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  #11  
Old 05/12/2014, 07:59 PM
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gribley gribley is offline
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Location: Bolton Lancs
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What is the purpouse of the thrust washer? The crank is located axially by the ball race behind the drive sprocket
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  #12  
Old 05/12/2014, 09:23 PM
druid druid is offline
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Default Challenger oil seal

I believe the washer is to stop the cage and rollers moving out of position.
Druid
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  #13  
Old 05/12/2014, 09:42 PM
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gribley gribley is offline
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Ahh that makes sense. With the Nametab bearing conversion it isn't needed
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  #14  
Old 05/12/2014, 09:55 PM
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dave higgins dave higgins is offline
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Location: bikes owned, 380 qub griffon. maico 400, 560 rotax ccm, living in north somerset
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As you say gribs, thrust washer not needed, the endfloat is dictated by the ball race behind the primary drive sprocket, but even with new good quality bearings, once run a while endfloat is quite considerable static, but running, trues itself, at least thats how it goes on the griffons...

Last edited by dave higgins; 05/12/2014 at 09:58 PM.
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  #15  
Old 29/07/2017, 10:59 PM
Stan Nicholson Stan Nicholson is offline
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I didn't get around to sorting out a labyrinth seal for the timing side of my Silverstone as I figured I would have to remove all or most of the spigot on the ignition back plate that carries the existing seal to make space and this was a one off, machined to carry the PVL system I have been using for a few years now. Difficult to put the material back if the lab seal didn't work out.
Anyway, when I stripped the motor at the end of last season the TS oil seal was dry, despite changing it once during my 4 weekend race season. The seal lip had disappeared and some seal material had melted onto the crank! That would account for having to keep going up in main jet sizes during that last race weekend.
When rebuilding the motor for this year I decided to try and improve the lubrication to this seal and change the seal material to a higher temperature spec. I drilled 8 x 5/32" diameter holes equi-spaced on a 1.450" PCD in the steel spacer (it is not hardened as I thought it was). These aligned with the gap between the outer sleeve in the case and the aluminium bearing cage. The holes were carefully chamfered on both sides and I made sure there were no burrs that might break off and enter the bearing. I bought Viton seals to replace the standard Nitrile seals, that although 3 times the price are still peanuts in the scheme of things.
So, having just completed my 2nd race weekend I pulled out the seal to change it and found it was in perfect condition and there was lots of oil present. I have always used R at 20:1 so that hasn't changed. I replaced the seal anyway as I had bought several spares.
It looks like holes in the spacer allows lubricant to reach this seal and, although not as sophisticated as a lab seal, it seems an easy remedy to the problem of lack of lubrication.
Stan
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