MkIII chain tensioner/ adjuster and BST BOLTS

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Rusty bucket

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Does anyone make a decent set of these to replace the originals? They are crappy at best IMO and look like something quickly cobbled up. I acquired a set of new stamped steel gizmos but now need to source the nuts and bolts, I assume they are BST like the rest of the bike (mostly)!

I am used to having a plethora of metric fasteners on hand so I'm really lost with the BST stuff. Anyone recommend a source for not only these chain tensioner fasteners but a decent variety of the finer smaller screws and bolts? I don't like not having all the bits I need, makes for an extremely long wait on the postman.
Thanks Ken.
 
BST ??

All the cycleparts are UNF, and the motor/gearbox is a fair ole mix of British Cycle 26 tpi and some UNF.
With an odd assortment of stray others scattered thinly about.
British Standard spanners/wrenches will fit most of the engine stuff, possibly related to your BST ?

Not sure about the chain tensioner, my beast is earlier, doesn't have one.
I'd have thought, being a new feature, the tensioner would all be UNF (?)
Hopethishelps.
 
OK, 98.273646858696097607 % then......
Give or take a few percent.

The precise details need to be listed somewhere easy to access ?
 
Rohan said:
OK, 98.273646858696097607 % then......
Give or take a few percent.
Click to expand...


Either it's all or it isn't all.
Again, what I think you really mean is Unified, not "UNF" (as there are also UNC etc.).
 
We can keep it easy and understandable, or precise and confusing.
Explain...
 
I bought my stainless replacement bolts and nuts for the chain adjusters at the local hardware.
 
I guess I'm not following. The nuts that hold the hydraulic chain tensioner on a MKIII are 5/16-24, or UNF. No need for stainless inside the chaincase.

I think I have one of the most mixed hardware machines, a 1954 MG TF. By '54 the Brits were moving towards the Unified thread form so some of the chassis has UNF. The body has mostly BSF (we used to call it British Strip Fine). The engine fasteners have metric thread form but the bolt and nut heads have British Standard or Whitworth sizes so mechanics could use their spanners on them. The engine maker was a French company that moved to England about WWI and didn't change the tooling. There's a few 2ba screws in the instruments and some wood screws in the body timbers.
 
Thanks to all for responses. I had assumed the bike was British Standard Thread or BST, I've dealt with that animal on other projects. Nonetheless, I thought I had seen a nice stainless machinced setup on fleabay a few months back but find nothing now. Of course being a 75' I find myself a bit like the bastard child of Norton for bits. I thought I was doing myself a favor by going with a low mile electric start (racked back) but I have been regretting the choice more and more lately...
 
JimNH said:
I guess I'm not following. The nuts that hold the hydraulic chain tensioner on a MKIII are 5/16-24, or UNF. No need for stainless inside the chaincase.
Click to expand...

I was under the impression Rusty bucket was talking about the drive chain adjuster bolts-as he said he'd: "...acquired a set of new stamped steel gizmos.."
 
Rusty bucket said:
Thanks to all for responses. I had assumed the bike was British Standard Thread or BST, I've dealt with that animal on other projects. Nonetheless, I thought I had seen a nice stainless machinced setup on fleabay a few months back but find nothing now. Of course being a 75' I find myself a bit like the bastard child of Norton for bits. I thought I was doing myself a favor by going with a low mile electric start (racked back) but I have been regretting the choice more and more lately...
Click to expand...

I would say you've done the right thing with a MKIII. It has improvements over the previous models and the electric start system can be made to work reliably with a Dyno Dave starter, some heavier starter cables and a three phase alternator to keep the battery charged.

The only hardware changes are arguably for the better as the primary has UNF or UNC hardware. The fixed gearbox and hydraulic tensioner means no adjustments necessary.

Speaking of the primary, when adding oil, drain and add the recommended amount, don't fill to the witness hole or it will be overfull and get on your clutch plates.
 
Rusty bucket said:
I had assumed the bike was British Standard Thread or BST
Click to expand...

There are various "British Standard" threads, but they are not "BST".
 
L.A.B. said:
JimNH said:
I guess I'm not following. The nuts that hold the hydraulic chain tensioner on a MKIII are 5/16-24, or UNF. No need for stainless inside the chaincase.
Click to expand...

I was under the impression Rusty bucket was talking about the drive chain adjuster bolts-as he said he'd: "...acquired a set of new stamped steel gizmos.."
Click to expand...

Ah Ha! You're exactly right!

There's no particular problem with them. The originals are UNF and the stainless replacements I bought might be metric, I don't remember.

I don't get upset with a mix of fasteners, I just grab the correct wrench for the job. Many of the screws I see bitched up are clearly marked posidrive that have been attacked with a probably worn Phillips screwdriver.
 
Rusty, I've never heard of BST because it doesn't exist. What I guess you are referring to is British Standard Whitworth (BSW) or British Standard Fine (BSF), British Standard Cycle is found on some engine parts, generally always 26 TPI These threads all require Whitworth spanners.

UNF and UNC (Unified National Fine and Coarse) are what the Commando was supposed to go to for frame fittings and cycle parts. These threads all require imperial (inches) AF spanners.

Beware of leftover BSF/W threads on Commando frames/forks though
 
Re: MkIII chain tensioner/ adjuster For rear wheel!

Yes I'm talking about the rear chain adjuster!

Regarding the nomenclature of BST I have dealt with BSPT for fuel lines on various cars. This is my first vintage British bike. I've owned several Hinckley Triumphs of which all were metric.

I'm used to seeing a bit more robust adjusters from various modern bikes. As heavy as this thing is the adjusters look like something off a Schwinn bike.
 
Aha. The adjusters only have to move the wheel to adjust the chain, until you clinch up the axle to keep everything there. Not move the Queen Mary. !!
If you expect heavyweight fasteners in a brit bike, probably the wrong brand entirely.

Now, about that BST. Again, almost all the fasteners on the cycleparts on a Commando are UNF = american threads = american wrenches fit.
Pipe threads are something different entirely, talk to a plumber about those.
hopethishelps.
 
The T in bspt stands for taper not thread, bspp is the other version where the p stands for parallel.
 
Rohan said:
Pipe threads are something different entirely, talk to a plumber about those.
Click to expand...

I wouldn't necessarily recommend Rusty bucket talks to a plumber where he lives-as any plumber will likely know American National Pipe (NP) threads-of which there are none on any standard Commando.

The Commando pipe thread (fuel tank/fuel tap/petcock) is 1/4" (.518"-19) BSP (British Standard Pipe parallel thread) the hexagons of which are W/BS spanner size.

http://britishfasteners.com/threads/bsp.html
 
L.A.B. said:
Rohan said:
Pipe threads are something different entirely, talk to a plumber about those.
Click to expand...

I wouldn't necessarily recommend Rusty bucket talks to a plumber where he lives-as any plumber will likely know American National Pipe (NP) threads-of which there are none on any standard Commando.

The Commando pipe thread (fuel tank/fuel tap/petcock) is 1/4" (.518"-19) BSP (British Standard Pipe parallel thread) the hexagons of which are W/BS spanner size.

http://britishfasteners.com/threads/bsp.html
Click to expand...

Thank you thank you thank you! Rohan! I didn't realize I could stroll into the hardware shop and buy my bolts! I knew many of my wrenches and spanner fit. I bought some Whitworth wrenches a while back I see they use a different sizing method , maybe the bolt shaft? Who knows, I'm happier than a pig in a puddle knowing something on the bike is off the shelf simple!
I got the taper bit, same deal here in the U.S. I guess I'll have to suck it up on the stamped cheapy stuff... Maybe I'll stuff some stainless in the and try and keep the rust gremlins at bay.
 
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