Transfer box breather

[dunnin21]

Iv got hold of a new transfer box. Before I put it on I'm gona do the breather. So who can tell me what size elbow and tap I need to use. Just the hole is 12mm already

Thanks andy

[dunnin21]

Any idears

[Tramp]

1/4 bsp, did you pull the collar out if the casing? It's an interference fit,

Edit*
Definatley 1/4 bspf as its the only bsp tap set I have.....

[Darrell]

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[dunnin21]

Yeh I took nipple out the hole just seams large for a 3/8

[Ladaman]

BSP threads are based on the bore of the pipe, not the outside diameter of the bolt as normal threads are.

If you notice on the table Darrel attached the outside diameter of a 3/8"BSP thread is 0.656" or 16.6mm

Having said all that though, I've just checked mine, and I'm sure it's a 1/4"BSP thread I used which is 0.518" or 13.15mm outside diameter. The hole already in the case is close enough to the correct tapping drill size to not need to drill it out.

I recall I put some grease on the tap to hold the swarf, and had the gearbox as close to upside down as I could get it to stop the swarf entering the casing.

So believe it is 1/4" BSP you really need.

[Darrell]

BSP threads are based on the bore of the pipe, not the outside diameter of the bolt as normal threads are.

If you notice on the table Darrel attached the outside diameter of a 3/8"BSP thread is 0.656" or 16.6mm

Having said all that though, I've just checked mine, and I'm sure it's a 1/4"BSP thread I used which is 0.518" or 13.15mm outside diameter. The hole already in the case is close enough to the correct tapping drill size to not need to drill it out.

I recall I put some grease on the tap to hold the swarf, and had the gearbox as close to upside down as I could get it to stop the swarf entering the casing.

So believe it is 1/4" BSP you really need.

I've no idea of the hole size , but that makes sense

[dunnin21]

Thanks guys I shall go for the 1/4