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 Post subject: Layshaft Bearing
PostPosted: Mon May 07, 2012 1:19 am 
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Joined: Mon Oct 18, 2010 12:54 pm
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Location: Philippines, Western Pacific
The engine from the "Donor Bike" for my TT2 is still requiring attention. Initial problems were "graunched-down"
fasteners, care of previous owners, but now that I've removed the clutch, I've discovered that additionally, the
layshaft clutch-side bearing has lost its cage....................... The bearing in question is a 6203 having the
ubiquitous C3 suffix, however I remember (or DO I?) reading in these pages that some of the bearings in this
area had been upgraded to beefier specimens, or maybe even upgraded to roller bearings. Anyone care to verify
my assumptions on this one...................................???

;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;)

Poison


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 Post subject: Re: Layshaft Bearing
PostPosted: Tue May 08, 2012 11:46 am 
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Yes you can convert to roller style bearings to significantly upgrade load capacity at the ends of the transmission shaft (by 3X). This would be the bearing just in board of the clutch and the one below the chain sprocket SKF NJ 205 ECP and NUP 205 ECP. Also upgrading the other end of the shaft to roller like the later cases would be good as well. The earliest (500) one can’t be upgraded. All this assumed that your running straight cut primary gears which produce little side load on the shaft. The rollers don’t have as much capacity in that direction.


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 Post subject: Re: Layshaft Bearing
PostPosted: Fri May 11, 2012 6:52 am 
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Joined: Mon Oct 18, 2010 12:54 pm
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Location: Philippines, Western Pacific
Thanks for that Kranky. I am still leery of the standard bearing sitting on the clutch side of the layshaft. Thus I am considering using a 62203 bearing instead of the standard 6203. The 62203 is 4mm wider than the standard bearing, so may be better able to handle any overload in this area.

Poison


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 Post subject: Re: Layshaft Bearing
PostPosted: Fri May 11, 2012 12:12 pm 
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Joined: Thu Oct 14, 2010 11:23 am
Posts: 1100
Will there be room for shims? Will there be room for the shaft inside the case? MikeV


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 Post subject: Re: Layshaft Bearing
PostPosted: Fri May 11, 2012 9:09 pm 
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Joined: Mon Oct 18, 2010 12:54 pm
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Location: Philippines, Western Pacific
Good questions Mike!
There is a retaining plate - 2mm thick - holding the clutch bearing AND the layshaft bearing in their seats, so i will trim off this plate, so that it only retains the clutch bearing. Additionally I will machine the seat of the layshaft bearing 1.5mm deeper..............that means i only need to find/lose 0.5mm at the clutch end of the layshaft, which I think is most likely doable................. ;) ;) ;)
I'll probably perform these tricks on a RHS casing which I have going spare, so IF it doesn't work out, there'll be no serious problems with my original - albeit maltreated - engine!!!

Poison


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 Post subject: Re: Layshaft Bearing
PostPosted: Sat May 12, 2012 2:45 pm 
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Hi Poison Why wouldnt you just upgrade with NJ 203 bearing like the later (Paso and beyond) motors had fitted. It is a direct replacement. This bearing offers 3 times the load capacity as the 6203. The bigger version (NJ205 and NUP 205)of this bearing as mentioned can be used on the other end of the shaft as well.
-Cranky-


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 Post subject: Re: Layshaft Bearing
PostPosted: Sat May 12, 2012 11:12 pm 
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Location: Philippines, Western Pacific
Thanks again Cranky. However I have a query or two about axial location of the layshaft, especially with the sprocket hanging on the business end of the shaft. Do the combination of NJ203 and NJ205 bearings on the layshft provide sufficient axial stability? To my sceptical eye I would guestimate that a more stable solution would be a normal ball-bearing on the clutch end and the clunky roller bearing at the sprocket end. ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;)


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 Post subject: Re: Layshaft Bearing
PostPosted: Sun May 13, 2012 2:49 pm 
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Hi Poison I too was skeptical about axial loads and used to fit heavy duty cagged versions of the 6205... that being the bearing that takes the brunt of the abrupt race launch. The bearing goes from zero to full speed with the drop of that clutch causing the cage to split. Now fitting the roller style NUP205/NJ205 which has 3 times the static load capacity with the NJ203 has made all the bearing failures go away in high output race motors for the last few years. There is not much axial load WITH STRAIGHT CUT PRIMARES. The original 6203s are floaters anyway so the only proper captured bearing is the 6205 under the clutch drum which should be switch to NUP 205. That bearing has proven to have enough axile load to keep the shaft in the cases.
-Cranky-


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 Post subject: Re: Layshaft Bearing
PostPosted: Tue May 15, 2012 2:15 am 
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Joined: Mon Oct 18, 2010 12:54 pm
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Actually Cranky, immediately after hitting the "Submit" button after my last message, I reallised (while reading the spec-sheets) that the NJ203 and the NJ205 DO in fact provide a certain amount of axial location - albeit in one direction - which means that if they are installed in pairs (I imagine) would provide virtually complete axial stability. You have thus converted me!!!!!!!!!!! All that remains is to double-check whether my bearing supplier actually stocks these - not as automatic as you might think................... :o :o :o :o :o :o

Poison


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 Post subject: Re: Layshaft Bearing
PostPosted: Thu May 17, 2012 6:17 am 
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Joined: Mon Oct 18, 2010 12:54 pm
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Location: Philippines, Western Pacific
So far so good Kranky!

I now have my bearing supplier ready to rock-and-roll................ ;) But my original query was for the NJ203, and like bearing suppliers the world over, he wants to know whether its an NU, N, NJ or NUP version of the bearing! Can you quote me the normal upgrade bearing numbers as per the "official" upgrade items for use on the layshaft (only)..................both for inboard (clutch side) and to replace the 6205 bearing?

Poison


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