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Smiths Mk1 speedo recondition
https://www.ausmini.com/forums/viewtopic.php?f=2&t=98536		 Page 1 of 2
Author:  Bill B [ Sat May 04, 2019 7:48 pm ]
Post subject:  Smiths Mk1 speedo recondition
I am attempting to recondition a Mk1 Smiths speedo made in UK. There are 2 of them but one seems to have been 'molested', so probably useful for parts.
Have done some research but not for mini speedos. The speedo part is sorted; now up to the odometer part where both units have problems locking on multiple numbers like 39999.9.
Questions:
a) Where is the retaining clip to release the axle for the number wheels?
b) What is a suitable lubricant for the drag cup bearings?
c) What is a good cleaner for the number wheels that won't dissolve the numbers?
Author:  9YaTaH [ Sun May 05, 2019 7:41 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
a) Where is the retaining clip to release the axle for the number wheels? on the other side
b) What is a suitable lubricant for the drag cup bearings? molybdenum disulphide grease used sparingly
c) What is a good cleaner for the number wheels that won't dissolve the numbers? alcohol from the chemist, but be gentle "rubbing" the chalky 50 year old paint!

Noting: that if some of the parts are worn...they need either refurbishing or replacement with less worn versions (particularly, the odometer pawl)

http://obswww.unige.ch/~wildif/cars/doc ... repair.pdf

NO WD-40 :!:
CLEAN ENVIRONMENT, NO MAGNETIC SWARF!
Author:  Bill B [ Sun May 05, 2019 11:38 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
Thanks for that 9YaTaH. Found it!

I have read Anthony Rhodes' article but he casually remarks that there is a split nylon washer but I didn't know what I was looking for. The washer could be just a spacer.
The ratcheting pawl on both units have wear marks. One might be better than the other.

I assume that the drag cup has to be cleaned while attached to the spindle and hair spring as a unit, so as not to touch the hair spring?
Attachment:
Odometer unit and retaining clip.jpg


Am using pieces of sticky tape to remove metal from the magnet.
Author:  miniron [ Sun May 05, 2019 11:48 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
A bit more info.
I had the same problem and it took me several days to work it out.
On the opposite end of the shaft to the ratchet & pawl mechanism there is a spring and white plastic "C" shaped circlip on the shaft.
Under a magnifying glass you can see the circlip gap and you need a small jewellers type screwdriver to lever off the circlip and extract it through the spring coils.
The shaft can then be extracted from the odometer drum from the ratchet end.
The odometer wheels rotate on a tube that the shaft passes through and it my case it was covered in dust and corrosion which caused too much drag on the ratchet & pawl and this causes the pawl to slide sideways off the ratchet wheel and the odometer wheels no longer rotate.
I photographed my way in and out and if I can still find the pics I will try and post them here.
Polish the tube with a fine scotch brite pad and don't use any lubricant.
The hardest part is assembling the odometer wheels in the right sequence and aligning them.
If you look closely at the wheels you can see a thin metal plate between each wheel and a yellow plastic toothed pinion wheel which drives each odometer wheel in turn.
The pinion has, IIRC, 3 teeth on one side and 6 teeth on the other side.The odometer wheels have teeth on the underside edges which mate with the pinion.
Photograph you way in and out.
You will also need a special "Smiths" assembly tool which consists of a block of wood with a hole the same size as the brass tube to assist in assembling the wheels and pinions. You will also need at least 5 hands as well.
Good luck

RonR
Author:  miniron [ Sun May 05, 2019 11:59 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
My reply is slightly too late.
Looks like you have got it apart.
Just be aware the Rhodes pdf doesn't cover the MK1 speedo exact setup as the ratchet and pawl setup is different.
How many different variations did Smiths actually make?
The Aussie Smiths speedos in 1100s, Mini Ks and MK2 S are different again.
I was also considering if it was possible to add a trip meter to the S speedo but it looks a bit too hard plus I don't have a box full of other speedos to find the appropriate bits.
Edit: Added MK2 S

RonR
Author:  winabbey [ Sun May 05, 2019 1:10 pm ]
Post subject:  Re: Smiths Mk1 speedo recondition
Not specifically responding to the initial question but thought this document produced by Smiths on a Canadian website may be of interest.

http://vintagebritishcables.com/The-Car ... uments.php
Author:  Bill B [ Sun May 05, 2019 3:09 pm ]
Post subject:  Re: Smiths Mk1 speedo recondition
Thank you all for your comments and advice.
Yes, miniron, I was planning on not using any lubrication on the number wheels and guess they would be self-lubricating.
Once the whole thing is cleaned, the ratchet and pawl bits might be able to do their job again.
At least I have 2 dead speedos to start with and I might get one working unit from them.

Ron: Is the Smiths Assembly Tool meant to hold the actual brass tube while fitting all the bits onto it? Or do you use a dummy tube for a trial assembly?
Author:  miniron [ Mon May 06, 2019 9:30 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
Some pics that will help you.

[attachment=0]RH components grooved shaft drive.JPG[/attachment]
[attachment=1]LH end components.JPG[/attachment]
[attachment=3]Odometer parts disassembly.JPG[/attachment]
[attachment=2]Smiths special tool.JPG[/attachment]

RonR
Author:  9YaTaH [ Mon May 06, 2019 9:37 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
miniron wrote:
I was also considering if it was possible to add a trip meter to the S speedo but it looks a bit too hard plus I don't have a box full of other speedos to find the appropriate bits.
Edit: Added MK2 S

RonR


I did one for a Rally Cooper S...not too hard...
Author:  miniron [ Mon May 06, 2019 9:48 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
A few more pics.
[attachment=1]Odometer wheel tube.JPG[/attachment]
[attachment=2]Pinion wheel 6 tooth side.JPG[/attachment]
[attachment=3]Pinion wheel 3 tooth side.JPG[/attachment]
[attachment=4]10ths wheel LH side teeth.JPG[/attachment]
[attachment=0]IMG_0830.JPG[/attachment]

Edit: The large hole in the Smiths Special Tool is to take the speedo cable connection when you need to support the speedo head assembly.

RonR
Author:  9YaTaH [ Mon May 06, 2019 9:49 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
Bill B wrote:
Am using pieces of sticky tape to remove metal from the magnet.


Stop! be very careful around the mag drag cup and return spring...easily damaged or glugged up with WD40 or Sewing Machine Oil ! Don't use.

Instrument techs use a tool made from a hacksaw blade and a Jewellers Eye Glass to gently pick off the iron filings from under or near the mag drag cup and magnet...will try and find a picture...

EDIT: stop looking! found it :-)
Author:  Bill B [ Mon May 06, 2019 10:37 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
Thanks Ron for the photos.
One of the odometers has a broken-off peg on that first ratcheting disc so that is scrap.
Will dismantle the first one when I have the time to complete the job without interruptions.

Just got the 2nd batch of photos too.
Thanks - it is starting to make sense. I also have the block of wood with large hole for speedo drive end.
Will drill another hole for the number wheel shaft.

9YaTaH: I have only used the sticky tape on the magnet itself - as there are no delicate or moving parts on it.
To clean the drag cup and its carrier with hair spring, I expected to have to manually use cotton buds or tissues to get into the tight gaps. This first draw cup is covered with oil.
Author:  9YaTaH [ Mon May 06, 2019 1:36 pm ]
Post subject:  Re: Smiths Mk1 speedo recondition
Bill B wrote:
9YaTaH: I have only used the sticky tape on the magnet itself - as there are no delicate or moving parts on it.
To clean the drag cup and its carrier with hair spring, I expected to have to manually use cotton buds or tissues to get into the tight gaps. This first draw cup is covered with oil.


Just to clarify, the tool I pictured is for the magnet and drag cup area...not the Odometer.

Do not let anything ferrous actually drag across the magnet...it can effect the calibration of the movement.
Author:  Bill B [ Mon May 06, 2019 2:14 pm ]
Post subject:  Re: Smiths Mk1 speedo recondition
9YaTaH wrote:
Bill B wrote:
9YaTaH: I have only used the sticky tape on the magnet itself - as there are no delicate or moving parts on it.
To clean the drag cup and its carrier with hair spring, I expected to have to manually use cotton buds or tissues to get into the tight gaps. This first draw cup is covered with oil.


Just to clarify, the tool I pictured is for the magnet and drag cup area...not the Odometer.

Do not let anything ferrous actually drag across the magnet...it can effect the calibration of the movement.


Thanks for the clarification. That was how I understood it. Was intending to use cotton buds, tooth picks or paddle-pop sticks for cleaning. Wouldn't the tool made from a hacksaw blade be iron based?
Author:  9YaTaH [ Tue May 07, 2019 8:14 am ]
Post subject:  Re: Smiths Mk1 speedo recondition
Bill B wrote:
Thanks for the clarification. That was how I understood it. Was intending to use cotton buds, tooth picks or paddle-pop sticks for cleaning. Wouldn't the tool made from a hacksaw blade be iron based?


Yes...but you grind the blade thin (carefully so it remains springy) and only use the tip to carefully pick up the iron filings ...it can be a tiresome task but well worth it if you have ever been annoyed by a "sticking" speedo

Blade cross section should look something like this...<>
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