The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: jonny web on 23.05. 2019 08:57
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Dear all
I am having a head scratching moment and maybe someone out there can shed light upon.
I have a 51 plunger A10 goldenflash, all bog standard. There appears to be a new splined ring on the brake plate and a new rear hub bearing sleeve and nut on the drive side.
The hub is standard but when it is on with the spindle bolted in, the distance between the hub collar (67-6077) and the timing side plunger lug is too small to fit the distance piece 67-6066
my only thought is that the problem lies with the rear hub bearing sleeve 67-6060 which may be too long ?
Shouls the hub be closer to the rear brake drum on assembly than mine is ?
any advice appreciated
best
JW
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I may be wrong but that spacer in pic #4 doesn't quite look right. *conf2*..... I'll have another look when I'm back at th ranch
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JW.. .Is this the hub you need to dismantle, or have you had it apart, reassembled it at it won't fit? Is it another hub entirely?
Looks to be a plunger hub, with the two bearing retainers. To my estimation they both need to be further into the hub, the right side one is especially proud and will prevent the shell cover seating. So, could be wrong bearings, or bearings not seated, wrong centre bearing spacer.
The centre spacer is a simple tube, with two pressed on discs, which have cut outs to pass the hub rivets on assembly. The design is such that the wheel spindle passes through the sprocket drum right through the bearing sleeve and its large retaining nut, then being tightened with its own stepped nut. You need to check you have the right parts and they are made to correct dimensions.
The brake back plate lip runs in a groove in the sprocket drum, the clearance here should be just a couple of mm at most, and the problem could be in the assembly of the drum/back plate. Perhaps a now unnecessary spacer to remedy some previous bodge. Spurious parts and poorly made pattern parts are all to be expected. The answer to this will be simple, so have a look at internet images of these parts, see how they compare.
Anyone got one in bits to hand for a bit of measuring?
Swarfy.
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Hi swarfy here is my reply
JW.. .Is this the hub you need to dismantle, or have you had it apart, reassembled it at it won't fit? Is it another hub entirely?
yes this is the hub i would like to use....once it fits !!
Looks to be a plunger hub, with the two bearing retainers. To my estimation they both need to be further into the hub, the right side one is especially proud and will prevent the shell cover seating. So, could be wrong bearings, or bearings not seated, wrong centre bearing spacer.
i unscrewed both bearing retainers and loosely refitted to test fit, so no they are not fully home, but that wont affect widths of bearings etc
The centre spacer is a simple tube, with two pressed on discs, which have cut outs to pass the hub rivets on assembly.
yes i have one of those in an empty hub i have, cant use that hub as the rivets are v loose
The design is such that the wheel spindle passes through the sprocket drum right through the bearing sleeve and its large retaining nut, then being tightened with its own stepped nut. You need to check you have the right parts and they are made to correct dimensions.
The brake back plate lip runs in a groove in the sprocket drum, the clearance here should be just a couple of mm at most, and the problem could be in the assembly of the drum/back plate. Perhaps a now unnecessary spacer to remedy some previous bodge. Spurious parts and poorly made pattern parts are all to be expected. The answer to this will be simple, so have a look at internet images of these parts, see how they compare.
yes i will dismantle brake drum and spindle stub on that side, it seems to be protruding a bit too far through the spines on the brake drum ?
Anyone got one in bits to hand for a bit of measuring?[
Swarfy.
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hi there
after the last batch of comments, i thought about the brake drum and took it off, that is i removed the rear drum bearing sleeve 67-6060 from the brake drum and built the whole spindle and hab back together, and hey presto it fit !
but as you can see from the pictures, the space between the back of the brake plate, and the step on the bearing sleeve is somewhat narrower than the width of the bearing that should fill the gap. About 5mm or so
as soon as the sleeve is back on, everything is shifted towards the timing side again and doesn t fit
My thought is; were there different rear sprockets ?
Do i have a later one?
are there different bearing widths ?
Can anyone help ?
cheers
best
JW
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Yes, the drum sprockets for the plunger models have the same basic form differing only in the number of teeth. The later S/A version looks similar, but has a centre bearing the same size as the wheel bearings. The Plunger drum bearing is different, with a slightly larger O.D. Your pictures are too close to distinguish which drum you have, it may actually be a S/A drum.
Swarfy.
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Looking at it again, it may just be that the dust-cover is not fitted, but that R/S spacer (67-6077) protrudes further than I recall.....can you take it out to compare ?
Yes, the drum sprockets for the plunger models have the same basic form differing only in the number of teeth. The later S/A version looks similar, but has a centre bearing the same size as the wheel bearings. The Plunger drum bearing is different, with a slightly larger O.D. Your pictures are too close to distinguish which drum you have, it may actually be a S/A drum.
It looks like the correct chainwheel as the hole for the spacer is bigger (~2" x 1/4" section if I recall) than the S/A ones which has a different spacer profile too...
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I have not been to the pub, going tmow *beer* and I don't know anything about plungers apart from I was given a plungy crinkle hub and they are slightly different to swing arm crinkle hubs. BUT I do know I once got a stub axle [ bearing sleeve in the book] to put in my swing arm single sided brake drum and it turned out to be for an A65 and was about half an inch longer , have you got the correct stub axle [bearing sleeve] or am I barking up the wrong tree again. the 1954/55 single sided rear brake drum bearing sleeve[ stub axle] on a plunger is 67-6060 and on a 1954/55 swing arm is 67-6030 you might have a mish mash of bits *dunno2*
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bergs- I'm giving you a free license to go to the pub now or do as I do and bring it to me... *beer*....they are completely different... as in the Plungo one goes right through, but the S/A one threads into the stubbie bit... get into it- I have but don't let me be a influence *eek*
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duTch... Looks to be the right drum, the knock in collar 67 6078 which covers the ball race is missing. On the other side of the bearing there should just be be a a steel grease retaining circular shim and the bearing circlip.
bergs...This could be an answer, but until we get some measurements for comparison this could run and run.
Swarfy.
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The Plunger drum bearing is different, with a slightly larger O.D.
I think this must be the right drum as the bearing in it has a larger OD than the two in the crinkle hub
best
JW
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Looking at it again, it may just be that the dust-cover is not fitted, but that R/S spacer (67-6077) protrudes further than I recall.....can you take it out to compare ?
yes here it is with length measured
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have you got the correct stub axle [bearing sleeve] or am I barking up the wrong tree again. the 1954/55 single sided rear brake drum bearing sleeve[ stub axle] on a plunger is 67-6060 and on a 1954/55 swing arm is 67-6030 you might have a mish mash of bits *dunno2*
Hi Berger, yes this looks like the right one
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the knock in collar 67 6078 which covers the ball race is missing. On the other side of the bearing there should just be be a a steel grease retaining circular shim and the bearing circlip.
Swarfy, the hub collar appears to be pressed home in the brake plate itself, and the shim and circlip on the other side were removed by me but dont effect the spacing of any bearings or spacers
best
JW
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Ok JDub- the 67-6077 looks the part and was thinking 11/16", but 17mm is close enough *wink2*...but the 67-6078 should be ( is normally) just a separate square section ring, I think 2" OD x 1/4" section. That bit on your brake plate doesn't seem right, but *may* do the job...if it's the right profile *conf2*
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J Dub.. The sprocket bearing should be a 1 x 2 1/4 x 5/8 (Imperial) race. The 5/8" is critical so worth checking first. The fitted sleeve pulls this inner race against the centre boss of the backplate, which should end up very close to the rotating drum. If the hub still won't fit, the length of the larger diameter part of the sleeve is suspect, if all other parts are correct and assembled correctly. The bore of the sleeve should be plain, not threaded.
Like duTch says, the collar 67 6078 is a plain square section ring, which knocks into the drum centre, acts as a grease seal, and rotates with the drum around the centre boss of the backplate. Yours is missing, the collar is not the bit in the centre of the raised boss.
Your backplate should have a cutout to match a lug on the suspension slider, so check here in case someone has chopped it off and the backplate is wrong. Again I am with duTch, the boss doesn't look right, but it could be the camera angle. Give us a view of the other side of the backplate.
Swarfy.
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........ the collar 67 6078 is a plain square section ring, which knocks into the drum centre, acts as a grease seal, and rotates with the drum around the centre boss of the backplate. .......
No way- it's sandwiched between the bearing inner race and backing plate, none of which spin- should just be an easy slide fit on the stub axle, not pressed in as there is a small clearance between it and the chainwheel bearing housing which spins around it.
....Your backplate should have a cutout to match a lug on the suspension slider, so check here in case someone has chopped it off and the backplate is wrong...
as Swarfo says, initially it appeared to be the proper brake-plate, but after a closer look now I'm also not so sure- in fact almost convinced it's not, but .... a clear pic of the sides will clear that up
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The collar is the conundrum. On my bike it was knocked into the drum, and so rotated around the backplate boss.
duTch you are right and the collar you mention is the centre boss, and is sandwiched between backplate and bearing inner.
Looking at the pictures closely I reckon I can just see the outline of the lug slot reinforcing plate, so the backplate is a good chance of being correct. A picture is what we need. Just hoping not to dig myself a bigger hole!
Swarfy.
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..........Looking at the pictures closely I reckon I can just see the outline of the lug slot reinforcing plate, so the backplate is a good chance of being correct. A picture is what we need. ..........
yep the *internal* of the lug slot is what I initially saw too, but the rest just doesn't look right
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duTch That square section collar looks to have been there from new, as it looks to be painted. So perhaps mine is completely wrong. Be interesting to see if it is holding the drum off. Like you, I agree, it just doesn't look right.
Swarfy.
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I dug out a couple of spare brake plates.... unless there's a couple of different types I don't know about, it should look like these....as jw's doesn't quite *conf2*
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duTch those look like the early version used on A,B,M plunger. Later versions have a hefty strengthening web running across from cam spindle location to shoe pivot. This web incorporates the spacer to set backplate to drum face running clearance. JW's looks like the later one, but still the centre boss looks not quite right. Your back plates need a separate spacer to support the drum bearing.
Swarfy.
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duTch those look like the early version used on A,B,M plunger. ..........
*conf2* aaaaahh yeah...? Well we are talking about a '51 Plunger setup aren't we (given the only other choice was Late Rigid) ? What am I missing?
** Edit; Just had a look at the plans, and the early list ('49-'53) "Rear Brake Cover Plate" has two listings;- Pn# 67-6180/3 & 67-6180/7, and the '54-'57 Model is just a straight 67-6180.....so what's the /3 & /7 all about ?
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here better photos of the rear brake plate
part number 67-6078 hub collar is loose on my parts diagram, but that maybe because the earlier brake plate had no horizontal brace welded on, mine has that brace and the collar sits within it. The thing is, that whatever the case, the hub collar has to space the brake plate away from the brake drum, this is the case and removing any metal from the hub collar will cause the brake plate to hit brake drum.
i seem to have the later brake plate with the added bracing over the slot and the inner brace also but this appears in my parts book years 49-53
and what looks to be the correct brake drum,
the space between the hub collar 67-6078 and the step on the bearing sleeve 67-6060 is 11.5mm and the width of the bearing is a shade under 16mm so i need to find where i can lose 4.5 mm, possibly the only answer is to turn that amount of the step on the bearing sleeve, this would have the advantage of pushing the drum to the timing side and getting more spined contact on the QD spines, any ideas anyone ?
hopefully
JW
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J W The good news is that those parts look to be the right ones. Later braced backplate with integral bearing spacer. The only item questionable is the new bearing sleeve, and I reckon this is the cause of the grief. You need to do a bit of precision measuring to determine which side of the step needs material to be removed. The sleeve supports the wheel bearing inner race so don't remove too much, the spline of the wheel needs to go as deep as possible into the drum without bottoming to ensure the inner race is still supported. Looks like pattern parts strike again. Hub collar sounds fine.
duTch The suffix on those parts is the finish code. /3.....Bright Chrome /7.....Black Enamel
Swarfy.
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well I know nothing , but his bearing sleeve isn't one of these
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.........duTch The suffix on those parts is the finish code. /3.....Bright Chrome /7.....Black Enamel
Too easy- Live and learn, I wasn't aware of the change- wonder why the later plate has the same p/n then .... *conf2* Maybe the reason I've only seen the early ones is because people swap them out for the later (maybe better) ones and flog the other off
the only other thing I can think of is maybe the frame is slightly bent so the Axle Lugs are too close together, so wouldn't go machining anything just yet.....(mine was pushed equally to one side so the sprocket didn't align properly *pull hair out*)
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duTch We all assume the basics are correct, so you are right to consider the frame as well. Just been into the archives, the distance between the slots in the plunger column lugs is given as 9.875", near as makes no difference to 251mm. Also measured a bare rear frame section and was relieved to see that's what I've got.
Bergs has eliminated sleeves that don't fit, now we just need the dimensions of the correct sleeve part for comparison before JW gets carving.
Swarfy
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well now i hadn t thought of the frame either ! Goodness knows when it had a wheel in last, certainly not since the early 90s and it was a project long before then, so the frame way well have been banged about since.
The distance between the slots is 247-248 mil so i will get a car jack between the rear lugs and see if it moves apart the required 4 mil, then who knows ? I will keep you chaps posted and thanks for all the help so far !
JW
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I'm also thinking maybe if possible could be good to add up the sum of all the bits assembled on the axle for comparison to a known figure (or something like that if there is one)...if yea know what I mean ?
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dear all
after all that fuss about part numbers and lathe work, the solution was a simple one.
I put a car jack inbetween the rear footrest mounts and opened up the frame a bit.
after removal the frame was seen to have the correct width between the plungers
and the rear axle went in with the brake drum just right.
the next stage will be for me to rebuild a new wheel onto the hub i have. And that will mean paintingthe hub first so i will need to find the right color !
More soon.
Many thanks for all the help advice and encouragement....invaluable !!
best
JW
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J-Dub, unrelated specifically to yours, I sometimes ponder the Plunger geometry as I'm trekkin' about on mine, and the other week I concluded that if the columns are out of parallel or general alignment in any way- like in the same plane fore and aft (eyeballing across), I reckon the chance of wear is greatly increased.....jus sumfin to keep in mind *conf2*
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J-Dub, unrelated specifically to yours, I sometimes ponder the Plunger geometry as I'm trekkin' about on mine, and the other week I concluded that if the columns are out of parallel or general alignment in any way- like in the same plane fore and aft (eyeballing across), I reckon the chance of wear is greatly increased.....jus sumfin to keep in mind *conf2*
i dont doubt it !
i had a 54 plunger years ago which i think had well clapped out plungers, the wheel would hop about all over the road in corners, but this 51 has all new parts and will get a very low mileage