4141 x 1. A new modern spec. Lower Ball Pin Seat in Nylon, to supercede the original factory fitted Ferrobestos (molded fibre material) that is no longer available. This material has been used for the last 30 years and has a deep shoulder, so requires no spigot. Original Number C11934

NOTE : The early O.E. type ball pin seat design was made from a 'newly' developed brass material, known in the day as 'Morganite' ( made by Morgan Crucible Co. of Swansea) and seperate steel spigot ring that was factory fitted to XK120 and also late run XK150 (exact data is vague). In the period between they used a deeper cup (with integral spigot) made of a compressed asbestos fibre material known as "Ferobestos" (made by Tenmat of Manchester) which we now replace with the nylon cup listed here which is a superior, modern alternative .

This may explain some original XK caps not having a grease nipple fitted, as it was not in the Ferrobestos materials design to require re-greasing. This tells us that a Morganite insert WILL require a grease nipple fitting to the cap if blank, SEE :  4313