Axle width of a 1949 rigid model 18

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Invicta
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Axle width of a 1949 rigid model 18

Post by Invicta »

Having at last located a speedometer gear drive with a 5/8" hole in it and had new spacers turned the same width as the originals , but with the one on the inside of the speedo gear drive having a spigot slightly shorter than the thickness of the speedo drive to locate it centrally and the outer spacer made with a larger diameter to properly grip the speedo drive over a larger surface area, I thought that at last I can fit my newly rebuilt rear wheel into my basket case 1949 rigid model 18. When I put the wheel in the frame with the speedometer drive side spacers against the frame there was a big gap on the sprocket side. The spacer that locates the brake plate with the 2 flats on it that is supposed to fit in the slot in the frame did not even come close. The inner distance between the axle mounts is 7 5/8" The overall length of the new hollow spindle for the wheel bearings is 4.5" the spacer inside the speedometer drive is 0.375" the thickness of the drive is 0.125" the outer spacer is 0.675" the distance from the brake plate inner spacer including the thickness of the brake plate and the spacer which fits on the outside of the brake plate adds up to 1.532" Adding all of these dimensions together comes to 7.207" and the axle width is 7.625". Leaving a gap of 0.418". My question is what should the axle gap be on a 1949 rigid frame. The frame was in one piece with the front forks and bottom end of the engine and gear box when I got the bike . The frame number matches the buff log book for 1949 so I am assuming the frame is the correct one. the 7/16" diameter rear wheel spindle is the correct length for the frame. The front and rear hubs had been rebuilt onto new rims by the previous owner many years ago and were rusting, which is why I had them done again and fitted with new bearings. I was assured that the rear bearings were correct for a 1949 cotton reel hub and they seem to fit OK . Yet something is clearly wrong. I expected a little bit of a gap to be able to slide the wheel in and out but not over 0.4". When the wheel is in the bike and pulled over to the speedo drive side it is central in the frame but has this big gap on the sprocket side Image]Image Any pointers as to what is wrong would be greatly appreciated. Have I had a wrong hub rebuilt into my new rim as that is what it looks like to me.
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clive
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Re: Axle width of a 1949 rigid model 18

Post by clive »

Cannot help with all those dimensions but simply by appearance the spacer on the outside of the speedo drive is too short. I can measure mine later on this morning and will report back. If yours is a 49 rear loop the slots in frame will be the same size both sides and you will need a slotted spacer on the speedo side similar to the slotted spacer on the brake side but longer. I believe this was a one year only issue with the diameter of the spindle increased the next year and before that I think the slots were of different sizes. The spacer on the speedo side should be fixed to the spindle not slide along it and the whole lot locks up first on the speedo side and then separately on the brake side. There is another thread where the issue is discussed as I found my 48 frame had a 49 rear loop and the slotted part of the spacer on the speedo side was missing as I had the earlier spindle. I see that in this previous thread that Steven from AMC classics also commented that your photo of the spindle and spacers that the spacer you had for the speedo drive side looked too short and he gave the dimension as 1 and 1/8.
clive
if it ain't broke don't fix
Invicta
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Location: Kent , England

Re: Axle width of a 1949 rigid model 18

Post by Invicta »

Clive, Thank you for the reply. I have measured the axle slots in the rear frame and they are different. The speedometer drive side is 7/16" wide to just clear the 7/16" spindle and the sprocket side is 0.525" wide to accommodate the flats on the spacer. The spindle sits comfortably inside the axle slot so there is no need for a slotted spacer on that side. On that basis, as the wheel spindle for 1949 is 7/16" and my parts book does not show a slotted spacer for that side, I think the rear frame loop is the correct part. Looking in my parts book the wheel spindle 013870 does appear to have a longer boss/spacer than the one that was on my spindle. It was a drive fit on the spindle and when I first tried to sort out the fit I found it was in the wrong place, but that was discussed in another thread. If you could let me have the dimension of your speedo drive side outer spacer I would appreciate it very much. I can then have one turned to the correct length. I think that you are right , as having looked at the photograph of your spacer it is certainly longer than the one that I have. Cheers David
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clive
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Re: Axle width of a 1949 rigid model 18

Post by clive »

David after lots of discussion in the last thread I think I can tell you the following.
I have been told the 1948 and earlier rear frame had slots that were different sizes either side but I know that the sidestand mounting point was behind the riders footrest.
In 1949 the two slots were in the frame were made the same size and both were the size of the one on the brake side so a slotted spacer was needed both side. At the same time the mounting point for the sidestand was brought forward to in front of the riders footrest. No additional spacer was listed because the one year only the spindle had a built in slotted end as per the clubs advertised 1949 spindle, you can just see the slotted part in the illustration. https://www.amoc-parts.com//store/comer ... duct=21059. If the club picture is correct these spindles look to be New Old Stock.
In 1950 the thickness of the spindle was increased to 1/2 inch.

The moral of this is don't assume the illustration in the parts list is correct, they often only altered the part number and if it is different from the previous year assume some change occurred (the illustration was often changed the following year unless there was a further change!)
So the critical issue is where is your sidestand mounting point, in front or behind the riders footrest? If in front you have a 49 rear frame, if behind its earlier. If it is in front then I suggest double checking your measurement of the slot by trying to insert the spacer from the brake side, if it fits then the slots are the same size and you will need the 49 spindle.
As to measurement my spacer is 1 inch BUT my whole spacer system is approx 1/8 inch too short. BUT then I have the earlier rear wheel with the 5 1/2 inch brake hub, yours should have a 7 inch one if it is 1949. I have been using my bike for over 25 years with the frame just sprung across that 1/8 without noticeable problem so that is how it is staying.
:headbang: :headbang: :headbang: :headbang:
clive
if it ain't broke don't fix
Invicta
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Joined: Mon Jan 29, 2018 9:42 pm
Location: Kent , England

Re: Axle width of a 1949 rigid model 18

Post by Invicta »

Hi Clive, Thank you for the pointer not to trust the illustrations in the parts book. I won't be doing that again. I think that as my bike was made in early 1949 that Plumstead either used up the last of the older type of rear frame loop , or at some time later someone has fitted a pre 1949 rear frame loop , as the side stand mount is in front of the hole for the riders footrest and as you say and the parts book for 1949 shows it should be behind for 1949 . We shall never know. Having checked the measurements, if I get a new spacer made to 1 1/8" long , as Steve from AMC Spares suggested, all should be well. The joy of trying to rebuild a bike from a box of bits the provenance of which is a mystery. :( Thanks once again. Cheers David
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clive
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Re: Axle width of a 1949 rigid model 18

Post by clive »

David there is obviously some confusion about what I said. In fact if the side stand mount is forward of the riders footrest it must be 49. Also the illustration in the 1949 parts list is incorrect as it illustrates the earlier incorrect frame but gives the later correct part number. I would seriously check the dimension of the right hand slot in the way I suggested above. I managed to ride my bike for 25 years without realising there was a difference between the width of the spindle and the width of the slot.
clive
if it ain't broke don't fix
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