Clutch Chat

[Doorag]

I thought I'd start a thread to talk about the pros and cons of the different types of clutches. (Sad, I know)

As far as I know, there are two main kinds of clutches: wet (like ours) and dry (racing?). There are also 'slipper' clutches mainly used for racing, but I could see the point of maybe using one on the road.

So... what's the difference between 'wet' and 'dry' (other than no oil?) and why would someone want one or the other? Has anyone on the forum had any experience with them?

I really like the idea of a slipper clutch. What are they like to live with on a day-to-day basis?

 

[Wyotech kid]

Dry clutches one name comes to mind. Ducati. Several of their models have the dry clutch setup. The "possible" benefit of a dry clutch is that it wont have as much a chance to slip as a clutch in an oil bath would. More of a positive engagement one might say. The down fall to Ducati's dry clutch setup is that its LOUD. That chattering noise for some can be considered annoying, especially at idle. It sounds like some choppers with the clutch basket banging back and forth against the fiber plates, and leaving notches in the basket itself....never a good thing.

Wet clutches like in most of our bikes nowadays are nice a quiet....til sumthing goes wrong. The steels and fiber plates are always sitting in an oil bath or sprayed by oil nozzles. Keeps them cooler cuz they're always in oil. Dry clutches may get a little warmer than wet clutches. Another benefit is that wet clutches are know to last a little longer than dry. Dry clutches can (and i use "can" very loosely) wear out quicker cuz the lack of lubrication. Wet may slip just a little more than dry clutches, but not so much that it will make a difference especially on the street. Now put a very slick synthetic it your motor and have a good bit of horsepower the clutches WILL slip. AMSoil being one of the oils Ive hard being one to make clutches slip. I have it in my bike and I have no problems, but i dont have a 200+ hp bike either.

As for slipper clutches I have no experience with them, I could a little bit of added benefit for one on the street but not one to be really justified. Now on the track yes there is benefit to a slipper but for a newbie to the track I dont think they would really tell a different and they might not use it correctly or to it potential.

 

[RJ2112]

Dry clutches simply use different formulations of friction materials on their plates.... they've been around as long as automobiles have. I don't know of a car, that uses a 'wet' clutch.
The friction material for these, is pretty much the same as brake pad material. Because they only have air for cooling, they tend to be larger than 'wet' designs. HD, BMW, Ducati, Ural, (I suspect) Moto Guzzi would be the main users for 'dry' in motorcycles. They're durable, proven technology.

Wet clutches? Compact. Sensitive to which kind of engine oil you use to cool them. As they are consumed, the friction material gets dumped into your engine oil, where it can circulate around the motor into all sorts of troublesome nooks and crannies.......

Slipper clutches are in wide spread use in high torque twins.... most Japanese cruisers have them; my last 40 HP Suzuki had one. You can't skid the back tire, due to a botched down shift. That's a good thing for a newbie.

You also have one heck of a hard time bump starting a bike, so equipped. The very design of the slipper, makes is work to prevent the rear wheel from 'spinning' the engine......

 

[Doorag]

Interesting. I hadn't thought of that. Although I've only ever needed to bump-start a bike once it is something to consider.

I'm not thinking of changing - I was just curious about the differences and why MotoGP bikes have dry clutches. I reckon it's partly a safety issue since oil won't p*ss all over the track if the case breaks and maybe a weight saving one too? They try to save every once possible so I guess it could be possible.

 

[RJ2112]

I'd guess it's the 'quick change' ability, plus a slight increase in HP due to not having the clutch 'drag' through a pool of oil in the case.... that resistance would take away a HP or 2, depending on how deep the pool, surface in contact, etc., etc.

 

[TownsendsFJR1300]

Somewhat related, I just left my left my local shop, they had an r6 (maybe) (very similar to the FZ6) engine out of the frame, the engine upside down, partially disassembled (oil pan/clutch cover/cam chain cover, etc removed).

Seemed the owner dogged the clutch really bad and the fiber plates literally let loose. These lots of little fiber parts got stuck in the gears (clutch basket gear and its adjacent gear) and wouldn't let the engine rotate, just up to a point, then you could spin it backwards... Cams/valves were checked, all ok there...

Just something to think about....

 

[RJ2112]

Somewhat related, I just left my left my local shop, they had an r6 (maybe) (very similar to the FZ6) engine out of the frame, the engine upside down, partially disassembled (oil pan/clutch cover/cam chain cover, etc removed).

Seemed the owner dogged the clutch really bad and the fiber plates literally let loose. These lots of little fiber parts got stuck in the gears (clutch basket gear and its adjacent gear) and wouldn't let the engine rotate, just up to a point, then you could spin it backwards... Cams/valves were checked, all ok there...

Just something to think about....

Wow. I shudder to think of the labor charges on that one......

 

[TownsendsFJR1300]

The guy can't afford to break the motor down all the way however it was now turning over when I was about to leave. I believe they were going to spray brake cleaner or something once the engine was flipped back upside right.

Short of crawling under the bike and pulling the pan, clutch cover etc, I suspect most of it could have been done in frame. Lots of little clutch fiber pieces...... The clutch pieces had very small pieces of steel attached as well.....

Hopefully he got them all....

I've seen clutches burnt, worn, never a fiber disc exploded though...

 

[sxty8goats]

I've seen quite a few exploded clutches but all in cars and 90% popped via drag racing....

 

[(none)]

Dry clutches simply use different formulations of friction materials on their plates.... they've been around as long as automobiles have. I don't know of a car, that uses a 'wet' clutch.

Never seen a car with an automatic transmission? Nearly all of them have at least one wet clutch pack in them, some (hondas and Acuras) have as many as 5 or 6. The new style "dual clutch" transmissions (VW/Audi's DSG, Porsches new one, Ferrari's, etc) all use 2 wet clutches instead of a torque converter or single plate dry clutch.

Many bikes depending on their motor orientation use a dry clutch, BMW uses them in the R-bikes and the older K-bikes. They use a single plate clutch very similar to that in a manual transmission car, as teh bikes are setup much like a car with the engine separate from the transmission. IIRC, some MotoGuzzis also run this setup.
Some ducatis still have the multi-plate dry-clutch setup which allows them to run the small diameter clutch pack with multiple plates to transmit all the power. The disadvantage of mutli-plate clutches is that they can be noisy and can be hard to modulate. The Porsche Carrera GT is a road car that uses a multi-plate dry clutch setup. Many racecars also go this route because the clutches are durable and can transmit power well, but aren't very driver friendly.

 

[RJ2112]

Never seen a car with an automatic transmission? Nearly all of them have at least one wet clutch pack in them, some (hondas and Acuras) have as many as 5 or 6. The new style "dual clutch" transmissions (VW/Audi's DSG, Porsches new one, Ferrari's, etc) all use 2 wet clutches instead of a torque converter or single plate dry clutch.

Many bikes depending on their motor orientation use a dry clutch, BMW uses them in the R-bikes and the older K-bikes. They use a single plate clutch very similar to that in a manual transmission car, as teh bikes are setup much like a car with the engine separate from the transmission. IIRC, some MotoGuzzis also run this setup.
Some ducatis still have the multi-plate dry-clutch setup which allows them to run the small diameter clutch pack with multiple plates to transmit all the power. The disadvantage of mutli-plate clutches is that they can be noisy and can be hard to modulate. The Porsche Carrera GT is a road car that uses a multi-plate dry clutch setup. Many racecars also go this route because the clutches are durable and can transmit power well, but aren't very driver friendly.

'Wet' in the sense that it shares the lubrication with the engine internals.... yes, absolutely, most transmissions use full lock up torque converters any more. The transmission fluid is isolated from the engine tho.