Main Shaft Gear Box

J

Jugs_S

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<DIV>Have just found a damaged bearing surface on the Bear Box Main shaft Drive side needle roller. Pix at </DIV> <DIV> </DIV> <DIV><A target=_top href="http://laverdapedia.com/coppermine/displayimage.php?album=65&pos=32">http://laverdapedia.com/coppermine/displayimage.php?album=65&pos=32</A></DIV> <DIV> </DIV> <DIV>Any one had or seen this before ?</DIV> <DIV> </DIV> <DIV>Jugs_S</DIV>
 
<DIV>Jugs,</DIV> <DIV> </DIV> <DIV>That is the normal result of too much drive chain tension!  The output shaft is pulled rearwards by the chain under suspension movement, tips in its' bearing slightly and loads the inner needle bearing beyond its's limits....  Seen plenty of 'em.  Next step is a snapped shaft, usually just inboard of the inner needle bearing.</DIV> <DIV> </DIV> <DIV>piet</DIV>
 
<DIV> <DIV>Piet</DIV> <DIV> </DIV> <DIV>That would explain the blue heat loading in the inboard needle rollers, I was thinking about grinding and hard chrome and grind, any one gone this route ? </DIV> <DIV> </DIV> <DIV>Jugs_S</DIV></DIV>
 
<DIV>Hi Jugs </DIV> <DIV>            I've seen a few like that - the shim washer next to this area tends to cut off lube to the bearing - making the problem that Piet described even worse. I always used a new shaft and bearings as couldn't risk a customer having gearbox problems that could result in a seizure. I also filed a few half moons in the washer to help oil get into bearings as well. I did modify my own 120 shaft - I ground down to remove the damage and shrunk on a couple of needle roller inner sleeves, then ground out the top gear cog and pushed in bushes similar to the 180/750 set up. Has worked fine for ages with no ill effects - Egli bob now has this motor so when he dismantles it he will be able to comment - HTH - Phil</DIV>
 
<DIV> <P align=left><SPAN>Spoke to my Hard Chrome guy and hard chrome is defiantly out, so now exploring sleeve and metal spray options.</SPAN></P> <P align=left><SPAN></SPAN> </P> <P align=left><SPAN>Oh fun</SPAN></P> <P align=left><SPAN></SPAN> </P> <P align=left><SPAN>Jugs_S</SPAN></P></DIV>
 
<DIV>Phil, </DIV> <DIV> Dismantle it? Me? But surely, that would invalidate the lifetime parts and labour warranty? </DIV>
 
<DIV>Sorry Bob - warranty states "not for race or rally use"<IMG height=19 src="/forum/msnemoticons/emteeth.gif" width=19></DIV>
 
<DIV>Phil</DIV> <DIV> </DIV> <DIV>Do you remember how much you ground off for the sleeve. The ones I can find have a wall thickness of ~2.5mm and did you regrind to round after the install ? </DIV> <DIV> </DIV> <DIV>Jugs </DIV>
 
<DIV>Hi Jugs - It was nearly 12 years ago that i did that motor - I would have only ground off the smallest amount, but I had the luxury of opening out the cog and inserting (relatively) thin wall bushes. I wouldn't be happy reducing diameter by 5mm - HTH - Phil</DIV>
 
<DIV>Hi Jugs_S</DIV> <DIV> </DIV> <DIV>how much is a replacement shaft, compared to repair cost?</DIV> <DIV> </DIV> <DIV>is that the 5th gear output shaft? If so, I probably have a used spare in one of my parts boxes, out of an 82 1200 with about 100,000 kms on it when I broke it for parts. I left the large bearing on it, so don't know if the shaft is any better than the one you have, but it might be worth a look.</DIV> <DIV> </DIV> <DIV>I know Wolfgang is around, as I just spoke to him a few minutes ago about parts for my RGS motor, he may even have new shafts, worth checking?</DIV> <DIV> </DIV> <DIV>Paul LeClair</DIV>
 
<DIV>Hi Jugs..</DIV> <DIV> </DIV> <DIV>  look for a foundary nearby to yourself..... These guys can advise and guide you on the correct course.... If there is a choice , go with a ministry approved company....Or a metalugist</DIV> <DIV> </DIV> <DIV>     Surely this is not rocket science..... But close to gun science ??</DIV> <DIV> </DIV> <DIV>              I </DIV>
 
<DIV> <P><SPAN><FONT face=Arial>Your right its not anything that has not been done before.</FONT></SPAN></P> <P><SPAN><FONT face=Arial></FONT></SPAN> </P> <P><SPAN><FONT face=Arial> I'm still going with the plan mentioned earlier. Just put some of the research options up I went through. The only variation I?m thinking through now that I?m going with the bush is I could hard chrome the shaft. I only need to take ~.005? of the shaft dia to remove the damage on the shaft. If I run the steel shaft in a bush. I?d need to take of ~.015? and hard chrome back to original to run hard Chrome shaft to bush. I think I?ll just Keep it simple (KISS) and go with the steel shaft. I?ll have it tested to make sure we haven?t gone through the case hardening on the shaft when we grind it and go with the simplest option.</FONT></SPAN></P> <P><SPAN><FONT face=Arial></FONT></SPAN> </P> <P><SPAN><FONT face=Arial>Jugs</FONT></SPAN></P> </DIV>
 
<DIV> <P><SPAN><FONT face=Arial>Paul<o:p></o:p></FONT></SPAN></P> <P><SPAN><FONT face=Arial> <o:p></o:p></FONT></SPAN></P> <P><SPAN><FONT face=Arial>Hi have been away for the weekend, Not riding unfortunately. I did check with Wolfgang and he did not have any of the 120 Jota shafts. It is the actual main shaft right end where it goes inside the 5th gear, where the needle rollers run on the shaft, the hardening has started to let go http://laverdapedia.com/coppermine/displayimage.php?album=65&pos=33  </FONT><FONT face=Arial>The internal 5th gear surface is still fine,</FONT></SPAN></P> <P><SPAN></SPAN> </P> <P><SPAN></SPAN><SPAN><FONT face=Arial>At the moment the plan is to lightly grind the shaft to get a clean face it's only a few .000' My gear grinder thinks he can do it without going through the hard casing, and have a bush made to go in the 5th gear. There going to cut an oil spiral to try to help with the lubrication.  So I'll be back to the old style bush and lose the needle rollers on 5th,  I have also sourced needle roller sleeves where I could grind the shaft down and fit the sleeve and keep the needle rollers but the sleeve wall is 2-2.5mm so I would have to go from a 19mm shaft to 14 - 15mm shaft. Which I was not very keen on. Hence the decision to go with the bush style fix. </FONT></SPAN></P> <P><SPAN></SPAN> </P> <P><SPAN></SPAN><SPAN>I also checked into metal spray I found 1 big engineering firm that could do it. But the process called for getting the surface red hot so the coating welded in. They were very straight forward in there assessment and said 70% chance of no problem and possible chance the end would bend and they would have to recut the centre and re-machine which they could do. Also they was the possibility of the hardening on the adjacent piece of the shaft being affected.  cost was A$480-or $570 if they needed to recut centre</SPAN></P> <P><SPAN></SPAN> </P> <P><SPAN>Jugs</SPAN></P></DIV>
 
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