Seals or No Seals
There are several people I know personally that are running with no seals, with no problems so far. One of them is a Turbo HCR that gets ridden hard every weekend. Don't believe it just because some fancy shop said so. There's lots of people on here that don't make a dime off anyone that likely know just as much about this kind of stuff as any shop.
One of BDX's posts in this thread is completely wrong. It may be just worded poorly, but its still wrong. Be careful.
I agree. Some of what BDX wrote in the past was wrong (same for my posts). And we all know most of what BDX said on this issue is correct. I take my hat off to BDX because they've done a lot of work to get this problem solved, including some of the very first work to identify defective (tight) tunnels. BDX has loyally supported Arctic Cat owners with great service and good products, to the best of their knowledge at the time. The small stuff we disagree about is like nit-picking. None of us are perfect or all-knowing. That's why we work together, to solve reliability root-cause issues. None of us has all the information or all the answers. In the end, we don't want to break down on a steep climb, or way out in the boonies.
My specific issues with prior BDX advice (remember this is nit-picking):
1. The Chinese Peer bearing BDX sells is definitely not the best quality 5203 bearing in the world. Everyone who knows about roller bearings knows the new 3203 series bearings are better than old-spec 5203 type bearings. Everyone also knows that SKF, FAG, NTN, and a few other brands make the best quality ball bearings in the world, with better metallurgy, tighter tolerances, better surface finish, better QC, and better packaging that Chinese bearings.
2. BDX promotes a sealed bearing which is continuing Arctic Cat's original mistake. All the talk about the 5203 bearing not getting enough oil due to it's location in the DD is nothing but silly, shade-tree-mechanic, BS in my opinion. The 6203/4203/5203/3203 bearing is in the bottom of the drive, submerged in synthetic oil! A bearing needs only 10 microns of oil film (1/10 human hair). Any more oil does damage due to a "plowing" effect (as researched by NASA). It would take hours of high-speed running in a hot and dry environment to blow out DD synthetic oil to less than 10 microns film thickness. If you don't believe me, look at the bearing posts in this thread, all of them talk of blown out seals and damaged cages (that's caused by heat from high-speed grease churning). Based on the posts in this thread, the sealed 6203/4203/5203/3203 bearings run better after they overheat and blow out the rubber seals. The bearing then gets relief from grease-churning heat, and they get good cooling from the DD oil. When your DD oil comes out black, that's an indication you've char-broiled the grease, blown out the rubber seals, and washed cheap, burnt Chinese grease into your expensive DD oil. Another problem is that Polyurea grease contaminates synthetic oil. Anyone who knows bearings and lubrication will tell you the lubricants should never be mixed, because they cross-contaminate (the sum is worse than either component). In another similar application, Ski-Doo tried to use sealed, greased crank bearings, with the same result: char-broiled grease after long-hard engine pulls. (Skidoo added water-cooling to the crank bearing area.) Grease is for slow speed, dirty applications, like down on the farm. Grease is NOT better for high-speed lubrication. Think of grease as oil with a contaminant in it (the soap thickener). The oil does the lubricating, not the soap thickener. The 6203/4203/5203/3203 bearing spins at 12,000 rpm - way too fast for grease! In industry, 1000 rpm is about the limit for grease. I've not seen any posts on these forums where a used DD transfer shaft bearing with seals was inspected with a) the factory seals intact and b) the grease intact - including my M8 and HCR. At best, the grease boils away and contaminates the DD syn-lube, and at worst the cage and seals blow out, contaminating your DD with charred grease, steel chunks and rubber bits. It's an obvious Mechanical and Lubrication Engineering error. And if it hasn't worked for anyone in several years of DD use, why do people keep using sealed bearings? It seems to be one of several Arctic Cat and BDX engineering screw-ups. Being a degreed Mechanical Engineer with 30 years experience, I feel qualified to evaluate their their design skills. (Side note: When I interviewed for an "engineering" job at the Arctic factory in Thief River Falls many years ago, I was amazed they did not have any degreed engineers on staff. Just a race team and draftsmen to draw up new parts. Their R&D Department was in the customers garage!)
3. BDX has talked about gear tooth misalignment after machining the transfer shaft. That is a valid concern, but it doesn't occur between the transfer gear and five planetary gears as BDX claims. Those gears are fixed in alignment by the aluminum DD housing and cover. After machining the transfer shaft, what moves is the DD output shaft with the outer ring gear, which is pushed into the DD gearbox, slightly offsetting the outer planetary gear mesh. As long as the ring gear doesn't rub the planetary frame or disengage the rubber lip seal, it's not a problem. The outer planetary gear mesh can probably take more horsepower than the inner gear mesh due to geometry, with much more tooth contact at the outer ring. A little offset a that location is not a problem, as long as no interference occurs. You could trim the width of the output shaft ring gear a small amount if needed to keep it from rubbing the planetary frame. I trimmed my M8 transfer shaft 0.040" (0.014 for the 3203 bearing and 0.026" for axial clearance) and it worked fine. Your machine, with different tunnel problems, will be different.
4. BDX told some people, without looking at their machine, they don't need to trim any shafts. Just install the wider 5203 bearing, and off you go! In some machines that will work, and in other machines it will make the problem worse. Every Arctic Cat tunnel has a different width, and some of the DD shafts, spacers, and drive shafts are different. There are also bearing width tolerances to consider - different brands of 5203/3203 bearings have slightly different widths. My SKF bearing is 0.002" wider than a BDX Peer bearing.
5. Update 5/12/2012: I removed a BDX sealed bearing (Peer, China) from my 2011 HCR. It was under severe axial pressure for about 700 miles due to my 0.120" too-narrow tunnel / too-long drive shaft. The BDX bearing and seals were intact, running smooth, and looked great, with about 1/1000" axial clearance. The new SKF 3203 bearing I installed has no axial clearance. Popped the seals off the BDX to inspect, and the factory grease was totally gone. Only DD syn-lube was in the bearing. Black sludge was everywhere inside the DD case - probably from the cheap, burnt Chinese factory-installed grease. That bearing must have run very hot when the rubber seals were new and it was full of grease. Probably boiled and charred the grease. Left heat-stress signs on the cage. Which is why I think seals on a gearbox internal bearing are dumb. As I said before, that bearing spins at 12,000 rpm when the clutches are maxed out - way too fast for grease!
Good luck. Knowledge is power! Very impressed with posts by bgreen776. In my opinion, he has identified and understands DD reliability issues more than anyone on this thread. If there is a controversy, I'd look for his posts and go with his advice.
Well I guess it's time to tear down and check the brng the 2010 has the same one as the 2011. Will post what I find later.
