which are the strongest lambretta clutch springs

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holty
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hi folks, ive got clutch slip on my 290, I had mb springs last year, they slipped, changed to malossi, and they were ok, but ive had a power increase so I changed to the lth xxx strong ones from chiselspeed but they slip as soon as I hit the powerband, ive got 7 bgm plates in the extended standard type basket, I think a bit stronger spring will do, I have considered a center spring but have used one in the past and seem to think it was mega hard to pull in, I don't want to use an alternative type of clutch as it has a cush drive grafted onto it from a motorcycle to help save the gearbox, any suggestions ?
thanks in advance,
holty
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could try a different gear oil see if it helps
C’est la vie
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garry inglis
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what about the casa powermaster clutch springs i dont no the strength grade but good for 45hp
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garry inglis
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ive just had a look and 12 springs for the 265 and if useing it on a normal engine you just put 4 in so i dont think there strong its how many you put in
Scooterdude
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Maybe try a GL3/GL4 gear oil . Or I wonder if you could modify your already modified clutch to take more springs like the BGM 10 spring jobbie, sounds like you’ve reached the limits for 5 springs.
hendy
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Clutches are a nice example of where classroom physics can be applied with little effort. Which means you can analyse them easily. So here goes.

You can stop them slipping by making sure they can handle the torque through each plate. I know that's obvious, but simplicity makes things easier to think about.

So to make them able to handle the torque, you either make them more capable or you reduce the torque.

First try to reduce the torque per plate by increasing number of plates, or reduce the overall torque by going to a lower ratio gearbox (gp200).

Alternatively you can make them able to handle more torque per plate by increasing spring force , increasing radius of plates, increasing area of plates, increasing coefficient of friction (either by changing material, oil or roughing up the steels).

I did some testing on a few different springs which you can find on lcgb forum which showed malossi and mb springs to be best. Malossi will be more effective depending on how compressed they are in your motor, but for most, you get the same force from mb for less lever effort, counter intuitive but true.

Sorry for long winded answer but I find this stuff interesting. :D
holty
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hendy wrote: Wed Feb 27, 2019 10:40 pm Clutches are a nice example of where classroom physics can be applied with little effort. Which means you can analyse them easily. So here goes.

You can stop them slipping by making sure they can handle the torque through each plate. I know that's obvious, but simplicity makes things easier to think about.

So to make them able to handle the torque, you either make them more capable or you reduce the torque.

First try to reduce the torque per plate by increasing number of plates, or reduce the overall torque by going to a lower ratio gearbox (gp200).

Alternatively you can make them able to handle more torque per plate by increasing spring force , increasing radius of plates, increasing area of plates, increasing coefficient of friction (either by changing material, oil or roughing up the steels).

I did some testing on a few different springs which you can find on lcgb forum which showed malossi and mb springs to be best. Malossi will be more effective depending on how compressed they are in your motor, but for most, you get the same force from mb for less lever effort, counter intuitive but true.

Sorry for long winded answer but I find this stuff interesting. :D
yeah I get the genral idea , im running a 3.7 to 1 final drive ratio at the moment and 7 bgm plates so both of those things are in my favour, I could extend my clutch basket more and maybe go to 8 or 9 plates if I had to, but im pretty sure stronger springs will stop the slippage, I may just add a centre spring and try that, the lever does pull in very easy at the moment as well
Warkton Tornado No.1
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I looked @ the BGM site, but could not see the plate thickness. Presuming that the plates are of the standard generic design, then CamLam thin green plates might offer a solution, though they are far from cheap.

Ultimately, Hendy is correct in that more plates might be the way to go. Certainly, that is not a new concept as nine plates were common in racing until motorcycle clutches were adapted.

I might have enough to do a nine plater if you want to try that as a solution.

I should have sets of stronger springs obtained from the likes of JB Tuning, specifically for racing.

Ultimately, I'm unlikely to use them other than in road bikes belonging to other's, as I developed my own six plater using an alloy, motorcycle clutch that handled the abuse as well as a nine plater of the generic, Lambretta design.....
holty
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the one thing going against more plates is that ive already got a 10 mm packer so adding more will mean extending the kickstart shaft which I don't want to do, I will try stronger springs first.
Warkton Tornado No.1
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holty wrote: Thu Feb 28, 2019 10:48 am the one thing going against more plates is that ive already got a 10 mm packer so adding more will mean extending the kickstart shaft which I don't want to do, I will try stronger springs first.
....not if they are clutch plates & steels of a thinner variety.

If you can measure the existing springs gauge (wire diameter), free length, compressed length (in a vice) & number of turns, I will have a look for what I have here.

If I've anything that looks to be stronger, you can have them to try. Are you going to Wickies?
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