rebuilding the speedo drive

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stu

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My original Smiths speedo drive failed and I replaced it 2 or 3 years ago with a modern copy. Now that has failed I'm a bit reluctant to buy another and thinking maybe I could fix the original. I found the post on here and this excellent offering on youtube

- anyone else tackled this repair with success ? tips ??

 
I have a box of original cores. Mix and match probably will yield a good unit. But there are no spares that I know of. No
rivets no gears no shells. Some have used tiny model screws to replace the rivets. You can flatten the housing but it still
remains made of soft nearly useless metal.
Nobody has seen fit to run up new units made of good alloy with easily replaceable innards. No doubt not cost effective especially
with digital replacements on offer.
 
I overhauled the original with no particular trouble and it has worked fine since '08. You have to drill out the rivets/install new ones or screws but that's not difficult at all. I just recently purchased the new Smiths electronic speedo/tach. I did that after seeing a speedo drive on a Norton become red hot and had to be removed in a pub parking lot. I decided that even though mine is working fine, retirement is probably a good thing! :)
 
Stu, is your pattern drive an EMGO copy or one of the unbranded copies?
 
They are easily pulled apart/re-assembled, and the small pinion gears are usually okay, but the ring gears are typically shot.
If you cd find someone to make this gear and harden it properly, you'd be elected immediately to the Commando Hall of Fame.
They begin life flat across the top, and end like the one in the photo.
 

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Liked the Video . someone had time on their hands . Yes it's always the big ring gear that goes south , the rest seems O.K.
If someone could set up a CNC program to cut them , then harden , there could be money to be made for sure.
 
It is sort of funny that we spend a lot of time and money trying to remake the bike. A bike that was just a stopgap and really not a bike expected to last like a BMW.
...oh sure Im ready to order the ring gear or a complete high quality billet remake!
 
other than a rivet counters restoration why waist your time and money on this POS drive system when there is better electronic instruments.
 
bill said:
other than a rivet counters restoration why waist your time and money on this POS drive system when there is better electronic instruments.
Click to expand...
I agree.I use Legendary Motorcycles green globe instruments. I have them on 3 bikes. But originals on a restoration of course.
 
I agree 100% with all the replies above.

Easy to rebuild, but no spare parts available, repro units are trash and expected life is 3-5K miles, ring gear is the weak component, electronic replacement may be best option see https://www.accessnorton.com/NortonCommando/digital-instruments-for-a-p11.26223/, but for those who are nostalgia buffs, there may be an option:

I was fortunate to find on Ebay, a NOS drive, but unfortunately it did not have the proper "top hat" bushing. The bushing is easily removed, and a member of this Forum graciously turned me a spacer to adapt the bushing to my axle. If you can find a NOS drive with the proper ratio, a little machine work can get you back to near original

Slick

PS: There is an NOS drive on Ebay now: https://www.ebay.com/itm/TRIUMPH-NO...775630?hash=item1a607a458e:g:8zYAAOSwn8pbtZh-
 
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bill said:
other than a rivet counters restoration why waist your time and money on this POS drive system when there is better electronic instruments.
Click to expand...

Its ok to replace with electronic if you can aford them, but then I must be the most lucky one as my orginal speedo drive is still working good, has done over 150k and has never been rebuilt, I am still running the orginal cable as well, my speedo has been rebuilt but that was because of the fire back in the early 80s.

Ashley
 
bill said:
other than a rivet counters restoration why waist your time and money on this POS drive system when there is better electronic instruments.
Click to expand...

IMHO electronic instruments look fake on a classic bike they just don't belong there! Why waist your time and money on a classic bike anyway when there are better retro bikes :confused: Btw the unbranded Smiths gearbox copy is indeed of questionable quality but the recent EMGO copy is a very well made copy. Also most speedo gearboxes die due to lack of greasing.
 
ashman said:
Its ok to replace with electronic if you can aford them, but then I must be the most lucky one as my orginal speedo drive is still working good, has done over 150k and has never been rebuilt, I am still running the orginal cable as well, my speedo has been rebuilt but that was because of the fire back in the early 80s.

Ashley
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exactly Ash. I would say most failures occur due to poor fitment (abuse)
 
when you look at the cost of a speedo rebuild, a new drive and cable you are not far from an electronic unit. i have the legendary set on my bike and have been very happy with them. yes i know the drawbacks of the GPS drive but it is dead on,a dead steady needle, looks close enough to stock for me and is very well illuminated at night which you cannot say of the original ones. i have no experience with the smiths repops but from what i see on here they are another great option once setup.
 
I have both types here, and when the EMGO part came out this was the sales blurb:
'This gearbox is brand new production and has been carefully hardened to slightly exceed the OEM specifications for increased longevity.'
I don't do big mileages so I'm unlikely to see the benefit personally, but my recent experiences with other EMGO parts as been positive, which does indicate some form of Quality Management process is being applied.
 
Just goes to show the spread of Norton interest from box stock to hardly Norton. All entirely acceptable ways of having fun with a
Norton. Take yer pick.
 
Onder said:
Just goes to show the spread of Norton interest from box stock to hardly Norton. All entirely acceptable ways of having fun with a
Norton. Take yer pick.
Click to expand...

Absolutely :)
Just look at all the tuned motors on the forum & race tracks. I think most of them have a genuine Norton timing cover...
 
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