PDA

View Full Version : Smiths Classic mechanical odometer - speedo



kenf
28-07-12, 09:51 PM
Does anyone have a Smiths Classic 100mm Mechanical odometer surplus to requirements (either working or not)? Ideally one that is correctly calibrated for a 3.54 diff. If you have a speedo, in any condition, that you no longer need then please let me know.

Ken

slogger
28-07-12, 10:08 PM
I have the one fitted to this dash available. It was used on my Dax driven from a Rover LT77 with a 3.31 Jag diff as far as I can remember. Also has a right angle drive fitted but no cable. That was donated to a fellow member. Have the Rev counter available also.

Purple AK
28-07-12, 10:17 PM
Does anyone have a Smiths Classic 100mm Mechanical odometer surplus to requirements (either working or not)? Ideally one that is correctly calibrated for a 3.54 diff. If you have a speedo, in any condition, that you no longer need then please let me know.

KenWhat have you done???

kenf
29-07-12, 08:34 AM
Thanks for the quick reply Ian. I'll send you a PM.

Ken

kenf
29-07-12, 09:24 AM
What have you done???

Nothing yet. I was hoping to find a replacement worm gear wheel so I could attempt to recalibrate for the 3.54 diff...

kdavies3
29-07-12, 09:33 AM
Ken you would normally not change the speedo, but change the speedo drive gear in the gearbox to suit the diff.
Various ones are available.

kenf
29-07-12, 10:01 AM
Hi Kev, I don't fancy doing any work on the gearbox and I've 'heard' that these gear ratio boxes aren't cheap. If I can change the worm gear in my speedo it should solve the problem. I haven't taken mine apart yet (!) to find out what size I need but I need the next size up for the diff that I'm using. No idea how easy any of this is hence the request for an old or unneeded speedo of the same type as mine to practice on and cannibalize.

slogger
29-07-12, 11:25 AM
Hi Kev, I don't fancy doing any work on the gearbox and I've 'heard' that these gear ratio boxes aren't cheap. If I can change the worm gear in my speedo it should solve the problem. I haven't taken mine apart yet (!) to find out what size I need but I need the next size up for the diff that I'm using. No idea how easy any of this is hence the request for an old or unneeded speedo of the same type as mine to practice on and cannibalize.

Ken, as Kev said, it is the nylon gear that pushes into the gearbox you change normally. 5 min job to do on the LT77 and not too bad on many other boxes. My Super T10 box has a retaining plate held with one small bolt. Undo and pull out, push in new gear and refit.

kenf
29-07-12, 01:11 PM
Thanks for the advice guys. Maybe I need to rethink my approach. where do I get the nylon gear from for an LT77 and how do I work out which gear I need?

slogger
29-07-12, 01:32 PM
Here is a start! Of course the calibration of your speedo to the previous ratio will have a bearing but you may be able to come up with the 20% shift you require.

The V8 Owners Forum - :: View topic - Rover 5 speed speedo drives (LT77 etc) (http://www.v8forum.co.uk/forum/viewtopic.php?t=5365)

Rimmer Bros should be able to supply the drive gears.

kenf
29-07-12, 01:43 PM
Thanks Ian, I'll do some more investigation; find out what I've got and what I need to replace it with. Cheers.

slogger
29-07-12, 01:46 PM
If your speedo read correctly before the diff change and the axle ratio was one from the listed, check if the drive gear you have matches the list. If so, then select the one for the new ratio from the list.

On the other hand, if nothing matches up then look for the axle ratio that corresponds with your drive gear. Calculate the change in final drive ratio ie. if it was 3.05 and now 3.45 then the change is 0.4 then select, if available, the next drive gear from what you have to give you that ratio difference.

I hope that makes sense.