Moto Laverda recall

I've run an 11-ball roller in the LH outer main on my SFC crank for ages, std 8-ball on the RH end. Was a recommendation from an old-school engine builder. Tipoie has the same in his racer and maybe road SF2 IIRC. Never had an issue. Am going to convert back to roller on this build - just for a change  :D

I was pretty surprised when I heard about the triple inner main ball issue. We (West Australian concessionares) raced a very early 1200 and sold maybe one or two others from memory, but can't recall whether there were warranty repairs.
 
Mine are twelve ball, not eleven. The only SF/twin crankshaft main bearing problems I have heard of were the early cranks with ball left main, which were far from the spec that I use. The crank issues on the triples came long after I had worked at Stanco, and from my memory affected pre series 2 Jota and later 1200s as far as Australian delivered bikes went. Aren't all the details of affected engine numbers listed on Laverdamania?
As usual some interesting info coming out here.
 
From Laverdamaina:

* Note concerning the wrong bearing batches in 1979:
In 1979, like described in the "1000" chapter of this site, some bikes had been equipped with a wrong batch of bearings, meaning failures and broken engines.
Here are the serial number of these bikes:
1000:
- From the serial number 6204 to 6594
- From the serial number 6598 to 6603
1200:
- From the serial number 1519 to 1566
- From the serial number 1833 to 2533
 
Tippie said:
Mine are twelve ball, not eleven. The only SF/twin crankshaft main bearing problems I have heard of were the early cranks with ball left main, which were far from the spec that I use. The crank issues on the triples came long after I had worked at Stanco, and from my memory affected pre series 2 Jota and later 1200s as far as Australian delivered bikes went. Aren't all the details of affected engine numbers listed on Laverdamania?
As usual some interesting info coming out here.
Click to expand...

For the twin, not early cranks, all cranks from 1968 to mid 72.

Paul
 
Grant said:
Here are the serial number of these bikes:
1000:
- From the serial number 6204 to 6594
- From the serial number 6598 to 6603
1200:
- From the serial number 1519 to 1566
- From the serial number 1833 to 2533
Click to expand...
kind of makes me wonder why they paused with the folly before pushing on and continuing with it... Mb there was a shortage of rollers available and a glut of balls to use up...
 
Dellortoman said:
I'm confused. Is it a ball or roller bearing - can't be both.
Click to expand...

I never \quite get the terminology right - a 'ball bearing' to my mind os the round thing (large versions of which made great tom bowlers in games of marbles back when  ;) ). I spose what I mean is a caged ball bearing?? But you're right, 'roller' doesn't belong there. 'Spherical bearing'??

Got the number wrong as well - haven't counted them in decades  :D

I have a vague memory of Bruce rebuilding a triple crank ... and not enjoying the experience, Dave! That may have been a warranty job.
 
Grants listing #24 contains good info but Mick Walkers book quotes different numbers although fairly similar
and then there is the poor old knobby no mates, all on his own 1200 triple 2594
which does tend to qualify the thought that the bikes were not at all times assembled in numerical order (but don't tell DVLA that!)
CLEM
 
Dellortoman said:
I'm confused. Is it a ball or roller bearing - can't be both.
Click to expand...

SKF CARB (Toroidal) bearings kinda sit in the middle. Bigger contact areas plus some capacity for misalignment.  Might well have done the noise reduction job WITH acceptable durability for Laverda back in the day (if SKF had invented them at the time  :) )

https://www.skf.com/binaries/327-497266/0901d1968089d1b4-6102_I_EN.pdf
 
In 1980 our 79 JOTA *6574* failed at over 160kph two up and loaded when overtaking a semi in northern Queensland - up near Tully in fact.
Quick clutch in saved the day, but the undies had to be thrown away. 
Speedo read 27,177kms after 15 months of ownership (from new).

I had questioned Eades regarding the known problem of the ball bearings being installed on/in some cranks prior to the blow up.  The reply was that our bike was not in the number sequence.  It was always rough feeling compared to our traded in 76 3CL.
Net result was one twisted and mangled crank, broken cam chain, valves and guides everywhere, bent cams, one bent rod, three donald ducked pistons and heaps of other smaller items, plus of course an engine full of shrapnel.

Eades / Stanco refused warranty, tho Max Eade did effect repairs at less than cost (I have the receipt for all the work, goes on for 3 pages)  Cost was $790.  I'm not sure who rebuilt the crankshaft, but they did a very nice job !
Note that for $3,800 I could have purchased a brand new Guzzi Le Mans.  No 80 JOTAs available thank god, caus that would have opened up another 44 gallon drum of boiling oil.
It was an entirely different motor after the rebuild - much smoother, and seemed to have more power, rev much easier, but that was a seat of the pants experience.

And just to show you can be lucky, we picked the bike up on a Thursday and the following Monday I went past in the car and Eades shop had burnt out !
Quite a few LAVs were lost to the fire.

So from my experience, no warranty was provided by Stanco or the agents.
 
Anybody heard of the 'bathtub curve'?
If you haven't, yeah it looks like a bathtub with failure vs time as parameters.

Basically if a bearing is going to fail it will happen quite quickly with initial use.
If not, it will last for yonks.

So as some comfort to those that worry, if an engine has lasted many thousands of Km's with centre ball bearings, then chances are it will last many more thousands.
 
Paul H said:
SKF CARB (Toroidal) bearings kinda sit in the middle.
Click to expand...

If you're suggesting that they're a cross between a ball and roller, then I think you're mistaken. They're definitely roller bearings. Ball bearings have little spherical things called balls in them. Toroidal roller bearings have (as the name suggests) rollers. They're slightly barrel-shaped but still rollers.
 
Are they also known as Superblend, what were the bearings they changed in Norton cranks after the Combat engine disaster?
 
Superblend bearings are a different thing again Vince.

They have cylindrical (parallel sided) rollers, but they have a slightly different fillet shape on the ends to standard rollers. The name 'superblend' comes from special fillet shape where the parallel sides blend into the end of the roller. They're more tolerant of small shaft misalignment than standard rollers.

Seems to me to be not quite a perfect solution to deal with crankshaft flex in Norton engines. But it had the advantage of being cheap and quick, which is exactly what Norton needed. A better solution would have been to re-design the bottom end with a centre main bearing, but they didn't have the resources to do that. It's all ancient history now.

I think AJS/Matchless was the only British bike manufacturer to put a centre main bearing in a parallel twin. I don't think it made their engines any more reliable though because they had other problems. Yamaha showed the world how to build a parallel twin when they came out with the XS1 in 1970.
 
"Yamaha showed the world how to build a parallel twin when they came out with the XS1 in 1970."
After Laverda had done some years earlier. The Honda 180 twins also had good crankshaft support.
 
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