Author Topic: QD rear hub - new sprocket  (Read 229 times)

Online Black Sheep

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QD rear hub - new sprocket
« on: 22.01. 2019 10:09 »
Trying to fit a new sprocket to a QD rear hub (1951 plunger A7). I've go to the point where I have removed the circlip and stub axle and can see the bearing but can't see how to extract it or the splines to transfer to the new sprocket. Before I reach for the angle grinder, any ideas please?
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Online duTch

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Re: QD rear hub - new sprocket
« Reply #1 on: 22.01. 2019 10:34 »

 Should be straightforward- just undo the 6 nuts on the inside and punch the bolts out....a bit of heat on the inside (brae side) of the bearing boss and the bearing should drop out....or did I miss some pre-amble info... *conf2*


 ***don't touch the *work*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Offline Swarfcut

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Re: QD rear hub - new sprocket
« Reply #2 on: 22.01. 2019 11:30 »
Black Sheep

    As duTch says, the drive spline ring comes off after knocking back the tabs, undo the nuts and remove the 6 bolts and it should drop off. Centre circlip should have a thin sheet steel grease retainer, described as a bearing shim, between it and the bearing. Depending how you want to treat the bearing, warm everything up and it should come out easily with a draw bolt and washers or a big hammer.  Smacking a centre race, unsupported in this way is not good for bearings, but you knew this already.  You may also have to swap over the other "collar", the ring that keeps the grease in on the inside, backplate side of the drum. This will knock out with a bit of care. Put a dab of loctite on it when you replace it in the new sprocket drum. This assumes you have the right sprocket, made to original dimensions.

  Swarfy

Online Black Sheep

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Re: QD rear hub - new sprocket
« Reply #3 on: 22.01. 2019 14:26 »
The drive spline ring and bearing have been there since 1951 and seem reluctant to let go. I'll try more heat and drawing them out. Fingers crossed this time. The new sprocket is British made so hopefully should fit.
At least the new gearbox sprocket is on. All in all, I can see why I kept putting off the sprocket replacements...     
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Online Greybeard

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Re: QD rear hub - new sprocket
« Reply #4 on: 22.01. 2019 15:05 »
Is this the machine in your avatar?

Offline Swarfcut

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Re: QD rear hub - new sprocket
« Reply #5 on: 22.01. 2019 17:10 »
 Black Sheep... If you can tactfully avoid the ensuing acrimony, Gas Mk 4 for 30mins or until the spit dances should be hot enough. Drip tray to catch the grease!

 Swarfy.

Online Black Sheep

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Re: QD rear hub - new sprocket
« Reply #6 on: 22.01. 2019 19:11 »
Yes same machine. 1951 Star Twin. Have been told I have to use roasting bags in future for things in the oven. She never used to be this fussy, but then it was usually her A10 cylinder head in there.
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Online chaterlea25

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Re: QD rear hub - new sprocket
« Reply #7 on: 22.01. 2019 19:33 »
Hi All,

Quote
I have to use roasting bags in future for things in the oven

Now why didn't I think of that  *bright idea* *bright idea* *bright idea* *bright idea*

John
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Online Colsbeeza

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Re: QD rear hub - new sprocket
« Reply #8 on: 22.01. 2019 21:42 »
JCL, Women Do sometimes think outside the square.! Sometimes worth listening to.!
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Online Greybeard

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Re: QD rear hub - new sprocket
« Reply #9 on: 22.01. 2019 23:09 »
... Have been told I have to use roasting bags in future for things in the oven...
Well, that will save you having to baste

Online muskrat

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Re: QD rear hub - new sprocket
« Reply #10 on: 23.01. 2019 00:24 »
The hooded gas BBQ is the best thing invented for bike parts. My problem is it's just outside the kitchen window!
Looking at the cost of these drum/sprockets I'll be doing the same as I did to the Cafe. Mount drum in lathe and turn the sprocket off leaving a stepped spigot. The buy a sprocket blank and turn out the guts to match the drum spigot. A few tacks with the welder (stainless rods), job done for 1/5 the cost.
Cheers
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Muskys Plunger A7

Online Black Sheep

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Re: QD rear hub - new sprocket
« Reply #11 on: 23.01. 2019 06:58 »
An outside BBQ! Not a snowflake's chance here in Scotland. If the rain and wind don't put you off, the midges will get you. -7 here today and snow lying. Not BBQ weather... You clearly have a decent sized lathe. Luxury!
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Offline Swarfcut

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Re: QD rear hub - new sprocket
« Reply #12 on: 23.01. 2019 08:50 »
 Black Sheep..... Now we come to putting the bearing back in the new drum, if its already nicely finished, heating up too much will spoil the lovely finish. So it's bearing in the freezer,  big hammer and smack it in squarely with pressure only on the outer race. On reflection, just getting a new bearing could be a more harmonious (for you) and less violent and stressful (for the bearing).

  Musky.....You make it sound just so easy peasey.

Online Black Sheep

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Re: QD rear hub - new sprocket
« Reply #13 on: 23.01. 2019 10:06 »
Success! Lots of heat and a rubber mallet and it all came apart happily. A new bearing may be the way to go. Mind you, the original is still looking pretty good for 68 years old. Better than me anyway. There are freezers in the shed so I'll go for the combination of hot sprocket and cold bearing.
Thanks for all the help and advice. Much appreciated.
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Online duTch

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Re: QD rear hub - new sprocket
« Reply #14 on: 23.01. 2019 10:50 »

 
Quote
....Not a snowflake's chance here in Scotland. ......... -7 here today and snow lying.  ....

 Why are you heating it up in the freezer when it's already -7° air temp outside ? *conf2*

 Ooooh- silly me... you're heating the chainwheel in the freezer and leaving the bearing on the grass to cool .... *doh* *doh*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia