Front Wheel Brake Drum

[dicsaer]

Hi,Could anyone tell me if it is possible to replace brake drum on cotton reel full width hub without dismantling rim from hub,and how to go about it.I have a spare hub with brake drum fitted.
Keep safe Richard.

[Invicta]

Hi Richard ,
I am a bit confused about the description, "cotton reel and full width hub" What year and model is your bike.
Dave

[Groily]

liner.JPG

Me too. But isn't it a case of a liner in cast iron, attached by SIX allen screws? Very hard to get in and out in my own experience,, having made a new liner for one of mine, see pic. (Aplogies if different type of wheel altogether . . .)

[clive]

Do I get a prize for spotting Groily's is a full width hub? You would want plenty of interference fit between the brake lining and the hub rather than relying on 6 bolts to stop you.
However why do you want to change the brake drum? I have had one skimmed because of ovality very successfully with a big improvement.

[Groily]

You shall have prizes Clive.
It is - a parallel-not-barrel shaped '54-only version. But maybe the same basic design if the one in the Q is 'full width'?
Yes, careful machining required to get a correct interference fit, which is probably quite enough to resist the massive forces of that particular brake! But the allen screws are high tensile methinks and probably equally up to the task even if the interference fit weren't that good. That one has lasted 12+ years now and a lot of miles . . .
Good fun 'getting to round' after fitting to the hub, and then after lacing the spokes . . . (I don't think)
Not really a job for the faint-hearted (forget the new liner bit, which I made 'cos mine was cracked), because even with a replacement original liner, it'll still need truing after fitting, I'm guessing? It takes a lot of heat on the hub after stripping out the spindle and bearings to get a liner in or out, at least that is what I found.

[Greybeard]

rather than relying on 6 bolts to stop you.

I think they'll be more than up to the task. It might even be over engineering when you consider that motorcycle brake discs are held by 5 or 6 bolts on a much smaller radius (so subject to a greater force) on much heavier bikes and gripped by very efficient calipers - and no interference fit either

Steve

[Mick D]

rather than relying on 6 bolts to stop you.

Jings!!!

Next someone will suggest securing the rear brake drum with five pins to resist both drive and braking

[Andy51]

Look at page 128 of Fred Neil's AJS singles 49 - 57. He says liner can be removed but should be done at factory; he then describes how to do it if you cannot get it back to Plumstead (which you obviously can't!). Given the relatively low cost of drums at autojumbles/fleabay I would be reluctant to do this job, but would investigate getting an engineering shop to skim the old drum. I have skimmed a BSA 8 inch drum with success, and it is always worth skimming the liners (did the job on a Myford) - gives you perfect contact from the outset, and really improves the brakes. Cheers, Andy

[Groily]

drum skimmer.jpg

Yup to that Andy. I used the gap in the bed on a Myford and a day and half in back gear + pints of cutting oil to make my liner.
For skimming I made a tool - in fact for a BSA originally - which proved to be rather effective. A flycutter bit mounted to move on two axes, and attached to the wheel spindle. Then spin wheel while playing with cutter height. Sounds Heath Robinson, but actually did a really neat job on a B31 I had, and can be adapted for other spindle diameters (using some ingenuiy to achieve a solid means of attachment to the spindle). Finished off with fine emery and elbow strain.

[dicsaer]

My bike is a 1954 G80CS with the original full width parallel hub,the brake drum has some hairline cracks.Safest bet is to use the spare hub which I have.Never laced a hub before but going to have a go.
Thanks for all your suggestions and replys.Richard