9 THINGS YOU NEED TO KNOW
1 Friction plates
Made from steel with friction material bonded on. Some are cork-based, whereas some dry clutches can be sintered with bronze to give the right amount of wear, grip and smoothness. If you’re replacing frictions, let the new plates soak in fresh engine oil overnight before you fit them.
Friction plates have teeth on the outside to lock into the clutch basket, while the plain steel plates have more teeth on the inside to move with the inner basket that is connected to the gearbox input shaft.
3 Clutch basket
This has an inner and an outer. The inner rarely gives trouble but the outer, normally made from aluminium, can wear from the teeth of the friction plates digging in. This can be filed smooth, but will never be as good as new.
4 Steel plates
These suffer and overheat with constant slipping or fast starts (when racing). Inspect them; if they look blue, check to see if warped using a piece of glass. Leading Supersport teams change the inside four steels (the hottest) every weekend for better starts.
You should regularly grease the lever pivot, and check cables for frayed ends. If your clutch is slipping first try adjusting the cable – you should have 2-3mm of free play at the clutch end of the cable to allow for the steering. If hydraulic, check fluid levels and consider bleeding with fresh fluid.
Standard springs are designed for normal clutch use while also making the lever easy to use. Heavier clutch springs are needed for faster riding or trackdays to prevent damage from slip, but will be stiffer to use.
Motorcycle oil for bikes with wet clutches doesn’t have any additives that could promote slip. It is also able to absorb any dust from the clutch without degrading. Bikes with dry clutches such as BMWS and older Ducatis can use a different oil.
8 The best standard clutch…
Is the Hayabusa’s. Firms like Radical put them in cars weighing more than twice as much and they cope fine.
9 And the worst…
The Suzuki SV650’S. OK for a road bike but when you race and tune them they struggle with the torque.
Soak friction plates in oil