Minimum Steering Angle
Minimum Steering Angle
(OP)
Hi all,
What is consider the minimum required steering angle (at the wheels) for a street driven vehicle in order to have a reasonable turning radius? This will be a function of the wheelbase, so if anyone has a handy formula available as well as any comment it would be greatly appreciated. Thanks.
Joest
What is consider the minimum required steering angle (at the wheels) for a street driven vehicle in order to have a reasonable turning radius? This will be a function of the wheelbase, so if anyone has a handy formula available as well as any comment it would be greatly appreciated. Thanks.
Joest





RE: Minimum Steering Angle
radius=track/2+wheelbase/sin(average steer angle)
This does not define the wall to wall turning circle, for which you need to consider body overhangs.
Reasonable is a bit hard to define, it depends on the vehicle. For instance a London Taxi will have an 8m turning circle, whereas we'd say 11-12 m is reasonable.
For a sports car more than that would be acceptable.
You'll find that in practice your Ackerman has a strong effect on what is achievable, it may be worth exceeding 100% at full lock, as usually the back of the inside tyre hits the chassis rail before the front of the outside wheel.
Cheers
Greg Locock
RE: Minimum Steering Angle
is there a typo in there somewhere?
RE: Minimum Steering Angle
I think the formula work as long as you enter everything is consistant units. Also make sure your calculator is set for input in degrees and not radians if that is what your angles are in.
Joest
RE: Minimum Steering Angle
From a consumer standpoint - "reasonable" depends on the intended use of the car. If it frequently involves tight turns, as in parallel parking or parking in lots with relatively narrow spaces and aisles, anything greater than about 10m will feel "clumsy". Note that the above are common design features for increasing lot capacity, customer convenience be damned.
My '01 Nissan Maxima, which with 17" wheels requires ~10.5m/~41 ft, frequently demands a back-and-fill straightening maneuver in the above circumstances. That's very annoying and impossible to avoid noticing, especially when another car that I have that features a wheelbase that's barely 5mm shorter than the Maxima almost never needs a second attempt to get square and centered in the space.
Norm
RE: Minimum Steering Angle
Excel uses radians by default. how clever. using computer software to simplify things......
ok, so the formula works. on my 61.75" track, 108" whlbase camaro, i'd need roughly 46 degrees of steering to pull a 10yd turning circle. ouch....
anyone know off-hand what maximum steer angle is for a typical RWD production car? i doubt it's that high.
RE: Minimum Steering Angle
Let's see, typically (just less than) three turns lock to lock, through a 20:1 ratio that's 54 degrees.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Minimum Steering Angle
maybe a little over 30 feet "between curbs"
240s have about a 108 inch wheel base, and at full lock the there is an im-modest amount of suspension exposed to the outside world.
RE: Minimum Steering Angle
Wheelbase = 102.8" (2611 mm)
Track = 59.1" (1501 mm), same for both front & rear tracks
Maximum steering angle, inner = 37* +/-2*
Maximum steering angle, outer = 32* +/-2*
Rack stroke = 5.39" (137 mm)
Published ratio = 17.0:1
Steering wheel turns, lock to lock = 2.9 (sales brochure)
Steering wheel turns, lock to lock = 3.1 (service manual)
Turn circle diameter, curb to curb = 34.8 ft (10.6 m)
Car is a 1995 Mazda 626.
I'd also like to correct my earlier statement to say that it is more like a 12 m turn circle where maneuvering in tight places has a clumsy feel. (Math done in haste is also a waste.) Apologies to Greg and anybody who assumed that the metric value was the primary data.
Norm