Smith Speedo Drive Lubrication

Glenn

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When I replaced my rear drive belt I had to take the wheel out as well as the swing arm. I forgot to do two things. 1. I was going to resurface (5 step sand and polish procedure) the 3 cases. I put the swing arm back on and realized that these cases had to come of and be resurfaced before I put it all back together. Once this happened it was too late. So, this is a project for another time. I did do the process for the left case that covers the clutch and alternator assembly. 2. I forgot to grease the speedo drive. I tried every method available to shoot some grease into it via the grease fitting. I have every tool in my grease gun arsenal but non would work because there is very little space. Plus the fact that the fitting is not a standard fitting. It is smaller in diameter. Why they did not put a 90 degree fitting on it is beyond my pay grade. So, I ended up pushing the wheel rod back into the hub and removing the spacer, chain tightener and dropping (rotating) the brake assembly out of the way to expose the grease fitting. This was not all that bad. Perhaps a 30 minute job, but it is the principal of the thing. A 90 degree standard size 1/8" fitting would have solved all the frustration I felt when I realized that I had forgotten to put grease in the speedo. The next time I have it out (hopefully never) I will drill it out and tap for a standard size 1/8" 90 degree fitting.
 

Rudie

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the fitting is not a standard fitting.
It is a standard British grease nipple on a British-made speedo drive fitting on a British-made motorcycle.

Why they did not put a 90 degree fitting on it
Because Smiths supplied it and Triumph fitted it for years before they fitted a rear disc brake caliper mounting that restricted access to the drive's grease nipple. The triple with a rear disc brake has the speedo drive on the same side as the sprocket.

next time I have it out
I will drill it out and tap for a standard size 1/8" 90 degree fitting.
Why and how?

If you have identified it as a 1/8" pipe thread, it is 1/8"BSP (British Standard Pipe). Your "standard" is 1/8"NPT? You cannot "drill ... out" 1/8"BSP and "tap" the resulting hole to 1/8"NPT.

The next-larger pipe diameter is 1/4"; given 1/4"NP thread o.d. is over 1/2", the drive casing has enough material?

If the existing grease nipple thread is 1/8"BSP and you really must have a "90 degree fitting" and nothing else, why don't you just buy a 1/8"BSP 90 degree fitting? BSP is an ISO (International Standards Organisation) thread so far more "standard" than NP.
 

Glenn

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It is a standard British grease nipple on a British-made speedo drive fitting on a British-made motorcycle.


Because Smiths supplied it and Triumph fitted it for years before they fitted a rear disc brake caliper mounting that restricted access to the drive's grease nipple. The triple with a rear disc brake has the speedo drive on the same side as the sprocket.


Why and how?

If you have identified it as a 1/8" pipe thread, it is 1/8"BSP (British Standard Pipe). Your "standard" is 1/8"NPT? You cannot "drill ... out" 1/8"BSP and "tap" the resulting hole to 1/8"NPT.

The next-larger pipe diameter is 1/4"; given 1/4"NP thread o.d. is over 1/2", the drive casing has enough material?

If the existing grease nipple thread is 1/8"BSP and you really must have a "90 degree fitting" and nothing else, why don't you just buy a 1/8"BSP 90 degree fitting? BSP is an ISO (International Standards Organisation) thread so far more "standard" than NP.
I did not identify it as a 1/8" NPT pipe thread. I simply said that it is impossible to grease as it sits. My thought is because the grease nipple is smaller in size, the base must be smaller as well. Good information because I have never had to deal with anything other than NPT Zerk fittings. All I know is a grease gun with a fitting designed for a Zerk fitting will not attach to the grease fitting on my bike because the fitting on my bike is smaller than the Zerk fitting nipple. All I want to do is be able to put a 90 degree Zerk fitting on the Speedo Drive to make it a 10 second job of greasing the speedo drive instead of the 30 minute job which I now have to do which is a lot of trouble. I just found out talking to a friend of mine and he tells me that a 1/8-28 Zerk fitting will screw into this BSP (if I remove it) but it will not seal because the threads are not the same. Why would I not want something that makes it easier for me? I had no idea what a BSP grease fitting was until today and I have no idea where to purchase one, so help me out. Thanks.
 

Glenn

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Rudie, is this what I need? What puzzles me is the word Zerk. I am not sure if this is a Zerk NPT pipe thread 1/8"-28 screw in fitting and a BSP nipple. If this is what it is I do not need it. I do not care what nipple is on it. I need the correct fitting that will screw into the threaded hole and not leak. Also, what is the difference between a BSP grease fitting and a BSPT grease fitting?
 
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Rocky

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The old British grease fittings and my North American grease gun did not match of course, but I was able to get some grease nipples with the correct British thread and had the head to match the grease gun.
I got them from a British parts supplier and my problem was solved.
 

Glenn

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Greyfell, great information. I will keep this information for future reference. One question. Is the BSP threads on the Smith Speedo Drive BSPP or BSPT?
 

Glenn

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The old British grease fittings and my North American grease gun did not match of course, but I was able to get some grease nipples with the correct British thread and had the head to match the grease gun.
I got them from a British parts supplier and my problem was solved.
Rocky, do you remember who you got them from?
 

Glenn

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Rudie, is this what I need? What puzzles me is the word Zerk. I am not sure if this is a Zerk NPT pipe thread 1/8"-28 screw in fitting and a BSP nipple. If this is what it is I do not need it. I do not care what nipple is on it. I need the correct fitting that will screw into the threaded hole and not leak. Also, what is the difference between a BSP grease fitting and a BSPT grease fitting?
Rudie, one thing that I guess gets in my way is when I worked for my uncle at his hometown gas station /garage when I was a teenager is that I knew that there were SAE fittings and Metric fittings. I never knew that these other fittings existed. Now that I know then I find out that there are BSPP and BSPT threads. In this case I now have to find out which of these two the Smith Speedo uses. I am glad we are having this discussion because my guess is that there are a lot of people out there who are/were unaware of this information. Some are wondering why their new grease fitting is leaking. Now they know. I was going to order this fitting from eBay but now I am not sure if it will work.
 

Rocky

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Rocky, do you remember who you got them from?
This was probably 20 years ago so I don't remember now.
I looked for a package they may have come in, but couldn't find it. I got most of my spares from British Cycle Supply and Walridge Motors here in Canada so it was probably either of them, but that's only a guess. Back then, through the magic of the internet, I was importing parts from all over the world.
 

Glenn

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This was probably 20 years ago so I don't remember now.
I looked for a package they may have come in, but couldn't find it. I got most of my spares from British Cycle Supply and Walridge Motors here in Canada so it was probably either of them, but that's only a guess. Back then, through the magic of the internet, I was importing parts from all over the world.
I know the feeling. I made a lot of friends when I rebuilt my newly acquired '79 T140 almost 20 years ago. The pretty blond lady at Waldridge, Keith Moore at Moore's Cycles in CA (who died a few years back) who was a great guy to talk to, Jon Bergland at Countryside Cycles in Tallahassee, FL (who is selling out and retiring ASAP) and my good friend Ozzie Oswald (QPD) in Parksburg, PA. made the process of rebuilding/restoring my bike a lot of fun.
 

Rudie

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help me out.
Background
Up to the mid-1960's, in line with most of the rest of the British manufacturing industry, Triumph and its component suppliers used British Standard threads. In 1965, the British government announced than the UK would be metric within ten years. From then on, the British automotive industry mostly swopped to Unified threads (as the whole industry became more and more dependent on exports to the US) ...

Afaict, Triumph started fitting rear wheel speedo drives around the same time as its first unit-construction engines, so the 1957 model year for the 350 "21" (although the 650's continued with gearbox-driven speedos for a couple of years after the engines became unit from '63), certainly long before any change to Unified threads. Rear wheel speedo drives were supplied by Smiths, same company that supplied the speedo and tacho heads and cables - Smiths made dial-type instrument for a wide variety of other industries nothing to do with motorcycles, cars, etc. (my first wristwatch was a Smiths - didn't keep very good time and although allegedly self-winding, it needed hand-winding once a month ... Seiko I bought in Singapore for £5 was kept better time and didn't need the hand-winding :rolleyes:).

In line with the rest of particularly the British automotive industry, Triumph began to change to Unified threads from the late 1960's, although it took 'til the mid-1970's to either change or eliminate components with British Standard threads, why most of the threads on your '79 are Unified. But not all of them ... Triumph's component suppliers like Lucas and Smiths were slower to change or eliminate components with British Standard threads, particularly as the British motorcycle industry contracted through the 1970's, requiring smaller and smaller quantities of some specialist components from suppliers. Is one reason the fuel taps and the Smiths speedo drive even on a '79 Triumph are still BSP threads (the taps aren't any of the other thread types @Greyfell posted, I'd be very surprised if a Smiths speedo drive grease nipple is either).

However, what stops BSP threads being obsolete along with other British Standard thread types is somewhere along the line, the ISO adopted BSP as a standard specifically-pipe thread, (y) in preference to US National Pipe or very fine-pitch metric threads.

Why would I not want something that makes it easier for me?
By "[if] you really must have a "90 degree fitting" and nothing else", I meant if you wouldn't consider any other alternative "to make it a 10 second job of greasing the speedo drive"; e.g. I have a grease gun with a long steel pipe to the nipple fitting, the pipe is long enough to reach a Smiths speedo drive grease nipple from below a rear disc caliper.

What puzzles me is the word Zerk.
From https://www.machinerylubrication.com/Read/584/grease-gun:-
The Zerk design, named after Oscar Zerk, used a fitting much smaller than the Alemite pin-type
... however, note:-
and did not lock the hose coupler or hand gun and fitting together. Instead, the seal between them was maintained by the pressure of a pushing action when the operator applied the coupler to the fitting.

I am not sure if this is a Zerk NPT pipe thread 1/8"-28 screw in fitting and a BSP nipple.
"Zerk" applies to the nipple form (as opposed to "Alemite" on that "Machinery Lubrication" website page).

Otoh, "BSP" is a threadform - 1/8" nominal pipe diameter and 28 tpi (threads or turns per inch) is 1/8"BSP, 1/8"NP (NPS or NPT) is 27 tpi and, as I posted earlier, the thread has a larger o.d. than 1/8"BSP. As with "zerk", you can enter "bsp thread", "npt thread" into any internet search engine and it should return links to tables showing dimensions like o.d., tpi, etc.

difference between a BSP grease fitting and a BSPT grease fitting?
As I say, BSP - British Standard Pipe - is a threadform (group of threads of different diameters but having certain common features).

By standard, "BSP" is specifically a 'straight' or 'parallel' thread - same diameter all the way along. Otoh, the "T" suffix in BSPT stands for "Taper" or "Tapered", meaning one end of any given thread is thinner than the other end - given a great enough length any "Taper" thread would end in a point. Tapered threads are often used where the connection transmits a liquid and speedy coupling/uncoupling is required; a tapered male thread will engage a female thread further 'in' and more threads will engage at the same time; similarly when disengaging.

As an aside, the oil pressure switch in the front edge of your bike's timing cover is 1/8"NPS - National Pipe Straight.
 

Glenn

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Rudie, I bought this and attached it to my grease gun (which has a solid pipe tube about 6" long) but all it did was make a mess because the BSP nipple on the Speedo Drive fitting is smaller than the grease gun dispenser. Some grease may have made its way into the fitting but not sure how much. Most of it ended up elsewhere.
1594435213532.png

The Speedo on my '79 with disc brakes mounts at the bottom and there is no open area in which I can get a tube up to the nipple. If I could go in this way my problem would be solved. The only way I can get to the speedo grease fitting is through the end of the disc brake frame. That is why I am so determined to put a 90 degree fitting which would allow me to stick the grease gun tubing with a grease dispenser straight onto the nipple. I did finally push the axle rod back far enough to drop (swing) the brake frame down which allowed me to use one of my many grease dispensers (I had one that fit the BSP Nipple) to get the grease into the speedo housing. So, really, all is well. At least I did learn a lot about grease fittings. I am still wondering if the 90 degree BSP fittings on eBay will work. 1/8-28 BSP 90 Degree British Grease Zerk Nipple Fitting 2 pcs | eBay Thanks.
 

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Nortony

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When I replaced my rear drive belt I had to take the wheel out as well as the swing arm. I forgot to do two things. 1. I was going to resurface (5 step sand and polish procedure) the 3 cases. I put the swing arm back on and realized that these cases had to come of and be resurfaced before I put it all back together. Once this happened it was too late. So, this is a project for another time. I did do the process for the left case that covers the clutch and alternator assembly. 2. I forgot to grease the speedo drive. I tried every method available to shoot some grease into it via the grease fitting. I have every tool in my grease gun arsenal but non would work because there is very little space. Plus the fact that the fitting is not a standard fitting. It is smaller in diameter. Why they did not put a 90 degree fitting on it is beyond my pay grade. So, I ended up pushing the wheel rod back into the hub and removing the spacer, chain tightener and dropping (rotating) the brake assembly out of the way to expose the grease fitting. This was not all that bad. Perhaps a 30 minute job, but it is the principal of the thing. A 90 degree standard size 1/8" fitting would have solved all the frustration I felt when I realized that I had forgotten to put grease in the speedo. The next time I have it out (hopefully never) I will drill it out and tap for a standard size 1/8" 90 degree fitting.
Although I haven’t done one in years I don’t recall having to drill out the Smith speedo drive. Just buy some small 90 degree Zerk fittings from your local auto parts store. Ones that closely resemble the existing ones supplied by Smith, figure out the thread size and tap the drive, the metal housing is crap pot metal and taps very easily. I’ve probably done at least a dozen this way, but the axel and wheel have to come off to tap the body. I usually disassembled the speedo drive, cleaned out all the old accumulated grease, dirt and the felt then it all goes in a parts washer, inspect that the two tabs that rotate the drive are okay, then place the drive carefully in a vise with soft jaws, tap the bodythen back in the parts washer to remove any metal debris. Pack the drive with new grease like you would a bearing, reassemble the whole thing and then back on the bike.
 

Glenn

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Nortony. Thanks for replying. I actually though about doing that. However I did not realize that the BSP fitting and the 1/8" 28 Zerk were the same size. I figured the BSP hole was smaller so that is why I said drill it out and re-tap it to1/8"-28. Re-taping it out might just work. From what I have learned on this subject or should I saw from all I have learned on here about the various fittings (because I knew practically nothing in the beginning) is that if I simply screw a Zerk 1/8"-28 SAE NPT grease fitting in a hole tapped for a BSP thread (even though it will screw in) will always leak grease because the thread angle is different. In other words the Zerk will not fit tight thereby allowing grease to find its way back out the loose fitting. Akin to putting pistons into cylinders minus the oil rings. I was going to do this to make greasing the Speedo easier since the way my Speedo is attached there is no way for me to grease it unless I knock the rear wheel spindle back a little ways and remover the wheel adjuster, spacer and let the rear caliper down. Then I can attach the grease gun to the fitting and grease the Speedo Drive. That is what I did because i forgot to do it when I put the rear swing arm assembly back on. I had rather waste 30-40 minutes doing this than take a chance the Speedo was devoid of grease. Better safe than sorry. $.20 vs $100 US.
 

Rudie

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if I simply screw a Zerk 1/8"-28 SAE NPT grease fitting
There isn't any such thing:-
1/8" nominal pipe diameter and 28 tpi (threads or turns per inch) is 1/8"BSP,

1/8"NP (NPS or NPT) is 27 tpi
the thread has a larger o.d. than 1/8"BSP.
... the link you posted:-


... even says, "1/8-28 BSP" ...
 

Glenn

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There isn't any such thing:-

... the link you posted:-


... even says, "1/8-28 BSP" ...
What I should have said that if I tap it out to the Zerk specs it would probably leak because from what I read the threads are different. That is what I meant to say.
 
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