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Re: Alignment woes, again...
Power steering systems were widely criticized back in the fifties and sixties due to overboosting and lack of feel. Since the Corvette power steering system came from the passenger car, it suffers the same deficiencies. The Corvette's manual steering system with good alignment has good feel and reasonble effort. The fast ratio is great, but low speed effort is high.
We've also been "spoiled" by modern cars, which generally have good sensitivity (not to little, not too much), linearity, self centering torque, and reasonable effort without being overboosted, so hopping into your vintage Corvette on the weekend after driving a modern vehicle all week can be a shock.
High caster promotes more self-centering steering wheel torque, but unless the car has standard power steering, one to two degrees is about the most that can be designed in to avoid excess effort and kickback without boost, but low caster and high boost don't make a very good system.
A good steering system should be precise and linear, and as lateral g increases the self aligning torque should increase. As you reach the limit of adhesion, non-linearity should set in and self aligning torque should decrease slightly, which tells you that the limit of adhesion is approaching.
Even modern cars can have vastly different steering feel. My '88 MBZ steering is relatively numb on center and slow (but precise), so if you sneeze on the autobahn at 130 you don't steer off into the weeds, but it communciates reasonable tire information at high lateral g. To maintain straight travel or a line in a curve you actually must move the wheel slightly. All together - a decent system for a touring sedan, but not too good on a racetrack. It has about 10 degrees caster.
My '91 MR2 (six degrees caster) has an electro-hydraulic power steering system that provides boost based on speed. Above 80 MPH there is no boost. It is extremely precise and sensitive and nearly as communciative as an old 911, but without feeding back every little bit of road texture. Unlike the Merc you don't actually move the wheel to maintain a straight line or line in a corner - just vary pressure on it - like how you handle the stick on a jet fighter. It's like your brain is connected directly to the wheels - altogether a very good system for a serious sports car and excellent on a race track. The one situation where I never liked it was Willow Spring's Turn 8, which is flat in fifth at about 110 MPH. It feels like heavy push, but it's probably the lack of boost. My Cosworth Vega (manual steering zero caster because the adjustment range won't allow postive caster with -1 camber) feels much more neutral (with less effort) at the same speed in Turn 8. Nothing's perfect!
Since I swap the Merc and MR2 back and forth every six months as my daily driver I have to virtually learn to drive all over again, but that makes life interesting.
Duke
Power steering systems were widely criticized back in the fifties and sixties due to overboosting and lack of feel. Since the Corvette power steering system came from the passenger car, it suffers the same deficiencies. The Corvette's manual steering system with good alignment has good feel and reasonble effort. The fast ratio is great, but low speed effort is high.
We've also been "spoiled" by modern cars, which generally have good sensitivity (not to little, not too much), linearity, self centering torque, and reasonable effort without being overboosted, so hopping into your vintage Corvette on the weekend after driving a modern vehicle all week can be a shock.
High caster promotes more self-centering steering wheel torque, but unless the car has standard power steering, one to two degrees is about the most that can be designed in to avoid excess effort and kickback without boost, but low caster and high boost don't make a very good system.
A good steering system should be precise and linear, and as lateral g increases the self aligning torque should increase. As you reach the limit of adhesion, non-linearity should set in and self aligning torque should decrease slightly, which tells you that the limit of adhesion is approaching.
Even modern cars can have vastly different steering feel. My '88 MBZ steering is relatively numb on center and slow (but precise), so if you sneeze on the autobahn at 130 you don't steer off into the weeds, but it communciates reasonable tire information at high lateral g. To maintain straight travel or a line in a curve you actually must move the wheel slightly. All together - a decent system for a touring sedan, but not too good on a racetrack. It has about 10 degrees caster.
My '91 MR2 (six degrees caster) has an electro-hydraulic power steering system that provides boost based on speed. Above 80 MPH there is no boost. It is extremely precise and sensitive and nearly as communciative as an old 911, but without feeding back every little bit of road texture. Unlike the Merc you don't actually move the wheel to maintain a straight line or line in a corner - just vary pressure on it - like how you handle the stick on a jet fighter. It's like your brain is connected directly to the wheels - altogether a very good system for a serious sports car and excellent on a race track. The one situation where I never liked it was Willow Spring's Turn 8, which is flat in fifth at about 110 MPH. It feels like heavy push, but it's probably the lack of boost. My Cosworth Vega (manual steering zero caster because the adjustment range won't allow postive caster with -1 camber) feels much more neutral (with less effort) at the same speed in Turn 8. Nothing's perfect!
Since I swap the Merc and MR2 back and forth every six months as my daily driver I have to virtually learn to drive all over again, but that makes life interesting.
Duke
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