As many Austin Seven owners have discovered, the kingpin/axle eye has always been regarded as a problem area. The tell-tale discovery of movement in the kingpin more often reveals a worn axle eye rather than a worn kingpin and bushes. The common problem of wear occurring in the axle eye stems from the relatively small diameter (0.5") kingpin which is located in a slender axle beam.

The usual methods of correcting the problem are:

    a. dismantle and take the axle unit to a specialist who will "shrink" the bell mouthed axle eye back to the normal size.

    b. dismantle the axle and bore out the axle eye to accept a thin-walled hardened steel bush (9/16" dia) that must be an interference fit. (There is a distinct risk of cracking the surrounding axle eye material when using this method).

    c.  use an oversize kingpin (usually + 1/64") and ream out the axle

Methods a. and b. will require the removal of the axle from the car and will generally entail the use of a specialist to carry out the work.  Method c. will undoubtedly prove a tricky experience of having to use an expanding reamer to line ream the top and bottom bushes to accept the oversize kingpin. (Remembering of course that the bottom bush is housed in a blind hole).

A modern alternative. method of overcoming the problem is by the use of an engineering adhesive such as Loctite 641 to retain the kingpin in the worn axle eye. Loctite 641 is a recommended adhesive for cylindrical parts that require easy disassembly at some future date. This type of adhesive has an "anaerobic" fixing action, which means that it will remain liquid in the presence of air and will only become solid when confined between two surfaces. It is recommended that the adhesive works best within a maximum diametrical clearance of 0.15mm (0.006") but it can be successfully used on much larger gaps. A fixture time of approximately 10 to 30 minutes can be expected when the two components are brought together within the recommended clearance tolerance. (The smaller the gap the quicker the fixture time).

Before explaining how to go about effecting the repair, two simple but very important instructions must be followed to ensure a good result.  All parts must be thoroughly cleaned and free from any oil or grease, preferably by using Trichloroethylene and the clearance between the worn axle eye and the kingpin must be completely filled with the adhesive to be effective.

Repair Procedure

Having carefully examined and established that the existing kingpin and bushes are re-useable and that the wear is confined to an oversized axle eye, proceed by first cleaning the kingpin and bushes with Tric to remove any traces of oil or grease. Next, lightly coat the internal surfaces and top of the lower bush with grease, (too much grease will prevent the kingpin from fully entering the lower bush due to compression) leaving the top bush clean and dry. Next remove the kingpin cotter from the axle eye and thoroughly clean the worn axle eye and cotter hole, again using Tric.

Replace the old cotter pin using a high tensile replacement and make sure this is also free from oil and grease.

Using the Loctite 641, coat the entire internal surface of the axle eye ensuring that the adhesive is evenly distributed over the whole area including the small machined recess in the cotter pin surface. (Loctite 641 is "Thixotropic" and will not flow under its own weight and will therefore readily cling to the vertical surfaces of the axle eye). Now wipe the top and bottom faces of the axle eye to remove any excess adhesive. Next locate the stub axle hub assembly about the axle eye (remembering to position the thrust washer) and then finally insert the kingpin through the whole assembly. Then the kingpin is fully home tighten the cotter pin.

It must be appreciated that the action of the kingpin passing through the axle eye will have caused a certain amount of the adhesive to migrate to the bottom bush. Although the bottom bush was lightly greased beforehand, any traces of the excess adhesive are best removed to avoid the possibility of a fixture occurring between kingpin and bush. The is best carried out by injecting the lower bush with grease to disperse any trace of adhesive.

To ensure only the bottom bush receives grease, use a 5/16" dia B.S.F, hexagonal-headed set-pin approx 1.6" long with a 1/8" dia hole drilled through its centre. The hexagon head of the set-pin should be tapped to accept a grease nipple. The pin is then screwed into the threaded hole situated in the top of the kingpin and the grease injected through the centre of the kingpin and into the bottom bush without contaminating the adhesive in the axle eye. The whole stub axle assembly should be rotated to and fro on the kingpin whilst injecting the grease to assist the dispersal of the adhesive mixed with grease leaving the bottom bush.

The adhesive will require approximately 10 to 30 minutes fixture time and a further 3 to 6 hours to cure fully. Loctite 641 adhesive is designed to accommodate large compressive strains (65,250 lb/in sq for a 0.08mm film thickness, 26,100 lb/in sq for a 0.25mm film thickness) but is unable to withstand high tensile strains. These basic design properties make the adhesive ideal for any cylindrical assembles that require easy disassembly, whilst at the same time preventing any micro-movement that may exist between two mating surfaces.