Oil Thread w/ a Ducati Twist

IAG

IAG

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From Brook Henry of Vee Two Ducati:
"Roller Big Ends have been around in motorcycles for many years. They are also used in many of the late model 4 stroke Moto X engines. Many of these later engines do not have pressurized oil feed to the big end. They rely totally on oil mist and oil splash to supply oil feed to the big end.
Laverda Triples have never had a direct oil feed to their roller big ends. Again, they rely on what is called an oil slinger. This is a method of collecting oil and oil mist from what is floating around the crank cases. The oil is collected within a thin metal disc fixed to the side of the crank shaft and then directed into the big end assembly. There is no pressure or direct oil feed at all. Interestingly, Laverda crank shafts and big ends do huge milage before requiring any attention. As a comparison Ducati Bevel big ends do not do any where near the same milage before failing. The Laverda Tripple engine was one of the most reliable engines in endurance racing of that time. Interesting fact since they only rely on a splash and mist feed to the big end."

Link to entire article:
https://www.veetwo.com/Info/what-en...h-tqaxYR7mdFaBELvgPB8dMmSA7Z4OjAbRXmcovCus-9Y
 
"There is no pressure or direct oil feed at all"
not quite accurate
the Laverda triple has a positive feed to the centre main bearings (not the outers) and the oil slingers are very close to the sides of those bearings where oil lost through them is passed to the slingers which then do their sling thing and reatin the cack (hopefully) the cylinder base oil gallerry then provides a supply of oil up six of the tweleve cylinder studs which all directly lubriacte the plain camshaft bearings, and provides copious quantities of oil to splash and puddle around everywhere up top and drain in many places including the well for each valve tappet (bucket)
CLEM
 
Clem,

Brook is referring to big ends only. He's correct, oil feed to Laverda crank mains and big-ends is by no means direct, relying on oil pissing out of an orifice above the centre mains. A fair bit finds its way to the big ends, this being pressurized solely by the centrifugal force of the spinning crank. Not that it would be very crucial, roller big ends require surprisingly little lube, see 2-strokes and the sometimes crazy revs they're capable of. The centre mains recieve the dribble that doesn't find its way into the slingers. The only Lavs that have positive feed (at a very low pressure) to centre mains are the 120 triples as well as the 500 and its derivatives. The outer races are drilled, oil is directed into the bearing as well as sideways into the adjacent slinger. All else within the crankcase is splash- or mist-lubed.

Imho, it isn't an oil feed issue that eats Ducati bevel big-ends as they actually have a forced feed from one crank end. Bad tolerance management in crank components leads to most premature failures. I've found considerable taper in both crank pins and rod big ends, resulting in worn thrust washers and rods. Re-worked cranks built to closer tolerances tend to do decent mileage before giving up again.

piet
 
When Harley Davidson started making the XR750 and the tuners were in search of more power, big end life was terrible. So the first thought was the big end was not getting enough oil so various methods were tried to get more oil to the bearing. That did not help and big end life was even shorter than before. So attempts were made to get even more oil to the bearing and it decreased life of the bearing even further. They eventually figured out the the more oil the bearing received the faster it failed.

Then someone said lets try restricting the amount of oil the bearing receives and the problem was solved. The theory was the large amount of oil in the bearing was making the rollers skid and wearing flat spots on the rollers. It looks like Laverda already knew this!
 
As you'd expect, Phil Irving has a bit to say on oiling roller bigends. One comment I liked was that if there is an optimum amount of oil which can be fed in, then it follows there is a "pessimum" amount. Which will lead to failure
As illustrated above, often less is better.

Like Red, my experience with Ducati's has been one of poor tolerances. The singles weren't bad but when production numbers rose for the twins, quality checks got lost. I've always thought they went to plain bearings to simplify production and reduce warranty claims.
 
sfcpiet said:
Imho, it isn't an oil feed issue that eats Ducati bevel big-ends as they actually have a forced feed from one crank end. Bad tolerance management in crank components leads to most premature failures.
Click to expand...
Just to second Piet here (as if that was necessary ;)). The general consensus is that big end and/or main bearing failures in Ducati beveldrives were/are simply due to poor assembly.

Maybe the difference in worker skill/dedication between small town Laverda and big city Bologna La Rossa? But it does sound spookily
like the Zané Laverdas ....
 
GregT said:
I've always thought they went to plain bearings to simplify production and reduce warranty claims.
Click to expand...
Indeed. Somewhat bizarrely, it was the success of plain bearings in the Parallel Twins that finally persuaded Ign. Taglioni to drop his life-long dislike of them and use them in the Pantahs.
 
Paul Marx said:
Since when was the Laverda triple one of the most reliable engines in endurance racing?
Paul
Click to expand...
Compared to a Ducati bevel... ;)

Reckon a carefully assembled 180° triple restricted to maybe 100-105hp with mechanically sympathetic riders, could punch a fair bit above its' weight for a full 24 hours if needed. In the triples heyday, max. output of the front runners wouldn't have been much higher, perhaps 115-120 (1975 Godier-Genoud was stated to produce 105 rwhp), until 4-valves and liquid-cooling took over. Most twins running back then would have topped out at around 90-95hp.

Sure, Z-Kawasakis and GS Suzukis are "easily" pushing 150+ these days, but they need new crankcases after 4-5 hours. A team I know of campaigning Zeds scour bike bone yards for good crankcases (driving tears to collector eyes!), they are/were scrapped after every event of the Euro Classic series. These were 4-hour races at the most, with 2 hours practice/qualifying, a 150hp Zed wouldn't last 24 hours.

piet
 
I know of guys racing CB350 Hondas in classic here, maxed out in the horsepower department, that have had to chuck it in because there are just no replacement crankcases available. Here I have been racing against ´96 Guzzi 1100 motors in the up to ´79 class with my crankcases from 1974. Jurgen from Germany with a Honda Bol D´ Or engined Nikko Bakker framed bike (who went on to win the Euro classic series that year) was on his third engine already at Anderstorp in June - (where I came in ahead of him in both races).
The Ducati bevels with the stepped pin had far better service life than the older straight pin ones.
 
sfcpiet said:
Compared to a Ducati bevel... ;)

Reckon a carefully assembled 180° triple restricted to maybe 100-105hp with mechanically sympathetic riders, could punch a fair bit above its' weight for a full 24 hours if needed. In the triples heyday, max. output of the front runners wouldn't have been much higher, perhaps 115-120 (1975 Godier-Genoud was stated to produce 105 rwhp), until 4-valves and liquid-cooling took over. Most twins running back then would have topped out at around 90-95hp.

Sure, Z-Kawasakis and GS Suzukis are "easily" pushing 150+ these days, but they need new crankcases after 4-5 hours. A team I know of campaigning Zeds scour bike bone yards for good crankcases (driving tears to collector eyes!), they are/were scrapped after every event of the Euro Classic series. These were 4-hour races at the most, with 2 hours practice/qualifying, a 150hp Zed wouldn't last 24 hours.

piet
Click to expand...
What actually goes wrong with the cases?
 
I had a peep into Pete Muir's race bevel cases at Gowys old shop decades ago. It was more weld than cast.
 
Exmoor beast said:
What actually goes wrong with the cases?
Click to expand...
i'd like to know too. I have a 140plusHP 8V GS1000 which has run the same set of cases for 4 years hard use now with no problems. The 160plusHP GSX1100's - at least those I've had anything to do with - last well too. The 190HP Aussie ones go through cases cos they stick rods out....
 
It took ages for Ducati 2 valve ribber band engines to get to 750cc from the original Pantah 500cc, I don't know if it was a crank geometry issue or a case strength issue.
 
Exmoor beast said:
What actually goes wrong with the cases?
Click to expand...

The bearing bosses simply wear out, be it from spun bearings or heat distortion, mostly the latter. Not only crank bosses are afflicted, many mainshafts begin to wobble considerably after a few hours too. I've seen their engines pissing oil from every imaginable crevice late in a 4-hour race.

The team I referred to replace the cases as a matter of course, they've had too many failures from using them just that one time too often. Team boss said their re-built engines had a total lifespan of about 8-10 hours, including dyno runs, they regularly see 150-155hp. Not sure of the capacity they're running, up to 1300cc is allowed. Most internals last a bit longer and can be re-used, but head castings were a big problem area as well. He also said limiting max. power to around 140 would greatly increase the lifespan, but, as everybody else was going for max. power, they'd need to as well to remain competitive.

European Endurance Cup rules stipulate stock engine castings are to be used. No manufacturer builds their bikes to last forever, especially road bikes were built to a price. Air-cooled 8V fours were designed to last maybe 8-10 years at 80-100hp. 160 is really pushing the envelope, especially when expecting it to hold together for more than an hour of WOT... It needs to be considered that most of these engines have already led a hard life at the hands of mostly insane 18-year-olds when they first left the showroom floor, not all scrounged crankcases are deemed suitable for use in the race bikes.

Reckon small, winding tracks to be a lot kinder to engines than long, fast ones with straights of a km or more, such as Spa Franchorchamps, Paul Ricard or Nürburgring. Sadly, the 2022 Spa event has been cancelled.

piet

piet
 
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