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Checking clutch

Technical help for Series one, two and three Lambrettas. Models include the Li, Li Special, TV, SX, GP, Serveta and API/SIL models

Checking clutch

Postby stonerosesmod » Mon Apr 03, 2017 7:30 pm

Hi all,

Does anyone have any tips for checking clutches on rebuild to eliminate drag? Running my Li150 with Mugello 195 on Suflex B plates and MB springs,cable all adjusted ok even tighter than normal but when the engines hot the clutch will drag in gear and is difficult to select neutral.I will investigate soon but just wondered what I should be looking for and any tips!

Thanks
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Re: Checking clutch

Postby Wack » Tue Apr 04, 2017 5:46 pm

The plates are obviously swelling when hot reducing clearance, even the tight cable could be responsible. To get more clearance fit 1.2 steels if using 1.5's and maybe a thinner top plate and also check the springs are not coilbound when compressed and not allowing the plates to free enough.
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Re: Checking clutch

Postby Adam_Winstone » Tue Apr 04, 2017 7:22 pm

^... as above... but strangely enough, I've had my clutch in and out a number of times recently, trying to stop drag, and I've addressed everything... tried different sprockets (including deep), different spiders and pressure plates, different steel, cable/routing, checked everything at both ends (lever housing and casing), different top plate and different springs, yet I'm still suffering drag on a standard 4-plate using Surflex B plates (soaked in and used with traditional ST90). I've had plenty of separation room each time and nothing is notched, worn, bent or other.

I'm hoping that this may bed in but I'm starting to think that I might need to swap the Surflex Bs out or swap the whole thing out for a different clutch. Very frustrating!

Adam
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Re: Checking clutch

Postby hullygully » Wed Apr 05, 2017 6:01 pm

check the thickness of your springs, I had a lot of drag using 2.2mm thk springs in my TS1 :( , changed them for 1.8mm thk ones, & it slipped like a good 'un :roll: , but since replacing with 2.0mm thk ones BRILLIANT :D
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Re: Checking clutch

Postby stonerosesmod » Sun Apr 09, 2017 9:36 am

Very frustrating indeed! I'm going from 16x47 to 16x46 whilst I'm there too so really need to look at this clutch.How do you check for clearance? I mate told me that I need to wind in the compressor with clutch fully assembled then measure underneath the top plate?
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Re: Checking clutch

Postby holty » Sun Apr 09, 2017 2:30 pm

stonerosesmod wrote:Very frustrating indeed! I'm going from 16x47 to 16x46 whilst I'm there too so really need to look at this clutch.How do you check for clearance? I mate told me that I need to wind in the compressor with clutch fully assembled then measure underneath the top plate?

yes your mate is right, it wont go in any farther once the springs become coilbound, also check that your clutch lever is pulling in far enough, worn or miss aligned clutch arm can limit how much push in the top plate will get, the yamaha clutch lever conversion helps with this
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Re: Checking clutch

Postby Bilko » Sun Apr 09, 2017 7:47 pm

Glad I'm not the only one who's suffering from clutch conundrums!

I burnt out my old 4 plate clutch last week on the way to Donegal. I took my newly purchased Readspeed 5 plate clutch with me, but the friction plates wouldn't fit. Tabs were too big.

Put in a mates 5 plate and had terrible problems with it until I burnt that out too! Another friend gave me his 4 plate clutch and got back home from Donegal, but couldn't get rid of drag. Doesn't seem too bad at the moment, but With so many combinations of steels, friction plates, top plates, springs, baskets and sprockets it's no wonder we sometimes struggle to find a combination that works.
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Re: Checking clutch

Postby Wack » Sun Apr 09, 2017 8:22 pm

The Readspeed 5 plate clutches are normally very good but I have noticed that sometimes the tabs need filing to fit certain crownwheels.
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Re: Checking clutch

Postby Bilko » Sun Apr 09, 2017 8:54 pm

I should have checked first. Lesson learnt!
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Re: Checking clutch

Postby stonerosesmod » Mon Apr 10, 2017 6:32 pm

What are the tolerances when measuring the clutch under the top plate,is it 1.5 to 2.0 mm?
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Re: Checking clutch

Postby Meds » Tue Apr 11, 2017 7:23 am

i had a similar drag problem when the engine got warm! I cured it by using these
http://www.lambrettaupgrades.co.uk/apps ... ow/4887821
I had plenty of movement in the clutch when it was cold.
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Re: Checking clutch

Postby Wee Mark » Mon May 08, 2017 10:04 pm

For information on this one, I had to file down the tabs on the corks on the Readspeed 5-plate too, Innocenti standard tabs are 20mm and the Readspeed ones are about 20.20mm, a little work with a small file and checking with the Veiners callipers soon sorts this if you are using this clutch on standard Crownwheel, this should help with spongey feeling & slip
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Re: Checking clutch

Postby terryj » Mon May 08, 2017 10:25 pm

just athought is your clutch cable pulling through the hole in the housing at the lever end
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Re: Checking clutch

Postby Adam_Winstone » Mon May 08, 2017 11:16 pm

A pal has just resolved his frustrating clutch drag issue by changing his cable inner :!: Whilst this sounds crazy easy, it seems that there are a number of cables available at the moment that have too much stretch in them and the beefier the clutch = the more likely that the inner stretches, rather than pulls. Said pal had been through his components a number of times, changing things out as he went, but the change of inner resolved it immediately.

Good luck.

Adam
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Re: Checking clutch

Postby Wack » Tue May 09, 2017 6:34 pm

Another tip is to shorten the clutch arm by cutting the fork off and removing around 10 mm on the arm then weld the fork back on. It makes the pull slightly harder but requires less h/bar lever action and is a handy spare to have to test before stripping a clutch out.
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