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Eaten Diamond Drive

S
I've had a double row bearing in the DD since the first year I had this 09 HCR. I put in another double row before the 2015 season just to be safe. I don't get to do much riding so there hasn't been many miles put on the sled since. But early this season heard a bad grinding noise for a couple of seconds. Sled still rode, so thought it was something stupid. A few weeks later heard it again. I was far from the trucks so had no choice to ride, but never heard it again. Last night decided to check the DD. Yep, the double row bearing went. Can't believe it still worked.

Each of the 5 little gears in that 5-gear pinion have a tooth partially gone. The outer ring gear cracked. I think I can get away with the 5-gear pinion as it is and replace the splined assembly and the gear ring.


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Coldfinger

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So was the damage from the balls going thru the gears?

What do you suppose caused the failure on a fresh bearing?
 
J

jim

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Nov 26, 2007
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From what I've read, some of the sleds have a tolerance stack-up that ends up putting a large axial load on the bearing when you go to the double row...so they fail. There is a way to measure this to be sure, but I can't recall the details. I'm ready to do mine...will be looking into things more when I do. But, then again, if my bearing looks good after 1000 miles with a turbo...I might just put the single row bearing back in and avoid issues? What to do. Because some have actually caused the problem due to the extra width of the double row...when the single two may very well have gone just fine. Crummy tolerancing and design is the core issue here. This should have been a double row conical bearing to handle possible axial loads. My 2 cents.
 
S
I don't know why it failed prematurely. I think jim is on to something though and I think I read that years ago. It was the bearing from the Bearing Replacement Kit from BD that failed. The double row I had before came from a local bearing shop here. I ordered a used DD on eBay today. Was cheaper than ordering parts from the dealer. Think I'm going to take the seal off the bearing on this used DD so oil gets in there and keeps it lubricated.
 

boondocker97

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Assemble the diamond drive in the sled with the back case bolted in solid and track shaft in place. If you can put everything in the back case, then put the cover on and have it sit down tight by hand then there is enough space for the dual row bearing. If the outer cover doesn't sit down flush then you need to cut the track shaft down 0.050". Or you can machine the shoulder down 0.050" on the gear where the double bearing slides on it.
 

Thunder101

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Feb 7, 2008
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Assemble the diamond drive in the sled with the back case bolted in solid and track shaft in place. If you can put everything in the back case, then put the cover on and have it sit down tight by hand then there is enough space for the dual row bearing. If the outer cover doesn't sit down flush then you need to cut the track shaft down 0.050". Or you can machine the shoulder down 0.050" on the gear where the double bearing slides on it.

BINGO !

HCS has a good write up done buy Silverman or Silver___ something like that. It's a good write up. As for bearings I don't think the double bearing is the fix a good quality bearing is the fix not a China bearing. And no side load on the bearing.
 

Paul27

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Dec 25, 2008
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Reno, NV
Reference info FYI. Good luck!

//www.snowest.com/forum/showthread.php?t=207098 (2009 M8 turbo)

//www.snowest.com/forum/showthread.php?t=300771 (2009 M8 teardown & shaft trim)

//www.snowest.com/forum/showthread.php?t=324077 (2009 M8 bearings)

//www.snowest.com/forum/showthread.php?t=151644 (original & best DD info - 2011 HCR findings)

//www.snowest.com/forum/showthread.php?t=310238 (2011 PG TM8 bearing failure & My 2011 HCR DD track shaft trim)
 
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