ET: Engine (Twin) 2BA Countersunk Screws (406)

[oexing]

Not quite the topic with the BA clutch screws but many millions of Jap bikes are still holding together with all metric screws. I came across BSW studs in the 1964 E-Type head with BSF or UNF thread for nuts on same studs but in reality this distinction for alu joints is a bit pointless so nobody thinks it is worthwhile. It is more important to use lubricants or Loctite on bolts when fasteners are undone often in alu cases. BSW is sort of UNC coarse thread so more likely to rattle free unless some locking method used. UNF or metric is a better choice on bikes, BMW had all fine metric thread on their 1920ies bikes, small bolt heads, nuts modern hex heads - a bit eccentric I´d say. Maybe because they started with aeroplane engines with more critical view on fasteners.

Vic

 

[LoneStar]

Sympathies to the next owners of these bikes, who will have to deal not only with the normal mix of BA, BSF, BSW and CEI (documented, at least), but also random re-tapped threads in metric form.

 

[oexing]

Yes, he´d just have to pop into next home supply to get his metric replacements at no price at all then . . . .

Vic

 

[Bill Thomas]

As I said a long time ago, imperial even in UK or certain other colonies is no longer practical, lose one screw and you are in trouble to get one quick. Look below in my link and find 10 each M 5 Torx at 2 Pounds something and you got lot of change for a M 5 tap to chase the 2 BA in the clutch. No technical issue to do this, all sizes suitable for the mod - and no worries ever after. It is not a point to use an electric driver here, just a shape of screw that you don´t screw when undoing later - with a little help from Loctite to be safe that any screw will not work its way out to get stuck on the cover.

Vic
Torx M 5 stainless 10 each

I have been making use of the metric thread for years,
As you say they are as near as Dam it !.

 

[Peter Holmes]

They are near as Dammit, but only one way, you can step up to M5 if that is what you want (zero benefit) but you can’t revert to 2BA, it is too slack and will strip out.

 

[Michael Vane-Hunt]

Could those metric screws that Vic shows, be threaded 2 BA?

 

[oexing]

Michael, basically yes as all sizes of 2 BA are a tad smaller than M 5. But then you need a BA die, my guess no cheaper than a common M 5 tap that you get anywhere. When you fu*** up a BA screw you are back to finding or making up a BA replacement - does not make much sense. And why would anybody want to revert to BA once you have tapped for M 5 ?? Again, you´d be back to the present calamities we talk about . Nobody will care about what thread was inside the engine - in some decades as nobody will drive these things we spend our pastimes on. Put your old imperial fasteners in your cupboard of collectables for reminiscing, not much more use to them then. Practicality of these was no more existant really for quite a while in most civilized countries , hard to get in short time, so a bad idea when you want to do decent travelling.

Vic

 

[Michael Vane-Hunt]

Well I have lots of 2 BA taps. So I would prefer to use a 2 BA threaded screw but I do like the torx type drive.
I did have a few of the clutch screws back out a little and bring things to a halt. Ground out a good groove in the clutch cover, made a horrible noise and bent the screw heads over. I suspect I just did not have the screws tight enough. but that only happened once about 50,000 miles ago. Never had this happen again with the stainless replacement screws. I also have a made to fit flat screwdriver.

 

[greg brillus]

Of course there's so much room in the tool tray for metric, AN imperial and British Imperial tools, along with a good supply of spark plugs, zip ties and electrical tape........ The stock 2 BA screws are fine so long as they are done up tight........The original screws are best, stainless.........next. Most all countersunk fasteners like allan head or others use tooling that is very small, so you can not do them up very tight or else you will strip the center hole out.

 

[stu spalding]

Hi Greg. Raised countersunk 2ba socket head screws take a 1/8" allan key. I know they exist because I've got some but I'm damned if I can find any online. Cheers, Stu.

Most all countersunk fasteners like allan head or others use tooling that is very small, so you can not do them up very tight or else you will strip the center hole out.