Chassis grease nipple threads

[Harv]

My FB is a real hodge-podge of grease nipples. Most work OK, but some want replacing (angled fittings which make accessing the nipple harder).

Not too sure whether the FB/EK grease nipples are BSPT or NPT thread. Anyone certain which one?

They are pretty similar, so I'd imagine you could jam one into the other... would prefer to use the correct ones though if I can.

Cheers,
Harv

[Craig Allardyce]

Harv do you have a thread pitch gauge? 1/4 Npt is 18 TPI were as BSPT is 19 TPI. 1/8 Npt is 27 TPI where as BSPT is 28 TPI.
I could measure some original bushes tomorrow if you don't have a gauge.

[Harv]

Harv do you have a thread pitch gauge? 1/4 Npt is 18 TPI were as BSPT is 19 TPI. 1/8 Npt is 27 TPI where as BSPT is 28 TPI.
I could measure some original bushes tomorrow if you don't have a gauge.

Thanks Craig. Sadly, I don't have a pitch gauge. I normally bodgy it up by counting threads against a steel rule. I figured the nipples were so short that I would not be able to pick the difference between 18/19 or 27/28. Appreciate the measurement.

Cheers,
Harv

[Craig Allardyce]

Ok Harv I've done some measuring and checking. This should be the go but I'm happy to stand corrected were needed.

The larger grease nipples are 1/8" NPT 27 TPI (thread OD should measure around 13/32" (.41)).
NPT nominal thread size is generally found by measuring thread diameter and subtracting 1/4".
The smaller nipples such as used in the UJ's should be 1/4" UNF 28 TPI (Commonly listed as SAE-LT taper thread) and should be screwed into 1/4''-28 UNF-3B straight-threaded hole. There are also 1/4" UNF straight thread grease nipples.
You may also come across 1/4" Pipe Thread Grease Fittings which are used for heavy industrial equipment and large bearings, especially recommended where heavy lubricants are used. 1/4" pipe thread grease fittings have 18 threads per inch.
BSP is generally used for lower pressure brass connections.

I hope I haven't confused the shit out of you.

[Harv]

Thanks mate - appreciated.

I figure I'll buy a bulk lot of nipples... would rather have the correct NPT ones than be bodgying BSP ones forever.

Cheers,
Harv