Dangerous rocking at speed - why?

[Nickol]

Please forgive the intrusion as this question does not apply to my '69 Traveller but to a 1947 Austin - however, it could do. At least it is a British car!

When I drive at more than say 70kmh the car becomes increasingly unstable and, how can I describe it, wanders ? It feels like I am about to lose control and swerve all over the place. Thus this is really the limiting speed. When the tyres, after the winter hibernation are a bit low in pressure, and I forget to pump them up, the effect is worse.

My question is what is likely to be at fault: the shock absorbers or the leaf springs....or maybe something else? One could say remove all the shocks, reonovate them and try but I thought I would ask first as this is a major exercise. I would add that they are all 4 very similar, lever arm type to those on a minor

[Bill_qaz]

Worn joints or free play in steering, how much is free play at steering wheel when stationary? What model Austin do you have? If its worm and peg steering box the free play is adjustable its unlikely to be rack and pinion like a minor.
Is it steering wander or bouncing that's the main symptom?

[Nickol]

It has a steering box which is adjustable and I have done that. It now has much less play albeit at the expense of being harder to turn.

The car itself is an Austin 8 Trav. "Is it steering wander or bouncing" you ask. Had to have along think on that one, probably wander is my conclusion. If you have seen towed caravans gradually swinging left and right, that is how I feel the car is behaving.

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[philthehill]

It could well be that the steering box is too tight.

[Nickol]

That is an interesting thought - I know people did say to me that in the old pre-war films where you see drivers constantly moving the steering wheel left and right, that this was not hollywood invention but the way you had to drive. I am trying to remember when it was that I tightened up the steering. It is a bummer to do though - for access you must remove the radiator!

[philthehill]

To allow the caster of the steering to do its job the steering must not be too tight.
The caster setting of the steering allows the steering to find its centre position and so keep the vehicle on the straight.
The vehicle steering must be able to self centre without help from the driver.