After reading this thread word for word, I’m starting to wonder why about 10 of you don’t start up a company together that builds snowmobiles. Based on what everyone seems to have for expertise and understanding of the market, warranty impacts, what people will pay for durability 90% of them don’t need, and understanding of mass production, you’d quickly have a product that sells 10X more snowmobiles than Polaris. Considering Polaris is about a $5-6B company doing what they do....you’d all be rich! I’ll keep you all in mind on my next sled purchase.
850 gone down already??
- Thread starter ANTHONY11
- Start date
No there is clearly a design or manufacturing "whoops" with some of these 850's on the PTO bearing. I am not intimately familiar with the design or assembly. All I'm saying is that an interference fit assembly with dissimilar materials works perfectly fine when properly executed.
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Possibly, possibly not? We will know for sure by the end of the season!
Let's try to keep things in perspective here.
Almost anything and everything that comes from a corporate mass production assembly line can be improved. No snowmobile manufacturer designs and builds for reliability and longevity. The costs and weight penalties are too high. Especially when recent sales of sleds have fallen for the past 10 years.
They build for performance and the lowest costs possible. I believe they also build a sled with the idea the owner will sell in a max of 2-3 years and buy a new one. We may not like this, but if you think you are mechanically and electrically inclined, dig real deep in your sled and look closely at how it's built and designed.
Companies like Dan work to improve the OEM longevity with the least financial penalty possible. He has to overbuild as much as allowable for him to stay in business and do what he thinks is the best quality job. Small shops (think auto repair also) are not insulated from irate customers like Polaris and other Corporate OEM's are when their machine or automobile breaks down. Especially when it may be premature. They have dealers to take the heat for them. Shops like Dan often have face to face or mouth to mouth contact with their customers. This brings a different element and business model for Dan and other small shops than it does for PI, BRP, etc. When were you able to yell at the CEO of Polaris for your piston skirt blowing through the bottom of your case? You can with Dan.
It can be a real difficult situation for both customer and shop when the shops work comes back. Comeback's or warranty claims have a much bigger impact for a small shop and can be financially disastrous if they get to be too much. So of course shops like Dan will do everything they can to improve on the OE's design to make sure their work doesn't comeback. Something that may work for Polaris' bottom line may not necessarily work for Dan's bottom line.
As for Polaris' test motors working for thousands of miles and time without issues, these motors are delicately assembled by The Real Engineers (thank you to this group) to absolute perfection, much like Dan's motors are. Things often change when you get to the Production line and those Engineers might not like it or agree with it. Assembly line workers are not Engineers and not mechanics. They are being directed to build those motors as fast as possible with work instructions. This is often when decisions are made by senior leadership to be as fast as possible and to cut costs as much as possible. This is often where risk is taken that might lead to premature failures. Shareholders demand returns on their investment.
Almost anything and everything that comes from a corporate mass production assembly line can be improved. No snowmobile manufacturer designs and builds for reliability and longevity. The costs and weight penalties are too high. Especially when recent sales of sleds have fallen for the past 10 years.
They build for performance and the lowest costs possible. I believe they also build a sled with the idea the owner will sell in a max of 2-3 years and buy a new one. We may not like this, but if you think you are mechanically and electrically inclined, dig real deep in your sled and look closely at how it's built and designed.
Companies like Dan work to improve the OEM longevity with the least financial penalty possible. He has to overbuild as much as allowable for him to stay in business and do what he thinks is the best quality job. Small shops (think auto repair also) are not insulated from irate customers like Polaris and other Corporate OEM's are when their machine or automobile breaks down. Especially when it may be premature. They have dealers to take the heat for them. Shops like Dan often have face to face or mouth to mouth contact with their customers. This brings a different element and business model for Dan and other small shops than it does for PI, BRP, etc. When were you able to yell at the CEO of Polaris for your piston skirt blowing through the bottom of your case? You can with Dan.
It can be a real difficult situation for both customer and shop when the shops work comes back. Comeback's or warranty claims have a much bigger impact for a small shop and can be financially disastrous if they get to be too much. So of course shops like Dan will do everything they can to improve on the OE's design to make sure their work doesn't comeback. Something that may work for Polaris' bottom line may not necessarily work for Dan's bottom line.
As for Polaris' test motors working for thousands of miles and time without issues, these motors are delicately assembled by The Real Engineers (thank you to this group) to absolute perfection, much like Dan's motors are. Things often change when you get to the Production line and those Engineers might not like it or agree with it. Assembly line workers are not Engineers and not mechanics. They are being directed to build those motors as fast as possible with work instructions. This is often when decisions are made by senior leadership to be as fast as possible and to cut costs as much as possible. This is often where risk is taken that might lead to premature failures. Shareholders demand returns on their investment.
"Warmup" caught my eye. Everyone remembers the 07 Summits. Massive crank bearing failures. People (won't say who, lol) were telling buyers to just pinch the oil lines and blow them up on the stand instead of waiting for it to happen in the backcountry. Well, by friend bought three, one for his nephew, one for him, and one for his son. One was wrecked somewhere between 1200-2000 miles (don't remember exactly), the other two are at 2000+ and still around. None of the three had bearing failures. The only think that was unique about these sleds is that they were 100% ridden from the house, taken from a warm garage. They were also religiously warmed up before riding.
I know that we are talking about different types of bearings, but in my opinion warmup was what made those Summits engines last.
Totally agree with the jet engine comment. You are matching up titanium with aluminum with steel. But one thing just engines have is thrust conical bearings to handle axial and radial loading. They also have a constant stress, non cyclical loading situation...thrust on the shaft and centripetal loading on the blades and hubs. They can also be ramped to full power and speed relatively slowly. A sled has a very cyclic, insane accelerating internal combustion motor with a bunch of parts pushed to their limit simply with g forces alone...and a huge crank load. The jet engine is simply genius...super reliable, conservation of momentum, slow loading stresses, etc. But to me, a very different application.
I would imagine a conversation regarding final engine design took place similar to the following...
"How much will we lower engine costs by eliminating the need for a physical locating device for pto side crankshaft bearing? And how many additional failures do you predict this will cause?"
I also imagine that the answer submitted will appear somewhat optimistic when compared with final statistics.
Yes, this is Monday morning quarterbacking, but right now I bet that the additional expense of a bearing location device would have been a justifiable expense.
As Dan mentioned at some point, the 800 has an inner race and a spherical bearing. In that case the inner race is pressed onto the crank, and the outer race is squeezed by the cases. You have more holding power to keep the bearing moving than what is on the 850.
So are you guys saying there is no axial support (i.e. spherical roller or ball) for crankshaft...at all???
I can see if there is only ONE ball/sph. roller bearing on the crank somewhere to hold everything in place axially and then a big roller on the PTO side that takes overhung (clutch) load. The PTO side is free to move axially a bit, but the whole mess won't move much.
Think I'll go read more back pages...kinda confused.
OTM
I can see if there is only ONE ball/sph. roller bearing on the crank somewhere to hold everything in place axially and then a big roller on the PTO side that takes overhung (clutch) load. The PTO side is free to move axially a bit, but the whole mess won't move much.
Think I'll go read more back pages...kinda confused.
OTM
S
2 balls in the middle.one has a ring.maybe
Here is another variable that could cause less interference fit. Is there sealant/adhesive applied to the two halves. Was the interference designed without the sealant, or with? Otherwise you could loose a thou or two real easy.
For an interference fit I would rather see a "O" ring seal around the case halves. But none the less it should have a positive lock due to the different thermal expansion rates and very smooth surface finishes. Believe me Polaris will make changes, as now the cat is out of the bag and sales could suffer in the future?
For an interference fit I would rather see a "O" ring seal around the case halves. But none the less it should have a positive lock due to the different thermal expansion rates and very smooth surface finishes. Believe me Polaris will make changes, as now the cat is out of the bag and sales could suffer in the future?
Just because Polaris is a "$5-6B company" doesn't mean any one of us couldn't make constructive suggestions to improve their products. For instance, how about a tether as stock? Now there's a whole new thread!
While I appreciate your humor here, I simply see this thread as several people sharing perspectives, ideas and theories on this topic. Does it mean I'm right? Nope...it would take months, if not years, of design, testing and refinement to know for sure. I'm all theory here based on my background. But add a guy like Dan, and others with years of real-world knowledge (which I value much more than theory) and you have some great discussions which tend to support each other. And one thing I have always seen constant is that real-world knowledge/experience always translates back to sound engineering principles/theory. However, engineering theory/principles don't always translate to the real-world application (ever watch the show "engineering disasters"?). Lastly, the cost of quality for mass production is real. Maybe this configuration works great if assembled correctly...but allowing variability to occur by an operator/assembler is a poor approach. One should design-out the chance for variation, and this doesn't have to be expensive...it is cheaper if done correctly. Does this whole issue sound cheap? What is the ROI for moving bearings vs ring located vs failure rates? I sure don't know, but sounds like you might based on your comments?
That said, sitting back and saying people are wrong with no rational or information to back that up is empty and not constructive. The number of times that approach has accomplished anything in the history of the world is still zero. If we are wrong, share your thoughts why? I would like to hear why I may be wrong and learn. I'm passionate about having an open mind and learning...and my ego is not my priority here...not anyone's on here from what I can see.
Indy Dan has some great opinions on crank case sealing posted in the past that relate to this. You'd have to dig it up, but yes the right amount of sealant on crankcase halves does make a difference.
S
Isn't the holding power for the outer race coming from bolting the cases together? If the interference fit is the same than the holding power will be the same. Only the 850 bearing isn't tied to crankshaft side play so it should be less likely to move.
I understand that having an inner race with a spherical bearing naturally keeps the outer in line but it also applies the crankshaft side play to the outer race.
I don’t get why some people get so butt hurt about guys offering their opinion or advice. Some of these guys are obviously very experienced and very educated. I enjoy learning from folks that are a lot more knowledgeable than myself and I’m glad they are willing to take the time to share on here.
And there is at least 10 or more of these guys that together could probably engineer and build a sled as good or better and with less issues then certain $5-6B companies.
Especially if they had all the resources of certain 5-6B companies!
There a 4.1 billion dollar company btw....lol stock went from 97.00 to 72.00 a share after this thread started......JK but its the same time frame 
https://charting.nasdaq.com/ext/charts.dll?2-1-14-0-0-512-03NA000000pii-&SF:4|5-HT=350-
https://charting.nasdaq.com/ext/charts.dll?2-1-14-0-0-512-03NA000000pii-&SF:4|5-HT=350-
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When these 10 guys build thousands of sleds instead of hundreds the results could change somewhat though. Murphy likes the odds.
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