Slipper clutches

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Sleepyboy · #1 Post by **Sleepyboy** » Sun Jul 15, 2012 6:34 pm

Probably being thick here but was trying to work it out whilst I was out on bike this morning...

1. (Most) race bikes don't have starter motors - they are push/bump started.

2. (Most) race bikes now have slipper clutches to prevent the back wheel locking up on downshifts by allowing the wheel to travel faster than the engine.

So how the hell do you start the bike????

randomsquid · #2 Post by **randomsquid** » Sun Jul 15, 2012 6:39 pm

Rollers?

Sleepyboy · #3 Post by **Sleepyboy** » Sun Jul 15, 2012 6:41 pm

randomsquid wrote:Rollers?

On the back wheel? Same difference, surely the slipper clutch would kick in?

randomsquid · #4 Post by **randomsquid** » Sun Jul 15, 2012 6:46 pm

Would have thought slipper clutches were a decelerating thing and starting was an accelerating thing. I'm sure somebody here knows though.

Aladinsaneuk · #5 Post by **Aladinsaneuk** » Sun Jul 15, 2012 8:18 pm

forward gear engagement.....

HisNibbs · #6 Post by **HisNibbs** » Sun Jul 15, 2012 8:45 pm

I reckon starting from the wheel or slowing at the engine the torque is being applied in the same direction. Not sure about other systems but with the Falco the running engine generates a vacume efect helps ease the clutch so the diference being when you bump start the engine isn't running. Bstd to bump any way.

Sleepyboy · #7 Post by **Sleepyboy** » Sun Jul 15, 2012 9:46 pm

Was thinking more of race/track bikes that have mechanical slipper clutches rather than the Falco system.

Still can't figure it out....

D-Rider · #8 Post by **D-Rider** » Sun Jul 15, 2012 9:57 pm

I think that Mart is probably our expert on Pipe & Slipper Clutches ..... but this is what Sigma have to say (article written by Neil Spalding - so should be good)
http://www.sigmaperformance.com/motogpcurrentdeal.html

I'm presuming the superbike ones only allow a limited slip.

Sleepyboy · #9 Post by **Sleepyboy** » Sun Jul 15, 2012 10:44 pm

According to Sigma:

One of the issues to consider with the compromise that is slipper clutch design is the method of starting, with external dry clutches it is possible to lock the clutch manually for starting, In MotoGP Ducati, Suzuki and WCM use this method. With wet clutches it is very difficult to lock the clutch so the game depends on the likely start system, for Supersport Sigma assumes the electric start will be operational (its supposed to be under the rules!!) as our ramp design makes bump starting a bit difficult. Under Superbike rules the starters can come off and most starting is via a bump or an external starter motor, on our Superbike clutches you can bump start the bike without a locking device.

Still doesn't 100% explain how a wet slipper (ooo-err!) can be bumpe started though.