Hi All,
I was at a friends house and he is restoring a 1950 Model 18 and ordered by mistake a big end bearing for a Norton single which stated on the packaging that it was for 1929-1935 Nortons and the OD of the shaft that fits into the flywheels was 1.002 inches.
The original engines bearing that needs replacing is approx 1.020 inches.
I checked the new bearings I had home and found that mine are also 1.020 inches.
The question i have is did the diameter of the big end that fits into the flywheels change and if so what year did it change.
I have a 1935 ES2 that I have started to restore but have not yet commenced the engine rebuild and if this dimension change means I require the smaller diameter big end I will swap and everybody will be happy.
Thanks for any replies in advance
Regards
Andy
Hi Andrew,i've bought a 1…
Hi Andrew,i've bought a 1929/30 Model 24,which uses the 588cc Model 19 motor.The big end needs replacing and there is a new one in the kit of parts which came with it,unfortunately my motor requires the smaller one and (you've guessed it!) the new one is the later one at 1.020". So i need to source the correct one,and will sell or swap the new item-Anybody got one for sale or swap??
Good Luck
Ron Proctor
Previously richard_cornish…
Previously richard_cornish wrote:
Hi Andy,
Yes the big-end/flywheel dimension was changed in the 1930s although I thought it happened earlier sometime in 1933. The comments and stories written in the past seem to make you think there was a machining error made in boring the flywheels and the cheapest and quickest answer was to increase the size of the big-end outer shoulders to fit a new flywheel hole dimension of 1.020". There would belittle mechanical benefit in this relatively small increase as far as strength and reliability are concerned. You also need to consider the alternative of scrapping the flywheels and starting again bearing in mind the country was in the depths of theeconomic depression at the time. I would guess the change over would have taken several months before existing stocks of flywheels where used up and the new size was used on all OHV/SV models. At a guess I would think your 1935 engine will have the larger size, but of course you won't know until you strip it.
Regards, Richard.
Hi Richard thanks for your reply
Yes you are correct I thought to checked the Alpha Bearing website and they have Norton bearing list and the bearing changed in 1933.
Cheers
Andy
Previously ronald_proctor…
Previously ronald_proctor wrote:
Hi Andrew,i've bought a 1929/30 Model 24,which uses the 588cc Model 19 motor.The big end needs replacing and there is a new one in the kit of parts which came with it,unfortunately my motor requires the smaller one and (you've guessed it!) the new one is the later one at 1.020". So i need to source the correct one,and will sell or swap the new item-Anybody got one for sale or swap??
Good Luck
Ron Proctor
Hi Ron,
I ended up swapping my 1.020" bearing for the 1.002" as I also have a 1929 Model 19 engine I have just pulled out of the bike to rebuild.
I rang the person who I bought the bike from and he informed that he modified the fly wheels to take the later crankpin!!
So I now have a crankpin that I do not require and nead the later pin. For your information the crankpin was purchased from British only Austria if you are interested in swapping I would do that, only cost is postage from Australia and yours from the UK.
If you are interested please contact me.
Regards
Andy
Hi Andy,
Yes the big-end/flywheel dimension was changed in the 1930s although I thought it happened earlier sometime in 1933. The comments and stories written in the past seem to make you think there was a machining error made in boring the flywheels and the cheapest and quickest answer was to increase the size of the big-end outer shoulders to fit a new flywheel hole dimension of 1.020". There would belittle mechanical benefit in this relatively small increase as far as strength and reliability are concerned. You also need to consider the alternative of scrapping the flywheels and starting again bearing in mind the country was in the depths of theeconomic depression at the time. I would guess the change over would have taken several months before existing stocks of flywheels where used up and the new size was used on all OHV/SV models. At a guess I would think your 1935 engine will have the larger size, but of course you won't know until you strip it.
Regards, Richard.