Steering discussion

Wanted to get some feedback on what you guys think about a few steering topics all in one for sporty cars:

a) Steering ratio
b) Steering wheel diameter
c) Power vs. Manual Steering
d) Airbag vs. Non Airbag steering wheel

Seems like there is no perfect mix of the first 3, while the last one is just an issue of how big a deal airbags really are.

I tend to prefer manual steering but that's not realistic with every sports car, esp. with the weights and suspension alignments/tire sizes of modern day.

I always wondered why sporting cars with power steering are offered with wheels bigger than 350 mm? It seems like 350 is the sort of ideal size, so start with that and let people go smaller if they wish? Is it ok to go 320 --> 300 so long as you have the strength?

Also, since I haven't driven every car out there I wonder what the practical limits are for say a manual steering car with a semi-quick ratio and a small wheel for like a Caterham or Miata?

There are limits intended for the "average driver" and those who are hardcore drivers who can handle/tolerate a lot more. You could never convince me that Mazda couldn't have left the steering ratios the same for the manual steering cars for the proper enthusiast, which prompted all of those "depowered racks" conversions...

Lastly, considering 99% of cars have power steering why aren't the racks faster on average? 2.0 - 2.5 seems ideal in many cars, yet you still get cars with low 3.0 - 3.3 turns lock to lock needing to go aftermarket for extra speed.

Should be fun discussion.

 

Bump for discussion solely on steering wheel size.

What size wheel(s) do you prefer?

 

manual steering works great on my fiero but then it does take some work turning the wheel when parked and for spirited driving a somewhat quicker ratio would be nice.

how do you mean?

there is a limit to how quick a manual rack can be in a car that is used daily. you want a quick rack for active driving but then you also want it to be reasonably easy to live with when parking. I've found the loss of servo assistance in my volvo (engine died as I entered a turnabout) to be very problematic. Higher speeds and less tight turns require less servo assist.

because there is such a thing as too quick steering. Most drivers would be likely to get themselves into trouble with racks that are too quick as they aren't really active drivers. The hot chick in a small hatchback, the young dork in a corvette, the teacher in a volvo and the old dude in the ferrari all have different needs and expectations and most of them probably prefer a slightly slower rack for reasons of comfort.

 

1) Practical limits for manual steering - meaning, at what point is heavy too heavy for even the most hardcore driver? A Miata IMO shouldn't have a slower manual rack when the power rack ain't even that fast to begin with.

Caterham 7s are often fitted with 300mm or smaller steering wheels and sometimes with fast ratio racks...love it!

2) Loss of servo in a powered rack isn't the same as a pure manual rack. It's the worst for steering effort.

3) I hear you on the average driver thing. Just wondering why Ferrari now offers lightning fast racks on cars with twice the hp over 20-30 years ago? 458, F12 are close to 2.0 lock to lock, while a 308 is way slower.

I'm sure the engineers have good reasons for what they do, but often protecting amateurs is a reason I hate having to deal with.

 

indeed. But then they are also very light cars. like 600kg or thereabout? that does make things a bit easier.
How fast is the miata rack? And if you disable the servo, how much effort is it to steer the car? the lock-to-lock number is pretty meaningless, the interesting number is the ratio between the angle of the wheels and the angle of the steering wheel.

not exactly the same but pretty damn close. Of course this was a 1,5 ton car loaded with people and designed with servo-assisted steering. But remove all the servo stuff from that rack and you have a very heavy manual rack that's not really suited for the street in that car.

They do have variable servo now, don't they? Noticed on my dads C6 how easy it was to steer at slow speeds and then progressively needed more effort as the speed went up. That might be one reason why they can use quicker racks now. Not only can the servo be varied so that the steering feels good at all times while still being light, it can also be varied to avoid unintentional driver input. In the old days, you had one setting and that was it.
Plus the improvements in tires and suspension and all the driver aids available to save wanna-be racers asses (or rather to save everyone else from the messes wanna-be racers would otherwise create)

engineers always have good reasons for what they do. because that's what engineers do.

 

Also depends on the car, it's intended use and driver preference.

A Viper that is used in open road races will have different needs than an MR2 for Autocrossing.

LSJ