Posted: Tue Oct 31, 2006 5:53 pm
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Wet Clutch, Dry Clutch?
Page 2 of 3
Posted: Tue Oct 31, 2006 5:56 pm
That was floating around the internet a year ago.
L2INTARWEB
L2INTARWEB
Posted: Tue Oct 31, 2006 6:38 pm
PostHuman wrote:
Posted: Tue Oct 31, 2006 8:34 pm
Aaaah! Its like the attack of the birds all over again! Hide all your small house pets, and strap down the kids!
Posted: Tue Oct 31, 2006 9:28 pm
The main advantage of a dry clutch set-up is less slipage under power, hence why they are used on race bikes. For a stop and start road bike they are just a pain in the proverbial.PostHuman wrote: The only advantage of a dry clutch of which I'm aware is the weight savings. Other than that it doesn't slip as smoothly, wears out faster, and makes a horrible sound.
Posted: Wed Nov 01, 2006 4:00 am
A difinitive answer, from a friend whom I trust (oh, and by the way, watch who you call a CLOWN for having a different opinion than yours PostHuman):
The only BMWs with "wet" clutches are the F650 series, the new 800 parallel twins, and I think the new K1200 series has a wet clutch. ALL the older BMW airhead twins, all the newer BMW oilhead twins, all the BMW inline three and four cylinder bikes have dry clutches. Same for most all Ducatis, Moto-Guzzis, Urals and a LOT of vintage bikes.
A dry clutch is just like the clutch in a manual tranny car. Simple, though light, it consists of one "large" (for a bike) friction disc and two metal pressure discs. It is generally cable operated but can be hydraulically operated. Dry clutches tend to have a shorter, smaller friction zone, but that is also VERY dependent on proper setup. A dry clutch means it does not run in engine or tranny oil, which is an advantage in that the engine and tranny have seperate fluids, and the best fluid for each can be applied. The clutch wear does not "soil" the tranny or engine oil. A dry clutch tends to make more noise (stand near an idling Ducati). A dry clutch means the engine tranny as a whole take up a bit more room in the chassis as the "dry" area for the clutch has to be planned for. A dry clutch does not stand up to flat out abuse like drag-strip starts, wheelies, burn-outs and excessive slipping of the clutch. But a properly maintained, non-abused dry clutch can go 100,000 mile easily, as done in MANY BMWs. A dry clutch change on a BMW or Guzzi is a big job, but fairly simple on a Ducati.
A "wet" clutch is designed to run in oil. It is generally smaller in diameter, though thicker due to multiple plates (up to seven or nine). It has a larger/smoother friction zone and feel because of the mutiple plates. It stands up to abuse better because of the cooling effect of the oil (assuming your bike is not running hot) and also because the load is distributed across multiple frction plates. But, because the clutch runs in an integrated crankcase sharing engine oil with the engine and tranny, it also contaminates the oil as it wears. That's one reason wet-clutch bikes require more frequent oil changes. Also, a wet clutch limits your choices of oil to use, since it has to serve both lubrication for the engine and tranny. The extreme shearing action fo the tranny gears also quickly breaks down the oil, again another reason for more frequent oil changes. The integrated crankcase and tranny does mean the whole package can be made smaller/tighter. A wet clutch change on most bikes is a fairly easy job with the right tools. Almost ALL Japanese bikes use wet clutches, though there are few dry clutches. Wet clutches are also quieter in operation.
Harleys for many decades used dry clutches. But some of the older Harleys were converted to wet clutches, and some of the wet clutches converted to dry clutches. The driveline layout of a big twin Harley allows for either. I think most all the newr Harleys, and certainly the newest Harley 1000 use a wet clutch layout.
P
The only BMWs with "wet" clutches are the F650 series, the new 800 parallel twins, and I think the new K1200 series has a wet clutch. ALL the older BMW airhead twins, all the newer BMW oilhead twins, all the BMW inline three and four cylinder bikes have dry clutches. Same for most all Ducatis, Moto-Guzzis, Urals and a LOT of vintage bikes.
A dry clutch is just like the clutch in a manual tranny car. Simple, though light, it consists of one "large" (for a bike) friction disc and two metal pressure discs. It is generally cable operated but can be hydraulically operated. Dry clutches tend to have a shorter, smaller friction zone, but that is also VERY dependent on proper setup. A dry clutch means it does not run in engine or tranny oil, which is an advantage in that the engine and tranny have seperate fluids, and the best fluid for each can be applied. The clutch wear does not "soil" the tranny or engine oil. A dry clutch tends to make more noise (stand near an idling Ducati). A dry clutch means the engine tranny as a whole take up a bit more room in the chassis as the "dry" area for the clutch has to be planned for. A dry clutch does not stand up to flat out abuse like drag-strip starts, wheelies, burn-outs and excessive slipping of the clutch. But a properly maintained, non-abused dry clutch can go 100,000 mile easily, as done in MANY BMWs. A dry clutch change on a BMW or Guzzi is a big job, but fairly simple on a Ducati.
A "wet" clutch is designed to run in oil. It is generally smaller in diameter, though thicker due to multiple plates (up to seven or nine). It has a larger/smoother friction zone and feel because of the mutiple plates. It stands up to abuse better because of the cooling effect of the oil (assuming your bike is not running hot) and also because the load is distributed across multiple frction plates. But, because the clutch runs in an integrated crankcase sharing engine oil with the engine and tranny, it also contaminates the oil as it wears. That's one reason wet-clutch bikes require more frequent oil changes. Also, a wet clutch limits your choices of oil to use, since it has to serve both lubrication for the engine and tranny. The extreme shearing action fo the tranny gears also quickly breaks down the oil, again another reason for more frequent oil changes. The integrated crankcase and tranny does mean the whole package can be made smaller/tighter. A wet clutch change on most bikes is a fairly easy job with the right tools. Almost ALL Japanese bikes use wet clutches, though there are few dry clutches. Wet clutches are also quieter in operation.
Harleys for many decades used dry clutches. But some of the older Harleys were converted to wet clutches, and some of the wet clutches converted to dry clutches. The driveline layout of a big twin Harley allows for either. I think most all the newr Harleys, and certainly the newest Harley 1000 use a wet clutch layout.
P
Posted: Wed Nov 01, 2006 9:02 am
Just an FYI for Posthuman: I don't really expect you to grasp this subtle point, but I thought I'd let you know that a wet clutch saps horsepower and torque through dissipative (hydrodynamic) processes. Parasitic losses, if you will... So your pooh-poohing the "disadvantage" of shaft drive due to torque loss is, well, kind of silly considering the wet clutch you hail as the greatest thing since sliced bread does the exact same thing, albeit through different mechanisms. In other words,
Posted: Wed Nov 01, 2006 9:06 am
<3MontyCarlo wrote:Just an FYI for Posthuman: I don't really expect you to grasp this subtle point, but I thought I'd let you know that a wet clutch saps horsepower and torque through dissipative (hydrodynamic) processes. Parasitic losses, if you will... So your pooh-poohing the "disadvantage" of shaft drive due to torque loss is, well, kind of silly considering the wet clutch you hail as the greatest thing since sliced bread does the exact same thing, albeit through different mechanisms. In other words,
Posted: Wed Nov 01, 2006 6:44 pm
So in other words a bike with a wet clutch and a shaft drive is extra slow as well as being heavy and providing poor handling.MontyCarlo wrote:Just an FYI for Posthuman: I don't really expect you to grasp this subtle point, but I thought I'd let you know that a wet clutch saps horsepower and torque through dissipative (hydrodynamic) processes. Parasitic losses, if you will... So your pooh-poohing the "disadvantage" of shaft drive due to torque loss is, well, kind of silly considering the wet clutch you hail as the greatest thing since sliced bread does the exact same thing, albeit through different mechanisms. In other words,
Gotcha.
Posted: Wed Nov 01, 2006 7:03 pm
Extra super dooper slow. But don't tell them thatMintbread wrote:So in other words a bike with a wet clutch and a shaft drive is extra slow as well as being heavy and providing poor handling.MontyCarlo wrote:Just an FYI for Posthuman: I don't really expect you to grasp this subtle point, but I thought I'd let you know that a wet clutch saps horsepower and torque through dissipative (hydrodynamic) processes. Parasitic losses, if you will... So your pooh-poohing the "disadvantage" of shaft drive due to torque loss is, well, kind of silly considering the wet clutch you hail as the greatest thing since sliced bread does the exact same thing, albeit through different mechanisms. In other words,
Gotcha.
