Speedo direction confusion!

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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AndyO
Posts: 16
Joined: Mon Oct 26, 2020 5:24 pm
Location: Gloucestershire UK

Speedo direction confusion!

Post by AndyO »

My, new to me, G80S speedometer turns when hooked up to my drill, in reverse. Needle moves and trip works. However the Speedo gearbox seems to turn in the wrong direction. Am I missing something here? I had assumed that, as it’s a very original bike, the Speedo and g’box would match. The g’box is on the right hand side and drive comes from the top. Many images I’ve seen suggest the cable comes from the bottom. Does this reverse the direction? Thanks as always everyone.
Andy
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clive
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Joined: Mon Jan 01, 1990 12:00 am
Location: LONDON UK

Re: Speedo direction confusion!

Post by clive »

The speedo on your bike should be a smiths with clockwise mechanism. If you had to engage the reversing mechanism on your drill this is correct. The clockwise name means the cable should be turning in a clockwise direction when observed from above. The complication comes in when you look at the direction of rotation from behind ie from your drill, then it will be turning anticlockwise. So the easy way to check your speedo drive box is to connect up the cable and then look at the direction it rotates looking from above at the speedo end. If it rotates clockwise as you push the bike forward all is well.
The earlier speedo drives had the cable from the top and flat ends later ones had the drive from below with a torpedo end. Both are usually clockwise.
clive
if it ain't broke don't fix
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Stevecampy
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Posts: 42
Joined: Sat Sep 25, 2021 6:39 pm
Location: Lincolnshire UK

Re: Speedo direction confusion!

Post by Stevecampy »

Thank you just fitted a new drive and was concerned by the different ends and the top and bottom drive
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