Smith Speedo Gearbox parts.

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Corona850

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May 9, 2008
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Anybody know of a source for parts for the Smith rear-wheel speedo drive unit?
I have one I want to use for my '73 850, but the tangs on the bevel drive are dodgy and the centering ring thingy that's pinned to the housing has come loose. Just needs riveting back, I think.
I sent this unit and the clock to Nisonger. They repaired the clock OK, but returned the drive with the note that it's unrepairable. I guess I don't believe them. I've taken it to pieces and it seems like it just needs a bevel gear with good tangs and a couple of tiny rivets.
I've Googled for a source but come up with nothing. Anybody know of a place that sells the guts, either OEM or repro? Alternatively, has anybody got a method of repairing the tangs?
Thanks.
 
I guess the repro folks are holding onto their stocks!

No shortage of stripped speedo drives out there. :shock:
 
Good luck. I was where you were a while ago. Ended up buying a new drive from Old Britts.

If you have time though (i.e., are more patient than I am) you could watch ebay for a while. They come up there once in a while. I had just missed one when I was in the market.
 
Corona850 said:
I sent this unit and the clock to Nisonger. They repaired the clock OK, but returned the drive with the note that it's unrepairable. I guess I don't believe them.
Click to expand...

I would guess the truth of it is that the drive gearboxes are not economically repairable?
As the parts are not, and probably never were, available separately from Smiths as far as I know? Although Smiths did operate a repair service for them originally, now of course, they appear to be made in India.
 
There are 2 pattern types available, one from India and one from Taiwan. How they compare quality wise I don't know, will find out shortly as one is fitted to my Victor, so far speedo is steady and accurate at all speeds but have only had it up to 70 so far. I think I have the Indian version, body is painted with grey enamel paint.
 
Thanks for the responses.
I am using a pattern drive now that came with the bike. The speedo clock I'm using is the newly re-built, recalibrated one, so I am pretty sure it's OK; however, the reading wobbles about plus or minus 20 mph. So, I think the pattern drive is the problem, hence my desire to replace it with a genuine Smith drive. Also, the Smith drive would be authentic.
The only other component that could cause the fluctuating reading is the cable. There's not much to do there except lubricate it.
 
I've been there too. Repair is quite simple if we had the parts. Someone should start making the gears as we all need to repair these at some time. I got one off ebay and one from Walridge I think. They are very pricy unless you score one off ebay.
 
Hi all,
I have a problem with my speedo drive also! the 4 rivets have become very loose. surely there must be a way to repair these rivets?
like perhaps making some out of Tig wire or the core of an electrode???? and mushrooming the heads???? or perhaps some other rivets from something else could be modified to do the same purpose???

I am perhaps like most of us on this forum, who like to try and solve problems and repair, instead of just chucking things away and doing the easy way out, and more expensive task of just replacing with a new assembly.

Brewer
 
I always fix mine. I just use four # 2-56 S.S. flat head screws to replace the rivets. After doing this mod you can take it apart to property clean it and re-pack it with grease. Mine last forever now because I take them down every two years for service. It turns out that the rivet size and the tap drill for 2-56 are very close. taping out the retaining ring is easy and so is countersinking the heads into the body of the speedo drive. I believe it's in an old post of mine here somewhere.
 
Next time I go to my buddy's garage I will take pictures of the one I fixed. I ran a while on a flat tire to get home and the flapping tire tore the rear cable off destroying the speedo drive. I machined parts to replace the broken bits and while it is not stock looking, it works quite well and saved me buying a new speedo drive gearbox.

Jean
 
smiths speedo gearbox parts

My drive was damaged at the drive lugs. I removed the damaged metal with a dremal and silver soldered two pieces of key steel to the gear ring. Used small flathead nails cut to length and peened over to replace the 4 rivets. More trouble finding replacement felt seal. Turned up a centre plate to replace worn centre gear support. The two I have were damaged by the rear wheel not alinged to the drive lugs when fitting rear wheel, not me but I made sure the drive lugs were engaged before I refitted the wheel and axle.

Ian
 
My speedo drive gave up on March 2. I had run up to Daytona and back for a one-day to see the vintage races at Turn 6. On my way home, about 70 miles away, the speedo drive started going. By the time I got home, it was dead. I guess 500+ miles at 80-90 MPH was too much for it in one day. It hadn't shown any symptoms in the six months of regular riding since I resurrected the bike.

I got one of those Emgo drives from my local Norton guy a few days later. It looks like a pretty faithful copy, and at about $80, I figured would be cheaper than repairing the Smiths.

When I first mounted it, the needle was a bit wobbly. A good re-lube of the cable, and it settled down. I've put about 300 miles on the new unit.

The Speedometer does seem to read a little more optimistic, though. 3000 RPM used to be a pretty solid 50MPH, now its more like 55.
 
My experience of replacement drives is most disappointing. Regardless of how careful I am with fitting, spacing & alignment I don’t seem to be able to make them last more than a year. I buy from “proper” Norton dealers and still I have had one that wouldn’t even accept the cable! When the last one spat its insides I decided I wasn’t replacing it until I could find a reliable source.

Does anyone know of a good quality replacement – not too worried about the originality as long as its well made & drives the standard green spot clock?

David
 
Informative post - I didn't know the drive units could be disassembled and reassembled reliably. I purchased a USED reproduction unit back in '01, and some 20,000 miles later it's still working - amazing, isn't it!?

Just lucky I suppose. I don't perform any special maintenance, a squirt of grease once or twice a year is all the attention it gets.
 
RGM Motors has English made speedo gearboxes and the price is right.(38.34gbp) Recently got one for my MK1 and got it in record time from UK to California.
 
Does anyone please have any Pics of their speedo gearbox repairs, that they can post on the forum?

Brewer.
 
norbsa48503 said:
I always fix mine. I just use four # 2-56 S.S. flat head screws to replace the rivets. After doing this mod you can take it apart to property clean it and re-pack it with grease. Mine last forever now because I take them down every two years for service. It turns out that the rivet size and the tap drill for 2-56 are very close. taping out the retaining ring is easy and so is countersinking the heads into the body of the speedo drive. I believe it's in an old post of mine here somewhere.
Click to expand...

Norbsa,

I cleaned up two drives, one original Smiths and one aftermarket. Lifting off the felt seal exposes both gears. The rotational gear is lifted off the assembly for cleaning, and the pinion is cleaned through the removed zerk. What is the purpose of removing the 4 small rivets?? I did exactly that on a junk drive, to no effect. What am I missing?. I searched the archives for your earlier posts, but only found an earlier version of this post.
 
rick in seattle said:
The rotational gear is lifted off the assembly for cleaning, and the pinion is cleaned through the removed zerk. What is the purpose of removing the 4 small rivets?? I did exactly that on a junk drive, to no effect. What am I missing?.
Click to expand...


Theoretically, you shouldn't have been able to just lift out the ring gear, as it should have been held by a circular stepped location plate fixed in position by four small rivets?

Smith Speedo Gearbox parts.
 
L.A.B. said:
rick in seattle said:
The rotational gear is lifted off the assembly for cleaning, and the pinion is cleaned through the removed zerk. What is the purpose of removing the 4 small rivets?? I did exactly that on a junk drive, to no effect. What am I missing?.
Click to expand...


Theoretically, you shouldn't have been able to just lift out the ring gear, as it should have been held by a circular stepped location plate fixed in position by four small rivets?

Smith Speedo Gearbox parts.
Click to expand...

LAB,

Thanks for the reply. In both units the ring gear was held in place by the top plate and felt washer. The top plate is pressed on, and was removed by careful prying. Once off, the ring gear is exposed and was simply lifted out of the assembly. After cleaning and lubrication, the gear was replaced and the top plate pressed on. During this process, the four rivets were in place. Removing them had no effect. By "four rivets" I mean the rivets seen in the center of your photo. They do not engage the circular location plate. Again, in both of my units, this plate simply pries off.
 
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