51 plunger crinkle hub conundrum !!

[Swarfcut]

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.

[duTch]

 

........ 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

[Swarfcut]

 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.

[duTch]

 

..........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

[Swarfcut]

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.

[duTch]

 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 

[Swarfcut]

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.

[duTch]

 

duTch those look like the early version used on A,B,M plunger. ..........

  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 ?

[jonny web]

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

[Swarfcut]

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.

[berger]

well I know nothing , but his bearing sleeve isn't one of these

[duTch]

 

.........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 .... 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 )

[Swarfcut]

 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

[jonny web]

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

[duTch]

 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 ?