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6 plate clutch conversion

It has been found over the years that powerful top ends are too much for the standard Lambretta clutch set-ups.

After all we are dealing with what is basically a shopping/commuter machine.
One of the symptoms of the engine not handling the power is clutch slip.

The main way you feel this is the engine does not accelerate in proportion with how you work the throttle - i.e. on a non-slipping clutch you pull back the throttle quickly and the engine accelerates quickly. Pull it back slowly and it revs slowly.
When you have clutch slip, you rev the engine so it's screaming and the engine pulls as though it is being very gently revved.

Now that TS1's are being tuned up to 30 plus BHP more and more people are suffering from clutch slip.
A temporary cure is to use decent surflex plates and fit uprated springs, making sure you have the correct (750 ml) amount of gearbox oil.
There are 5 plate conversion kits on the market but the corks and steels are thinner than standard which makes them liable to wear and warp.

Ultimately, the only cure is to move up to a 6 plate conversion.
This adds an extra 2 cork plates and increases the surface area in your clutch by an extra 50%.
MB Developments do not claim to have invented the 6 plate conversion. What we have done, using our engineering background, is to make a conversion that is durable, reliable and easy to fit.

There are many road and race scooter out and about using our 6 plate clutch conversion. Whereas we used to see these people every fortnight buying new plates to keep on top of slippage, we only see them for other parts and services now.

6pl_2_th.jpg - 10948 Bytes At the bottom of the picture is a standard GP200 kickstart shaft.
At the top is a modified shaft needed for a road-going six plate clutch conversion.
6pl_1_th.jpg - 9884 Bytes On the left, a standard lambretta clutch spider.
On the right, the MBD 6 plate spider - a hardened CNC machined piece welded onto the splines from a standard spider.
6pl_3_th.jpg - 9360 Bytes On the left, as standard Lambretta crownwheel.
On the right, a crownwheel modified for a 6 plate conversion.
6pl_10_th.jpg - 12515 Bytes This photo shows all the parts needed to assemble the 6 plate clutch kit.
6pl_4_th.jpg - 14368 Bytes Showing the MBD 6 plate spider and crownwheel in position. If tightened up correctly as below then the nut doesn't need a tab washer.
Always use a blob of locktite to help prevent the nut from loosening.
6pl_5_th.jpg - 14135 Bytes Picture shows the MBD clutch holding tool, locked up in position allowing the nut to be tightened corrrectly with no damage.
6pl_6_th.jpg - 14902 Bytes This shows how the chain and clutch should look before the side casing goes on.
Note the MBD top chain slipper with the load spreading plate and nylock nuts.
It's a new japanese chain so there is no adjustment needed.
We always recommend a bottom chain guide in all road engines.
6pl_9_th.jpg - 14536 Bytes Compressing the clutch using the MBD clutch compressing tool.
6pl_8_th.jpg - 11270 Bytes The full six plate clutch assembled, ready for the packer and side casing.
6pl_7_th.jpg - 9819 Bytes This view shows the loose crankcase packer before the side casing is fitted.
6pl_11_th.jpg - 11818 Bytes The final view with the side cover in situ.
dsc0028.jpg - 11818 Bytes This photo shows a modified 6 plate crown wheel.
Some aftermarket crownwheels are so heavy that we have to drill them to reduce the turning weights mass.
You can clearly see the extended part of the sprockets required for the conversion.
The main reason for the photo was to show the machined area where the cork plates drop down to.
Sometimes if you don't machine this area the clutch assembly (mainly on standard 4 plate set ups) doesn't get enough clearance when the clutch lever is pulled and then clutch drag occours.

Please E-mail us with any questions or comments.