Steering

[Tiger]

This may be a problem with no easy answer.
But here goes :
I have driven 1930’s cars however never a A7
Should the car hold a reasonable straight line when driven on a good road surface.
A further car which I am considering buying apparently wonders about in the straight ahead position.
Although I have only driven my Ruby a short distance on the road (not ready yet) it held a good line.
Any comments much appreciated.
Regards
            Tim

PS Just realised I contradicted my self with a short drive in my 7

[Robert Leigh]

Is it another A7 you are considering or something different? Even with A7s you would find a big difference between a late Ruby and a Chummy. As far as steering goes even a car in concourse condition to look at may have badly set steering and worn out suspension. On some older cars adjusting the steering to have no play at all can make them more difficult to drive than a similar car with 'looser' settings.

[Tiger]

Robert
It’s an RP
Been standing for several years.
Am I correct in thinking very similar geometry as my Mk2 Ruby

[Andy Bennett]

My RP doesn't wander around.
There is a difference between having a bit of 'play' at the steering wheel as suggested by Robert. Mine has about an inch or so of free movement in the steering wheel which I have found to be at the higher end of standard (I've wiggled lots of steering wheels), but not as much as I have found on some cars. I have also replaced the rubbers in the shackles, which were perished. But it doesn't wander around on the road, rather it allows some 'give' for bumps and tramlines in the road. If yours is actively heading off then something is definitely wrong.

[Robert Leigh]

I agree with Andy; if it's not behaving reasonably something needs fixing. Could be shackles, king pins, shock absorber and links, track rod ends, radius arms, or even something at the back, but it's all fixable. If you are buying it's grounds for negotiation, and a careful look at all the bits which might be causing the problem.

[bob46320]

Tyre pressure, uneven wear on tread. You do have to concentrate with a 7

[Bob Culver]

With its high camber rear springs the destabilising positve feedback effect with an RP is greater, but this shows up more in spirited driving, patched surfaces and winding surfaces. (Although I found the general handling of a Ruby and my RP much the same.)
The cars have many inherent characteristic which in unlowered form esp lead to somewhat precarious stability. But at modest speeds on smooth surface should be steady.
There are a myriad maintenace factors which worsen stability, from slack shock absorbers to loss of castor to tight kingpins.. Curiously any excessive stiffness in the steering such as tight new kingpins, causes wander as the steering cannot self align. Similary, as mentioned above, having very little backlash causes the wheels to turn over bumps due geometic shortcomings, whereas with some slack the movement is often just lost in the box and the wheels self realign..

[Tony Press]

Incorrect caster is the most likely cause of the car wandering- recently discussed at great length on the forum. Not that hard to understand but some have difficulty.

The single large nut at the end of each of the radius arms on the front axle can slacken and the King Pin usually becomes  vertical  (zero caster) or leams forward (negative caster ).

Both result in the car wandering.

[Bob Culver]

Further to Tony, the pre Girling radisu rods tend to twist themselves to reduce castor. As a rough guide the walls should be vertical. Sometimes the rods are reveresed which also doe not assist.

[Tiger]

Many thanks gentlemen for your replies.
Very helpful.