Rear sprocket hub query

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Rear sprocket hub query

Postby asterysk_usa » Sat Nov 16, 2019 4:51 am

Image

Are the 5 bolts meant to be welded to the hub ? All the welds have broken so I’m thinking not !

If not , any suggestions as to why they were welded , would it have been to make them captive

And what would you recommend I do , leave it , get a new sprocket hub


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Last edited by asterysk_usa on Sat Nov 16, 2019 4:31 pm, edited 1 time in total.
1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: Rear sprocket hub query

Postby Mick D » Sat Nov 16, 2019 6:32 am

Hi

Those bolts shouldn't be captive, and to be honest, that's not welding :o :o

The bolts on my 61 G3 are recessed into the sprocket:

Sprocket.png


No idea why a PO would see the need to render them captive, it's not like they're difficult to access.

I definitely wouldn't leave as is, there's all sorts of pain and grief waiting if the 'welds' let go. I'd also be concerned that the heat from the 'welding' may have damaged the material properties of the sprocket. I'd replace the sprocket if possible - if not I'd spot face the 'weld' off and inspect test the area around the bores for cracks.

Regards Mick
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Re: Rear sprocket hub query

Postby Andy51 » Sat Nov 16, 2019 9:10 am

The bolts are loose. They are specials with longer heads, and are inserted through the hub flange, screwed into the threaded holes in the drum/sprocket with special tab washers, and then locknuts are used inside the drum to make sure! All is explained if you look at the appropriate parts list and workshop manual, available from Jampot.dk. cheers, Andy

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Re: Rear sprocket hub query

Postby asterysk_usa » Sat Nov 16, 2019 9:28 am

I think I have the 1955 sprocket hub, it is stamped with 021597 and the 1955 parts list has 021596 Sprocket and drum for the 18S (I was advised elsewhere that there is often a one digit mismatch between stamping and paper parts list)

This means I am looking for a "Pin, driving in hub" part number 021607 as opposed to a bolt. Does anyone have a photo of this "pin" ?

Neither the sprocket or "pin" seems to be available on AMOC spares of AMC classic, how would I go about determining what other years sprocket might fit ? Is there such a thing as a "compatibility parts matrix" i.e. something that shows what retro fit parts work ?
1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: Rear sprocket hub query

Postby Duncan » Sat Nov 16, 2019 2:08 pm

It looks like someone has tried to weld up the holes to take out some of the "clonk" that comes from worn pins and elongated holes.

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