Oscillation trepidation !

[andrew34ruby]

Over the past 4 years I have driven the seven about four thousand miles or more with no hint of a shimmy. Most of the items mentioned were then replaced or disturbed after the crash in March this year, but since the repair it was fine for over 300 miles, then two episodes of fairly violent shimmy within a couple of miles.

So where to start? I'm inclined to try one thing at a time and test drive to see, before moving onto the next item. Having examined carefully, nothing seems loose, but these are the ideas mentioned above by all the helpful people commenting.

Tracking?
Anything with slight wear?
Steering eye loose?
Loose shock absorber mountings?
Loose king pins, axle eyes, cotters?
Loose U-bolts on the spring?
Twisted axle beam affecting castor?

Then I could experiment with tyre pressures?

If it still persists I could try increasing the castor angle.
Looking in the Austin seven companion ...
Fig 3 on page 181 shows an interesting idea to increase castor angle.
The third paragraph on page 180 condemns this method.
Towards the end of the third paragraph on page 182 is another method of increasing castor angle by lowering the position of the ball that attaches the radius arms to the chassis.

This could take months! Especially as I don't want to test-drive the car on the road now, due to heavy salting by our new North Yorkshire Council.