Quaife gearbox breather thread

[windy]

Trying to get my head round NPT sizes

Does anyone know the thread size of the breather hole in the ally top cover on a quaife gearbox?

The threaded hole in the cover measures about 5/8" diameter. What is the NPT size please?

TIA

[Pistol Pete]

Nation Plumber (or Pipe) thread, I think it American.

Pete

Probably does help much .

[windy]

Yeh know what it means. I think its either 1/4" or 3/8" NPT but can't be too sure because its got a stupid taper on it. Can anyone confirm which one?

Need to order a fitting to screw into the hole so I can plumb in a bottle and a pipe to it to stop the gearbox p*****g out oil.  

[Keith the Teeth]

http://www.engineersedge.com/pipe_external_thrd.htm

Any help?

[Dave]

The hole in my quaife cover is 3/8 bsp

Dave

[windy]

Cheers Dave, now ordered a fitting.

[John Loudon - Sponsorship Liaison]

I am surprised that you are attempting screw it in. i thought you might weld it  

[windy]

John, would you like to learn how to do yours?

I have a book if you'd like to borrow it for some bedtime reading      

[Cam]

Windy, took my breather out yesterday to do exactly the same thing, did a search and there was your post.

Yep I ended up reckoning it was 3/8 BSP.

Soo how you going to do your gearbox breather then?

[windy]

Yep defo 3/8 bsp. Fitting came today from Think Automotive & it fits the hole.

I'm going to run a hose up to a brake reservoir bottle with the cap drilled out to vent some air. The idea being that there is a head of tube for the oil to run up to the bottle when its running, then it drains back down into the gbox when you stop, no loss of fluid hopefully.

[John Loudon - Sponsorship Liaison]

But it will be low on oil whilst running as there will be some in the tube and resevoir