speedometer gearbox/cable -- what's wrong and how do i fix it?

Status
Not open for further replies.
NPeteN said:
Interesting. I remember when I was assembling my rear wheel that the gearbox hole was an EXACT fit for the axle. So much so that it would not slide on unless held perfectly straight. Next time I have the wheel off I'll take some photos.
Click to expand...
Are you the original buyer of this norton? Never been serviced?
Yes but was it a genuine NOS Smiths or was it Chinese? No Commando or atlas I own has the top hat missing, I own well over a dozen...closer to 20
 
for the purest - a little bonus FYI info --

found this stamping on the housing when cleaning - "35_4" -- suspect a date code, 35th week of 74 - ??? that would be mid-august for my august 74 production

speedometer gearbox/cable -- what's wrong and how do i fix it?


also note the center hole and the edge being curved inward. clearly the top hat spacer came from the outside (at least on my assembly). I agree with dynodave's #2 point - it only makes sense that it was mounted on the outside of the speedo gearbox housing.

speedometer gearbox/cable -- what's wrong and how do i fix it?


still working on trying to get things cleaned up for a rebuild....
 
dynodave said:
Are you the original buyer of this norton? Never been serviced?
Yes but was it a genuine NOS Smiths or was it Chinese? No Commando or atlas I own has the top hat missing, I own well over a dozen...closer to 20
Click to expand...

I am in no way saying the book is wrong, just something I noticed. I posted the photo below earlier. I bought the bike from a family friend who had it stored untouched for 40 years, these photos are as it looked right out of the closet. Of course anything is possible. Apologies for keeping this thread going longer than necessary.

speedometer gearbox/cable -- what's wrong and how do i fix it?


speedometer gearbox/cable -- what's wrong and how do i fix it?
 
joe czech said:
for the purest - a little bonus FYI info --

found this stamping on the housing when cleaning - "35_4" -- suspect a date code, 35th week of 74 - ??? that would be mid-august for my august 74 production

speedometer gearbox/cable -- what's wrong and how do i fix it?


also note the center hole and the edge being curved inward. clearly the top hat spacer came from the outside (at least on my assembly). I agree with dynodave's #2 point - it only makes sense that it was mounted on the outside of the speedo gearbox housing.

speedometer gearbox/cable -- what's wrong and how do i fix it?


still working on trying to get things cleaned up for a rebuild....
Click to expand...

I really wish I had mine off right now to compare with yours.
 
It is fairly clear that these can be put together without a top hat. It will mean the body will be haphazardly floating around the big gear which WILL orient and mesh on the wheel drive dogs. The internal ring (and felt seal) will "generally" hold it in place until the axle is tightened . Any slight touching will be burnished away in use. The top hat is "in theory" a set and forget...except for the crushed potmetal syndrome :(
 
It has the top hat on the inside, sandwhiching the gearbox body in place between the top hat and outer spacer (this keeps the fragile distortable potmetal flat) when tightened this holds the body in place while allowing the wheel gear to engage and spin the dogs freely inside. Maybe I'm just repeating myself.

I don't know man, if it works it works... right? Hah
 
Last edited:
If you get things wrong you can put pressure on the speedo drive unit and the forces can bell out the drive itself and this alone can get the drive rubbing on the alloy cover plate. A press may straighten it up ,but its an expensive item to "F" " up. If the drive is spun round that can pull a cable to bits.
 
everything's cleaned, detailed, and ready for lube and reassembly. dry fit, things seem OK. need to make a decision on the lube though. might look into using gear oil as some suggested (have some 140 weight). I do have some hi-temp aviation grease and marine grease in the shop. ???? might use a combination of stuff. that felt seal definitely need some sort of grease.

speedometer gearbox/cable -- what's wrong and how do i fix it?


think I have a better understanding of things now than I did before I started this job. always good to learn something new - even at 72. to everyone the provided information, guidance and input, a big thanks!
 
joe czech said:
everything's cleaned, detailed, and ready for lube and reassembly. dry fit, things seem OK. need to make a decision on the lube though. might look into using gear oil as some suggested (have some 140 weight). I do have some hi-temp aviation grease and marine grease in the shop. ???? might use a combination of stuff. that felt seal definitely need some sort of grease.

speedometer gearbox/cable -- what's wrong and how do i fix it?


think I have a better understanding of things now than I did before I started this job. always good to learn something new - even at 72. to everyone the provided information, guidance and input, a big thanks!
Click to expand...
Nice job Joe. Just a thought, but maybe it's worth installing an old style oiler cap instead of the grease nipple if you choose to use oil to lube it?


Example..

https://www.ebay.com/itm/3-16-Inch-...-Oiler-Point-for-Vintage-Frames-/331553930069
 
Joe
If you want, 2-56 flat head screws will go into the 2-56 tapped "ring". nice & neat . That's what I do.
Oiler cap?
A regular grease nipple WILL accept gear oil ....DAMHIK 30 years and counting. Lotus Elan front suspension.....grease fittings and liquid gear oil in the grease gun.
 
dynodave said:
Joe
If you want, 2-56 flat head screws will go into the 2-56 tapped "ring". nice & neat . That's what I do.
Oiler cap?
A regular grease nipple WILL accept gear oil ....DAMHIK 30 years and counting. Lotus Elan front suspension.....grease fittings and liquid gear oil in the grease gun.
Click to expand...
Of course you can put oil in a grease gun, but I would wager most folks who are not professionals only have one and it's full of grease. So what's easier empty the grease gun and fill it with oil for that one little job, or while it's apart think about making it simpler to maintain?

Just saying :rolleyes:.
 
Just asking... Doesn't the lube point hang underneath the unit? Wouldn't oil migrate through that cap eventually if used there?
 
Disconnect the cable,
slacken the wheel spindle,
rotate drive gearbox 180 degrees,
unscrew nipple,
add oil from a bottle,
replace nipple...etc.
 
L.A.B. said:
Disconnect the cable,
slacken the wheel spindle,
rotate drive gearbox 180 degrees,
unscrew nipple,
add oil from a bottle,
replace nipple...etc.
Click to expand...
Yes... but I was referencing the 'oil cap' being suggested as an alternative...
 
EstuaryBoy said:
Yes... but I was referencing the 'oil cap' being suggested as an alternative...
Click to expand...

Yes, just saying how it can be done although it's also possible without having to rotate the drive gearbox using a squeeze bottle with a suitable nozzle.
 
still up in the air on what lube to use. I have a small pump oiler for the job, but would have to load it with 140 weight. seems it might be a bit of a PITA, to rotate that gearbox so the oil port is in the 12 o'clk position, or am I putting too much thought into this? right now, leaning toward marine grease - ?????

question - any issues with leakage when using oil? I realize that you only need an ounce or two to fill the bottom cavity, but I would worry about leakage, especially out on the road. seems grease would be the better solution.

speedometer gearbox/cable -- what's wrong and how do i fix it?
 
Can the UK style grease fitting on the speedo box be easily replaced with a US style? I have a grease gun but it won't snap onto the Smiths fitting.
 
Status
Not open for further replies.

Similar threads

Niagara850
  • Locked
Speedometer gearbox rotates with rear wheel
Replies
11
Views
2,054
frankdamp
F
Chris T
  • Locked
Speedometer gearbox - does it need painting?
Replies
7
Views
1,063
Chris T
Chris T
Back
Top