I wish I would write down more info I have got in the past. But I remember an issue with a crank ( I believe it was a truck engine) were the placement ( in degrees of on or off TDC) of the oil holes in the crank was a problem. I know the bearings are not the same as our Dales. I belive it was something like the pressure of the power stroke sealing off oil flow from the rod jurnol.
Two things come to mind on this topic. first is if the oil hole on lower pin is placed twards the center of the crank, would cintriffical force be a factor?
Next, on what my memmory can tell, is on two stroke engines the oil access for the rod and wrist pin bearings is in an area other than were the pressure is applied durring the power stroke. could the opening of a small oil hole take affect on the bearing if it was placed were the pressure is applied over the hole during the power stroke?
These could also affect the wrist pin bearing and would verry on the degree the hole is placed on either end of the rod.
Crankshaft Failures
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cannondale27
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I get what you are saying.But I believe Winky adds extra oiling holes for the rod.
I still think either the pin cant take the force necessary to rebuild it.Or my latest theory is that the crank is flexing enough to wear the thrust washers which destroy the bearing.This would explain why cannondale had such a huge side clearance.It would also explain why a new crank was being developed that was much stiffer.
I still think either the pin cant take the force necessary to rebuild it.Or my latest theory is that the crank is flexing enough to wear the thrust washers which destroy the bearing.This would explain why cannondale had such a huge side clearance.It would also explain why a new crank was being developed that was much stiffer.
okay guys, this is what we have come up with so far. We know that the faster the crank is spinning, the less oil gets to the rod bearing due to most of the oil being taken by the main bearing in the cart plate due to centrifical force. We spun a crank without the rod on it to confirm this. So now we know the rod gets starved at high rpms. We have blocked off the main bearing lube hole in a crank so that the rod will receive all the oil that goes into the crank and modified a cart plate to oil the main bearing in the cart plate the same as the flywheel side is. This mod "should" force more oil through the rod bearing and the more oil that goes through the rod... the more should splash onto the bottom of the piston/sleeve and into the wrist pin/top rod area, helping that problem also, and decrease the likelyhood of piston/sleeve scuffing. We are currently building an engine using these modifications, which we will install in a chassis an run it at full throttle till we are satisfied that we have fixed the problem or it blows. We have also removed the cast-in connecting rod pin and machined the crank half to accept a seperate pin and rod bearing from a well proven donor motor and opened-uped side clearances of the rod to match those of the donor motor specs due to the fact that we have received a number of core cranks (stock) which have cracked or broken pins which is not acceptable. We beleive that if we reconstruct/oil the crank in a manner which is used by honda, yamaha, and suzuki, (they use seperate pins and don't lose oil to main bearings through the crank oiling system) that we can get not only our cranks to live, but also stock cranks which haven't been damaged as of yet. As soon as we have results of our test, we will post to the subject. We intend to have the test motor completed by monday nite and start running it continuously at full throttle for at least 55 gallons of gas to prove out the crank and oiling setup, if satisfactory results are had, we will then offer the crank and cart plate modifications for the c-dales. Hope this answers the questions.
"When something doesn't work.... adapt something that does and has been proven to work".
"When something doesn't work.... adapt something that does and has been proven to work".
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cannibalq8
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.. hope for u best wishes in ur tests -
jerrygomez2002
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- Joined: Wed Mar 10, 2021 10:41 pm
Crank
>>My point is I am trying to understand WHY Cannondale did the crank this way.
Cannondale claimed a bullet proof one piece crank is their catalog. Maz claims not one failed (OEM crank), go figure. Mystery.
Cannondale claimed a bullet proof one piece crank is their catalog. Maz claims not one failed (OEM crank), go figure. Mystery.
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dunnbandit1
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- Joined: Wed Mar 10, 2021 10:41 pm
QUOTE
Originally posted by Big Winky
We are currently building an engine using these modifications, which we will install in a chassis an run it at full throttle till we are satisfied that we have fixed the problem or it blows.
We are currently building an engine using these modifications, which we will install in a chassis an run it at full throttle till we are satisfied that we have fixed the problem or it blows.
Will this motor be run with a load on it or will it just be free revving at redline? Just curious....thinking out loud. I would think that a load would make a difference but it's definately a fun test either way. Have you tried running one of your old cranks the same way you're gonna test the new one to get a more accurate comparisson? That would be some definitive proof to have the old one and the new one running side by side with all things being equal and have the old one fail. I would love to watch that.
Ok, I'm done dreaming.
I'm really happy to see you are going to such extremes. Good luck!
One more thing that hasn't been mentioned here. There was a problem with cartridge plates for awhile during production too. The crank hole was off center a little bit, which caused additional stress on the bearings and premature failure. This problem was discovered sometime around July 03 and corrected, but not sure exactly when it started or how to tell if you have a bad one.