Following the SKOSH chart - your experiences?
I've got a friend with a 69 Sport Fury convertible C body. We did a suspension and brake upgrade. Firm feel upper arms, strut rods,lower control arm plates, poly lower control arm bushings and strut rod bushings, solid tie rod sleeves and disc brakes on his drum spindles. Anyway skosh chart doesn't apply to C bodies. Any suggestions? Street driver with radials.
You have to remember where the SKOSH chart came from, it's the correction for running radial tires on cars where the original specs were for bias ply tires. The SKOSH chart is based on radial tires and their alignment needs, so really it applies generally to all cars running radial tires. Now, specific platforms have their own specific nuances, like the notes for the F/J/M cars.
There's no reason at all why the SKOSH chart shouldn't apply to C-body cars, at least in general. For higher level performance some minor tweaks might be needed, C-bodies are generally heavier so you might see more camber wear at lower degree settings than you would on an A-body. Or you might find that the steering gets heavier at lower settings than with an A, that sort of thing. But how you use the car will probably be a bigger factor, if you really want to make your C-body carve you might actually need more camber and caster to counter the physics of those beasts and just have to deal with some of the other things that come up.
No need for that much on a manual steering car.
Completely disagree. The effect of caster on steering and handling performance doesn't change if your steering is manual or power. Its benefit of additional high speed stability and additional camber gain on turn in is completely unchanged by whether or not the steering is boosted or not. If performance is improved by running additional positive caster on a power steering car it is the same for a manual steering car.
The only difference between the two is the steering effort felt by the driver, especially at lower speed. That's the only reason there are different recommendations for power and manual steering, driver comfort. Not performance.
And the more tire width you run up front the more important additional caster becomes. +2.5 to 3° might be fine if all you run up front are 225/60/15's. But if you run 275/35/18's, you will need more positive caster to counteract the wider tires tendency to get pulled around or "track" with ruts and road quality issues. The wider the tires get the more caster you need to keep them going where you want them- instead of them going where they want to go.
I've been running 275's up front for years now, on both my Challenger and my Duster. +3° of caster is stupid with those tires. I ran about +5° with my Challenger, which had power steering, and that was all I could get with the suspension components I had. It wasn't bad, but with my Duster and its more adjustable suspension set up I have found that more caster is still better. I run +6.5° of caster on my Duster, and it works great. I have run everywhere from about +5° all they was up to +8° of caster on the Duster, +6.5° is the sweet spot where the tires are well controlled and the car is nice and stable and the steering effort is manageable for every day driving scenarios. Much past +6.5° and the steering effort effect from the caster increases rapidly, much less and those 275's start to have a mind of their own. And yes, the Duster is a manual steering car with the 16:1 fast ratio steering, 275/35/18's, and +6.5° of caster that I use as a daily driver about 9 months out of the year, doing at least 120+ miles a week when I'm using it. Is the steering a bit heavy at parking lot speeds? Yes it is. But it's not unmanageable.
The other thing is, the quality of your steering components matters. Ball joints, tie rod ends, pitman and idler arm resistance is all very important. I recently installed a bearing idler arm set up from BergmanAutocraft on my Duster, and the steering effort was noticeably reduced.
