Anyone know the thread size of Kubota grease fittings?

[Frankenkubota]

Just broke one on the loader on MX 5800. First time for me in 52 years.

EZ out I hope, as soon as it stops raining.

Thx re the list of fittings and other comments.

 

[rScotty]

It can be difficult to identify grease fittings. I have made this table to help (or maybe not) from fittings available from manufacturers or suppliers; some may be missing.
Measuring the diameter, TPI or pitch can get you close to proper identification, but due to manufacturing tolerances and type of thread, getting the diameter right may be difficult. And identifying if there is a taper or not can be almost impossible for some.
Maybe it can help someone

diam. in. | diam. mm | fitting designation
0.138  3.5 6-40 UNF
0.190  4.8 10-32 UNF
0.197  5.0 M5x0.8
0.223  5.7 1/4"-28 SAE-LT
0.236  6.0 M6x0.75
0.236  6.0 M6x1
0.250  6.4 1/4"-28 UNF
0.250  6.4 1/4"-26 BSF
0.276  7.0 M7x1
0.313  7.9 5/16"-22 BSF
0.313  7.9 5/16"-24 UNF
0.313  7.9 5/16"-32 UNEF
0.315  8.0 M8x0.75
0.315  8.0 M8x1
0.315  8.0 M8x1.25
0.375  9.5 3/8"-24 UNF
0.375  9.5 3/8"-20 BSF
0.383  9.7 1/8"-28 BSPT
0.383  9.7 1/8"-28 BSPP
0.394 10.0 M10x1
0.394 10.0 M10x1.25
0.394 10.0 M10x1.5
0.405 10.3 1/8"-27 PTF
0.405 10.3 1/8"-27 NPT
0.472 12.0 M12x1
0.472 12.0 M12x1.25
0.472 12.0 M12x1.5
0.472 12.0 M12x1.75
0.500 12.7 1/2"-20 UNF
0.518 13.2 1/4"-19 BSPT
0.518 13.2 1/4"-19 BSPP
0.523 13.3 1/4"-18 PTF
0.551 14.0 M14x1.5
0.623 16.0 M16x1.5
0.656 16.7 3/8"-19 BSPT
0.656 16.7 3/8"-19 BSPP
0.675 17.1 3/8"-18 NPT
0.675 17.1 3/8"-18 PTF
0.820 20.8 1/2"-14 PTF
0.825 21.0 1/2"-14 BSPP
0.840 21.3 1/2"-14 NPT

Grease Fitting Thread Types

M        ISO Metric Taper - thread sealant recommended
S        Metric thread Forming
UNC      Unified National Coarse Thread - thread sealant recommended
UNF      Unified National Fine Thread - thread sealant recommended
UNEF     Unified National Extra Fine Thread - thread sealant recommended
NPT      National Pipe Thread (American National Standard Pipe Thread) - thread sealant recommended
NPTF/PTF PTF, National Pipe Taper Fuel, AKA Dryseal -NPTF threads have the same basic shape but with crest and root heights adjusted for an interference fit, eliminating the spiral leakage path.  Compatible with NPT but leak-free caracteristics are loss.
PTF-SAE Short     NPTF minus 1 thread at small end
PTF-Special short PTF-SAE Short minus 1 thread at large end
PTF-Special extra short PTF-SAE Short minus 2 threads at large end
SAE-LT   Society of Automotive Engineers Lubrication Threads -- Tapered but designed to be installed in a 1/4"-28 straight-thread hole.
NPSM     National Pipe Thread Parallel - thread sealant recommended
BSPT/BSP British Standard Pipe Taper or R-series pipe thread
BSPP	 British Standard Pipe Parallel or G-series pipe thread (previously BSPF and BSPM)
BSF/BSPF British Standard Fine - Parallel

I just had to post a reply so I could put up that crazy chart again. I know of nothing in the thread world that even approaches the rich complexity of zerk fitting threads. And I just love that chart you made up.
The only thing that competes with a chart like that is the world of metric O rings.

Just a note, for budding thread geeks: Hardly any designer will spec for the ISO Metric taper in any fluid-carrying application. It's known to be a troublesome and leaky thread form. So it almost makes sense that the Japanese manufacturers went to BSPT for most their tapered threads. (Except it doesn't explain why a whole metric country went to a British thread form which isn't popular anywhere else)

Question 1: How much would a good set of grease fitting thread gauges cost?
Question 2: Does McMaster Carr carry all these size fittings?
rScotty

 

[maritimefarmer]

If you are looking for a grease fitting thread tester, Amazon has something that looks pretty cool...
Amazon.com: Grease Fitting Thread Tester: Home Improvement at US$40.
But for me it is CA$106 - too expensive for the few fittings I had to replace over many years. A $10 thread gauge SAE and metric will suffice.

McMaster has many of the ones listed, SAE Products has some more
McMaster-Carr
Zerk Fittings / Grease Fittings

 

[Ed27]

I broke a zerk fitting on the LA 1154 front end loader on my Kubota M7060HD12. Who knew there are a million different sizes of zerks? It looked exactly like a metric M8x1,mwhich will start in the hole but does not fit. Turns out it is a 5/16"-22 BSF fitting. You will not find those in any of the grab-bag zerk kits. I bought some from McMaster-Carr.

 

[rScotty]

I broke a zerk fitting on the LA 1154 front end loader on my Kubota M7060HD12. Who knew there are a million different sizes of zerks? It looked exactly like a metric M8x1,mwhich will start in the hole but does not fit. Turns out it is a 5/16"-22 BSF fitting. You will not find those in any of the grab-bag zerk kits. I bought some from McMaster-Carr.

OK. That's an odd one. How did you figure out which thread it was?

 

[Ed27]

I bought a Lock and Lube thread tester after trying everything in my standard and metric grease fitting collection. Thanks for the great lists, rScotty. Not surprisingly, the M8x1 and the BSF 5/16"-22 are very similar in size.

 

[jmc]

Thanks for the great lists, Maritimefarmer.

 

[rScotty]

I bought a Lock and Lube thread tester after trying everything in my standard and metric grease fitting collection. Thanks for the great lists, rScotty. Not surprisingly, the M8x1 and the BSF 5/16"-22 are very similar in size.

We have to thank Maritimefarmer for originally making for that list. I only copied his work. Congrats on getting the thread gauge. I'm still trying to match threads with calipers and a magnifying glass.

I'm not all that familiar with the world of grease fittings and tiny zerks.... But anywhere else in mechanics when you run across something you suspect to be a metric tapered thread, it is probably one of the British tapered threads instead. Especially if it is being used where the threads have to seal a fluid.
rScotty

 

[sixdogs]

I broke a zerk fitting on the LA 1154 front end loader on my Kubota M7060HD12. Who knew there are a million different sizes of zerks? It looked exactly like a metric M8x1,mwhich will start in the hole but does not fit. Turns out it is a 5/16"-22 BSF fitting. You will not find those in any of the grab-bag zerk kits. I bought some from McMaster-Carr.

That grease zero list is pretty impressive and great to have. I've spent a lot of time on Kubota zerk threads and even found some drive-in ones on a loader that fooled me for a while. Is there really a need for all these sizes other than proprietary confusion?

 

[Ed27]

I broke a zerk fitting on the LA 1154 front end loader on my Kubota M7060HD12. Who knew there are a million different sizes of zerks? It looked exactly like a metric M8x1,mwhich will start in the hole but does not fit. Turns out it is a 5/16"-22 BSF fitting. You will not find those in any of the grab-bag zerk kits. I bought some from McMaster-Carr.

Darn it! I was wrong, not a BSF 5/16"-22. It did not fit. My Kubota dealer managed to track it down for me. Turns out it is an M8x1.25 (the difference between the M8x1.25 and M8x1 is the pitch of the threads). The zerk I'm talking about is on my LA1154 front end loader. See the picture below.