The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: Plammimam on 24.10. 2018 20:01
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Hi All
I am working my A10 Spitfire replica. I need some help identifying the swing arm fitted. It looks like the swing arm has had the chain guard lugs added on the left side and the plate for a left hand rod half width brake torque arm added. I can’t seem to get the right spacers for the rear wheel. The 67-6028 is too long for the half width crinkle hub set up.
Biggest conundrum is the right lug where the axle goes through is 1.00 inch, see the picture. I can’t seem to find either a spindle that size or any bushes to pack out.
Any clues would be appreciated
Phil
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Hi Phil,
There are 3 types of swing arm,
Crinkle hub, Ariel hub and the cast iron full width.
Early swing arm twin or single swing arms use a smaller diameter pivot spindle
One of the "Gold Star" swing arms which is the same as early B31/33 and A7/10 went for £374.02 on eBay last week *eek* *eek* *eek*
https://www.ebay.ie/itm/BSA-Original-Swinging-Arm-A10-A7-B31-B33-Goldstar-QD-Excellent-condition-Swing/323493242315?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649
Spacers to adapt one wheel to another swing arm will have to be "engineered" not bought
John
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A plunger crinkle hub shaft is 1” so might fit your setup ?
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i have not been to the pub, blinkin ek that swing arm is same as mine and many more, I know what to do when I run out of beer vouchers *work* *beer* *whistle*
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Hi John
The swing arm on eBay looks the same as my one, but I can’t tell the size of the right axle slot to be sure. The distance between the lugs across the arm is 7 inches. There is a comment from Berger that a plunger crinkle hub takes a 1inch axle, wouldn’t that mean bearing changes to suit?
Phil
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nowt to do we me that was morris , I will try and av a butchers at mine and do a bit of measuring and report back. I can't do piccies tho even if you lourve them
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Hi Phil
If I think of it I can measure a crinkle hub swing arm spindle slot tomorrow
John
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a plunger crinkle hub takes a 1inch axle, wouldn’t that mean bearing changes to suit?
Phil
Here's a picture from a plunger shaft from the De Groot website
The corresponding bearings are RLS8
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If you need something made up, in SS, I've had good experiences with these chaps: http://www.cpcengineering.co.uk/
I had them make me one of those rear wheel spindles. It was a tad tight on the threads so I mailed it back to them. They eased the threads and speedily sent it back, covering all postage costs. I've recently had some other parts made by them that are splendid. They are a couple of young chaps.
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Thanks for the picture of the plunger spindle and ref to associated bearings. I checked the RLS8 bearings spec and found they have an OD of 2.1/4. Inch. My crinkle hub will only take 2 inch which equates to RLS7.
I suppose the question is what BSA has a swing arm with the right slot at 1 inch
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My crinkle hub will only take 2 inch which equates to RLS7.
That’s a pity because it looks like lengthwise the plunger shaft would also fit. The distance between the lugs is 7” also. If nothing else works maybe you could have a plunger shaft turned down to accept the RLS 7 bearing?
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Thanks for the picture of the plunger spindle and ref to associated bearings. I checked the RLS8 bearings spec and found they have an OD of 2.1/4. Inch. My crinkle hub will only take 2 inch which equates to RLS7.
I suppose the question is what BSA has a swing arm with the right slot at 1 inch
Is the FW Ariel hub not fitted with a 1" spindle diameter?
cheers
derek
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BSA owners club tech section, says swing arm is from a later bike with full width hub. Didn’t say which bike or year, not so helpful. Looks like the easiest option is to make a top hat bush for the spindle to frame lug to eliminate the space and probable make a spacer from wheel to lug same dimension as a plunger spacer but with 7/8 ID.
Anyone know the length of that spacer, bets are on 1.403 or there about
Phil
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Anyone know the length of that spacer, bets are on 1.403 or there about
Phil
1.562 (1 9/16”)
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That’s my problem, the 67-6028 is that length and it’s to long. I need 1.40 with this swing arm and crinckle hub set up with 7 inches lug to lug. I have seen drawings on the net showing lug to lug as 7 15/32 and 7 1/32 for A10 so no consistency
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It seems the plunger set up would work other than a bearing change needed. Does anyone know the dimensions of the plunger spacer. Theory it should be the correct length but wrong ID
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Plam, I suddenly got unsure if the dimensions I gave you are correct... :-\
I dug up some notes I made long ago and it seems that a plunger shaft might be 7/8 instead of 1" ???
I'll get the shaft out for you tonight and make some measurements
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I'll measure mine (axle) as well.
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Plunger axle is 7/8" (0.875), but I've lost tabs of the r/h spacer for length but it's on here somewhere....Plunger bearings & spacer setup is different also- ID's is axle size, and spacer is between the bearings, but the S/A spacer is stepped and fit inside the bearings (probably telling at least some of what you already know)....Mix & match can be a bitch *work*, and usually just easier to run the stock items, but that's what you need to know.... *spider*
If you want to persist with what you have, I think as suggested you just need to make the bits to suit *conf2*
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Thanks guys for all the info
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Here’s a thought, if you distill this thread down there are two parts to it
1. The right side swing arm lug has a 1 inch slot
I don’t believe we ever potentially found a swing arm with that size lug, only a plunger axle was mentioned for size applicability .
2. Find the right length right wheel spacer
For this one there are three parts in play to span the 7 inch space between the lugs
Left stub axle
Centre bearing carrier and right
Right wheel spacer
Whist I concentrate on the right wheel spacer the other two items could be wrong or there is a space somewhere between one of these items. I am looking for 0.17 extra space to fit a standard right wheel spacer.
Don’t you just love a puzzle
(I am ignoring the axle diameter for now)
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Do you have the spacer #45 that sits on the left stub axle between the brake plate and chainwheel bearing ? That should be roughly about 1/4" wide (there's a few different types and maybe a 'top-hat' or square section profile)...
Also how is the brake plate anchored ?
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dutch you are a star, get you a beer for that *beer* and some of that karma sutra stuff because I can't do piccies-------yet!!!!! . I have measured some bits and mine is a 54/55 swing arm , even though this doesn't answer the wider hole where the spindle goes through the swing arm....- here goes number 30-- 1/9/16ths number 29-- 17/64 or maybe originaly a 1/4 and its grown / spread a bit haha.-32 is 8/7/8ths with 1/1/8th thread and a 6 inch long length from the shoulder to the threads, and is 11/16ths diameter. bearings are RLS 7-2RS 2 inch dia 7/8 inner--- 7 inch between swing fork, maybe this helps *dunno* but I do know the stub axle that the spindle screws into is shorter than A 65 stub axle,,,, its now nearly time for the barlypop shop *beer* edit / swing arm hole a clearance fit for the spindle about 45/64ths give or take a bit of paint
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whoops a daisy forgot---- number 29 fits on the bearing carrier inside the dust cap and up to the inner race and number 30 butts up to that
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Hi
Spacer 45 is in place, that was the start of the issue. Found left wheel nut loose, so tightened and wheel stop turning. Purchased from CPC engineering top hat version around 1/4 inch. Solved the lock up and did not move the back plate that I could see.
Attached is a photo of the torque bar, slaved in position for visibility. This attaches to a welded plate just out of picture with two bolts. I do not have any washers between back plate and swing arm.
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can't see on your first post picture but how long is that stub axle , there are two different ones, I know this doesn't sort out the frame lug size but this seems as dutch says a mixed bag, also what size slot in the sprocket side of swing arm
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That rear sprocket looks very much like a 49 Tooth "Dinner Plate" plunger type. berger mentioned the shaft to be 11/16" diameter, but the bearing ID to be 7/8". We would expect shaft diameter to closely match bearing ID.. It may have been originally set up with a plunger wheel and brake drum, to get a big sprocket for low speed torque and with a pre Ariel Hub S/A brake plate adapted to fit the plunger drum. A picture of the inside of the drum would help. Centre hole on brakeplate side of the drum is smaller on a S/A drum. The larger plunger hole has an extra pressed in collar to act as a grease/dust seal around the shaft. Plunger and S/A wheel bearings are the same. This bearing is also used on S/A drum. Plunger drum uses a larger ID bearing.
Swarfy.
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Probably too late now but I have my original Plunger rear axle here. I'm seeing a diameter of 0.873" on the unworn parts.
If it's useful I'll take the back wheel out and measure the axle components. Just give me a shout.
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Wow nothing like home work guys, no pain no gain as they say here are the answers to the various questions. I will post the pictures with a couple of replies in a moment
Stub axle length, this is an approximation with out removing 3 1/4, diameter 7/8
Left swing arm slot 0.681
Sprocket teeth 46
Back plate hole 0.878
Bearing in hub OD 2 inch ID 7/8
Total hub width from outside edge of spline to outer edge of right side hub 4 1/8
Stepped spacer hub bearings sit on is 3.450 length
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Pictures
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More picture
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More pictures
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One more dimension. When I fit the back plate in the hub with out the spacer and measure the stub axle, then refit the spacer between the hub and back plate. It lifts the back plate 0.059, which seems a reasonabl clearance
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Dunno 'bout the measurements, but for what it's worth that looks to be a Plunger type hub- S/A hubs don't have the R/H screw in bearing retainer....probably doesn't matter much though, I had what I think is a S/A hub/wheel in my Plunger and it 'worked'.....
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Looks like I was wrong. Brake drum is not a plunger type, it has the small centre hole and has finned drum, so are we looking at Gold Star/A65 Type? As duTch says, likely to be a plunger wheel with two screw in bearing locking rings. Best option is custom made spacers and bushes to get it to work. Non standard engineering is fine if you do it, but sorting someone else's dream is a nightmare.
Swarfy.
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Wow nothing like home work guys, no pain no gain as they say here are the answers to the various questions. I will post the pictures with a couple of replies in a moment
Stub axle length, this is an approximation with out removing 3 1/4, diameter 7/8
Left swing arm slot 0.681
Sprocket teeth 46
Back plate hole 0.878
Bearing in hub OD 2 inch ID 7/8
Total hub width from outside edge of spline to outer edge of right side hub 4 1/8
Stepped spacer hub bearings sit on is 3.450 length
You will find things a lot easier if you keep to fraction of an inch and forget decimal measurements.
0.681 ~ 11/16" ( 0.6875" )
0.878 ~ 7/8" ( 0.875 ")
BSA used fractions and all parts are measured in fractions.
Now I am no metrologist but when it comes to these type of measurements it is micrometers in multiple places then averaging because we are talking about parts that are 50 years old and subjected to all sorts of bodgery.
Get some fuse wire or hair wire and measure the axle slots diagonally .
Good chance is you will find the two sides are not parallel.
Next of course doubt every part. No reason to suspect any part on the bike is what was there when it left the factory.
In the USA where they were toys there is a good chance the owners made the effort to get the right parts for their bike.
Down here or in the UK where the bike was daily transport then whatever wheel the owner could get from a wrecker ( because BSA riders were too cheap to buy new parts ) that would go in the hole & work or be made to work was better than the No 52 bus + 3 minute walk to the No 106 and the chance of making the boss angry by being 3 minutes late..
Then you get collision damage where the swing arm is bent back to put the wheel into alignment. I had a bike done & it was fantastic , never tracked that good before, but when it came time to do the swing arm bearings the shaft would not come out. Carefull measurements confirmed that the pivot was in fact bent & it has to be cut like devon to get it out.
Finally to help you & us identify your wheel & swing arm & wheel, lay the entire axle out parts book style.
Usually if done like that you can compare it to the diagrams in the parts book.
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Right. Here's some more plunger data;
Shaft diameter 7/8", length 10 1/4"
Wheel bearings RLS7
Bearing distance inside hub from outer to outer edge 3 3/8"
Drum bearing RLS8
Stub axle length 3 9/32"
Outer distance piece 1 9/16
Frame lug 15/16"
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May be irrelevant, but what year frame is it ?
....Finally to help you & us identify your wheel & swing arm & wheel, lay the entire axle out parts book style....
After you've done that, I think you need to start by setting the sprocket in alignment with the drive sprocket....you may find you need a spacer between the swingarm and brake plate, then go from there ( I don't think chainwheel is A65- looks same, but fairly sure they all -after '65?- had bolt-on band )
..You will find things a lot easier if you keep to fraction of an inch and forget decimal measurements......BSA used fractions and all parts are measured in fractions........
I hear you Trev, but my digital caliper is in decimals, as was the vernier one before it went bush, even a micrometer is in decimals- a ruler in fractions is just a stick with scratches on it, good enough for ball-park guesswork *smile* I'm happy with metric also, but missed out on the cubit system- maybe my sisters did it *conf2*
I'm about to head out for the day and running late.....
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Frame is 1961
We seem to have very similar dimensions for the axle and bearing bits. How about a question on the swing arm lug to lug dimension. I have seen drawings on the site giving
7 1/32 an 7 15/32. My one measures 7inches so could be the 7 1/32. If it was 7 15/32 it would probable all fit with standard parts. Is there a confirmed lug to lug dimension?
Have to say machining up good spacers is the best option as long as this lot is put together correctly. I think I will pull the whole thing apart and check the assembly. When sure it is good manufacture an appropriate spacer.
Thanks all
Phil
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plam I will measure part number 17 and also if I can find it the one for an A 65. also number 17 is a different part number in a plunger hub, it looks like you have the same set up as mine apart from the bigger slot in the swing arm?? as the other slot looks same as mine where the stub axel sits --- swarfy the spindle goes through the hub spindle sleeve which carries the bearings part number 30 which is also different in a plungy--- I will report back tomorrow edit my swing arm is 7 inches but I could measure it better when I take the brake drum out
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there is some stuff on this forum from2010 about swing arms and but I don't know how to put it here, but I have noticed an A65 swing arm fits but is longer , and the spindle for a quick detachable rear wheel has what looks like a bigger diameter that fits in the frame where your swing arm has the larger slot is it possible it is an A65 arm *dunno*
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there is some stuff on this forum from2010 about swing arms and but I don't know how to put it here, but I have noticed an A65 swing arm fits but is longer , and the spindle for a quick detachable rear wheel has what looks like a bigger diameter that fits in the frame where your swing arm has the larger slot is it possible it is an A65 arm *dunno*
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It occurred to me that if it is A65 S/A and or hub, then there should've a speedo drive in there somewhere, but the '65 list doesn't show that...but it does show a chainwheel like yours with 42 teeth for a couple of models, and detachable one for a couple others
'70 List shows the speedo drive...
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I think Hub with speedo drive has a external thread on the RHS...
More hub pics which should be from '70 list......
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Spacer 67-6028 and sleeve 67-6027 appear common on all the crinkle hubs. Looking at the BSA owners club library parts books you can run down all the bike types to get a feel for the set up. I think it appears a bit easier to look at specific bikes as opposed to some of the net information that covers a couple of models in one list. This set up has a tendency to look like a Goldstar rear wheel which appeared on the earlier 50’s models and then came back in the 60’s. This might be part of the idea from who ever built this up originally as the bike is like a Spitfire scrambler or Catalina
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plam on a plunger crinkle hub the bearing sleeve is 67-6061 and hub is 67 -6126 .. hub on 54/55 swing arm is 67/6136---[ I may have a crinkle hub for plunger stashed away if I find it I will compare to my swing arm one tmow] the bearing sleeve on a 54/55 model part number 67-6027 has a long and short side where the bearings fit and I think it is possible to fit it the wrong way {not too sure long time ago} could you measure the length of the swing arm ,? I will measure mine as well as in between its forks and see if there is a difference------ 1956/57 used full width hub as did I think 1960 to 63, from frame number GA7-101 I don't know about 1958/59 no data
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Berger, the swing arm measures 16 1/2 inches from inside centre of the cross tube to the end of the wheel lugs, I put a rule across the end of both swing arm lugs to get the distance in the centre, so we are on the same page.
Width between the lugs is 7 inches
The 67-6027 bearing sleeve looks the right way round with the long end to the right side where I have spacer 67-5890 fitted to flush of the end of the tube for the 67-6028 spacer to fit against.
I did note the 67-6027 spacer sits slightly under the middle/ inner bearing, you can see that on previous pictures. I thought should have been flush?
I have also seen the hubs with rivets or bolts in the centre, mine has neither, it is clean. May help identification
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......I have also seen the hubs with rivets or bolts in the centre, mine has neither, it is clean. May help identification..
Given that you have a screw-in RH bearing retainer, I'm fairly certain that's a Plunger hub, and the rivet *heads* will be visible inside the hub.
I know little about Swing-arm models, but any chance of pics of the rest of the swing-arm as this has now morphed to 'wheel bits ID', and the brake pedal set-up may also help with ID...?
Looking at part lists shows similarities between 'Late A10' & some A65's but with variations....
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Morning all, I decided to strip out all the bearings and check the installation from scratch, found a number of assembly issues where not pressed together properly. I reassembled to remove all the additional space and I can now fit together with the 67-6028 spacer but I have to spring the swing arm to clear the hub plate when fitting the spacer. So I am now good with the exception of the 1 inch slot in the tight swing arm lug for which I will have a bush made.
Thanks all for the assistance I certainly learned a lot this week
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I have not been to the pub, ok plam getting somewhere now swing arm same as you on length , mine is a tad under 7/1/16 wide- this may explain why my distance piece 67-6028 slides in no problem along the dust cover to meet up with collar 65-5890 and inside of arm . stub axle 3/1/4 long ---what I think is an A 65 stub is 3/5/8ths.-- the long side of bearing sleeve 67-6027 is where collar 65-5890 sits, the bearing sleeve is 3/7/16ths long.-there is only one bearing retaining ring LH thread that holds the bearing in the sprocket side. collar 65-5890 and distance piece 67-6028 hold the right side bearing by butting up to the inner race .as dutch says plunger has two retaining rings. Swing Arm one retaining ring on sprocket side. ----plain as mud my brain hurts. now for something that may matter or not , on a plunger crinkle hub right side the outer bearing housing with the threads for locking ring stands proud of the hub crinkly bit , on swing arm this right hand side where the bearing outer sits is sunk back from the edge of the crinkly bit. the bearing sleeve -67-6027 where collar 65-5890 fits stands a tad proud of crinkly bit when its all in situ . as you have pointed out maybe the only thing you will nave to do is make a bush to take up the space of the bigger swing arm slot *yeah* *yeah* *yeah* *yeah* *yeah* *yeah* *yeah* *yeah* *yeah* I will have to go to the pub tomorrow *countdown* *beer*
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....... now for something that may matter or not , on a plunger crinkle hub right side the outer bearing housing with the threads for locking ring stands proud of the hub crinkly bit , on swing arm this right hand side where the bearing outer sits is sunk back from the edge of the crinkly bit. the bearing sleeve -67-6027 where collar 65-5890 fits stands a tad proud of crinkly bit when its all in situ . as you have pointed out maybe the only thing you will nave to do is make a bush to take up the space of the bigger swing arm slot *yeah*.......... *yeah* ........
I think the factory just machined off the redundant thread, but I expect the A65 ones with external thread for the speedo drive will again be longer (which is irrelevant here)....but I'm still curious what swingarm Plammo has, especially looking at the chainguard mount... *conf2*...which may have been modded on...
.... I will have to go to the pub tomorrow *countdown* *beer*
Why put off what you can do today...?....and again tomorrow... *smile*
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early start tomorrow dutch so not a good idea today, don't know when to throw towel in *beer* so tomorrow it is. yes that swing arm slot is confusing.com
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yes dutch I just had another look at the pictures IT is a plunger hub-- two retainers but the bearing sleeve sits same as mine ----- I think *pull hair out*
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.... IT is a plunger hub-- two retainers but the bearing sleeve sits same as mine ----- I think *pull hair out*
yep bearing spreaders are deffo diffo *smile*
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The chain guard mounts are an add on, I doubt BSA welding was that bad.
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Hi
My swinging arm, which looks BSA is 11/16" nearside spindle slot and 1" offside.
The larger offside slot looked as if it was machined that way.
Regards
Pat