Is this normal behaviour?

[toemc]

And the reason why I could only select 1st gear?



Is this the correct dogleg too on a 100 Sport?

[jbcollier]

The large xmas tree gear should not be removable.

Can you tells us anything more? It was working fine then...

[toemc]

May 26, 2021 13:42:19 GMT jbcollier said:

The large xmas tree gear should not be removable.

Can you tells us anything more? It was working fine then...

I only put the top end together, thought the cables were the wrong way round as it would only select 1st gear. Couldn't move the selector externally. Stripped it and realised it was just spinning on the primary drive. The kick start gear is badly worn down too and the pedal was hitting the clutch arm. Still, it had new clutch plates in!

It basically fell off in my hand. Someone had made a bad job of locktight-ing it and scoring the shaft. Might explain why the bearing was stuck on too and came out of the housing when I split the cases.

Ordered the parts from VE for tomorrow but could only get a 22 tooth. Relieved I've stripped it now, dread the thought of it seizing up and throwing someone off.

[tzsteve]

i have something similar on my gear box
i used the top gear from a 3 speed box machined down to thickness
but mine is welded on

[jbcollier]

Those gears are not normally removable. They are an interference fit, not just a normal press fit. Loctite will not do the job.

Take everything apart and check for wear. Check the shimming of the gears on the output shaft. Check the gears to see if the engagement slots are rounded. Check that the selector is correct and its faces are square not rounded.

When the engine isn't running, you need to activate the clutch and spin the rear wheel to change gears.

[toemc]

There is absolutely no way I would ever locktite any gear component! I was being rhetorical in my first post because I was gobsmacked anyone tried it. The thought of passing a machine on like that with the potential consequences is reckless.

Thanks for your comments, everything else except the kickstart gear seems OK. Any observations on the BGM selector/cam?

[toemc]

[tzsteve]

not a very good fit
even welding is unlikely to do the job

[toemc]

My guess is that it's come off from either brute force removing the primary drive shaft or replacing the bearing. Hard to fathom how it's so slack now though unless it's from a different cluster.

[henri]

if the numbers on loose gears start with a 4 thats the correct selector for them , if gear numbers start with a 3 its the longer 51mm square shoulder selector needed .
thats if there original piaggio gears ,there are re-made gears which are all marked with 4's as thats the number on the stamp/mould to make the blanks .they are then machined differently to suit 3's or 4's .on a true 4/2nd series 4th gear the internal lug is 6.9mm wide ,on a 3/1st series 4th the lug is 4.5mm ,measuring these will confirm what loose gears you have got an which cruciform is needed .H

[toemc]

That's excellent info thanks H for your help. It's all disassembled so I'll check later when my new tree arrives before I put it back together 👍

[toemc]

I'm losing the will to live with this now. Dry built it with the new primary drive which had the same tolerances as the broken one. The kickstart gear was 0.75 taller than the old one and that was all on the seating face.

I was able to select all the gears with the casing off holding down the Xmas tree. Fitted the casing with primary drive bearing pressed home and its all really tight. It feels like the spring in the selector is way too strong. When I can find neutral the cruciform is dinking on a gear and the clearance on the assembled cluster to the end of the layshaft is 1mm. I'm sure this a bitsa from a spares box.