I was looking through my stuff and couldn't find the second fork drain screw, I had one in the parts containers where I keep everything. Where there's one you expect the other one, no?

So I place a quick order with Old Britts for a used one (only a buck) and the washers. Shipping was more than the order by a few cents but with the show coming up this weekend I figured I should get oil in the forks, especially since the bike would be trailered.

I got the screw today and it wouldn't fit. If you recall my fun with the gearbox sprocket nut and dummy axles you know I'm full of luck when it comes to threads.

I think, great, no oil in one leg. Then I pull the bike out (it was stacked with the Tacos) and check the other fork leg. Uh, yeah, so, um, I guess I stuck the other screw in that leg at some point. So, I'm good. Oil in both legs. Phew.

Anyways, I wonder what the screw I got was for? It's just about the same size as the fork drain screw but a fine thread. The fork drain screw is 1/4-20 (on the left) and I'm guessing the other one is 1/4-28?

Easy! The fine thread is 00-0485 CEI plug for pre-Commando forks, the coarse one is 06-0354 plug for Commando forks. How many threads were ruined due to people mistaking one for the other?
This is one of the many traps Norton introduced with the Commando- wheel hubs, forks etc LOOK the same but all threads were changed on the chassis parts from British norm to UNF/UNC.
And I haven't even started on threads for engine studs and nuts, which were changed DURING Commando production..........

Yeah, that CEI thread screw is for pre-commando fork legs, including Matchless/AJS. My Ranger uses that same screw for its 'Tele-hydraulic' forks.

Its not 1/4 - 28, its 1/4 - 26

Everything CEI was 26 TPI until you get up to 1/2", where you could get 26 or 20 TPI

ZFD wrote:And I haven't even started on threads for engine studs and nuts, which were changed DURING Commando production..........

Actually that would be an excellent discussion. I assume there was no definite serial number cutover on that change?

I think most of the thread changes have already been discussed in the past, but I suppose there's no reason why ZFD shouldn't remind us if he wants to?

L.A.B. wrote:I think most of the thread changes have already been discussed in the past, but I suppose there's no reason why ZFD shouldn't remind us if he wants to?

You said "most". I would bet that if anyone is intimate with all the part changes over the years it will be ZFD.

Gents,

Buy a BS/UNF/UNC screw pitch gage! Guaranteed to save tears and curses!

mike provence wrote:Gents,

Buy a BS/UNF/UNC screw pitch gage! Guaranteed to save tears and curses!

I have the UNF/UNC one but I didn't take the time to stick it on the fine thread screw. That would have told me it wasn't 28.

swooshdave wrote:You said "most". I would bet that if anyone is intimate with all the part changes over the years it will be ZFD.

Well, I'm sure we've probably gone through all of them at one time or another, but if ZFD has a list then that would be useful.