Are Dry Clutches Becoming Extinct?

[ducatiz]

so.... What makes a Ducati a Ducati? 

The label.  Cutting edge looks.  Innovation in design.

Honda makes 400,000 vehicles per year.  Cars, lawnmowers, water pumps, hedge trimmers, generators...  if they make a crappy bike, they shrug and move on and copy the next thing.

Yamaha, same.  Pianos, boat engines, trombones, toasters, dishwashers.  Ford used a Yamaha engine in the Taurus SHO years ago.

Suzuki, is closer to Ducati in that they make small cars, motorcycles and boat engines ONLY.  They don't make everything, just motors and motorsport stuff.

Ducati is unique in that it only makes motorcycles, and only about 35,000-40,000 per year.  I think their peak was 45,000 a few years back.

1,100 employee world wide.

[Triple J]

I was never a real fan of the dry clutch on street bikes, although they do look cool. Too noisy though.

Now that I've raced a 748, 749, and an R6 (while my 749 is being repaired  ), I don't like them on race bikes either. Sure, you can change out the clutch quicker, but that isn't a common requirement in club level racing (I've never had to change out a clutch). Wet cluthes are MUCH easier to launch though....I'll take that wet clutch advantage over the quick change advantage of a dry clutch anyday. 

[duccarlos]

I don't like them on race bikes either. Sure, you can change out the clutch quicker, but that isn't a common requirement in club level racing (I've never had to change out a clutch). Wet cluthes are MUCH easier to launch though....I'll take that wet clutch advantage over the quick change advantage of a dry clutch anyday. 

That would be similar to the SSS. You're supposed to be able to swap out the wheel quicker, but the SSS is heavier than the DSS. The weight far outweighs the need to replace a wheel.

I love the look and sound of a dry clutch, but prefer a wet clutch for day to day riding. The pull is a lot easier in traffic without the need of buying a hefty clutch slave and no fear that it's going to eat my pants, since I would ride with that shit wide open.

[Triple J]

That would be similar to the SSS. You're supposed to be able to swap out the wheel quicker, but the SSS is heavier than the DSS. The weight far outweighs the need to replace a wheel.

I disagree about that. I much prefer a SSS on a race bike, because when you have to switch to rain tires 30 minutes before your race it is really hassle free. Same thing if you want to change gearing...much easier with a quick change sprocket on an SSS set-up...setting chain tension is a lot easier since you don't have to also worry about wheel alignment.

My 748 (SSS) was lighter than my 749 (DSS), and I can't tell a difference when I'm riding. I don't see any real advantage to a DSS.

[Cloner]

I disagree about that. I much prefer a SSS on a race bike, because when you have to switch to rain tires 30 minutes before your race it is really hassle free. Same thing if you want to change gearing...much easier with a quick change sprocket on an SSS set-up...setting chain tension is a lot easier since you don't have to also worry about wheel alignment.

My 748 (SSS) was lighter than my 749 (DSS), and I can't tell a difference when I'm riding. I don't see any real advantage to a DSS.

Let an engineer help you....it's easier to get a higher moment of inertia to resist bending and torsion using a DSS than it is with a SSS.  Typically you need significantly more material to resist both bending and torsion (especially torsion) between the swingarm pivot and the axle when using a SSS arrangement.  The 848/1098 gains that MOI by using very thin sections to gain distance from the neutral axis of the arm, but at the cost of survivability and possibly fatigue life.  I think you're incorrect about the weight of the SSS of the 9x6 bikes versus the DSS of the 999 models, though.  Terblanche switched back to DSS for the reasons I've given...to save weight and increase rigidity.  The early 999 DSS were cast and were, hence, quite heavy compared to the later (and Terblanche's original) thin section members.

As to dry clutches, the primary engineering advantage isn't in maintainability, but in reduced friction and decreased spring pressure.  When the rotating assembly runs in less dense air in lieu of more dense oil it requires less power to drive it.  It's a marginal gain, but it is a real one!  Also, friction/steel interfaces that are lubricated (that's what oil's for, after all!) require higher spring pressures to drive the rear wheel, which should lead to both fewer disks and lighter springs for a small weight savings in dry clutches versus wet clutches.

When it comes down to it, Ducati has built its reputation on performance.  They began using Desmodromic actuation because they couldn't rev their motors high enough in the '50s using contemporary spring technology.  They went to dry clutches because they wanted to homologate them for their racing bikes (just as Suzuki did with its limited edition GSX-R750R).  They've been early adopters for several metallurgical advances and coatings that they believed provided a competitive advantage.  They were the first manufacturer to offer streetbikes with traction control.  The trap is, now that those things are entrenched, how can they shed them and keep their "heritage".

The simple answer is to stay at the front of the technological curve and keep winning races!  If Desmodromic actuation adds cost to no significant advantage, ditch it!  Ditto trellis frame, 90° twins (folks seem to forget Ducati built its reputation in singles!), dry clutches, belt drives, and anything else that isn't what's needed to win races.

What makes a Ducati a Ducati?  WINNING!!!!!

[Goat_Herder]

What makes a Ducati a Ducati?  WINNING!!!!!

Can't argue with that.  Everybody loves a winner.  If Michael Jordan weren't such a great player, people wouldn't have shave their heads and wear Nike's in the 90s.  But winning sometimes isnt' enough.  You've gotta have the good looks, charms (quirks), and little things that differentiate you from other copy cats (desmo, SSSA, L-Twin, trellis frame, dry clutch).  Ducati had done a great job at all the others, besides just winning on the track.  Well, winning does help a lot.

[zooom]

What makes a Ducati a Ducati?  WINNING!!!!!

This quote makes me think Ducati is the Charlie Sheen of bikes and that isn't necessarily a comparison I want someone to draw...LOL

[duccarlos]

Let an engineer help you....it's easier to get a higher moment of inertia to resist bending and torsion using a DSS than it is with a SSS.  Typically you need significantly more material to resist both bending and torsion (especially torsion) between the swingarm pivot and the axle when using a SSS arrangement.  The 848/1098 gains that MOI by using very thin sections to gain distance from the neutral axis of the arm, but at the cost of survivability and possibly fatigue life.  I think you're incorrect about the weight of the SSS of the 9x6 bikes versus the DSS of the 999 models, though.  Terblanche switched back to DSS for the reasons I've given...to save weight and increase rigidity.  The early 999 DSS were cast and were, hence, quite heavy compared to the later (and Terblanche's original) thin section members.

As to dry clutches, the primary engineering advantage isn't in maintainability, but in reduced friction and decreased spring pressure.  When the rotating assembly runs in less dense air in lieu of more dense oil it requires less power to drive it.  It's a marginal gain, but it is a real one!  Also, friction/steel interfaces that are lubricated (that's what oil's for, after all!) require higher spring pressures to drive the rear wheel, which should lead to both fewer disks and lighter springs for a small weight savings in dry clutches versus wet clutches.

When it comes down to it, Ducati has built its reputation on performance.  They began using Desmodromic actuation because they couldn't rev their motors high enough in the '50s using contemporary spring technology.  They went to dry clutches because they wanted to homologate them for their racing bikes (just as Suzuki did with its limited edition GSX-R750R).  They've been early adopters for several metallurgical advances and coatings that they believed provided a competitive advantage.  They were the first manufacturer to offer streetbikes with traction control.  The trap is, now that those things are entrenched, how can they shed them and keep their "heritage".

The simple answer is to stay at the front of the technological curve and keep winning races!  If Desmodromic actuation adds cost to no significant advantage, ditch it!  Ditto trellis frame, 90° twins (folks seem to forget Ducati built its reputation in singles!), dry clutches, belt drives, and anything else that isn't what's needed to win races.

What makes a Ducati a Ducati?  WINNING!!!!!

What he said.

[Triple J]

Let an engineer help you....

I am an engineer actually...

For reference, I never said the SSS was lighter...I said the bike (748) was lighter, and I couldn't feel a difference in rigidity. My 748 with it's heavy ass, old-style design SSS was 15 lbs lighter than my 749 with its apparently lighter DSS...both full of fuel and both in full race trim (i.e., no lights, radiator fans, etc). It's also impossible to argue that a DSS isn't more of a pain in the ass to change a tire than an SSS. If you have to change your own tires, like the majority of racers (i.e., not pro) the SSS has a clear advantage over the DSS for racing as I've noticed first hand.

I get that a dry clutch has less drag, but I'd argue it is negligible unless you're in MotoGP trying to get every last 1/10 hp. Plenty of wet clutch bike do just fine in power when compared to Ducati. Dry clutches also have heavier lever pull than wet clutches, despite any theories on spring stiffness.  I'll take the supposed power loss and lack of quick change ability in exchange for a lighter lever and easier (i.e. smoother & more controlled) launches. My buddies 2003 R6 was FAR FAR easier to launch than my 748 or 749...both of which have high-end slipper clutches.

Theory is great...but I'll take practicality.

[NorDog]

so.... What makes a Ducati a Ducati? 

The tank badge; either an eagle or a bird.

[Speedbag]

If Desmodromic actuation adds cost to no significant advantage, ditch it!  

I truly believe that desmo could be ditched for a conventional valvetrain in this day and age (sacrilege I know, but I'm an engineer too).

Think of the aftermarket camshaft possibilities alone.

[JohnEE]

When it comes down to it, Ducati has built its reputation on performance.  They began using Desmodromic actuation because they couldn't rev their motors high enough in the '50s using contemporary spring technology.  They went to dry clutches because they wanted to homologate them for their racing bikes (just as Suzuki did with its limited edition GSX-R750R).  They've been early adopters for several metallurgical advances and coatings that they believed provided a competitive advantage.  They were the first manufacturer to offer streetbikes with traction control.  The trap is, now that those things are entrenched, how can they shed them and keep their "heritage".
What makes a Ducati a Ducati?  WINNING!!!!!

+1

Though i shudder to think of what a monster would look like with out a trelis frame........

[duccarlos]

I am an engineer actually...

For reference, I never said the SSS was lighter...I said the bike (748) was lighter, and I couldn't feel a difference in rigidity. My 748 with it's heavy ass, old-style design SSS was 15 lbs lighter than my 749 with its apparently lighter DSS...both full of fuel and both in full race trim (i.e., no lights, radiator fans, etc). It's also impossible to argue that a DSS isn't more of a pain in the ass to change a tire than an SSS. If you have to change your own tires, like the majority of racers (i.e., not pro) the SSS has a clear advantage over the DSS for racing as I've noticed first hand.

I get that a dry clutch has less drag, but I'd argue it is negligible unless you're in MotoGP trying to get every last 1/10 hp. Plenty of wet clutch bike do just fine in power when compared to Ducati. Dry clutches also have heavier lever pull than wet clutches, despite any theories on spring stiffness.  I'll take the supposed power loss and lack of quick change ability in exchange for a lighter lever and easier (i.e. smoother & more controlled) launches. My buddies 2003 R6 was FAR FAR easier to launch than my 748 or 749...both of which have high-end slipper clutches.

Theory is great...but I'll take practicality.

The 749 and 999 were heavier bikes compared to their predecessors. That is one of the reasons, beyond the looks, that people didn't dig it. I'm sure if you compare only the swing arms, the SSS would still be heavier. There are also quick change systems for DSS. I will agree that it's easier to change your own tire, but it should not be that frequently needed.

As to the dry clutch, completely agree. For me that is definitely more aesthetic than functional.

[Triple J]

The 749 and 999 were heavier bikes compared to their predecessors. That is one of the reasons, beyond the looks, that people didn't dig it. I'm sure if you compare only the swing arms, the SSS would still be heavier. There are also quick change systems for DSS. I will agree that it's easier to change your own tire, but it should not be that frequently needed.

Agreed that the 749/999 series are heavy in general. The point though was that an SSS bike can be light, so the weight penalty of the SSS isn't a big deal (look at the 1199 for proof). The benefits of an SSS are significant IMO.

You'd be surprised how often you have to remove the wheels. Gearing changes for different tracks, new tires...or the biggie up here...rain. Maybe I should move somewhere I can race where it doesn't rain often! 

[SDRider]

+1

Though i shudder to think of what a monster would look like with out a trelis frame........

A Buell?