unchained
New member
Was out riding last Sunday and chain started skipping. Long story short, my chaine case side lower drive bearing fell apart. Upon dissasembly and diagnoses, I noticed both the upper and lower bearings are all sealed. I know the guy I bought it from replaced all the drive bearings so did he put them in backwards, buy the wrong bearings or does Yamaha not use the chain case oil to lube the bearings on that side? Im assuming their NOT supposed to be sealed and it ran dry?? thanks!!
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Stephfg
New member
the seal should be on the oil side (the side you see). The other side shouldn't have seal.
unchained
New member
So the bearings run dry? If the seal is on the oil (outside), how do they get lube? If their greased/sealed bearings then they would have seals on both sides. Im confused...
bluemonster1
LIFE MEMBER ONLY ONCE!!!
I run my bearings open to the outside to get oil in there.Never had a bearing go in years..
unchained
New member
Makes perfect sense blue. Whats factory though?
Factory is to have a seal on the oil side and none on the back. Enough oil weeps through the seal to lube the bearing.
Others have run with no seal on the oil side and risk having metal particles from gear/chain damage the bearing. Blue does this and it seems to work for him as I'm sure others will attest to. I run mine the same as Yamaha installed it.
Others have run with no seal on the oil side and risk having metal particles from gear/chain damage the bearing. Blue does this and it seems to work for him as I'm sure others will attest to. I run mine the same as Yamaha installed it.
unchained
New member
OK thanks...crewchief47 said:
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rx1jim
New member
Exactly what CrewChief said, the seals of the upper and lower bearing face the inside of the chaincase. These seals allows enough chaincase lube to pass through the sealing lip to provide lubrication of the bearing. I pack all of the bearings full of Mobil 1 grease upon assembly. The seals keep the metal particles out of the bearings. There are metal particles being generated constantly from the interaction of the gears and chain. It is a good idea to open the chaincase every season to wipe out the sludge that accumulates at the bottom of the case. While you have the chaincase apart, check the chain fro broken links and stretch. the manual shows how to measure the chain for excessive stretch. I finally had a cahain stretch out beyond the wear limit last year with 12000 miles on it. There is a third bearing on the chaincase cover. It has no seals on it. Check it foe excessive play, if it is good, pack it with grease upon reassmbly. The last bearing in the case which needs to be checked ( an way too ofthen gets overlooked) is the needle bearing in the chain tensioner idler pulley. Check it for excessive play on the shaft.
bluemonster1
LIFE MEMBER ONLY ONCE!!!
if its good enough for the bearing on chain cover to be open,then its good enough for me to have the others open all around.The bearing on my cover are all original on both sleds and they are still good.
10 -4 on that! I run all the bearings in my casing open! Why call it a sealed bearing if you expect it NOT to seal? Don't make sense... As Mr. Spock would say " Its not logical" Run em open!bluemonster1 said:
unchained
New member
Well,,,,Yamaha did such a good job on every aspect of that sled and many many many other sleds that its hard to question that their not smart enough to have overlooked or accidentally put a seal between the oil and the bearing internals. I tend to lean towards they did it for a reason. Assuming as Crewchief said already to keep the metal debris that accumulates in the oil from contaminating the bearings.
I was just browsing eBay and noticed this drive bearing on there has a hole on the inner race so it appears the chain case lube would enter through from between the shaft and the inner race rather than weep through the seal. This here could be a left side bearing but I do agree it seems unlikely that the heavy gear lube would weep through enough to provide adequate lubrication especially on the top bearings.
I was just browsing eBay and noticed this drive bearing on there has a hole on the inner race so it appears the chain case lube would enter through from between the shaft and the inner race rather than weep through the seal. This here could be a left side bearing but I do agree it seems unlikely that the heavy gear lube would weep through enough to provide adequate lubrication especially on the top bearings.
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That is a drive axle bearing on the speedo side. I have all my bearings with the open side facing the oil. Why in Gods name would you want the drive bearing on the crankcase side to face towards the track for all of that debris to fly up in there? Even with the seal, it still does not make sense.
unchained
New member
Let me ask this. Has Yamaha changed on the newer models or still sealing off the oil side of the bearings?
i concur i always run them open and remove cover yearly to clean it out. but as rx1 jim says check tensioner bearing seen many of my customers over tighten chain and tears this needle bearing up and then u gotta replace all of them because of shrapnel all over and look wheel over make sure it not outta round
unchained
New member
Im going to grease them and put them back as installed from the factory. Sled has over 5k miles so Im surprised its shot but was suprised that it unraveled like that. Maybe ATF in the case isnt such a good idea after all. I did a drain, clean out, inspection and put it back together 2 yrs ago with ATF instead of gear lube. I have used ATF in dirtbike clutch/gear boxes and snowmobile chaincases for years but maybe that had something to do with it failing?
Here is the response from a Yamaha technician regarding which way the bearing goes in. FWIW.
all the ones i have installed have an open side on the bearing.
the
open
side goes toward the case so the oil in the case lubricates the
bearing.
the
seal side goes to the backside of the case to keep the oil from
coming
look at
the
upper
bearing. the balls should be visible on the inside of the case.
or
at
least
all the ones i have seen/done are this way.
all the ones i have installed have an open side on the bearing.
the
open
side goes toward the case so the oil in the case lubricates the
bearing.
the
seal side goes to the backside of the case to keep the oil from
coming
look at
the
upper
bearing. the balls should be visible on the inside of the case.
or
at
least
all the ones i have seen/done are this way.
The Yamaha tech you talked to is wrong. Yamaha is STILL installing this bearing with the seal towards the oil. The crap from the track is kept out of the bearing via the LIP seal installed in the case where the driveshaft goes through the back, before going through the bearing. The other bearings are open because they are not immersed in oil and have a greatly reduced chance of particles settling out in the bearing while the sled is stationary.
I change the oil every 1 to 2 seasons using a synthetic 75/90 gear oil.
The old man's Vector GT went 11,500 KM on the original bearing and we only retired it because we were in the case to change his track.
I'm only posting this to 'clear up' any mis information, you're all welcome to do what ever you like in regards to your lower chaincase bearing, as Blue will attest to, both ways seem to 'work'. The chaincase bearings are the cheap ones to replace if you catch them before explosion. Be sure you are servicing the clutch side bearings as well (jack and drive) by greasing, either by removing the seal or using a grease needle.
I change the oil every 1 to 2 seasons using a synthetic 75/90 gear oil.
The old man's Vector GT went 11,500 KM on the original bearing and we only retired it because we were in the case to change his track.
I'm only posting this to 'clear up' any mis information, you're all welcome to do what ever you like in regards to your lower chaincase bearing, as Blue will attest to, both ways seem to 'work'. The chaincase bearings are the cheap ones to replace if you catch them before explosion. Be sure you are servicing the clutch side bearings as well (jack and drive) by greasing, either by removing the seal or using a grease needle.
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unchained
New member
For what its worth, I put it back together as designed. I also filled it back up with Amsoil chaincase oil instead of ATF as I had in it prior to the bearing total failure...crewchief47 said: