Swinging Arm Oil Filler Screw

The combination of Hagon (or original Girling) rear suspension units and Norton Roadholder front forks, makes the 1966 G12 a pleasure to ride, especially on the somewhat uneven and pothole infested roads near me. Thankfully, these roads soon open out into gently curving, pretty well maintained and relatively quiet lanes…just inviting you and your motorcycle to explore them. Most have a cup of tea at the other end and, with luck, a scone or a slice of cake.

A point of essential lubrication is often overlooked by many, and in most cases won’t cause a problem. If it does however, quite a bit of work is required to repair the issue. I am of course, referring to the swinging arm pivot section of the frame. It looks like it will last forever as there’s no grease nipple. The pivot section has ‘oilite’ bushes which, by design, are porous to oil enough to reliably lubricate the pivot shaft. The manual states that once filled, the oil reservoir should last indefinitely. Note that there are also felt seals between the section of the pivot assembly; you will see them on your bike.

If the pivot is incorrectly lubricated, the bushes will wear quickly and the swinging arm will knock, like worn suspension bushes on your car. If you look at the picture, you will see a small screw in the endcap, with a fibre washer underneath it. Remove the screw and there will be a small hole, which if you can, insert a thin pipe and suck out any contents using a syringe. Once you have done this, use the syringe to insert 1.5 fluid ounces or 42.6 ml of classic SAE 140 heavy gear oil. It’s normally only available in larger quantities, but I did find a supplier of one litre bottles.

SAE 140 Gear Oil

I didn’t have a pipe thin enough to poke through the hole on my bike, but a thin screwdriver was returned from the hole with not even a smear of oil on it. I then injected 50 ml of the oil into the hole on my bike, checked nothing leaked back out or around the pivot, and replaced the screw. I also replaced the rather tired fibre washer, which has a 1/4 inch internal diameter.

Unsurprisingly, the bike felt just the same to ride, but chances are the pivot will last longer than it would have previously.