Clarke air filter thread size

richie00boy · 2026-03-21T19:56:51+0000

Its not BSP. I think voipio is correct. Trouble is you cant get aftermarket filters with that thread. I've got some nice filters off Temu with M16 thread and I'm going to drill out and helicoil convert to M16.

RetroPug · 2026-03-22T09:55:21+0000

richie00boy said:
Its not BSP. I think voipio is correct. Trouble is you cant get aftermarket filters with that thread. I've got some nice filters off Temu with M16 thread and I'm going to drill out and helicoil convert to M16.

5/8 - 16UN certainly seems like it would be close from what I remember the dimensions being. I'll take some measurements and photos today.

If I cannot get direct fitting air filters, a fitting or adaptor would work fine for then threading in generic filters or adding pipework to a generic pneumatic filter of some kind, I just don't want to start buying more and more things that don't work if I can help it.

123hotchef · 2026-03-22T12:11:29+0000

no I nevr found any filters to fit either

RetroPug · 2026-03-22T17:01:36+0000

Images below:

Unfortunately, I didn't have a standard M10 to hand. I'm sure there's one buried in the garage somewhere but I couldn't locate one.

I did measure the diameter with callipers as well and got very similar to the "just under 15mm" showing in these images, but it's plastic so you can squeeze it, and I didn't have enough hands to photograph it.

Threads look parallel to me, rule alongside the threads isn't great for looking at pitch unfortunately, I'll have to track down an M10. However, it looks like 6 teeth in 9ish mm, which if I'm not having a massive brain fart is 16.9ish TPI so pretty close to 1.5 pitch.

5/8 - 16UN is 16TPI so a bit low, although obviously this is just looking at a rule next to it so who knows really. If either were a readily available fastener I'd just go and get one and try them but neither are things lying on shelves all over the place. You can get M15 1.5 sump plugs for cars but what a ballache going and buying one would be just to see if it fits, and then drilling and tapping it, just to fit an air filter. Other than for sump plugs it seems pretty uncommon.

There are actually generic filters advertised as having a 15mm thread on ebay:

Pardon our interruption...

Any thoughts?