From an original post by Alan Jones, Wittsend, on the Forum, Dec 2008
Getting the pre-load right on the swivel pins is vital for proper operation of the steering and for an MOT pass.
You first have to ascertain exactly what type of swivel pin/housing you have, the original with cone bearings in both the top and bottom of the swivel and with the steering arms fixed to the top of the swivel – or maybe a PO has fitted the Series 2A “upgrade” a Railko bearing in the top position – with or without a steering arm conversion. Series 2As have “pendant” steering arms fixed to the bottom of the swivel housing.
It is possible to get the original cone bearings, etc. and restore to factory spec, but many owners prefer the upgrade as it’s said to improve the steering.
If you have cone bearings top & bottom then you fit shims between the swivel pin and the housing to a starting thickness of 40 thou’ top & bottom. You bolt the swivel pins down, tightening a little at a time in a diagonal sequence.
Shims come in various sizes – 30 thou’, 10 thou’, 5 thou’ & 3 thou’
They cost a few pennies each. Buy a good selection. It is not worth re-using old shims unless you are miles from anywhere (in the desert) and it’s a matter of life or death.
To make the 40 thou’ include a couple of the thin 3 thou’ shims (for fine adjustment latter).
And then you measure the preload with a spring balance (0 to 20 lbs range).
These you can buy from any good fishing tackle shop for about £5.
The value for the twin cone bearings is 14 to 16 lbs. This is not the initial value you get over-coming the inertia. You do this without the big oil seal fitted (but oil the cone bearings)…else you’ll get a false reading.
If the preload is too high you remove a shim, you are supposed to keep the shims “even” so try removing a 3 thou’ shim from each pin. Preload too low, then replace the bottom 3 thou shim….
Keep trying and testing with different combinations.
The 40 thou’ worth of shims is just a starting value, you may need to add shims.
It is best to work on the bench. Make a jig from angle iron to hold the swivel in the vice.
You can work on the vehicle – but cleanliness is vital. A bit of grit trapped in the shims could affect the preload. Aim for the higher reading, don’t worry if you are a pound too high.
When the vehicle is back in service, the pins/shims and bearings can settle and the preload will be fine. Over time the pins/bearing wear and you’ll find some play in the swivels. You can (if you keep things clean) remove a thin shim and take up the play, assuming the pin is not worn or scored too badly.
With the Railko bearing/bush conversion the preload value is less at 12 to 14 lbs. And you only put 40 thou’ worth of shims under the top (Railco) pin. The process is otherwise the same in the setting up.
When done, fit your well greased oil seal and retainer, checking the steering lock stop bolt is in the right place. And don’t forget to knock over the lock tabs on the swivel pin fixing bolts.