more cosa clutch drags

[byron]

ex spanish postie bike, all standard
came to me with seriously dragging clutch
cable ok
took clutch out, plates were dry as a nun's snatch, looked as if they could have just come out the packet...
So soaked them overnight, back together, no improvement.
Searched on here, did the basket mod to make the turrets 22mm; back together, no improvement...
Steels seem straight, and have no sign of heat discolouration.
Fitting thicker steel first.
Thickness of combined corks [inc steel on last one in] is 12.7mm
The clutch works without the engine running, as in the kickstart goes straight down with the lever pulled in.
Bike is up on bench with rear wheel off. In gear with the engine running, the rear hub cannot be held stationary with the clutch lever puled in, or even when the lever on the housing is operated manually.
So, running out of ideas what to try next...
A complete new clutch assembly...?

[cit205]

It could be that you have one with the centre boss level with the gear or sub-flush , this causes drag and SIP do a spacer washer to fix it ,or you could make one ,or sand the gear down 0.2 mm.
As you look at the gear end of the clutch the gear should be that amount lower than the boss which rests against the thin shim/geared shim on the crank.

http://www.sip-scootershop.com/en/produ ... 2_69821000

note it will only work on clutches with a problem ,if you fit it on one that it isn't the problem on you will not be able to adjust the clutch, i.e it will feel over adjusted.


"SIP-TiPP: A width of circa 0.5mm play is necessary between the outer edge of the clutch base plate and the clutch gear for exact separation. Tolerances with the clutch check disk as well as the clutch can lead to lowered play. This can cause clutch separation problems.

If this separation problem arise; try sanding the clutch gear lightly (2/10 mm) or, much more simple, use the distance washer # 69821000"

[byron]

thanks, the cente boss does protrude above the gear, but not by 0.5mm.
I'll take the 0.2mm off the gear face and try that...

[byron]

I made a shim, that was easier, and more reversible.
seems ok up on the bench, will get it off now and see how it is..

[byron]

yep, that did it
top tip
thanks
i thought I was going to be stuck with that one for a while, large frame vespas take up so much room in the workshop...

[byron]

on a couple of those dragging cosa threads threads, there was mention of a photo of the basket mod.
here's mine ~

not a great pic i know, but you can see the difference between the enlarged slot and the one above it yet to be done

[cit205]

Glad you sorted it..

When you do the lower the basket cut outs job do you use a diamond file?

[byron]

When you do the lower the basket cut outs job do you use a diamond file?

dremel with my favourite diamond bit, then selection of proper hard-as-feck old english files from my engineer father-in-law. It was softer than a Lambretta basket.