Quote:
Originally Posted by 142 Guy
You need to distinguish between lightness that might originate from a lack of self centering in the steering versus excessive play in the steering which results is a dead / floaty zone of steering response.
You appear to have addressed most of the sources of excessive steering system play. You said you changed the steering box. Since vintage Volvo steering boxes are out of production does that mean you replaced the box with another used box or you attempted a partial rebuild? Play in vintage Volvo steering boxes is a fairly well known issue and can to a certain extent can be improved with the pitman arm adjustment screw which grj0 refers to. Be careful with that adjustment as excessively tight can contribute to more steering box wear. The service manual describes the correct procedure for setting the adjustment.
Vintage Volvos run with the minimum amount of caster that is probably safe because of the lack power steering. Your caster angles are much more positive than factory spec which should be safe because it provides more self centering action at highway speeds; however, I expect that your steering when parking the car must now be rather heavy. Modern cars typically run with > +5 deg caster; but, have power steering to compensate for that. Your caster should be contributing to a car that has a fair amount of self centering in the steering at highway speeds. The normal tolerance for difference in the left - right caster values is 1/2 degree. Your difference is excessive. A significant difference in caster causes the car to pull to the side with less caster. People who race cars that only turn left (stock car racers) will set the steering up with differential caster. I assume you are not going oval track racing so this is not a desirable feature for you. However, aside from the tendency to pull and probably increase tire wear I don't know that the caster differential is causing overly light steering.
The seized upper wishbone bolt comment has me confused. Do you mean the actual wishbone pivot bolt has seized? If so and this means that the upper wishbone is not free to move that would create too many unknown steering effects. If what you mean is that the bolt for the adjustment shim at the upper wishbone pivot point is seized (which is responsible for your caster mis match) I don't think that is the cause of your overly light steering. If it is the adjustment bolt that is seized then you do need to disassemble that side so that you can extract and replace the bolt by whatever means so that you can get the caster values to match. I would be inclined to limit my caster experiments to +3 deg or less because increased caster will cause increased load on the steering box during low speed steering which will contribute to steering box wear which is something you need to avoid with the vintage steering box.
Aside from your caster mismatch, your caster values suggest that the car should have good self centering / tracking at highway speeds. All the other alignment values are consistent with Volvo specs. You could try a little more positive toe; but, this does tend to increase tire wear.
So, first thing I would check is the amount of play in the steering box just because that is the easiest thing to check. It may not be completely fixable; but, you may be able to minimize it with the correct adjustment of the pitman arm shaft adjustment screw. You need to fix the seized bolt which I assume is the shim adjustment bolt because a seized wishbone pivot should not have made it through any kind of MOT inspection.
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hi,
we attempted to increase caster to improve steering. when i got the car 28 years ago it had negative caster one side and positive the other- BUT- within spec!
so we corrected that and all was fine then about 10 years ago we started with this light steering- runs straight- no drift but you can steer with one finger touching the wheel. I begged the MOT test garage to find something wrong- they couldn't. so we replaced components and angles and had it checked by various dealers but no culprit found. we have kit to measure angles and are still baffled. Wife refuses to drive it as it is so sensitive... unlike me!