Smiths speedometer

greasemonkey62 · Post by **greasemonkey62** » Fri May 20, 2011 4:06 pm

I have a smiths chronometric speedometer that indicates up to 120mph on my 1962/3 model 31 AJS, it indicates the speed fairly accurately but the milometer reading is not increasing as the miles pass, it does have a trip milage readout at the bottom with a long (8 inch) reset knob, I have tried to reset the trip milage by turning this with it being left as it sits/pressed in and also pulled out but the trip milage does not alter.
The speedo has printed on it the numbers 1550 and also s.467/163n , does anyone have any ideas how to remedy this? if not is there a repair shop for these in the UK?
cheers Ray.

petert120r · Post by **petert120r** » Fri May 20, 2011 4:20 pm

David Woods 01903 724509

nottsSteve · Post by **nottsSteve** » Fri May 20, 2011 7:02 pm

I think Gaggs in Nottingham too

aobp11 · Post by **aobp11** » Fri May 20, 2011 7:18 pm

Ray, usually the the trip reset knob has to be pulled with some effort because of the strong internal spiral spring and the not so handy knob position. The odometer problem might be due to a worn or mis-adjusted pawl, you can search the forum for that. Anyway, for DIY you have to dismantle the speedo.
Albert

SideValve · Post by **SideValve** » Fri May 20, 2011 7:21 pm

If you're feeling brave they are fairly easy to disassemble and clean. Just done mine and the hardest part was getting the bevel off!

greasemonkey62 · Post by **greasemonkey62** » Fri May 20, 2011 11:35 pm

surprised you say they are easy to strip down, I might have a go but what is the bevel you mentioned?

aobp11 · Post by **aobp11** » Fri May 20, 2011 11:58 pm

The threaded chrome ring which holds the glass. I suggest you search for "speedo bezel" and also for other speedo info in the forum and in the articles.
Albert

Sorry, bevel?Edited by - aobp11 on 20 May 2011 11:01:06 PM

clive · Post by **clive** » Sat May 21, 2011 12:12 am

bezel comes off easier if you put nthe speedo in the freezer (in a bag of course) as the steel case contracts more than the brass (chromed) bezel. Use gloves when taking it off though.

greasemonkey62 · Post by **greasemonkey62** » Sat May 21, 2011 12:47 am

thanks for the tips.
experience is priceless
cheers Ray

aobp11 · Post by **aobp11** » Sat May 21, 2011 11:03 am

Cleve, no doubt that it works if you say so, but the explanation seems conflicting with the practice to use heat for steel bearing removal from alloy housings. The expansion coefficient of brass is 21 ppm/K and for steel only 12 ppm/K. According to that steel should contract less in the freezer.
Albert