The technical adventures of Dr_C
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Joined Jun 2007
4K Posts | 1K+
south east WA Australia
I would say probably a bit of both .. we know the only way the bearing can move in that direction relative to the case is if the crank pulls the bearing away from the case.
to decide how much of the actual movement is due to the cases moving outward or to the crank moving inward we need a video ...
to decide how much of the actual movement is due to the cases moving outward or to the crank moving inward we need a video ...
Joined Oct 2003
955 Posts | 1K+
Sweden
have you seen this picture of mine ? roller main bearing outer race PULLED 1.5mm inwards by the crank
if i had not made the retainer and seen it nearly broken off like that nobody could ever have convinced me the outer race of a roller bearing moves inwards at all let alone nearly twice as far as the axial play.
Well, I'd say it makes perfect sense! When then crank is spreading (during higher rpms) the bearing is forced to "tilt" in it's seat in the crank case. Just like when something is stuck you tilt it from side to side to make it come loose. I believe this is the phenomena making your roller bearing move!
Joined Oct 2003
955 Posts | 1K+
Sweden
Hi guys!
The 3D model says that the crankshaft (two cheeks and a big end pin) weigh in total 4,127 kg (maybe 20-30g over the real weight) and that the center of gravity is just 6,3 mm offset to the centerline! I would have thought CoG was more off set.
So how would you like a crank to look, given that it should fit in an OEM casing?
The 3D model says that the crankshaft (two cheeks and a big end pin) weigh in total 4,127 kg (maybe 20-30g over the real weight) and that the center of gravity is just 6,3 mm offset to the centerline! I would have thought CoG was more off set.
So how would you like a crank to look, given that it should fit in an OEM casing?
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Joined Jun 2007
4K Posts | 1K+
south east WA Australia
wobbling widgets yes does make sense .. poor cases LOL
i like the oem crank design except for the 2 sharpish corners that interfere with pressing the big end apart (shown in pic with red circle)
if aesthetic appeal is important maybe a nice round aerodynamic shape on the leading edge of the webs would be interesting. ive seen it done sometimes claimed to reduce drag but probably just because it looks nice
interested to see how far the cog moves when the drive side web is made thicker and also how much it adds to the mass
i like the oem crank design except for the 2 sharpish corners that interfere with pressing the big end apart (shown in pic with red circle)
if aesthetic appeal is important maybe a nice round aerodynamic shape on the leading edge of the webs would be interesting. ive seen it done sometimes claimed to reduce drag but probably just because it looks nice
interested to see how far the cog moves when the drive side web is made thicker and also how much it adds to the mass
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Joined Sep 2007
782 Posts | 291+
???
Was looking at ways of constructing a crankshaft a while back.
Thought it may be possible to electron beam weld the pins into a flywheels
The advantage being that the flywheels could be made from shorter 25mm slices of round bar, or flat bar/plate instead of turning the whole thing from a longer round billet.
Electron beam welding could penetrate the whole thickness of the flywheel.
Excuse my CAD
Thought it may be possible to electron beam weld the pins into a flywheels
The advantage being that the flywheels could be made from shorter 25mm slices of round bar, or flat bar/plate instead of turning the whole thing from a longer round billet.
Electron beam welding could penetrate the whole thickness of the flywheel.
Excuse my CAD
Last edited:
Joined Oct 2003
955 Posts | 1K+
Sweden
Really nice work!you also have the solution that i have choose for my KTM 690 engines , the pin is part of the right web of the crank , and it work's very well up to 100 ps
but it's an hard job to do !!!
That concept has been overviewed. You run 1-piece plain bearing conrod with that crank? Pin dia? Thickness of the single web?
My cases are machined, so axial play should work. 1,5mm Bushie?
Joined Jun 2007
4K Posts | 1K+
south east WA Australia
well i woke from a bad dream where i used that setup and my crank turned into a horse and started clapping its hooves in time to some swedish country and western
1.5mm with balls is unknown territory so a liitle scary with an RST
perhaps 1.2mm would be an easier decision and still be easier on the mains than 0.6 or so
nice crank FD I first heard of the idea used in a 710cc hillclimber berg on nitro
1.5mm with balls is unknown territory so a liitle scary with an RST
perhaps 1.2mm would be an easier decision and still be easier on the mains than 0.6 or so
nice crank FD I first heard of the idea used in a 710cc hillclimber berg on nitro
Joined Oct 2003
955 Posts | 1K+
Sweden
Closest thing to Swedish Country & Western might be one of the contestants at the swedish audition for the Eurovision Song contest this year: https://youtu.be/7fUT-iPlP0I
I picked up some schims today to get whatever axial play I decide upon. The machining of the bearing seats is made to allow max 1,5mm play. I'm guessing 1,0-1,2mm will have to do.
I picked up some schims today to get whatever axial play I decide upon. The machining of the bearing seats is made to allow max 1,5mm play. I'm guessing 1,0-1,2mm will have to do.
Joined Oct 2003
955 Posts | 1K+
Sweden
Maybe. If going all the way (new cases) I've considered a lower primary gear ratio to increase the distance between crank and clutch, allowing a billet crank with a 2-piece rod. Then the larger primary gear could incorporate a spring loaded "cush drive" as I had on my old TT600. That would ease the stresses on all components in the transmission!
Joined Jun 2007
4K Posts | 1K+
south east WA Australia
perhaps it was more like this?
https://www.youtube.com/watch?v=a1ThSi1wbqU
your countryman Smorgasbord sent me the link many years ago
https://www.youtube.com/watch?v=a1ThSi1wbqU
your countryman Smorgasbord sent me the link many years ago
Joined Oct 2003
955 Posts | 1K+
Sweden
I was thinking (believe it or not) about if it was possible to make a tougher crank (one fat web to the left and two bearings to the right) and still be able to use OEM flywheel, stator (SEM or Kokusan) and cover. Would that be a solution that would help more people besides myself? I was just figuring if doing this effort it would be nice if I could satisfy somebody else on the planet at the same time. Your thoughts, please!
Joined Oct 2003
955 Posts | 1K+
Sweden
Are the 550:s also chewing mains? I thought perhaps the shorter stroke (70mm?) was easing the stresses, but maybe higher rpm gets the revenge?
Joined Sep 2014
113 Posts | 61+
finland
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