King Pin inclination. To find out more about each of these measurements, click on them. 4. S.A.I. This is because Steering Axis Inclination is a non-adjustable angle. Tech A says that if steering axis inclination is out of spec, A bent control arm may be the cause. STEERING AXIS INCLINATION (and scrub radius) Steering axis inclination (SAI) is the angle measured between true vertical and the inward tilt of the steering knuckle, king pin or McPherson strut tube. Determine if SAI is greater than the specified angle, less than the specified angle, or the correct angle. I … Ditto if SAI is within specs, but the camber and included angle readings are both GREATER than specifications. Steering Axis Inclination (SAI) Steering Axis Inclination, or SAI, is the angle formed between pivot points and vertical line through center of wheel. Steering axis inclination is the angle, when viewed from the front or rear of the vehicle, between the vertical and an imaginary line drawn between the upper and lower suspension swivel balljoints or upper and lower strut mountings. The wheel is then turned to 20 deg outward for a total movement of 40 degrees. SAI & Included Angle Steering Axis Inclination (SAI) is the inward or side to side tilt of the suspension strut top towards the centre of the vehicle, and in all cases is positive. 7. The Steering Axis Inclination (SAI) angle has a direct effect on steering and handling because it causes the wheel spindle to angle downward slightly as the wheel is steered. 7. Above Spec. If the thrust line is to the right of the centerline, the angle is said to be positive; if the thrust line is to the left of center, the angle is negative. Steering Axis Inclination (SAI) SAI is the measurement in degrees of the steering pivot line when viewed from the front of the vehicle. Below Spec. The angle is measured in degrees and taken as positive if the top of the steering axis leans inwards as shown in Figure 4.29. And we don’t drive like granny. SLA - 5 ° - 8 ° McPherson Strut - 9 ° - 15 ° or more . Category: BMW. A multiple question ASE study guide each with a sample ASE Practice Test loaded with illustrated answers and examples for better understanding. Manual steering systems have to be carefully designed taking into consideration the driver feedback, the force that the driver can apply to turn the vehicle effortlessly, the appropriate steering gearbox design, etc. Thanks, T . Category: BMW. ADJUST CAMBER AND CASTER NOTICE: Inspect the toe-in after the camber has been adjusted. It's an angle formed by a line through the centers of the lower and upper ball joints of the strut mount. When a pair of wheels is set so their leading edges are pointed slightly towards each other, this is referred to as toe-in. Toe-in. Roles of Steering Axis Inclination. ADJUST CAMBER AND CASTER NOTICE: Inspect the toe-in after the camber has been adjusted. NOTICE: After the camber has been adjusted, inspect the toe−in. Positive caster is defined as the steering axis tilting back from the wheel centerline in side view (perpendicular to the longitudinal-vertical axis). 2015. Steering Axis Inclination (SAI) SAI is the measurement in degrees of the steering pivot line when viewed from the front of the vehicle. Conversely, "toe-out" would equate to an improved turn-in … pivots. Below Spec. Steering Axis Inclination) is the angle from the vertical defined by the centerline passing through the upper and lower ball joints. Please feel free to rate, comment, and subscribe! The thrust angle is the angle between the thrust line and centerline. The angle between the centre line of the tyre and the vertical line, when viewed from the front of the vehicle, is known as camber. If the angle is not correct, then the suspension system should be checked for damaged or worn parts. If the preferred setting is zero degrees camber, then try to get both wheels as close to zero camber as possible with no more than 1/2 a degree difference between the two. The underlying cause may be a bent strut, spindle or mislocated strut tower. And don’t forget to check out my Facebook page: ADJUST CAMBER. Consequently, you can check the SAI angle and compare it to the camber and Included Angle to diagnose bent parts and/or structural problems in the vehicle itself. Bent Control Arm or Strut Tower (out at … Show Less. If SAI is GREATER than specifications and camber is LESS than specifications, but the included angle is on the money, it’s a sure bet the strut tower is leaning in at the top. Tech A only B. The upper strut mount kits usually provide up to a degree and a half or more of camber/caster movement, while offset control arm bushings or camber bolts allow the lower end of the strut to be repositioned. Regardless of which way the front wheels are turned, the larger the Steering Axis Inclination angle is, the more the car will be raised. This means that if the ... For example, when the wheels are pushed out from the body of the car the scrub radius becomes more positive. This was done to reduce steering effort. A First Gen Camaro has 8.75 degrees steering axis inclination* (SAI) built into it, If you were able to turn the front wheels sharper to a 90 deg turn, the wheels would camber out by 8.75 degrees, minus any positive caster you have set. For example, a typical alignment spec might allow up to plus or minus 1/2 a degree of camber either way on either side. 7. When this angle is out of specifications, there is likely something bent somewhere in the steering or suspension.eval(ez_write_tag([[336,280],'freeasestudyguides_com-medrectangle-4','ezslot_0',116,'0','0'])); The included angle is the fixed SAI with the camber angle included. When realigning the wheels after replacing a set of struts, aim for the “preferred” camber, caster and toe settings. This measurement of degrees includes the measurement from the lower ball joint to the upper ball joint or the upper strut mount and true vertical (the tire sitting straight up and down). Tire Wear & Directional Control. Typical 9 ° – 15 ° SAI on MacPherson. Olson, who is also a regional trainer for Hunter, got right to the point in his Friday afternoon session “Alignment Expert in 90 Minutes,” moving past the caster and camber reds and greens on an alignment spec sheet, and circling the steering axis inclination (SAI). Like caster, SAI affects steering feel and stability. Steering axis inclination (SAI) is the angle measured between true vertical and the inward tilt of the steering knuckle, king pin or McPherson strut tube. The most important point to remember about the SAI angle is that it is a fixed angle that is designed into the suspension. Stay up to date with the latest Underhood Service news. When talking about how much one degree is, one may think, one degree is one degree. There are six basic factors which are the foundation of front wheel alignment, height, caster, camber, toe-in, steering axis inclination and toe-out on turns (Fig. The steering axis angle usually matches the angle of the head tube.. More on this in a minute. causes a) Tendency to assume toe-out orientation b) Generation of a braking effect at tight corners c) Poor recovery of the steering wheel after making a turn d) The vehicle to pull to the side of lesser inclination • Caster angle: angle in side elevation between the steering There is an adjustment screw on the back of the gauge that allows you to set it for 0 deg. Tech B only C. Both A and B D. Neither A or B This offset can be reduced in order to reduce the steering effort. It runs from the lower ball joint through the upper ball joint, or on most front-wheel vehicles, through the center of the strut mount. Functions Reduces or eliminates the scrub radius and gives the system a greater ability to self-centre (i.e. Determine if SAI is greater than the specified angle, less than the specified angle, or the correct angle. Remove the front wheel. SAI is not adjustable; SAI is a diagnostic angle; SAI assists steering returnability The illustration uses ball joints to represent the angle. The most likely cause would be a bent strut and/or knuckle. ADJUST CAMBER. The Steering Axis Inclination (SAI) angle has a direct effect on steering and handling because it causes the wheel spindle to angle downward slightly as the wheel is steered. Above Spec. axis inclination is correct, steering knuckle is bent. Submitted: 12 years ago. Camber is defined as the inclination angle between the side plane (vertical-longitudinal plane) and the rim plane lying on the centerline of the rim. 3) Replace parts and recheck all wheel alignment adjustments. Camber and steering axis inclination: If the caster and steering axis inclination are not within the specified ranges, after the camber has been correctly adjusted, recheck the suspension parts for damaged and/or worn out parts. c. King Pin axis inclination (a.k.a. If you look at the big picture—the state of performance, the quality of roads, the typical driver, etc., back in, say, 1962, you probably would have done the same. Above Spec. Coat the threads of the nuts with engine oil. Notice: After the camber has been adjusted, inspect the toein. Share this conversation. It is designed into the suspension of the vehicle. causes a) Tendency to assume toe-out orientation b) Generation of a braking effect at tight corners c) Poor recovery of the steering wheel after making a turn d) The vehicle to pull to the side of lesser inclination Equal camber angle is provided on both the front wheels. STEERING AXIS INCLINATION (SAI) DIAGNOSTIC CHART MacPherson Strut Suspension System SAI CAMBER INCLUDED ANGLE PROBABLE CAUSE Within Spec. Steering axis inclination angle is also known as the kingpin inclination angle. BMW Mechanic: Roger, BMW Master Tech replied 12 years ago. Above Spec. … • Kingpin inclination angle: Angle in front elevation between the steering axis and the vertical. SAI is not altered in the aftermarket, only returned to the factory setting, perhaps following accident damage. – Steering Axis Inclination . Toe-Out On Turns . SAI Steering Axis Inclination SLC Single Lane Change 1. Steering axis inclination is NOT adjustable. Whos is right? There is an increase in the steering moment at the steering wheel. NOTICE: After the camber has been adjusted, inspect the toe−in. The combination of SAI and caster helps the steering return to center and stay centered because that’s when the spindles are at their highest and most stable position. The Steering Axis Inclination (SAI) angle has a direct effect on steering and handling because it causes the wheel spindle to angle downward slightly as the wheel is steered. Caster, which is the forward or rearward tilt of the steering axis as viewed from the side, does the same thing. Steering Axis Inclination Steering axis inclination (SAI) (fig. Kingpin inclination is also known as: • Steering Axis Inclination (SAI) • Ball Joint Inclination (BJI) KPI is never expressed as a negative measurement. Toe-out on turns, also known as turning radius angle, is the amount the front wheels toe-out when turning corners. The steering axis inclination angle is read off the gauge. Most rear-in vehicles have a high "toe-in," which improves steering stability as the wheels are turning in toward each other slightly. Above Spec. Finally, don’t forget the affect rear wheel alignment can have on steering stability. If SAI is GREATER than specifications, and the camber and included angle readings are also GREATER than specifications, the strut tower is leaning in at the top and/or the spindle or strut may be bent. Usually, the upper ball joint is closer to the vehicle centerline than the lower, as shown in Fig. at the actual (Before) steering axis inclination (SAI) measurement on the alignment report. This angle, when added to the camber to form the included angle (see below) causes the vehicle to lift slightly when you turn the wheel away from a straight ahead position. All this comes down to the design parameters of steering geometry viz. Bent Spindle and/or Strut or Camber Adjustment Below Spec. Yes, we know that some people bend struts successfully to correct alignment problems, but it’s a risky repair that may come back and bite you. SAI (Steering Axis Inclination) spec? INTRODUCTION 1.1 Introduction to Vehicle Dynamics of a SUV Vehicle dynamics is the study concerned with the motion of vehicles on a road surface. You can't turn your front wheels that sharply, but you can turn them around 26 degrees, which is almost 30% of 90 degrees. The major difference between the SAI and the included angle is that the camber angle is added to the SAI angle to obtain the included angle. Therefore, mark the Alignment Angle Diagnostic chart in A free ASE practice test to help automotive technicians and students pass the A4 Suspension and Steering test. Toe @ Curb Ride Height (Positive Value Is Toe-In, Negative Value Is Toe-Out) — — 0.03° ± 0.25° Steering Axis Inclination (SAI) @ Full Load — — 12.3° Included Angle @ Full Load — — 12.3° .. Alignment Specifications — F-250 and F-350, 4x4 . Fig. This is why it's called the included angle. In this example, the specification is 12.7º and the actual angle is 12.7º. This line is tilted inward as viewed from the front of the car and is called “steering axis inclination”( S.A.I) or “kingpin angle”. The SAI angle doesn't include the camber angle. For more information about ASE, visit the official ASE website at www.ase.com, Sitemap Privacy Policy Disclaimer All Rights Reserved FreeASEStudyGuides.com ©Copyright 2008-2021. “SAI is the most important number on the sheet,” Olson said. It is not an adjustable angle and should not change unless something is bent (like the strut, steering knuckle or spindle) or is out of position (like the strut tower, lower control arm, engine cradle or subframe). Kingpin Angle Inclination (KPI) is the inward tilt of the steering axis from the vertical, as v from the front of the vehicle. 3. Typical 5 ° - 8 ° on SLA. The included angle is the … Rear wheel camber and toe also must be checked for a four-wheel alignment. Bent Spindle and/or Strut or Camber Adjstment Within Spec. Most cars are set for 6-10 degrees. Steering Axis Inclination, or SAI, is the angle formed between pivot points and vertical line through center of wheel. 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