2010 m8 SP Diamond Drive bearing blown up/ upgrade requiring machining?

[mallard d69]

Hey guys, I've been looking at threads all over the net about this and from what I have read sleds up to 2009 have the stock output shaft machined for 5203 and also BDX brand gears are still machined for 5203 but apparently stock 2010/2011 CAT output gears have a slightly shorter surface for that bearing ( I have not measured this myself but comes from "experts" on snow west lol). I think the stock spacer and bearing was 15.9mm and 5203 are 17mm width, the solution is a 16mm wide 4203 double row bearing, this is not a common bearing, I just ordered mine today and they had to get them from a warehouse in Ontario! This way you should have no worries with pre-load coming from the drive assembly itself but if you are unfortunate enough to get one of the sleds with narrow tunnel + slightly oversize track shaft you may still get some pre-load from that.

4203 double row bearings are not recomended for diamond drive applications as they do not have the ability to handel the side load that is put on these bearnings... now haveing said that they are still better then the 6203 bearing that came stock and many people have used them and like most things, some people like em some don't. but if you want the best bearing for the 09-11 m serries its the 3203 bearing. i say 3203 because they do not manuafacture 5203 bearnings any more and if you are able to find them your just helping that company clear out there old stock. 3203 bearings will not require the shaft to be machiened as long as you do not try to reuse the stock spacer/washer

 

[Paul2727]

Also when installing the case back into the sled, if it doesn't seat completely and easily against the tunnel, you may have to machine the track shaft. According to to Jeff from BDX, and most of the guys who seem to know what they are talking about in these forums, this is a case by case, sled by sled situation. I got lucky, everything went back together perfectly once the case was removed. ... Again, every sled seams to be different, its just ****ty manufacturing practices by Arctic Cat and their suppliers.

Good summary. Everything you wrote James is spot on! However, I will add one additional precaution / clarification:

When you install your assembled DD back into your sled, it's very hard to see behind the case, so you can't tell if the DD case seats completely against the tunnel. And when you tighten the DD mounting bolts, it all looks and feels normal, smooth, and hunky-dory. I found the only way I could tell if the tunnel was springing apart, was to measure. I explained two different measurement methods in this post:

2009-2011 Diamond Drive Bearing Failure - SnoWest Snowmobile Forum

Another indicator is a blown 6203 bearing. The Cat owners lucky enough to have a good match between their track drive shaft and tunnel can run a standard 6203 bearing for years, even with 300 hp turbos. On my stock machines (2009 M8 and 2011 HCR) the 6203 bearing came apart within a few hundred miles. Luckily, I caught both before the bearing shrapnel took out the DD. In my 2011 HCR, a replacement BDX 5203 bearing lasted longer, about 800 miles. The cause for both machines was axial load. There was no indication when bolting them together, if I hadn't measured. The tunnel is very stiff near the bulk head, so when it's "sprung", it puts a lot of axial load on the bearings. I had to trim my HCR drive shaft 0.130" to make it right.

Bottom line, if you're losing that little bearing in your DD, it's not because you aren't changing your oil often enough. That's what the turbo guys used to tell me. That I wasn't servicing my sled properly.

Good Luck and Merry Christmas!

 

[bj_lucky]

Well decided to go the 3203 upgrade this week. I figured I was playing Russian Roulette with the 6203 as it's still the original bearing with 2000+ hard miles on it. And seeing as how the diamond drive was being removed, I may aswell get and install a new track. Well when I pulled the driveshaft to put the new 2.5 camo extreme in I found there to be no bearings on the brake side of the tunnel. And I mean no bearings, nothing. Completely shot. So I threw 2 new bearings in and reinstalled drive shaft and track. Well I started installing 1st half of diamond drive and found it barely wants to sit flush with he tunnel with out even having the second half of the diamond drive on. Then I tied to install the diamond drives second half and ofcourse no luck with getting metal to metal contact. So turns out I have one of the damn narrow tunnels. So right now am getting the bearing shaft machined 2mm's so the two halfs come together but still doesn't fix the issue of the 1st gear set putting lateral pressure on the c- clip. It atleast gets me riding this weekend. But got me wondering if that narrow tunnel is what took out the 2 bearings on the brake side?



Here is some pics of whats left of the bearings on the brake side.

 

[bj_lucky]

This is what the diamond drive looks like against the drive shaft when just the 1st half of the diamond drive is in place (not even bolted yet) causing pressure of 1st gear set against the c-clip. Looks like this summer I'll take it apart and get the drive shaft shortens a couple mm's on each side. Id do it now but I've spent till 2am wrenching the last few nights and don't feeling like re doing it all over again tonight. Just hope that machining the bearing shaft and moving of 3203 a couple mm's works.

 

[mallard d69]

this is a helpfull thread but i personaly think this one https://www.snowandmud.com/arctic-c...-drive-bearing-upgrade-thread-lots-47974.html
is a much better thread and has lots a pics which maks things easyer
but if you are still haveing problems send me a pm well chat on the phone and get you back on the snow hopefully with out machine work... i would come over and give you a hand but red deer is a bit of a drive.

 

[bj_lucky]

Got the shaft back from the machine shop. Installed the 1st half of the diamond drive and the set the second half in. And for the 1st time I got metal to metal contact of the two halves of the diamond drive with out bolting it together. Who knows, maybe my sled was built on a Friday... Or Monday...... My brother in law did his 3203 upgrade last year and fit together with no issues.



Here is how much was machined. Before machining the bearing sat flush at the end of the shaft.



Big big thanks to Dittrich Machine Shop in red deer for getting it back same day on such short notice. Definitely recommend them.

 

[DaltonW]

The 3203 bearing a from cat bearing or aftermarket? sounds like I should do mine.

 

[bj_lucky]

The 3203 bearing a from cat bearing or aftermarket? sounds like I should do mine.

An aftermarket bearing from Comercial Bearing.