Clutch Cosa FL2

I’ve put an new Cosa FL2 in my T5 engine, but the clutch didn’t operate well. I didn’t have the plates in oil ahead, but now I opened the clutch and the plates seems OK. Have put them in oil now, and will try again. Have put in the original clutch in, and that one is OK. The 3mm space washer is there. Using T5-engine in a GTR with original handles. It should be OK to just install a Cosa FL2 clutch in a T5, shouldn’t it? Anyone having experience?

Hi Pondus,

this might be obvious but it sounds to me like you just need to tighten the cable when you’ve installed the new clutch. You are getting drag from the plates not separating enough upon compression.

I’m constantly adjusting my clutch tension… but then i tend to get a bit obsessive about things like that ![:shock1:]


Yes it is supposed to be and to be fair ive only had one new boxed clutch where this was a problem. It does seem to be what you are experiencing. A friend in the trade told me there was a mix up between piaggio and the people that make the plates with regard to plate thickness. You will solve the problem by getting the turrets milled to 21mm-look for a friendly backstreet machine shop should cost no more than 10-15 quid. usually this problem only rears its head when the plates are replaced.

All cosa clutches are easy to pull in. You should find no problems with them as long as the engine is below 20bhp. Hardly any T5s make more than this. The metals should move up and down on the serated edge of the centrewithout sticking. Check them on a mirror for warpage. If they are flat but sticking a bit a bit of file action is neccesary. Hope this helps

Talked with SIP. They sad that the springs in Cosa clutch could be to hard, - and should send me new softer springs. OK, - try again then.

I was driving some time with the wire very much tightened up, - so the push rod was in permanent contact with the clutch. Metal/brass dust have then come in oil and inside casing. Have to change oil, but is that enough? Should not do any other cleaning, to save the bearings…?

i’ll strip the clutch to put the new springs in so how do i check that their not catching on the centre boss? Out with the file?


Hi gaz,

just that i think it means that the pressure is too light and the plates are slipping on hard acceleration. Nice and easy to ride though!


Thanks Diablo, you are fund o knowledge.

just to expand on the problems i’m having… when i kick the bike to start it, if i push down pretty vigourously (with the bike in neutral and hand off clutch) the kickstart just pushes down without turning the motor over… hmmmm. to be guarenteed of actually kicking it over i have to be kind of steady and smooth with the kickstart, not hard and sharp.

So does this mean that the clutch is slipping? I’m not sure why this would be happening as it just a standard cosa ordered from sip and thrown in (with a new pushrod to boot!)

Some harder springs just arrived in the post from Beedspeed so i’ll pull it out and check things over this weeekend and maybe try the stiffer springs.

Any ideas as to what’s going on? As i said earlier, it’s kinda slow to disengage giving cruchy changes and also only kicks in and engages right at the last bit of travel of the lever as i let it out… wierd combination as these two things seems to work against each other don’t they?

Sorry for the long ramble!
Thanks Jonni

I put a brand new and complete Cosa FL2 clutch into my T5. When activating the clutch and putting into gear, the scooter would start running, and difficulties changing gears. The clutch didnt really work. I suppose it can have something to do with that I didnt put the clutch i oil overnight before I installed it. I put back the original clutch, and that one is OK (exept that by in upper rev it tend reving up without encreasing of speed…).
Ive checked the Cosa clutch and the plates looks OK. Hav now had them inoil for some days, and will try it again.

Had the plates in oil for 24hours. Arm seems OK. Cant really understand that springs should be to hard. When operating handle, it is soft, and arm operates OK. Strange !?

You dont mention what the problem was. Did you put the plates in yourself or did they come with the clutch? Cosa clutches work fine in T5s

jonni whats wrong with the clutch being easy to pull in

Ok there is a problem with some cosa clutches but you shouldn’t be having this with a brand new one. When you compress the plates on the workbench you should find at least 1mm gap between any one cork and metal plate. You are suffering from clutch drag and no amount of cable tension will cure this. Split you clutch and see if the plates are made by surflex. If they are the easiest fix is to junk them and fit either newfren or genuine vespa. Alternatively you will have to mill/grind/file the turrets intill they have a depth of at least 21mm.
If you havn’t bought the clutch mail order take it back to where you got it-you won’t be the first person to have done it!

ok pondus…

just for some feedback… i got a cosa 21T from Sip and fitted it to my Mk1 T5 a few days ago. If anything, i think the springs are really soft rather than hard. This is not a critisism though cause the clutch works fine , it’s just much easier to pull in than my old four plate kitted T5 one (and much more controlled delivery of power!).

I’ve got dogleg levers with a pretty short throw and they work fine with the Cosa too.

I know this isn’t direct help for you but just thought i’d add my experience to the mix!



Jonnie make sure your metal plates are not warped and are also maybe getting stuck on the centre boss-this is common.

yes thats right

Hi it would seem that to get the clutch to work you have had to tighten the cable so much that it disengages the clutch. If you loosen the cable untill you can kick the bike over but it still creeps then this is clutch drag. Have you got a clutch compresser? If you have compress the clutch on the bench and see whether you can slip a 1mm feeler gauge easily between the top cork and the first metal. If you cant the clutch will drag and is probably faulty. This does happen (i have returned a few to VE). A good remedy for this is to mill the turrets down to 21mm. This will allow the plates to seperate nicely. Ive also found Newfren plates are slightly thinner and seem to work better than surflex. Hope this clarifys things-if not post again!

Hmmm. I just tried again. Clutch/plates have been in oil for a while and I put it again now. Im tighten up very much, but starting engine and putting in 1.gear it will pull away. Braking will stop the engine if not throttling up. Ive tried to tighten up so much that the kick will spin when trying starting. Seems that plates are hanging together. Ive separeted the clutch and everythings seem OK, and the plates were soaking wet of oil. Cant really understand this…
Shoudnt this clutch have normal function from first second, - should not be necessary to keep the brakes on, activated the clutch and force to spin in 1.gear (for smoothing it up) ???

A bit off subject! but I have fixed 2 new 200’s with the clutch arm siezed in the cover, (no grease/oil) could it be this stopping the clutch disengageing?

Funny thing is that i have just ordered some stronger springs from Beedspeed for my new Cosa FL2 in the T5. It’s super easy to pull the clutch in right now and i’m convinced that i’m getting a bit of slip at hard acceleration. Anyone else experienced this?

The Fl2 also seems to spin down more reluctantly after disengagement than other clutches resulting in pretty clunky changes if i try to change too fast. Myabe the harder springs will make it more snappy to disengage as well as engage?

Also… while i;m rambling on(!), has anyone tried a 23 tooth cosa in the T5? Would you ever get off from the lights? I went for a big ride Sunday and the slight upgear of the 21T was good but i am curious as to how far you could go and still have the bike perform ok power wise.