The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: Lippi on 07.06. 2020 15:56
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Hi all
Let me introduce myself. My name is Lippi and I'm living in the Prinipality of Liechtenstein. Several years ago, I bought a BSA A10 Golden Flash from 1953. The bike was not used often since last year. I upgraded it with a new BTH Magneto and driving was fun. So actually I'm working on some maintenance. Also the front breakes. With a lot of effort I was able to pull out the spindle. I cleaned everything and it was very smooth to reassemble the wheel again. But now the problem came up. I have no idea how the spindle is fixed to the fork. Before i disassembled everything, the spindle just sticked in the fork. I was in luck that nothing happened. Could someone of you tell me how the spindle is fixed and what do I need? There's no thread inside the fork which fits to the thread on the spindle. Attache you will find a picture how it looks.
Best regards in advance and greetings from Liechtenstein
Lippi
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Hi Lippi. MOST URGENT.. Do not use the bike as it is. The fork leg is the wrong one for your front wheel and spindle. With no thread, there is nothing to hold the spindle in place on that side.
The spindle has a left hand thread, and the fork leg you need has a matching thread to fit the spindle. If the leg originally had a thread, it has been removed or ruined. The spindle screws in and secures the hub brake plate tightly against the fork leg.
Show some more pictures and we can tell you what you need to put it right. The other leg may be wrong as well. The front wheel and brake are the correct parts for your model.
Swarfy.
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Hi Swarfy
This is exactly what I thought. There is something really, really wrong! And that's exactly why, I asked the specialists. Please tell me what do you like to see on the pictures and I will provide them.
Thank you very much in advance and have a nice evening!
Lippi
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Lippi Welcome along to the Forum. Pictures of both fork legs, front mudguard, wheel spindle and if you like a picture of the whole bike.
There is a section on the Forum for introductions. Meanwhile, head on over there, give us a little bit of of your story and how you got your bike.
Swarfy.
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Hi Lippi,
Welcome to the Forum
It looks like you need the correct fork slider with the threaded hole
The thread is 9/16 x20 Left Hand
A clever engineer might be able to make a sleeve with the thread and fit it to the leg ??
John
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Hi and *welcome*
Fork slider is not correct. The brake cable lug shouldn’t be there so I guess it’s from another model.
Below a picture of a correct one.
The other side should have a clamp bolt. Is it there?
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Hi Lippi, *welcome*
As sliders are a bit hard to come by (good ones) what you could do is have a new spindle shaft made with a bit longer thread and use a nut to fix it in place. Some might disagree, but that is what I wood do. *beer*
Peter
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Morris.
The cable lug definitely puts it from another model. With no thread in the lug, I am thinking that slider is from the slightly later Ariel Full Width Hub type, which uses a through spindle and retaining nut.
Anyone else think it is Ariel Type? A picture of the other leg is what we need.
Swarfy.
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Think it is C10 C11 fork bottom for 5 1/2 inch brake. Had plain hole and spindle nut with left hand thread and brake cable anchor on the leg.
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Hi All,
Without having the slider in hand to compare its hard to say what model its from
From memory the C spindle is only a half inch
The C models mudguard bracket is in a different position to the A
If the lefthand leg has a clamp then as mentioned a custom spindle would work as well
John
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Hi all
As requested here some pictures from both side. Sorry for the poor quality. I took it in my garage. If anyone need more or magnified pics, let me know!
You guys are real specialists. Thank you so much for your help. I'm sure that we can find a solution.
Best regards and cheers
Lippi
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Hi Lippi. Very good pictures. The bike looks to have had a lot of time and money spent, it looks a pleasure to ride.
The fork leg on the left side looks to be correct. The spindle should just fit in, matching the hole closely. If it is sloppy, then chance it is also the wrong leg. There is a vacant hole, facing forward, under the spindle. This takes a bolt and when this bolt is tightened, this clamps the spindle.
The nuts and bolts on your bike are not in general use these days, most common threads now are metric. BSA used a thread system which we refer to as Cycle Thread. BSA originally made bicycles, and this was the thread system they continued to use. This means any fastenings you need will have to come from specialist suppliers, not from your nearby auto store.
So you need the correct fork slider for the right side.
Part numbers to help you.
Right fork slider 67 5050.... The one you need
Left fork slider 67 5057.....The one I think you have, and looks correct.
Clamp Bolt 65 5295 This is missing. It is cycle thread, 26 threads per inch, 3/8"diameter shank, 1 3/8" long.
Here is a link to an online parts catalogue
https://www.google.com/search?q=Draganfly&oq=Draganfly&aqs=chrome..69i57.6048j0j1&sourceid=chrome&ie=UTF-8
You can search for any parts you need, and with the part numbers find your best deal.
The forum has a literature section. Have a look for BSA Service Sheet 212B. This shows the front brake and hub and how it all fits together.
Swarfy.
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Those fork sliders are most likely B31 or Goldstar. If in fact there is no thread in the right hand slider, then the most likely explanation is a previous owner didn't know the thread is left hand and ended up drilling it out. If it were mine I'd get a new spindle turned up a shade longer, and put a nut on the outside. A half nut would be sufficient, so it needen't look out of place. Alternatively, can you get left hand helicoils?
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Another alternative might be to keep the existing assembly as is, turn down the protruding part of the axle on the RHS and drill and tap a bolt in, to secure the RHS being careful to get it clamped but not "pulled in" - this assumes that the LHS is securely clamped and the RHS is still "snug" in the slider axle bore - does it matter if the slider (can the slider move inboard since it would not be "locked" on the inside perse')?? maybe not a good idea for hard riding, but ok for a café run?
OR instead of turning down the end of the axle, how about just turning up a steel bush that fits snugly over the end of the axle and securing it against the leg with a bolt tapped inside the end of the axle per above??..... the objective here is really only to locate the RH slider and stop it moving outboard, but I'm unsure about the possibility of it moving inboard, per above *dunno2*...
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H Jules and All
The design is such that the wheel and brake are anchored to the righthand leg by the threaded spindle
I would not be in favour of drilling the spindle,
We do not know if the spindle thread is intact? but the spindle looks loose in the fork leg in the photo
An inside/ outside threaded sleeve might work if the fork leg could be tapped????
The threaded section of the leg is not full width, the top hat sleeve that comes through the bearing and brake plate locates in a plain section of the leg
John
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My Plunger A10 has a bottom slider with a lug for the brake cable like Lippi’s but the fork bottom is threaded. I have assumed that it came off a B something. As it is fine in all other respects it seems sensible for me to keep it, the lug is redundant.
When I bought the bike the spindle that was in was straight with no step and packed with about 5 washers on the left hand side. It was a wonder that the wheel turned at all.
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Hi all
Thanks for all your inputs. It seems to be difficult to get a fork slider. Nevertheless I still search, but I have maybe a solution which should work.
I plan to turn down the spindle approximately 1 - 2mm in the diameter and make a fine pitch thread on it. To fix the spindle to the fork slider I will turn a stainless steel counterpart. Also with a fine pitch thread to fix it to the fork slider. From my point of view it should work and it is easier to get a new spindle instead a fork slider.
Attached you will see how I planned it. It would be gread if you can give me some input. This is just an idea without any dimensions.
Cheers Lippi
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Hi Lippy,
The only "snag" I can see with your plan is that the outside of the fork leg is not flat for the nut to sit against
This why I suggested a threaded sleeve
Is the spindle thread damaged? If it is OK the tap for the sleeve is the same as old type bicycle pedals so taps are available (Try a long established cycle shop)
Keep the spindle size as large as possible if you go to machine it originally 9/16 =14.5mm
John
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Hi John
What do you mean with a threaded sleeve? I can't imagine, sorry, different languages :-)
Could you make a sketch for people like me :-)
Thanks and cheers
Lippi
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Hi Lippy
Something like this image, threads inside and outside of a steel sleeve
Tap out part of the fork leg and screw in the insert with loctite on the outside threads to secure it
John
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Just curious. Would both threads need to be left handed?
Adrian
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i think the left handed thing was good old fashioned engineering and if the bearings locked for some reason it wouldn't undo the spindle *help*, but there is little chance of that happening present day *shh* also the other side has a pinch bolt to nip the left fork leg to the spindle, notice the clue in the word pinch, not 65ftlbs and possibly smash the leg, that was a mistake some people made on the ally notrun legs *bash*
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Hi all
I checked the surface from the fork slider. It looks there was a machining work after casting. The surface looks milled. I assume the flatness is sufficient for a sleeve nut. Do you agree?
Cheers Lippi
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Lippi. The crankshaft has a left hand thread on the oilpump drive, so the locking nut used here, part 67 643 could be used to fit on the end of the wheel spindle as it is the same thread.
Do not remove metal from the fork leg, just turn down a few mm from the large diameter on the spindle so that if fits further into the wheel hub, and the spindle sticks out a little bit more to take the nut. The thread showing is not enough to take a nut safely.
Some folks may not think this a good idea, altering spindle, but you should be able to get this left hand nut easily from British Bike suppliers and is an easy fix and better than what you have. The proper fork leg is what you really need.
Here is a link for a UK supplier: https://www.feked.com/bsa-crankshaft-timing-side-pinion-drive-nut-a50-a65-a7-a10-models-lh-thread.html
The company name is a variation of the English slang term meaning "broken, ruined", as in kaput.
Swarfy.
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Hi All,
Swarfy, The threaded end of the spindle looks loose in the fork leg so a plain nut would not really work????
John
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CJ. Yes I can see that, and the spindle end needs supporting with an insert into the fork end. The problem is the geographical location and the unusual thread required. Not easy for Lippi to sort.
As I see it, any fix is better that what is there now. The spindle is supported poorly by the top hat bush in the hub, where it enters the fork slider. You could grind down an old oilpump scroll (if you had one) to make a matching internally threaded sleeve to suit the spindle thread and the hole in the fork end. Just thought nut 67 643 would be easier to obtain than the correct fork slider, and in the short term get the bike back in use with a greater degree of safety than before.
Most practical answers are a custom spindle, with a longer thread to suit a modern fine thread nut, and your threaded sleeve solution.
Swarfy.
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Hi Lippi, seems like we are all suggesting similar things to what you are proposing that you think you can do! I would have thought that machined surface on the side of the slider should work ok to seat the sleeve you are proposing (no different to Swarfy's idea of seating a nut against it) which seems to all intent and purpose what John is proposing too, its just how your sketch is drawn (very thick sleeve) vs John's pic of a thin sleeve....
in the meantime fyi, I've dealt with this company in the past for bits and they may be a bit more local to you, I cant comment on their quality now though, sorry....
https://degroot-bsa.nl/
Lets know how you end up :!, cheers
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Hi all
First of all, thank you very much for your effort and your inputs.
I think I go for the solution which I sketched before. The main reasons are:
- I just have to modify the spindle (if I will find a fork slider, I just Need to exchange the spindle)
- A friend of mine is design engineer and I have relations to a machine shop with expierience with Stainless steel
I will measure all the parts and my friend will make a drawing for the sleeve. In parallel I will search a fork slider. Thanks for the link to the dutch men :-)
I will Keep you updatet!
Cheers Lippi
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Lippi,
Sorry to enter the discussion late, after you've seemingly settled on a fix. If this were mine, I would look hard at Swarfy's method with his additional suggestion of a plain insert (bush). It looks like there is already enough gap to fit one. If the bush has quite a thin wall, that would likely be OK, as it only has to stabilize the spindle as it passes through the leg. One thing I would change from Swarfy's thoughts would be to machine the large end enough to allow a washer as well as the nut. To me, creating the bush and turning down the large end of the spindle seems like less and easier machining than turning down and rethreading the spindle, then creating a thin-wall shoulder nut, not to mention internal and external left-hand threads (if left-hand was your intention).
Whatever method you choose, we will be most interested to see a bunch of photos of it.
Richard L
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Oh, one more thing about this. While, at first blush, it looks like there may be some concern about how far back you can turn the large diameter without obscuring the lever hole, the lever hole is really irrelevant in this method (that is, the "Swarfy Method").
Richard L.
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Been thinking about this a bit more deeply this afternoon. I have to say a bush would be my first choice were the spindle threading into a substantial casting, but it isn’t. Fitting a bush in the context of a slider and spindle means boring out the slider AND reducing the dia of the spindle, thereby weakening both. Were I doing it, I’d go for one of the following, in descending order:
1. reduce head of spindle enough to get a half nut on the threaded end. If I was feeling particularly fussy, I’d slightly counter-bore the slider from the outside and give the nut a shoulder to enter the counter-bore.
2. check to see if the present slider hole is of suitable size for a helicoil (I believe the original thread diameter is 9/16” – LH) If that is correct, I’d go for 9/16” UNF – RH on the basis there’s no close metric size and helicoils / taps and dies are available in those sizes. I wouldn’t worry too much about using RH thread. As berger says, it’s best engineering practise, but if a front wheel bearing seized you’d probably be coming off anyway. More likely insurance against an apprentice forgetting the pinch bolt. As an aside, Jaguar uses RH thread on its LH wheel hub spinners, and LH on the RH side! In that case, if your splines fail a wheel coming off is guaranteed.
3. if (2) isn’t possible, I’d open out the slider hole to the next thread size (5/8” or M16) which is the size you’d have to go to for a threaded insert anyway. More than I'd like to remove from a slider, but we are where we are. Then, rather than using a bush and machining the spindle smaller to suit, I’d turn up a new spindle with thread to match the slider.
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RD,
I'm pretty sure you have your own machine shop and awesome machining skills, but what you've described just sounds sooo much harder than just buying one of these (see link) for about $2.50 (or making one), then, turning the outside of it to fit the inside diameter of the leg. It looks like there is about 1/16" of radial clearance all around the spindle, which I believe is more than enough for the static purpose it needs to serve.
https://www.mcmaster.com/6391K233
Plenty of other sizes and materials available through McMaster.
Lippi,
If you need a U.S. go-between that will mail it to you I can handle that. I don't know the EU equivalent to McMaster. (Does EU still include UK?)
All this said, it would be interesting to hear if my preference is blessed or cursed by others.
Richard L.
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Afraid you’ve lost me, Richard. First of all the hole in the slider will in all probability need machining (who knows whether it’s round or parallel?) And then I’m stumped as to how an oilite bush (as these are known in UK) is going to hold the spindle in place, or are you proposing threading it into the slider and tapping it to suit the spindle thread? That’s more work than I envisaged and, if I may say, unsuitable material. Oilite tends to be 'crumbly' so I doubt it would be possible to use it as a 'reducer' bush. Lippi does say he’s got access to excellent machining facilities and my option (1) for example should take a turner less than five minutes.
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RD,
For the record, because I am neither the most expert member here with regard to every possible A7/A10 nuance, and probably 100th in line for best machinist, I started my recommendation by saying I thought Swarfy had it about right. Here is part of what he said (with date and time, for your reference):
Re: Fixation from the spindle of the front wheel
« Reply #23 on: 10.06. 2020 10:23 »
Quote
Lippi. The crankshaft has a left hand thread on the oilpump drive, so the locking nut used here, part 67 643 could be used to fit on the end of the wheel spindle as it is the same thread.
Do not remove metal from the fork leg, just turn down a few mm from the large diameter on the spindle so that it fits further into the wheel hub, and the spindle sticks out a little bit more to take the nut. The thread showing is not enough to take a nut safely.
Swarfy's idea is, turn down the large plain diameter of the spindle so the thread sticks out further, then, put a washer and LH nut on what now sticks out. The PLAIN sleeve (be it oilite or steel, doesn't really matter) does nothing but stabilize the lateral or up and down movement of the spindle in the leg hole. As I see it, no threading is involved, no abrasion occurs and less wear than an oilite bearing would see when it's actually working as a bearing.
I also threw in that obscuring the lever hole should not matter with this fix.
Even though I'm a crappy machinist. I think I could have completed the job in the time we've spent talking about it. You could have done the same, with lunch and a smoke thrown in.
Richard L.
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So there you have it Lippi, sooooo many choices and I'm sure you will work out what suits your circumstances the best lol. One of the best things I find about this forum is the depth of knowledge and understanding of these old bikes PLUS the depth of general knowledge that always helps when things look "bad", as Richard said earlier, lets know how you end up, cheers
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Hi all
Ok, so many solutions and I have to do the choice. But thank you so much for your inputs!
What I'm a little confusing, I don't think it is a left hand thread on the spindle! But let me doublecheck. Unfortunately this weekend I did not had time to work on my bike.
I think I will go for the solution from John with the threaded sleeve. I don't have to modify the spindle (adding weakness by reducing material) and the fork slider is not original anyway. I will take out the spindle and try to identify the thread dimension (not that easy in our metric environment). If I have everything, someone of you could help me to find a shop where I can get the sleeve and also the screw tap? Then I will make a thread and fix the sleeeve with Loctite 270.
Cheers Lippi
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Hi Lippi,
Get an accurate measurement of the spindle hole in the fork leg
This will be a guide to selecting a thread for the outside of the sleeve,
I have left hand taps that suit the original spindle size, so could tap a steel piece for you or make the insert if you can decide on the external thread needed
John
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Hi all
First of all sorry for the delay. I had some other activities which I had to set priority on it, i think the name of it is job :-)
Today I measured all the parts and took pictures. The problem is, I'm (actually) absolutly not familiar with BS thread family. Therefore I measured everything. I fitted a BTH Magneto to my bike and the nut on the pic was also delivered but it was not necessary to use it. But now I'm happy to have it. It has exactly the same thread as the spindle. The borehole in the fork leg has 16mm diameter.
Guys, if anyone can help me to get a thread sleeve and someone could borrow a tap in the right dimension that would be great. Here in this area it is almost impossible to find something liket this.
Attached you will find the PDF with the pictures I took. Thank you so much in advance and cheers
Lippi
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Hi Lippi,
Can you measure the total length of the spindle? and the male thread diameter?
Either it has been shortened or there is a thin sleeve added to the threaded end ? as the thread is shorter than the spindles I have
If there is a sleeve threaded on, is there enough length of spindle to stick out through the fork to add a nut if the threaded sleeve was shortened or removed?
Here is what I think has happened ???
A previous repair attempt was to put a threaded sleeve into the fork leg, over time and brute force the sleeve has been pulled into the end of the thread , then the clamp bolt on the left fork was not tight and the spindle worked its way to the left
John
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The way that thread runs into nothing makes me agree with John - that spindle already has a bush on it
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Hi all
I will measure the spindle after work. The length of the spindle is not enough to add a nut. I will come back to you this evening with a total Picture of the spindle and the length.
Cheers, Lippi
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Here we are...
Attached the pics from the spindle and the length over all. I added also a picture of the profile from the spindle.
Cheers, Lippi
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Have you tried unscrewing what looks like a sleeve on that thread?
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Wow! Good input, never thought about it!
I will let you know tomorrow!
Cheers, Lippi
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Hi Lippi
That spindle is standard length (230mm) and the threaded section should be 28mm approx
I definitely looks as though a sleeve has been threaded on (left hand thread)
If you can refit the sleeve to the fork and it is still tight It might be possible to loctite it in place ??
John
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that's a good pickup John/RD, good call *clap* *bright idea*
if the sleeve can be loctited back in place that's a great start but its unlikely to be a robust joint after its been wobbling about for a while, so will still need a mechanical "hold" of some sort to stop it walking out again if/when the bond breaks - I know drilling and threading the centre for a bolt could weaken the axle a bit, but realistically a high tensile fine threaded bolt of a smallish diameter with thread length inside the axle of only say 20/25mm (ie within the length of the slider bush) with a big washer, in conjunction with the loctited bush and the clamp bolt on the other side should be reasonably robust I would have thought. It wont have much tensile load on it, more of a location holder, so could be just 8mm ish, just to inhibit the side thrust in conjunction with the clamp bolt on the other leg. AND, when you look at the end of the axle its already been centre bored, so wont need to be too much more than whats there already.....what do you think??
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Funny, had thought of that but didn't want to further confuse the issue. An M8 allen bolt (the high tensile black ones) would seem a good call.
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just checked the spindle I stripped some threads on in 70's and dad had to make a longer one with a safety nut for it. john and rd are on the money regards the added sleeve for sure *yeah*
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Hi all
First of all sorry for my late response. We removed as seen before the sleeve from the spindle. After this we pressed in and glued it with liquid metal back to the fork. Today, I had the first ride. Everything is fixed and the spindle stays where it should. I marked the position with color. If anything will move, I will see it.
Many many thanks for your patience and help
A big cheers from Liechtenstein
Lippi