adjusting the six speed

[belfastguzzi]

Thanks BFG!

That is good evidence that the pin does something!!!

Does it have a lock nut?

Maybe it needs thread locking compound??????

I don't think there would be a locknut. Mine has the roll pin (top picture).

There was an assumption before that the pin was later replaced with the adjustable post, but it seems from this thread that it was the other way round: earlier models had the adjustable eccentric? Do the later bikes, say circa 2004... still have the roll pin or was there a change again? ~ Not that it makes any difference ~

 

As regards its purpose, Baldini wrote a coupla yrs ago: "I think the pin is a stop for pawl arm. Guess that w/o it, even against spring pressure, the pawl arm may come away too far from shift wheel pins & allow uncontrolled movement of wheel."

 

The position of the pin makes no difference to ease of parts assembly (Docc).

 

I think it's clear from all the previous discussion and trials and errors and then fixes, that THE thing that causes the spring fatigue and break is the mismatch of spring coil and boss sizes, which causes obvious binding, stress and then *snap*!

[docc]

So with my 15 mm boss, what broke my spring?

[Dan M]

So with my 15 mm boss, what broke my spring?

 

Did it break at the base of the long arm? Right next to the start of the bend? Seems they mostly break there. If the coil is bound and kept from flexing, that point gets the work. I think some of these springs are wound tight enough to grab a 15mm boss. Obviously if yours was, it wasn't by much - hence the long life. Couldn't be that Guzzi is using poor quality springs, could it?

[docc]

This one broke in the first coil. I checked it really closely in the upshift and found that the coils slide and twist outward on the boss. This boss had a little groove worn into it and I don't imagine the (flimsy) little spring liked being bent sideways.

 

Unfortunately I didn't have the insight at the time to look at the spring in downshift. As has been noted, that's when the coils tighten the most.

[Dan M]

This one broke in the first coil. I checked it really closely in the upshift and found that the coils slide and twist outward on the boss. This boss had a little groove worn into it and I don't imagine the (flimsy) little spring liked being bent sideways.

 

Unfortunately I didn't have the insight at the time to look at the spring in downshift. As has been noted, that's when the coils tighten the most.

 

Sounds like normal wear if it snapped in the coil. The coil is where the spring should be flexing. If you look at the action in both directions, the spring relaxes some in the upshift, as the angle of the pawl opens unwinding the coil.

 

With a tight spring that grabs the boss, (on the downshift) the coil cannot flex so the arm that hooks on the pawl does too much of the work, snapping it before the coil. Sounds like yours just plain wore out. You should be good for a long time.