Hi Folks
While removing gearbox one of the top mounting lugs sheared off i dont know if it was ready to go or my mechanical skills or lack of that caused this.
Anyway anybody any ideas of how much of a problem this is are we looking at replacement gearbox
Cheers
Billy
Hi Billy I am fairly new t…
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Previously wrote: Hi Billy…
Previously wrote:
Hi Billy
I am fairly new to Nortons and as such am far from an expert, but I know when I was looking for one quite a few people said this was fairly common so keep and eye out for it. I think they are fairly brittle so do quite often go, a good ally welder could probably weld it back on for you though.
To try and avoid it happening again, I understand there can be two causes of it. The first is when the two lugs arent a tight fit on the frame, so as you tighten up the pinch bolt you pull the tops in and this can snap them off. The second is when the pivot bolt hole at the bottom of the casing is slightly ovaled so the vibrations and such make it rock from side to side and can twist the lugs. Again, making them break off. I got lucky when I bought my project in that both of them where in tact and a tight fit on the frame, the pivot hole is slightly ovaled though so I plan to bore it out to a biger diameter and fit some steel bushed in it to stop that moving about.
Hope this is of some help, and I'm sure there will be plenty of other people on here that can help you out a bit more.
Andy
Hi Andy
Thanks for the speedy reply yes it will have to go down the welding road i think
and i will buy a rubber hammer as i think i might be to blame for this set back
Anyway i only now grasp the task i have given myself restoring this old beast
and my hat is off to all you classic bike people
Cheers
Billy
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Hi Billy, This is a common…
Hi Billy,
This is a common problem which can be cause from a loose bottom gearbox mount which allows the gearbox to twist, so this needs to be tight. But you need to be careful with the top mount as people seem to think if the top mount is moving on the frame they need to do it up tighter....! WRONG..! You can't expect 1/2" ally lugs to bend, they just snap. If your gearbox is loose on the top mount and the nut is tight, loosen the nut and slide a shimin-betweenthe frame and ally mount, then don't over tighten the nut, the adjuster will stop it moving backwards.
The ally on these boxes isn't the best and well impregnated with oil, so it can be difficult to weld. I had mine done and the lug broke off again as he was machining it. The weld wouldn't take. Eventually the welder had to build a new lug out of weld and re-machine. So I'm verycarefulwith it now.
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Hi Billy, As mentioned bef…
Hi Billy,
As mentioned before if your bottom mount is worn it will cause this to happen when riding. I had the bottom mount drilled out and top hat bushes made that meet in the middle to fix this problem. The top hat bushes also negated the need for shims between frame and lower mount. My top mount was a tight fit so no problem there. If your frame holes are worn also it would be worth having these bushed as well. Check out item 6 on following link. http://www.norton.uk.com/expert.htm
Regards Glenn
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Previously wrote: Hi Billy…
Previously wrote:
Hi Billy,
As mentioned before if your bottom mount is worn it will cause this to happen when riding. I had the bottom mount drilled out and top hat bushes made that meet in the middle to fix this problem. The top hat bushes also negated the need for shims between frame and lower mount. My top mount was a tight fit so no problem there. If your frame holes are worn also it would be worth having these bushed as well. Check out item 6 on following link. http://www.norton.uk.com/expert.htm
Regards Glenn
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Hi Billy
I am fairly new to Nortons and as such am far from an expert, but I know when I was looking for one quite a few people said this was fairly common so keep and eye out for it. I think they are fairly brittle so do quite often go, a good ally welder could probably weld it back on for you though.
To try and avoid it happening again, I understand there can be two causes of it. The first is when the two lugs arent a tight fit on the frame, so as you tighten up the pinch bolt you pull the tops in and this can snap them off. The second is when the pivot bolt hole at the bottom of the casing is slightly ovaled so the vibrations and such make it rock from side to side and can twist the lugs. Again, making them break off. I got lucky when I bought my project in that both of them where in tact and a tight fit on the frame, the pivot hole is slightly ovaled though so I plan to bore it out to a biger diameter and fit some steel bushed in it to stop that moving about.
Hope this is of some help, and I'm sure there will be plenty of other people on here that can help you out a bit more.
Andy