Modern Vespa

Hey,

I have a Vespa LX 50, and I recently changed the front brake lever.
But after the bike was put back together after installing the new lever, the front wheel was locked.
I replaced the lever as video guides and my haynes manual directed though.

Has this happened to anyone else?

Does anyone know how I can fix this?

Many thanks,

Josh

Was it an original-equipment brake lever or aftermarket?

The only thing I can think of off the top of my head that would lock up a hydraulically actuated front brake like this would be if the new lever depressed the master brake cylinder slightly more than the old one due to a slight difference in dimensional tolerances.

Is there any "free play" in the new lever? If not, then this is likely the problem.

No chance that you may have used a lever designed for the left side mechanical brake on the right, is there?

Thanks for the reply,

The lever matches the old one, the only reason I replaced it was because of the ball missing of the end. The only difference I can see is that the piece that pushes on the plunger type thing (sorry for my un-technical description, I'm new to bikes) is slightly longer. There is no free play in the lever, in fact it's rather stiff.

Do you know any solutions to this?

Thanks

Well, the longer boss pressing on the plunger would certainly do it.

The only solutions I can see if you want to use this new lever are either to grind or file enough metal off the boss to exactly match the old lever or to bleed a bit of fluid out of the system at the caliper. You do need an inch or so of free play at the end of the lever

Okay, I think I'd rather bleed some of the fluid out than grind down a new part.
Are there guides online on how to do this? Or is it straight forward?

Thanks again

Bleeding hydraulic fluid out is bad advice with little chance of success and could be dangerous.

Hydraulic lines need to be full of fluid...ie air free.(bubble free)

It needs new fluid anyway, so I'll replace the fluid while making sure it's the right level at the same time.

I think its possibly wrong lever ,even if it looks the same
its fitted on too tight so its putting brake on,
i have this happen on a 100cc fly i dropped it and broke lever,one i fitted did same as yours ,
i changed lever again

The part I ordered was an official Piaggio Vesper one made for the LX50... I highly doubt it's the wrong part. What could really go wrong with bleeding the brake line? As long as I keep the reservoir filled and don't rush it... It should be fine?

Bleeding a brake line is about removing all the air in the lines from the reservoir to the calliper pistons..

Its not just a matter of filling the reservoir to a level line.

You do not want any air in the system at all.

There is a process for doing it.

I am sure you will find a Youtube tutorial on the subject or maybe a sticky FAQ here somewhere.

There is a possibility that they shipped you the wrong part or your dealer made a mistake in the order.

Bleeding the brake won't help with this problem. Filing or grinding the lever to suit is the right course.

Not bleeding the brake as such, just removing some of the oil to release the pressure. Surely that'll work?

there is something wrong with this picture. I know you said you "ordered" the correct part, but did you get the correct part. You shouldn't have to file off the lever, and the brake fluid should not need bleeding other than for air in the system. Have you compared the new lever to the old one? Are they identical at the point where the lever presses the master cylinder piston?

The lever that was on the bike was not the original, it was a cheap copy part that broke. The lever I bought is the actual replacement part. Surely releasing the pressure in the system by taking some of the oil out would work?

I have informed you ...that wont work. Hydraulics rely on the line being full. They are not under pressure until you squeezee the brake.

If you dump fluid..you put aiir in the line..and thats what you might grab when you really need some brakes.

Whatever... like JIMC confirmed...this is not the cause of your issue.

Get an expert to take a look maybe for your own safetys sake.

There must be some free play between the lever and the master cylinder piston. Period. How you get that freeplay I can't answer without seeing the set-up...

Try this. Take off the lever. Can you move the bike? Put the lever back on. Is it locked again? If so, you are going to have to solve the freeplay problem. The lever is engaging the brake even when seemingly at rest.

Best of luck,

John

I can't believe I didn't think things through any better than I did. I've been bleeding brakes, hydraulic clutches, and other hydraulic systems since about 1967 and should know better by now.

I was thinking (or perhaps not) it would be possible to bleed a bit of fluid out without introducing air, reducing the volume in the pressurized part of the system and allowing the master cylinder piston to be a bit more recessed. Of course, it is impossible to do this in any system that is designed to have the volume automatically replenished from the reservoir through the master cylinder check valve. Doh!

Grinding or filing the lever is really the only solution to using the new one you've got.

I can't even blame my stupid suggestion on wine or tryptophan because I hadn't eaten my Thanksgiving meal... guess I'll have to use encroaching senility.

I understand now I cannot let a bit of fluid out. what I don not understand is how they managed to get the plunger farther out to suit the the smaller lever. If they managed to get it out, surely I can get it back to its original position?

I am so grateful for your help.

Again, I'm flying a little blind here as I don't have your bike in front of me...

The master cylinder piston (plunger) in virtually all hydraulic systems worldwide is retained by an e-clip placed into a groove cut at the end of the cylinder. To move the piston further out as you suggest would require a new internal groove cut closer to the end, something really not possible. And if the e*-clip isn't in there, the piston would slide out of the end when the lever was off.

Like I suggested, take the lever off. Does the bike move? Then the lever is your problem...

You're welcome, but how about pics of the levers and M/C? Then I can thank you!

Cheers!

John

*edit- of course it's a c-clip. I'm generally not allowed to respond to anything before coffee. Now everyone can see why...

They didn't. You either have the wrong part (and yes that's quite possible, even in an OEM sealed package with the part number on it, BTDTGTTS) or something else has changed. If the lever otherwise fits, just file it a tad - it shouldn't need much. I'm assuming you checked the pistons are clean and not sticking in the caliper, the pad retaining pin(s) are free of corrosion, and the master cylinder hasn't twisted on the bars so the lever is caught by the plastic (seen that before as well, especially after an 'off')...

Another reason that you can't just bleed out excess pressure is that there is a hole in the bottom of the reservois on the master cylinder. it is open to the cylinder whenever the piston is fully retracted. When the caliper heats up under normal use the fluid expands pushing back up the brake line, into the master cylinder and thgrough the hole and back into the reservois. If the piston in the master cylinder is not fully retracted, exposine the hole then pressure will build up and cause the brake to drag and create even more heat.

Time for scientific method, it still exists despite all attempts to kill it.

Everything worked with old lever.

Doesn't work with new lever.

Install old lever again. Does everything work? I thought so.

It's the lever.

You got the wrong part.

Return it and get the right part.

Do not bleed your hydraulics. If you don't know how hydraulics work, look it up.

P.