General Clutch questions

[snerkler]

So, in my quest to understand the workings of both cars and bikes I'm stuck on motorcycle clutches. I understand how clutches work on cars, but not so sure on bikes.
So what I'd like to know is how you can slip/feather the clutch on a bike without causing excess wear, whereas if you do this on a car you'll wear your clutch in no time?
I've seen several diagrams of bike clutches, some with just one clutch plate and friction plate, and some with several. Do all modern bikes use several plates, and is this what allows the clutched to be slipped/feathered?
What exactly is a wet clutch vs a dry clutch? I understand that oil is involved in a wet clutch, but where is the clutch? I'd have thought if it was between the plates it would cause them to stick?
Has anyone got any good diagrams of the 1200GS clutch and gearbox?

Cheers

 

[BrianGriffin]

So, in my quest to understand the workings of both cars and bikes I'm stuck on motorcycle clutches. I understand how clutches work on cars, but not so sure on bikes.
So what I'd like to know is how you can slip/feather the clutch on a bike without causing excess wear, whereas if you do this on a car you'll wear your clutch in no time?
I've seen several diagrams of bike clutches, some with just one clutch plate and friction plate, and some with several. Do all modern bikes use several plates, and is this what allows the clutched to be slipped/feathered?
What exactly is a wet clutch vs a dry clutch? I understand that oil is involved in a wet clutch, but where is the clutch? I'd have thought if it was between the plates it would cause them to stick?
Has anyone got any good diagrams of the 1200GS clutch and gearbox?

Cheers

The GS clutch, along with all the other boxer twins, have a single plate clutch just like a car. The vast majority of other bikes have a wet clutch, multi plate system that runs in the engine oil, often on the right hand side of the engine, behind the large engine cover. They have cork pad (or a modern equivalent) inserts on the plates (usually about 7 of them), that will still operate whilst bathing in oil although they can start to slip if fully synthetic oil is used. Lastly, Ducati's generally run a dry multi plate clutch system and that is why they rattle when the engine is ticking over. Hope this helps a little and I haven't just caused more confusion.

 

[snerkler]

The GS clutch, along with all the other boxer twins, have a single plate clutch just like a car. The vast majority of other bikes have a wet clutch, multi plate system that runs in the engine oil, often on the right hand side of the engine, behind the large engine cover. They have cork pad (or a modern equivalent) inserts on the plates (usually about 7 of them), that will still operate whilst bathing in oil although they can start to slip if fully synthetic oil is used. Lastly, Ducati's generally run a dry multi plate clutch system and that is why they rattle when the engine is ticking over. Hope this helps a little and I haven't just caused more confusion.

That's great thanks
If the GS has a single plate dry clutch I'm guessing slipping the clutch eg in slow manoeuvres is not a good idea then as will cause premature wear? If this is the case why do they these clutches? When doing my direct access I was taught to slip/feather the clutch during slow speed manoeuvres for control and that bikes were designed to allow this unlike cars

 

[cookie]

you can slip any type of clutch, wet, dry, single plate, multi plate, car or bike. that's what they are designed for.

just don't do it too much

 

[Greg Masters]

That's great thanks
If the GS has a single plate dry clutch I'm guessing slipping the clutch eg in slow manoeuvres is not a good idea then as will cause premature wear? If this is the case why do they these clutches? When doing my direct access I was taught to slip/feather the clutch during slow speed manoeuvres for control and that bikes were designed to allow this unlike cars

You weren't taught well!

As Brian has said, the GS bikes have car-like 'dry-plate' clutches. Slipping a dry clutch will cause wear. The plate wears faster if it gets hot enough to burn.

But even 'wet-plate' clutches shouldn't be slipped if you can avoid it as the plates will also wear, heat up and contaminate the engine oil in which they run.

I try to apply a rule of never having my foot/hand on the clutch for more that 5 second.

Greg

 

[snerkler]

You weren't taught well!

As Brian has said, the GS bikes have car-like 'dry-plate' clutches. Slipping a dry clutch will cause wear. The plate wears faster if it gets hot enough to burn.

But even 'wet-plate' clutches shouldn't be slipped if you can avoid it as the plates will also wear, heat up and contaminate the engine oil in which they run.

I try to apply a rule of never having my foot/hand on the clutch for more that 5 second.

Greg

If you're not supposed to 'slip' the clutch why does every bit of info on the net regarding slow manoeuvres advise you to do this? In some articles they use the term friction zone.
http://bettermotorcycling.wordpress.com/2009/04/19/slow-speed-maneuvers/
http://www.ridemyown.com/articles/riding/BTB-slowspeed.shtml
http://www.whybike.com/motorcycle178.htm

If you're not supposed to slip the clutch how do you perform slow manoeuvres such as u-turns as it's sometimes not easy to hold constant revs as walking pace? I was taught to slip the clutch and use the rear brake

Fortunately I haven't done any slow manoeuvres per se on my GSA so never unduly 'slipped/feathered' the clutch.

The reason for this line of questioning as that I'm baffled as to why I was taught to do this and told that motorcycles are built to withstand this, and why all info on the net says the same. I'm not talking slipping for long periods, just the time it would take you to perform a u-turn etc.
I did however read an article that recommended riding using the "friction zone" and rear brake when riding in a parade etc. These can sometimes go on for hours, talk about excess wear

 

[Spout]

I try to apply a rule of never having my foot/hand on the clutch for more that 5 second.

Per year

 

[Steptoe]

If you slip the clutch for long periods on BMW's or hold the clutch in while stationery (i.e. while waiting at traffic lights etc) you'll also feck up the thrust bearing in the clutch slave cylinder.

Think of the BMW clutch as a switch used just to change gear.

 

[Greg Masters]

If you're not supposed to 'slip' the clutch why does every bit of info on the net regarding slow manoeuvres advise you to do this? In some articles they use the term friction zone.
http://bettermotorcycling.wordpress.com/2009/04/19/slow-speed-maneuvers/
http://www.ridemyown.com/articles/riding/BTB-slowspeed.shtml
http://www.whybike.com/motorcycle178.htm

If you're not supposed to slip the clutch how do you perform slow manoeuvres such as u-turns as it's sometimes not easy to hold constant revs as walking pace? I was taught to slip the clutch and use the rear brake

Fortunately I haven't done any slow manoeuvres per se on my GSA so never unduly 'slipped/feathered' the clutch.

The reason for this line of questioning as that I'm baffled as to why I was taught to do this and told that motorcycles are built to withstand this, and why all info on the net says the same. I'm not talking slipping for long periods, just the time it would take you to perform a u-turn etc.
I did however read an article that recommended riding using the "friction zone" and rear brake when riding in a parade etc. These can sometimes go on for hours, talk about excess wear

Of course it easier to slip the clutch when doing tight turns. But it will wear the clutch when you do.

Clutches (wet or dry) have to be slipped all of the time but the veiled suggestion that a wet-plate clutch can be slipped constantly without causing problems simply isn't true.

Motorcycle wet-plate clutches run in the bike's engine oil. The oil absorbs much of the heat generated from slipping and, accordingly, wet-plate clutches are more tolerant to slipping than dry-plate clutches.

The engine oil gets contaminated from clutch particles and has to be changed more often as a result.

Wet-plate clutches can run in oil because they are multi-plate - meaning the engine's torque is shared by each one of the mating surfaces. The reduced loadings on each clutch plate add to longevity and mean that the entire clutch basket can be of a smaller diameter with the resultant reduction in rotating mass.

But don't think for a minute that even wet-plate clutches can be slipped for ever. Dr JM, tosserette of the parish, will attest to the contrary! (Link)

Greg

 

[snerkler]

Of course it easier to slip the clutch when doing tight turns. But it will wear the clutch when you do.

Clutches (wet or dry) have to be slipped all of the time but the veiled suggestion that a wet-plate clutch can be slipped constantly without causing problems simply isn't true.

Motorcycle wet-plate clutches run in the bike's engine oil. The oil absorbs much of the heat generated from slipping and, accordingly, wet-plate clutches are more tolerant to slipping than dry-plate clutches.

The engine oil gets contaminated from clutch particles and has to be changed more often as a result.

Wet-plate clutches can run in oil because they are multi-plate - meaning the engine's torque is shared by each one of the mating surfaces. The reduced loadings on each clutch plate add to longevity and mean that the entire clutch basket can be of a smaller diameter with the resultant reduction in rotating mass.

But don't think for a minute that even wet-plate clutches can be slipped for ever. Dr JM, tosserette of the parish, will attest to the contrary! (Link)

Greg

Many thnaks for your answer. What you're saying makes much more sense to me than information I have been provided with before
Why do manufacturers use dry clutches and/or single plate clutches then as wet clutches and multiplate clutches would seem the obvious choice to me as there are certain situations where slipping a clutch is needed, as in u-turns? Is it a weight and/or cost issue?
Also I'd have thought that off-roading you would encounter more scenarios where you would probably want to slip the clutch (please correct me if I'm wrong as have only done one day greemn laning on a WR250), so I'd have thought a wet multiplate clutch would be a better choice for the GS?

 

[cookie]

Why do manufacturers use dry clutches and/or single plate clutches then as wet clutches and multiplate clutches would seem the obvious choice to me as there are certain situations where slipping a clutch is needed, as in u-turns? Is it a weight and/or cost issue?

suits the engine layout.

Also I'd have thought that off-roading you would encounter more scenarios where you would probably want to slip the clutch (please correct me if I'm wrong as have only done one day greemn laning on a WR250), so I'd have thought a wet multiplate clutch would be a better choice for the GS?


bmw just used the engine from the other R series bikes. they're not really designed as green laning bikes

having said that, the clutches are not prone to premature failure, unless they get contaminated with oil.


i think you worry too much.

 

[Wapping]

... If this is the case why do they these clutches?

Because they can these clutches.

Would seem to be the answer.

 

[Pukmeister]

If you go offroad on your GS and slip the clutch, you'll soon smell the stink of burning friction plate. It'll still work. My last GS did.

My current GSA had a spate of clutch slip at 5500rpm in 5th gear, put down to a glazed friction plate. Seems to have fixed itself now (not caused through abuse or off-roading).

The GS dry plate clutch is like a cars, only fitted backwards so that the pressure plate gets the wear on its face and not the flywheel. The flywheel and starter ring gear is pretty thin.

The pressure plate is like a bridge piece that bolts onto the flywheel, the friction plate then squeezes backwards towards the gearbox under spring pressure. When you squeeze the clutch lever, the clutch slave cylinder pushes the clutch friction plate forwards towards the engine to release (slip). That's why as the friction plate material slowly wears away with use, the slave cylinder is pushed backwards, displacing clutch fluid back in to the handlebar reservoir and the level rises. Sometimes it can rise so much it hydraulically locks the clutch due to a lack of room for expansion, causing premature clutch slip.

If in doubt, disconnect your battery, whip out your starter motor and operate the clutch lever whilst watching with a torch - all will become crystal clear.

 

[snerkler]

i think you worry too much.

I'm not worrying, just learning and was curious

Thanks for all the other replies, very interesting

 

[Giles]

Snerkers, if you go off roading on a pukka errrrr, off roader, you'll be amazed how much it will do without having to dip the clutch. (were talking single cylinder 350 / 400 / 450...). The temptation for those new to off roading (and i include myself in this bracket .. only the last couple of years...) is to dip the clutch and slip it at every opportunity, but a pukka pogo, will tick over and pick up drive with no clutch, at very very low revs.

 

[Greg Masters]

Snerkers, if you go off roading on a pukka errrrr, off roader, you'll be amazed how much it will do without having to dip the clutch. (were talking single cylinder 350 / 400 / 450...). The temptation for those new to off roading (and i include myself in this bracket .. only the last couple of years...) is to dip the clutch and slip it at every opportunity, but a pukka pogo, will tick over and pick up drive with no clutch, at very very low revs.

Absolutely agreed!

 

[snerkler]

Snerkers, if you go off roading on a pukka errrrr, off roader, you'll be amazed how much it will do without having to dip the clutch. (were talking single cylinder 350 / 400 / 450...). The temptation for those new to off roading (and i include myself in this bracket .. only the last couple of years...) is to dip the clutch and slip it at every opportunity, but a pukka pogo, will tick over and pick up drive with no clutch, at very very low revs.

Interesting, thanks