Thread: Coon Ass 250x shaft mod
08-27-2011, 12:01 AM #1
Coon Ass 250x shaft mod
08-27-2011, 12:21 AM #2
08-28-2011, 10:57 AM #3
Yeah, there was ALOT of time put into this mod. After the shaft thrusting forward and tearing up my motor on a ski with 20 hrs, I wanted to do something to assure that wouldn't happen again. Maybe Kawasaki will show up with a check for me one day for all my time and effort put into it. I KNOW it saved, and will continue to save them, ALOT of $ having to replace motors under warranty as a result of their initial design driving the shaft into the crank, scarring the cases and basically knocking the thust bearings out.
08-30-2011, 07:01 AM #4
I think the second forward bearing in the 3 bearing configuration really helps more than the nut on the shaft. In a two bearing configuration once the forward bearing shits the bed the smaller one will go shortly after everything moves forward with the outer race making contact with the cone (it has a rather large air gap as the cone does not tough the bearing outer race when assembled). HTF can it take the load that the failed the larger bearing. The rear bearing outer race is a loose fit in the housing anyway freely spinning during bench checks-so load sharing doesn't happen unless loctited into the housing. I think whoever came up with the second forward bearing should be given the 'ataboy' for reasoning out the situation better.
08-30-2011, 10:37 PM #5
I tell you what...go ahead and remove the nut off the back of your 300 shaft (if you own one) then and continue to run it like the initial stock configuration of the stock 250/260 applications. Give that a try sport and tell me how it works out if your front bearing fails. I had a boat with right around 20 hrs that the pump bearing took a sh*t and cost me ALOT of money. I felt a vibration and before I knew it, my motor was hurt. A good buddy of mine and I came up with the mod to HELP prevent any instances of this happening again in not only my ski, but to help prevent others from tearing a motor and cases up as a result. Believe what you want, I really don't care. The whole "Coonass Engineering" was a joke, but on the same token it was a serious project to help fellow Ultra owners from potential damage. So give your "ataboy" to whoever you want..it's not just the recognition I wanted, yet the peace of mind thinking as a group we had some skis that could be ridden hard with a little more security with this preventive measure .
08-30-2011, 11:08 PM #6
wouldnt let it get to you keith he's picked it to bones since day one.
08-30-2011, 11:13 PM #7
Here is a testimonial from a satisfied "modded shaft client"
Thanks Coon Azz engineering!
I obtained the modified pump shaft and big nut for my 2007 Kawa Ultra 250X in July of 2009. About 3 weeks ago the pump went boom! Bearing bits were dropping out of the rear cone like BB's. I have to admit running for about 5 miles with horrible clanking because I didn't want to paddle......from the Gulf of Mexico to the dock......
Long story short.......pump gone, but the nut saved the motor. (to me, that in itself was worth the time and effort put into designing the mod, I KNOW what it feels like to destroy a motor in less than a minute basically of pump vibration)Kawa warranty fixed pump with new 2010 double bearings. I put the ski in my driveway on Sat and three hours later it sold. The test ride with buyer was first time it had been started since 5pm the day before when I got it back.
Great work! I've got the cash and that 300 Ultra looks bad to the bone!
08-30-2011, 11:18 PM #8
I know buddy....you of all people know how I feel about the whole situation. We, at the time, as a close knit group of Ultra owners went back and forth measuring etc together on this mod to make it happen. At this point it is what it is. If I were rich, I would love to own the new Ultra (NEVER thought I would say that), but for now I just started a conversion project. Take care...it's all in fun. He can THINK what he wants.
08-31-2011, 10:34 AM #9
There will always be a better mouse trap or someone creating a better engineered solution. A real man would accept this and suck it up. Seeing how the door has been opened in such a manner I shall clarify-
Nicjac an up and standing member of the good ole boys club found the same gap as other people between the lighter duty aft bearing outer race and the cone (and loose outer race fit). It is quite obvious from the post link below the type of initial research that was involved. It is interesting how others figured out the poor employment of the early ‘one nut wonder’. I personally would leave my ride in their care, the care of thoughtful and well measured individuals. Start at say page 7 of the link. Finally see the last page for similar opinions to mine.
If a bearing race is unrestrained it cannot share or carry thrust loads. Everyone, Nicjac, and their dog knows the outer race of the rear bearing is a loose-free spinning fit in the pump housing and a press fit to the shaft, so a thrust load will simply shift the bearing to carry on fat dumb and happy with its radial duty. Should the front bearing fail the weaker aft bearing will eventually bare thrust loads with the ‘one nut wonder’, once the outer race stops moving forward. That is a consideration with the dual bearing ‘one nut wonder’ patch,and as to how much longer you have before more shit hits the fan (thrusting a substantial weaker bearing while introducing the water ingesting wobble factor). The rest is elementary.
Some of the smarter guys employing the ‘one nut wonder’ carefully shimmed the rear bearing forward side so it could actually load share powered thrust with the front bearing. The intent of further thought on behalf of these critical individuals was to extend bearing life and reduce failure mode.
Someone clever, somewhere started to turn down the pump shaft and add a second thrust restrained bearing, restraining at both races to load share-clamped inner races between the shaft shoulder and the impeller/seal runner. The bearing outer races press fit and abut the forward housing shoulder, I might add employing a bearing type stronger than the rear cone end bearing, it is thus much better able to handle impeller axial loads.
Sport, as for running a 300 without an aft nut and self destruction I doubt anyone has. What the ‘one nut wonder’ does here is a guess- is the bearing fitted accurately or the same ole? Maybe Kawasaki has also changed the fit of the rear 300 bearing to actually carry/share axial loads, this I do not know. If they improved fits then they did a better job with ‘a one nut wonder’ employment. If it were me and I was the guy doing the modification to the shaft support I’d certainly be looking at this area for tolerance considerations. Shimming or modifying the cone to the rear bearing does nothing except to load the race for no spinning or take reversed stuffing thrust (the nut does nothing in this transient load reversal situation). More importantly you want the forward side of the rear bearing to be precision restrained axially just like the forward bearing (s), unless it is not needed using the dual forward bearing stackup. That definitely is a precision and QA matter for Kawasaki so two well sized bearings up front is the best and easiest idea so far. A true sport would have made sure the aft bearing outer race was restrained if he intended or claimed it to share axial loads with the front bearing.
The nut in a good design will assist with pump thrust loads. Maybe the Kawasaki intention of the ‘one nut wonder’ design is different that those of sport, or like sport maybe it is done without concern for load sharing? I do agree if Kawasaki copied the non-load sharing ‘one nut wonder’ application they should give credit to sport the original designer (maybe, maybe not give their head a shake too), if they employed load sharing they should not give credit as they fixed up or re-engineered a FU. I stand by my comments that the dual forward bearing stack-up is best so far for reasons stated. As for the rest of the fan club, what kind of rodents are found in Europe, the ones that run off the cliff every so often? They are certainly a very single minded lot ignoring some very important grounded facts.
Remember boys, you opened the door and what goes around comes around.
08-31-2011, 11:24 AM #10
Here buddy...have one . This is basically . In a nutshell, the mod was designed with intention and effort of saving the crank from getting thrusted and saving guys from having to spend thousands of dollars on a rebuild if it can possibly be avoided. It seems as though it worked in a situation where normally a couple hundred yards of riding would have damaged the motor with the original setup. The mod WAS NOT designed to strictly load share the bearings, yet to buy time from the shaft thrusting forward in event the front bearing took a sh*t. I said several times that the rear bearing basically stablized the shaft in its original application and IF the nut would help load share...then great, IF not it is still a preventive measure to stop the shaft from thrusting forward into the crank. I'll let you buy me a drink or something if you feel need be for my "one nut wonder" as you call it. With all your knowledge and technical abilities (as noted in your above novel of a post) maybe you should start coming up with your own mods in effort to help owners of these skis like I did. Thats right, to potentially HELP guys with the skis. I NEVER did it with intention of getting $ or making $ on the mods, yet to POTENTIALLY HELP GUYS IN FEAR OF HURTING THEIR MOTORS. I actually lost a few bucks in shipping for the ones I did do for guys.
No harm, no foul...Happy Riding.
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