Mark I Axle Nuts

A friend of mine is in search of the dimensions for axle nuts as fitted to the Mark cars. I assume this was used on almost every model for a very long time. An order was placed from a known vendor for part number 4141 which, when threaded, will make a half turn before locking up. I believe the thread pitch for the supplied part is incorrect. Can anyone offer specifics on this part so new ones can be sourced or does anyone have a pair for sale? I will relay the information accordingly. Thank you Jake Kreeger XK120OTS SE

It would help to update your forum information with your location and type of car. Someone in your area might have one or a suggestion.

The car is in a shop in California. They apparently removed and then lost the originals. I think the thread pitch on the replacements is incorrect.

My 1960 xk150 is 1in unf 14tpi i would think the mk1 would be the same…Steve

Looking at the SNGB website this nut is specific to the Mk1 and Mk2

A previous thread here says it’s 7/8th UNF which is 14tpi. Major diameter is 0.875".

Steve 1" UNF (from the chart) is 12TPI. So if Jake measures the thread pitch and diameter it should give him the answer.

Hi Andrew 1in 14tpi but i undetstand it may not be the correct one for this axel…i was giving a possible option…Steve

That’s odd as the charts for UNF say 12tpi.


My '58 Mk1 axle nuts are 14tpi, 21,86mm OD, this would fit 7/8" bolt size. 4HA differential.

Hello and thank you all for your input. So my buddy purchased two new axle nuts from SNG. These are 14TPI. While they appear to be correct it seems the threads on the axle shaft itself are stretched and or damaged prohibiting the nuts to fully thread home on the axle shaft. He is slowly dressing the threads with small files and cautiously using the nut as a thread chaser which appears to be working. I remember doing the very same thing on one of my XK’s a long time ago. Patience is required. The problem is ALMOST solved so it seems.
Jake Kreeger

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