Dry vs Wet Clutch

[bikerfish1100]

my thinking was based on the fact that i can't really think of a wet clutch bike that does not share its oil supply with the engine/trans-so if the clutch is dry, it means the engine is too. bad, and expensive, business, that.

 

[Polarbear]

Big Rigs and race bikes and Cops;

Both are rides that rarely use clutches! The rigs are a startoff and stop clutch routine, rarely touching the clutch pedal otherwise and most all my biker racing pals have said they rarely shift with a clutch either. The hardest folks I know on BMW clutches are the CA.CHP, professional riders on RTs. These guys like really fast takeoffs from shoulders, chasing speeders and take most of their clutches out at 60000m., according to a local BMW Dealer that does the work. Wet or dry, I cannot remember ever changing one on most my bikes, with one exception. I have a R100/7 with 370000m and its on a second clutch, so long ago I forgot when I did it. Randy

 

[mpmarty]

Yeah But.... Many years ago on vacation as I was nearing St.George Utah my clutch started letting the engine get away in top gear on hard pulls. I limped into town and found a dealer that was open. I was at that time riding a Suzuki 1150 as I recall. The shop manager informed me it would be three days before they could do a clutch job as they were stacked up with work and the clutch would take between four and six hours to do. I asked if the parts were available and they were in stock. I informed the shop I would perform my own clutch replacement in their parking lot using tools I had with me. The shop foreman laughed at me and told me I'd be at it all night. I told him I'd be done in less than an hour or I'd buy him dinner. Gathered parts and took bike onto dirt parking lot. Placed our plastic rain gear on the ground as a "pad" and laid the bike on its left side. Pulled cover and replaced clutch plates and put it back together. Total time 45 minutes and I was careful. It took more time to clean and check the gasket surfaces than to exchange the clutch plates and steels. Springs were fine. Shop guy bought us both dinner that evening. I hate to even think of trying that on my RT.

 

[ragtoplvr]

I have been pondering which is the least desirable: a wet dry clutch or a dry wet clutch. I haven't decided but tend to think the latter might be worse, but I'm not sure.

The Harley guys like the big wide dangerous open primary belt kits. Now I know of a rat Harley type that just took off the primary cover. left the chain, put in a roller tensioner made from a combine part? and ran it that way. It smoked a bit a first, then got a bit grabby, and then was fine. I thought he was a idiot, BUT hey, his ride. Of course, 1000 miles in a year as it wobbled from bar to bar is not a good test. He would squirt some oil on the chain and throwout bearing once and a while. I saw it running down the road the other day still open primary. So I think a wet dry clutch is worse.

Rod

 

[tinytrains]

My 1971 (?) Honda 600 car had a multiplate wet clutch. (That would be the really little bitty one, smaller than the original Civics.) It had "4 on the dash", as there was no room to put the stick on the floor.

Actually, the 600's had a single plate dry clutch, with a primary chain to the input shaft. At least every one I ever saw, and I saw a bunch back then. A 35 HP car, woo hoo! Today, my 160 HP Mazda 3 gets better fuel mileage than my 600 ever did.

The only cars I can think of with multi-plate clutches are Formula one cars, but they seem to be dry. http://http://www.youtube.com/watch?v=89kE6mcF2JM

As for holding the clutch at a stop, like most, I hold it in first gear until there is a good sized line of cars stopped behind me, or no one in sight.

Scott

 

[bikerfish1100]

The Harley guys like the big wide dangerous open primary belt kits. Now I know of a rat Harley type that just took off the primary cover. left the chain, put in a roller tensioner made from a combine part? and ran it that way. It smoked a bit a first, then got a bit grabby, and then was fine. I thought he was a idiot, BUT hey, his ride. Of course, 1000 miles in a year as it wobbled from bar to bar is not a good test. He would squirt some oil on the chain and throwout bearing once and a while. I saw it running down the road the other day still open primary. So I think a wet dry clutch is worse.

Rod

rod- i'm missing your point here. H-Ds run a (mostly) dry clutch (minus whatever minimal splatter tehy could pick up from the primary chain lubrication process), and opening the primary changes nothing in that equation. what did i miss?

 

[ragtoplvr]

It is a wet clutch, just splash lubed..lots of splash. Wet clutch is not normally immersed in oil. There would be too much drag. This is also true on automatic transmissions. Some bikes even have jets to squirt more oil on the clutch.

At work I have a test bike for testing starters, with window in the primary. Even at cranking speed there is a LOT of oil moving around. You should see it running. At rest part of the plates are immersed. At high RPM basically the entire housing is filled with a thick oil mist.

Rod

 

[bikerfish1100]

It is a wet clutch, just splash lubed..lots of splash. Wet clutch is not normally immersed in oil. There would be too much drag. This is also true on automatic transmissions. Some bikes even have jets to squirt more oil on the clutch.

At work I have a test bike for testing starters, with window in the primary. Even at cranking speed there is a LOT of oil moving around. You should see it running. At rest part of the plates are immersed. At high RPM basically the entire housing is filled with a thick oil mist.

Rod

gotcha. thanx.

 

[169993]

Hd

Sorry Rod...'Fraid I'm gonna have to disagree with you...HD's do not run a wet clutch...The differenct between Japanese and Harleys is....Hondas, etc use a serrated clutch basket that runs in a common oil bath with the rest of the eng/ trans/primary gears...This allows for a total soaking in oil..HD's use a solid walled clutch basket that permits virtually none of the primary chain oil to get into the clutch itself. This is for the big twins...The older Sportsters did use a wet clutch, which combined with the 50W HD oil guaranteed the rider had no clutch at all with a cold engine. If the big twin clutch got oil soaked it would slip badly.

 

[Dtominovich@yahoo.com]

I have a Harley Ultra Classic and the clutch is definitely soaked in oil. Have you ever added oil to the primary of a Harley? You have to soak the plates in oil when you install the clutch too. This oil is separate from the other two oils on the bike also.

 

[169993]

Ultra Glide

Perhaps I should have clarafied my latest post...In my earlier post on this subject I said I know nothing about Evo engined era HD's...My statements are in reference to non Evo engines, commonly known as shovelheads and earlier bikes...I will still say they run a dry clutch due to their construction.

 

[ragtoplvr]

I do not ride Harley's BUT I do get involved in them a bit from time to time.

The only times I have taken a Harley clutch apart the plates were wet with oil, the few times do NOT make me a expert. At rest the oil level overlaps the disks, so they do get some oil. Maybe they are a new class, Damp Clutch. Now on to the real question, what is the best oil for a damp clutch

Rod

PS I think when any of them fail they are a Damn Clutch though.

 

[bikerfish1100]

I do not ride Harley's BUT I do get involved in them a bit from time to time.

The only times I have taken a Harley clutch apart the plates were wet with oil, the few times do NOT make me a expert. At rest the oil level overlaps the disks, so they do get some oil. Maybe they are a new class, Damp Clutch. Now on to the real question, what is the best oil for a damp clutch

Rod

PS I think when any of them fail they are a Damn Clutch though.

at rest a Harley clutch pack should be dry. As in close to totally. The only oil it is exposed to is that from the primary chain oiler, which feeds off the motor oil line at a t-fitting (at least, that wa how it used to be). Very little oil should be collecting in the primary case; tablespoons worth of. If significantly wet, i'm suspecting a blown trans output shaft seal, of a blown left side motor seal.

oh yeah, same caveat as copandengr, i'm old school H-D too.

 

[ragtoplvr]

I have zero experience on older Harley Davidsons. The later ones hold about a quart of 20W 50 in the primary, complete with drain plug, fill port and chain tension shoe adjustment port. Your early ones in fact do appear to be dry, but the later ones are wet.

Rod