1962 3000 Mk II BT7 speedometer

Hello,

Is the 1962 3000 MKII BT7 speedometer the same as the BJ8, except for the dial (face) design?
Friends mechanic says his BT7 can not be repaired/rebuilt, for what ever reason. Mechanic states he has used Nisonger in the past, but it's beyond what they can do.
Anyone know where a used one is available? None on Ebay at the moment.
Ebay has some BJ8 speedometers. Can the Bj8 dial be swapped with a BT7 dial?

Moss shows the same part# for BT7 and BJ8 speedometer cables (different for OD/non-OD, but same for both cars), and the OD adapter are the same. I haven't dissected a BT7 speedo, but I'd bet a small amount of money the internals are the same, or very nearly so (I think two types of drive gears for the odometer and trip meter were availiable--plastic and fiber--but both are identical otherwise). Both speedos should have a small number on the bottom of the dials that indicate the number of turns of the cable to go a specific distance--a mile or a tenth, but I don't remember for sure--and if those are the same I think the BJ8 speedo would work. Getting the dials off is a bit of a job, so practice on the BT7 speedo since it's toast anyway (save the parts, the case, dial and maybe some of the internals could be useful to you or someone else). You'll lose the BJ8's MPH calibration, but on those there is a small white dot, at about where -5MPH would be that gets you in the ballpark (note the needle stop is spring-loaded). And, of course, the mileage indication will likely be off (it can be changed, but AFAIK the only way to do it is to rotate the 'tumblers,' which could get tedious).

Do you have the Anthony Rhodes dissertation on Smiths/Jaeger speedos? Any idea what was so broken in the BT7 speedo Nisonger's couldn't fix it (my guess would be the small watch spring that tensions the indicator needle)?

Also try West Valley Instruments in Los Angeles.
(818) 758-9500