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Discussion Starter #1
Newbie here and non-informed non-engineer, would like to get into motorcycles and Ducati's someday and like to learn more, so please mind my ignorance.

My questions are about Ducati's decision to use a belt driven cam instead of chain or gear driven cam system. I've read that some Ducati owners have had problems and ruined engines due to belts breaking.

Would most Ducati fans and buyers prefer if Ducati went with a chain or gear driven system similar to Honda's RC51?
 

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Ducati makes chain driven cam engines, the Superquadro and V4 in the Panigale series bikes. What is your question?
I wasn't aware that Ducati did make chain driven cams in the V4.

It's a hypothetical question but would have it been wiser for Ducati to have originally used chain driven cams for their 916/996/998 series VTwins ?
 

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There are advantages and disadvantages of each system. Chains last a long time, but they also do stretch in use and need to be adjusted. Belts are more constant and don't change during use, but need to be replaced more often. Gears work great, but they are noisy, and they consume/waste energy and power compared to chains and belts.

I think that when Ducati went to the belts for that generation of engines, they judged that most Ducati owners don't put a ton of miles on their bikes, or ride them daily, so that the belt interval wouldn't be a huge deal. So they chose belts, which are efficient and which don't need to be adjusted or fiddled with until its time to change them.
 

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Good summary... belts are a no brainer in low mileage applications (a thousand bucks every 5 years is not a huge burden imo). On the Multi (or for folks on other models that put on the miles) they can be a bit more annoying (I hit desmo service intervals nearly every year) but even for the Multi I don't think belts were a terrible call - just a bit more frequent maintenance what most of us would like.
 

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...It's a hypothetical question but would have it been wiser for Ducati to have originally used chain driven cams for their 916/996/998 series VTwins ?
No. Belts were the way to go for numerous reasons, including weight, rotating mass, parasitic losses and lubrication requirements. Accommodations would have to have been designed into the cases, heads etc to allow for the chain, sprockets, tensioner(s) etc., which all would have contributed to a much larger physical footprint for the engine itself.

The belt driven system was also quieter, less expensive, and had no need for lubrication. Plus, as the desmodromic system itself would need regular inspection/adjustment service intervals, belts probably began to look even more attractive as there was literally no downside to their use in that regard.

The older I get, and the more I see with regards to technological developments, especially as it pertains to internal combustion engine design, the more I appreciate what an absolute gem Massimo Bordi's Desmoquattro truly was.
 

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That time -80 and -90 also big part of car engines were belt driven. ProphetPVD probably listed most of the reasons. One thing to consider also. Manufacturers count certain amount of income from parts sold for maintenance of the product they sell. I think I read from somewhere that car manufacturers try to get about 1/3 of the price of the car from parts they sell for maintenance. It would be bad business to make something that doesn't need any parts after you sell something.
 

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the base engine was designed in 1978, and it was a convenient way to drive two cams on different heads. there was no time change interval back then either - that appeared in 1999.
 

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I liked the gear driven cams on my old VFR.
Seems to me the only real downside would be power loss, but how much? 1%? 2%?
Maybe a few extra ounces of weight? I doubt I would notice.
 

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<shrug> I went through quite a few sets of belts in the 265K I put on my M900 Monster. It really wasn't a big deal.

PhilB
 

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It's nostalgia. Tradition at this point. So is the Desmo valve train and the dry clutch. There's nothing wrong with them, but there's no point either and there certainly are drawbacks.
 

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You have a lot of choices when it comes to buying a motorcycle. Why wouldn't you buy the one that you thought was the best design ? Why would you buy one that you thought was not a good design ? I remember breaking a cam chain tensioner located at the center of an engine necessitating a full engine teardown and not being thrilled with that design too much either. I’ve bent pushrods, broken valve springs, bent valves. All inferior designs. Wankel ? Seals fail, don’t they ? Crappy design. Diesel ? Another goofy design. Flatheads ? If they were so good, where’d they go ? 2 strokes ? Polluting oil burners. Steam ? Who came up with that one ? Perfection is a funny thing, isn’t it.
 

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Discussion Starter #15
No. Belts were the way to go for numerous reasons, including weight, rotating mass, parasitic losses and lubrication requirements. Accommodations would have to have been designed into the cases, heads etc to allow for the chain, sprockets, tensioner(s) etc., which all would have contributed to a much larger physical footprint for the engine itself.

The belt driven system was also quieter, less expensive, and had no need for lubrication. Plus, as the desmodromic system itself would need regular inspection/adjustment service intervals, belts probably began to look even more attractive as there was literally no downside to their use in that regard.

The older I get, and the more I see with regards to technological developments, especially as it pertains to internal combustion engine design, the more I appreciate what an absolute gem Massimo Bordi's Desmoquattro truly was.
To play devil's advocate, wouldn't the gear driven cam system add to the nostalgia of the Desmo with the sound? I thought the purpose of Italian motorcycles and cars (Ferrari) is the passion, style and sound of the engines?

Also, the advantage to race engines with gear driven systems. For example, when Max Biaggi won the World Super Bike Championship on the Aprilia in 2010 they used gear driven cams which gave them an advantage then it was banned in 2011 because Aprilia didn't use gears for their road bikes.
 

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in 1979 the pantah engine was the new, cheap to build, modern (ish almost) entry model replacement for the bevel that was not so much. 41 years later it's the basis for a lot of what they sell. fantastic design. gear driven cams has never been part of the ducati tradition.
 

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More of a dream. A fantasy.
You guys are thinking about this all wrong... As someone who has been involved in design engineering for close to 40 years I believe that I can add context to this discussion, if you'll indulge me for a few minutes.

First of all, lets define some terminology:

981566


"The condition, state, or quality of being free or as free as possible from all flaws of defects." At any given point in our history, the "things" we create are intrinsically bound to the design and manufacturing technology of that period. Obviously, the things we create today are of a much higher overall level of quality, but that is due to factors that I'm sure many of you never take into account. Namely, material research and manufacturing, and manufacturing itself. Lets focus on that for a moment...






Some of the differences between these two milling machines are obvious... one is old, one is new, one is 3 axis, one is 4, one is manually controlled, one is CNC. But there are a couple of things you don't see, and they are quite important with regards to what it is we are able to create, namely precision, and repeatability. And those two properties are the ones that that factor most notably when we go back to our definition of "perfection".

That 1940's era Cincinnati 3 axis milling machine, with a VERY good operator at the helm, could "reliably" get you a precision of 1/10th of a mm. The modern CNC milling machine on the other hand is capable of machining precisions of at LEAST 100 times that. This is due to a number of factors which I won't get into here (e.g., the precision of the components of the machine centers themselves) lest we get dragged into a chicken/egg paradox. Regardless, with regards to mass produced items, precision must go hand in hand with repeatability.

Every single component that gentleman on the 1940's era Cincinnati milling machine created would have to be inspected to ensure that it was in compliance with the tolerances specified in the original design document. Every... single... one. Consider this scenario... from zero datum on the Z axis of that machine, which is the cutter axis itself, the machinist knows that his (or her) first roughing cut is 100mm from that datum. However, after X number of machining cycles the tool has worn, let's say by 1/10th of a mm. To get to the same roughing cut depth as the unworn tool, the cutter face must now travel 100.1mm. But the operator has no way of knowing the tool has worn, so the cuts he (or she) is making are 1/10th of a mm too shallow. There are other contributors as well, but I think you get the picture.

Contrast that with a modern CNC center, which by its very nature is always aware of the position of the cutting tool. A worn tool is a non issue these days, as the CNC center will automatically change a worn tool the first time it detects any anomaly between the programmed distance from the Clearance Plane to the stock itself.

So, at least as it pertains to manufactured products, we see now that perfection does exist, but it is the definition of perfection that allows for things to be as close as possible to a state where they are defect free. And as we can see, that state is a moving target, and is tied to the processes used for manufacturing.

Next topic of discussion:
981567


We tend to view technology thru the lens of our current experience and interaction with it. Hence, most of us will look on something like the Desmoquattro as being an antiquated design. However, at the time, it represented the state of the art in many areas. In high RPM, 4 stroke OHV applications, there was no simple solution to overcoming valve float. Designers could install stronger valve springs, but that change would bring higher parasitic losses. Lighter valves could be used, but not without significant increases in cost. Bordi's design and application of the desmodromic valve system to solve this problem was state of the art at that point in time.

Would it have been done differently if those same problems were being tackled today? Absolutely. But that does not mean that a design from a different period in history is inferior or flawed... again, it represented the state of the art at that point in time.
 

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Honda focused on gears because they wanted the precise cam timing at the cost of...well cost and weight. Over time they could catch up as they develop those systems and decrease the cost. Chains on the other end are a pretty good compromise of cost, precision, and durability. As stated above they still have issues though. Even modern manufacturers have issues with tensioner failure. The belt is smack dab in the middle. The reality is the cost is lower up front and driven into maintenance costs instead passed onto the user. Another benefit of belts is they isolate the valvetrain harmonics from the rotating assembly. That benefit pertains mostly to the high performance spectrum which is applicable to Ducati.
 

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It's nostalgia. Tradition at this point. So is the Desmo valve train and the dry clutch. There's nothing wrong with them, but there's no point either and there certainly are drawbacks.
Gentlemen, we have a modetraitor amongst us. We will convene in a fortnight to handle this. East coast brings the torches, west coast brings the pitchforks. Any moderator that doesn't join us is one of them, and I've had my suspicions with Scott for awhile now with all this Austrian/German business.
 

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Even with gears your going to have lash. With the desmo valve train you have another source of lash so seems to me that would increase maintenance. I mean Ducati used to have bevel heads which are in effect gears.
 
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