squeeze it, and if I used some force (I'm a big guy), it squeaked somewhere inside the master cylinder as if rubber rubs of rubber (but actuated the brake)
4. When temp lowered, brake worked again.

So, here's what happened: when I topped the reservoir, the pads were thin, but when I replaced them, the level in the reservoir became much higher. When the weather was hot, the level even increased because of expansion. That caused pressure inside the brake line and master cylinder, which caused brake pads rubbing of brake disk (without real brake force), which, in turn, warmed up the pads and the brake fluid causing even more expansion. And when there's some pressure in the line, the master cylinder won't work as it should.

So theoretically if the reservoir is overfilled, same could happen even in December.

There's also the possibility of corroded locating pins that stop the pads moving freely - this can cause all sorts of strange feel to the brakes.

Water / moisture in the brake fluid?

The brakes themselves would work even if pure water is flushed instead of brake fluid. The only thing is that they will quit working if overheated. So no, some water won't harm brake system work when it is cold.

Have you checked if your VIN belongs to the recalled vehicles that had brake related problems??

I'm checking as this bike is not a US consignment. Thanks

Thanks for this
The strange thing is that this happened after the bike was idle for a month. No problems immediately before that. Now when I apply pressure the handle releases and the brake works but then after a while it goes rigid again.

try http://recall.piaggiogroup.com/

This would be my guess.

And it's free and easy to check and correct if necessary. Infinitely cheaper than a new master cylinder...

Jimc I suspect is right about the pads sticking on the locating pins and not sliding. It's rare to have any issues with the master cylinder, but that can't be totally ruled out. If the master cylinder is overfull that must be addressed as it will cause issues as has been said by others. So check that too maybe first. When a bike is laid up even for a short while brake dust can cause a little extra corrosion to take hold on caliper pins etc causing this sticking issue with pads.

You might like to check that the caliper is mounted securely too. A very loose caliper has been known to cause some issues with the brake fluid level as it actually can lead to the caliper moving about over bumps etc and causing a 'pumping' action causing a raised level of fluid in the master cylinder.

If those things aren't the issue my next action would be to pop the rear wheel out and de-mount the caliper. Don't undo the hydraulics but just unclip the hose from the transmission case so you can move it about a bit. Next take out the pad locating pin and inspect. Give it a clean. If it's in good condition and nice and corrosion free then just clean it up. Pop the pads out and make sure they too are clean. Clean the dust out from around the piston and make sure the caliper is clean and not leaking. DO NOT put any pressure on the brake lever if the pads are not located in the caliper with caliper mounted on disc as this will cause the piston to pop out and you'll lose you fluid and make a mess! If everything looks good and you've cleaned up the brake pads and their sliding points, reassemble. You can put a little dry lubricant on the locating pin and any other sliding points that the pads come into contact with. Some like to use copper slip, just a tiny bit and that's ok. A little white grease is also ok but it needs to be heat resistant. And remember, only use a tiny tiny bit as grease and brakes don't actually mix well! I can't see you'll have any issues if you do these things, unless their is something more fundamentally wrong with the braking system mc or abs pump.

Thanks guys. I'll let you know next week.

Just got back from the Vespa dealer. He said the ABS is faulty and has to be changed. A new ABS costs around $900 and the scooter is only 2 1/2 years old!

That's pretty unusual. Get dealer to double check that there hasn't been a recall on the abs pump. If not, it's worth contacting Piaggio to see if there's some "goodwill" warranty to cover part of the cost of the repair. If mileage is low this may help. I've known them to help sometimes even 6 months out of warranty. Otherwise that's tough luck. Good luck!