AJS & Matchless Owners Club

Among the bits and pieces of the '54 G3/LS basket case that I acquired was a Smiths Chronometric speedometer. It had a 120mph dial so it wasn't the correct one for the bike, the needle was stuck at 120 and the cable connection wouldn't turn. I made an educated guess that is was 'broken'.
However, I parcelled it up and sent it to Chronometric Instrument Services in Nottingham and asked for their assessment. I spoke to them on the phone this morning and they agreed with my assumption but it wasn't beyond repair. To cut a long conversation shorter, they are going to do a 'Concours Restoration' (their words), fit the correct 80mph dial and recalibrate it for the Matchless. Total charge, including return postage £125.
I'm happy with that!!

That sounds champion

Its fairly easy to change a 120 speedo to 80 and viceversa. It only requires a change in the face and of the pendulum, otherwise all parts are the same. If you have a Chronometric speedo that does not work, unless it has been in water for years, it is usually repairable. Thats why even a non working speedo sells for £160 plus on ebay.

Isn't the ratio of 120 to 80 too large for only a change in pendulum (cycle time)? You know of course that driving pinions for the counting wheel exist with different numbers of teeth.
Albert

aobp11 wrote:Isn't the ratio of 120 to 80 too large for only a change in pendulum (cycle time)? You know of course that driving pinions for the counting wheel exist with different numbers of teeth.
Albert

Changing the number of teeth on the counting wheel changes the ratio (number of revolutions of the wheel to register 1 mile). I have changed a large number of speedos from 80 to 120 or the other way and only changed the pendulum weight, as you don't want to change the overall ratio, only how much the needle moves for a certain speed. The 120 speedos have a much thinner brass weight than the 80mph ones. You cannot do it with just the little clip in metal adjuster weights, the larger of which change the speed by about 0.75% each.

I shall probably keep my eyes open for an original now and put up with the one on the bike ,only thing is i have looked on the net for an image of the correct speedo for my 54 18s and cannot find one the manuals that were kindly supplied state my machine should have a 480/3/L type would i be right in saying it is a 80 mph with an odometer only , also i have not been to kempton park auto jumble yet i keep meaning to would this be a place that i could find one .

Martin.

This might not be a lot of help but this is a photo of the speedo fitted to my '55 M18S

Looks a nice looking instrument, but from the smiths catalogue my 54 should have a 480/3/L the speedo is mounted on the top fork yoke on a L shaped bracket whether there is much difference between 433 and 480 clocks i do not know.

Martin.

Rupert123 wrote:Looks a nice looking instrument, but from the smiths catalogue my 54 should have a 480/3/L the speedo is mounted on the top fork yoke on a L shaped bracket whether there is much difference between 433 and 480 clocks i do not know.

Martin.

I somehow doubt that the speedo on my bike is the one originally fitted at the factory. When I bought the bike, it had most of a '54 front end on it and the speedometer was fitted on a 'cobbled together' bracket that certainly wasn't standard. The trip reset knob came out of the side of the case at roughly the 5 o'clock position. It didn't have the flanged bezel, either. When I fitted the correct '55 headlamp, the speedometer was sent to CIS and they checked it over, converted it to have the trip reset knob coming out of the rear of the case and fitted the correct flanged bezel for me.
I don't know what the numbers on the dial mean or what difference it makes but I'm betting that someone on here does and will enlighten us in due course.

google A.Gagg and sons there is a list of fitments shown on their website, kind regards