Speedo drive mashed

Information relating to the Matchless G9 or AJS Model 20 500cc twin
JimFitz
Posts: 663
Joined: Thu Feb 27, 2014 9:27 am
Location: Kent, England

Re: Speedo drive mashed

Post by JimFitz »

Hi Oggers

I bought a drive from club spares and it works fine. IIRC the hole needs to be eased out a little with a reamer so that it fits the spindle unless a new batch has come in with the hole a little larger.
I also seem to remember that the factory drawing shows incorrect assembly details for the axle spacers. If you search the forum or the archive there is an excellent 3D drawing which shows the correct assembly sequence.

Jim
Too old to Rock and Roll but too young to die.

1952 G80 rigid, 1960 G12 DL / Watsonian Monza, 1954 G80S.
Oggers
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Joined: Mon Jan 14, 2019 5:37 pm
Location: Aberdeenshire

Re: Speedo drive mashed

Post by Oggers »

DSCF3016.JPG
DSCF3015.JPG
Some further pics for interest - top one shows where the centre of the speedo drive gearbox has just sheared away and ended up lodged firmly behind the hex nut. You can see the hole left in the drive gearbox!

Bottom shows the position of the locking ring as it came off the bike - presumably it should be hard up against the cover? to the right of it.....

I'll digest the technical stuff
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clive
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Re: Speedo drive mashed

Post by clive »

I would be interested to see a picture of the drive worm gear. You access it by taking the flat end off part odf the unit which is separate
clive
if it ain't broke don't fix
Mick D
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Location: Aberdeenshire

Re: Speedo drive mashed

Post by Mick D »

Hi Oggers

When you dis-assembled the wheel / drive was the bearing adjuster screwed out of the wheel hub? It looks like the drive has seized and caused the adjuster to unscrew and wreck the cast case - as Clive says, a look at the pinion gear would be informative.

Regards Mick
matg80s
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Joined: Fri Jan 04, 2019 6:05 am
Location: Sth.Aus.

Re: Speedo drive mashed

Post by matg80s »

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Last edited by matg80s on Sun Apr 07, 2019 10:22 am, edited 1 time in total.
JimFitz
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Joined: Thu Feb 27, 2014 9:27 am
Location: Kent, England

Re: Speedo drive mashed

Post by JimFitz »

That cutaway assembly was what I was referring to in an earlier post although I thought it was a drawing. It is not assembled as the factory drawings (which are incorrect). I think the right hand stepped washer with a 3 next to it on the cutaway is shown reversed on the drawing which results in the bearing tightening up until the wheel locks, the speedo drive spinning round and wrecking the drive and the cable - at least that is what happened to me.

Jim
Too old to Rock and Roll but too young to die.

1952 G80 rigid, 1960 G12 DL / Watsonian Monza, 1954 G80S.
Oggers
Posts: 135
Joined: Mon Jan 14, 2019 5:37 pm
Location: Aberdeenshire

Re: Speedo drive mashed

Post by Oggers »

Mick - excellent photo - Many thanks...

The plot thickens - Upon disassembly I found no thin washer or the "cup" for the hub rubber oil seal. Excellent photographic procedure in the archives which shows these items should be present - as does the manual. Not sure about the implications of them not being there, and whether they contributed to the catastrophic failure, but clearly it would seem they should be present.

Persoanlly I am leaning towards a loose locking ring on the hub as root cause. Also found the wheel spindle nut (on the nearside) was not paticularly tight. :o
56G80S
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Re: Speedo drive mashed

Post by 56G80S »

matg80s post of a picture looks like the post a long time ago by "Biscuit" (Alan Jacobs) but I can't find it in the Technical Tips, along with the text to accompany the numbers.

Johnny B
matg80s
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Joined: Fri Jan 04, 2019 6:05 am
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Re: Speedo drive mashed

Post by matg80s »

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Last edited by matg80s on Sun Apr 07, 2019 10:32 am, edited 1 time in total.
SPRIDDLER
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Re: Speedo drive mashed

Post by SPRIDDLER »

56G80S wrote:matg80s post of a picture looks like the post a long time ago by "Biscuit" (Alan Jacobs) but I can't find it in the Technical Tips, along with the text to accompany the numbers.
It's here, page 5 under............ Home >> Pictures >> Parts Pictures >> Post war twins >> Rear wheel oil seal arrangement

http://www.jampot.com/pic_display.asp?id=820
'There is a tide in the affairs of men
Which taken at the flood............'
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