Speedo help, G2CSR 1964 (allegedly)

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Janet
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Speedo help, G2CSR 1964 (allegedly)

Post by Janet »

I've done a search on this and found a similar question but various numbers referred to there didn't seem to be like mine.

As far as I can see, there are three main components involved in recording speed. These are the speedometer dial at one end, the cable in the middle and the gear/drive thingy at the other ( being at the rear wheel on this bike). I always like consistency so shouldn't be disappointed because all three are broken.
1) speedometer - the needle has fallen off. I don't yet know if the internals are working because of the other two bits being broken but when I get the speedo out frrom the headlamp shell I'll gently put an inner cable in and spin it for a long time to see if anything happens. I suspect by offering the right person a certain amount of money I will be able to have this fixed but before I do that I would like to know what exactly I've got as it has some bearing on the other parts.

It is a Smiths speedo going to 100mph. On it are the numbers 55M 2001/02 1600 These mean nothing to me so I don't know whether or not it is the proper one.

2)cable - The outer cable is mangled and broken so I need a new one. However, it seems there are two types for the G2, depending on which speedo it is. Apparently there is a chronometric one and a magnetic one. Guess what, they seemed to change around 1964 and as I've said before, I don't know exactly what I've got.

3) gear/drive - The one I've taken off has the following stamped on it. ratio 19-10 and BG 5330/857 I do have a working one of those but don't want to fit it if it's the wrong one, not from a purist point of view but if it's wheel size specific it won't be fit for purpose. The wheel on the G2 is 17".

At least one of these parts has been broken for years going by the old MOT certificates and, as with all old bikes, parts could have been changed.

Thank you for your time.

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Don Madden
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Speedo help, G2CSR 1964 (allegedly)

Post by Don Madden »

I have found that most of the old speedo gearboxes that have lain around for a long time are siezed due to hardened grease. I pry out the big retainger for the felt seal & unscrew the end cap/bearing for the spindle to clean out everything, then reassemble with waterproof grease. Sometimes the big worm is worn beyond use but I have recovered many. Cheers, Don.
itma
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Speedo help, G2CSR 1964 (allegedly)

Post by itma »

this any good?

http://archives.jampot.dk/Technical/Spe ... t_1962.pdf

also a google images search on chrono and/or magnetic will bring up loads of images to help ID it
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Janet
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Speedo help, G2CSR 1964 (allegedly)

Post by Janet »

Thank you both.

Don, the teeth on the bit the cable goes in seem to be almost perfect, but I'm guessing there should be some corresponding ones on the bit that goes round with the wheel ( I know, women shouldn't mess with things they don't know the names of ) . This appears to be almost perfectly circular so I'm pretty sure I've identified the problem at that end.

Ken, I've printed off the document you linked to and will give it some good looking at. Even if it doesn't sort out what I should have it will be useful whenever a similar problem arises on other machines.

I'll also follow your suggestions for googling.

thanks again.
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ranger
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Speedo help, G2CSR 1964 (allegedly)

Post by ranger »

Here's what I know:

Your speedo is a Smiths magnetic (SSM Smiths Speedo Magnetic) and 1600 refers to the speed. My bikes have SSM ....... 1600 and use a 2-1 rear wheel drive unit; this is stamped on the drive unit, but my rear wheel is 18 inch. Obviously a 19/10 is nearly 2-1 but I can't say what you need for 17 inch. You may already know all this from the web link.

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clive
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Speedo help, G2CSR 1964 (allegedly)

Post by clive »

Janet I would have expected the G2 which I believe is a lightweight to have the small speedo. These are all magnetic as the works for the chronometric cannot be forced into anything much smaller than the D shaped speedo on the Bantam. Yours I believe will be round and smaller. This means you can buy the magnetic cable as even if your speedo is not working you will have to replace it with another magnetic one. Smiths did make 3 inch magnetic speedos too which is where the confusion may have come in. (and possibly the CSR model had a bracket mounted larger speedo than the headlight mounted one in which case you could fit either magnetic or chronometric speedos so ignore my comments on the cable) On ratio I cannot help but I would have expected a 17 inch wheel to need a lower ratio gearbox than the more standard 18 or 19 inch as it will be doing more revolutions per mile than the larger wheels. But then again a 2.1 gearbox would only put your speedo out by 5% compared to a 19/10 one and I doubt the speedo will be that accurate because it is likely to flicker around with vibration! The 19/10 ratio boxes are rarer.Edited by - clive on 30 Jan 2010 6:53:42 PM
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hawkes
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Speedo help, G2CSR 1964 (allegedly)

Post by hawkes »

does this mean if my speedo no. begins with SC it is a smiths chronometric ? it weighs about 1 and a quarter pound ? works upside down too ! 10 mph is at 1 o'clock ?
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Speedo help, G2CSR 1964 (allegedly)

Post by wilko »

A photo will sort this out. As for the drive, it's usually the smaller driven gear that strips, or the drive tags are worn or broken off.
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Janet
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Speedo help, G2CSR 1964 (allegedly)

Post by Janet »

Right chaps, since I know you're all agog to hear the latest thrill.ng instalment...

As Ranger said, and verified by a google as suggested by ITMA, ( or had I googled and Ranger verified it? )I have a 60mm magnetic speedo. I've established that the little numbers go round. Well, the end one does. I've not spun it enough to register on the others. It was reluctant at first but some very slight lubrication and wiggling got them going. I think being stopped for years will have caused that. This shows that at least part of the internals work. Without the needle I don't know if the speedo bit does, but gifts of loads of money to Gaggs, or possibly others, can see it mended.

I now know which cable to buy and have ordered it from JSL.

I've fitted a working drive, with 19-10 stamped on it. This was stamped on the one I took off and may have been original. I haven't thrown away any of the bits as I'm sure there will be another one lying around with a different bit worn out. Once I've got my speedo mended I'll check the reading against my GPS to see how accurate it is. If it's way off I'll look for a different one. Of course, it may be possible to be way off and still the proper one.

Thanks again to everyone for your input.
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