Author Topic: Rear brake hub sprocket  (Read 235 times)

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Offline saluki42

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Rear brake hub sprocket
« on: 14 Nov 2022 at 14:07 »
Hi there, I have just obtained a rear hub and brake assembly to use on my model Z and have a problem the sprocket on the hub
 is much too badly worn to be used so needs replacing. Can anybody tell me if the sprocket is an integral part of the hub, steel sprocket ring shrunk onto the hub or welded steel sprocket ring ? If one of the latter two does anybody know of a supplier of these?

Regards
Chris

Offline eddie

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Re: Rear brake hub sprocket
« Reply #1 on: 14 Nov 2022 at 17:54 »
 Flat steel sprockets can be obtained from most bearing stockists - they know them as 'Plate wheels'!

   Regards,
                Eddie.

Offline Doug

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Re: Rear brake hub sprocket
« Reply #2 on: 15 Nov 2022 at 00:26 »
Chris,

Might be welded, might be pressed/keyed.

On both my 1934 and 1935 ohv models, the sprocket is tack welded (or tack brazed?) to the brake drum. You should see a small, 1/4 long tack weld about every 2-1/2 inches around the face of the brake drum -sprocket joint. On my 1936 600 Aero, the sprocket was a shrink fit. The drum was knurled for grip and there are three keys around the drum to provide positive drive (see photo). These are pegged through the drum so you should see the a little bit of the 1/8 inch diameter hole one the inside brake surface, as well as the joints for the key & key seats from the back face side. 



Unfortunately my original and replacement 50T plate sprocket are temporarily misplaced, or I would have taken a photo of them next to each other. But an older picture previously posted on the forum can be seen here:


Larger Image

Now as to what style the Z/Z1 model used (or tooth count) I do not know. I would expect they were tack welded like the ohv models of the same year. But at some point they changed to the pressed/keyed design of 1936 onward, and that might have started a year or two earlier on the side valve models. I think that less likely of the two scenarios.

Regardless, you are going to have to make your sprocket to suit the style of brake drum that you have acquired.

-Doug
 

Offline saluki42

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Re: Rear brake hub sprocket
« Reply #3 on: 15 Nov 2022 at 13:08 »
Thanks for the responses, regarding my Z I have no real idea of the age of either front wheel assembly or rear wheel hub and brake assembly mores the pity. The front wheel has a beaded rim which I will have to change but everything else is ok, the rear looks as if it was used as a boat anchor for the last 20 years but apart from the sprocket ring is recoverable the felt seals seemed to have keep the bearings and spindle dry. The thing is actually getting hold of model Z wheels would be just about impossible so I'm having to make do with what I've got I'm afraid. I've found a UK suppler who can sell me machinable sprockets so they are on order and I'll hand them over to our welding instructor to finish.

Thanks again
Chris