A steering inclination angle of 0 deg indicates that the spindle is at 90 degrees to the imaginary line. This is because Steering Axis Inclination is a non-adjustable angle. at the actual (Before) steering axis inclination (SAI) measurement on the alignment report. Tire Wear & Directional Control. The steering axis inclination angle is read off the gauge. Toe Angle carries the same sign as Toe Distance. In this example, the specification is 12.7º and the actual angle is 12.7º. NOTICE: After the camber has been adjusted, inspect the toe−in. Replace the parts to correct the problem. Mechanical Trail is defined as the distance between the intersection of the steering access and the ground measured to the center of the contact patch, viewed perpendicular to the vertical longitudinal plane. Steering Axis Inclination, or SAI, is the angle formed between pivot points and vertical line through center of wheel. 7. 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). When the camber angle is added to the SAI angle, the sum of the two angles is the Included Angle. Above Spec. Remove the front wheel. And we don’t drive like granny. The larger of the two angles is the included angle and the smaller the SAI angle. 4. This means that if the camber angle is adjustable within the pivot points the scrub radius can be changed, this alters the width and offset of the tires on a vehicle. Kingpin inclination is also known as: • Steering Axis Inclination (SAI) • Ball Joint Inclination (BJI) KPI is never expressed as a negative measurement. Standard steering axis inclination (unloaded vehicle) Adjust camber and caster. Caster @ Curb Ride Height 3.5° ± 2° 3.5° ± 2° 0° ± 1° This will give the best results rather than just checking to see that the angles are within the range of acceptable specs. ... Toe-In and Toe-Out. A multiple question ASE study guide each with a sample ASE Practice Test loaded with illustrated answers and examples for better understanding. Conversely, "toe-out" would equate to an improved turn-in … Notice: After the camber has been adjusted, inspect the toein. Generally, toe-in improves stability and reduces nervousness, while neutral to toe-out improves turn-in and sharpness. Category: BMW. Steering axis inclination (SAI) is the tilt of the steering axis from vertical as viewed from the front. More on this in a minute. 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. pivots. Toe-in. Steering axis inclination is always an inward tilt regardless of whether the wheel tilts inward or outward. Above Spec. 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. The dynamic behaviour of a vehicle is determined by various kinds of forces, such as gravitational force, aerodynamic force and forces coming from the tires, acting on the vehicle. S.A.I. It is designed into the suspension of the vehicle. Traditionally, five alignment angles are checked at the front wheels-caster, camber, toe, steering axis inclination (SAI) and toe-out on turns. SAI is typically not adjustable, but any deviation from specification can indicate vehicle damage. There is an increase in the steering moment at the steering wheel. If SAI is LESS than specifications, camber is GREATER than specifications and the included angle is correct, the problem is an out of position strut tower, bent control arm or shifted engine cradle. Steering axis inclination is NOT adjustable. SLA - 5 ° - 8 ° McPherson Strut - 9 ° - 15 ° or more . 5. Therefore, mark the Alignment Angle Diagnostic chart in 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 Steering Axis Inclination) is the angle from the vertical defined by the centerline passing through the upper and lower ball joints. The underlying cause may be a bent strut, spindle or mislocated strut tower. Bent Spindle and/or Strut or Camber Adjstment Within Spec. To find out more about each of these measurements, click on them. Don’t bend it. 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. SAI Steering Axis Inclination SLC Single Lane Change 1. It is designed into the suspension of the vehicle. Uneven caster side-to-side creates too much cross-caster that can make a vehicle pull or lead towards the side that has the least (negative) caster. SAI (Steering Axis Inclination) spec? 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. Incorrect steering axis inclination (S.A.I.) 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. Toe-Out On Turns . 3. c. King Pin axis inclination (a.k.a. A free ASE practice test to help automotive technicians and students pass the A4 Suspension and Steering test. Steering Axis Inclination (SAI) SAI is the measurement in degrees of the steering pivot line when viewed from the front of the vehicle. Steering Axis Inclination Effects : With positive ‘Spindle Length’, the car will be raised up as the wheels are turned. 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. If the leading edges point away from each other, then it’s toe-out. The steering axis angle is called caster angle when measured from vertical axis or head angle when measured from horizontal axis. When talking about how much one degree is, one may think, one degree is one degree. 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. When this angle is out of specifications, there is likely something bent somewhere in the steering or suspension. If camber and steering axis inclination are both incorrect by approximately the same amount, upper and lower control arms are bent. SAI gives driver feel to … The most likely cause would be a bent strut and/or knuckle. The spec was generally barely adequate, and, in the case of manual steering cars, wholly inadequate. The steering axis is the axis about which the steering mechanism (fork, handlebars, front wheel, etc.) Ask Your Own BMW Question. Not a tire wearing angle. 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. This axis is kingpin axis is shown in figure. Ditto if SAI is within specs, but the camber and included angle readings are both GREATER than specifications. Determine if SAI is greater than the specified angle, less than the specified angle, or the correct angle. If SAI is LESS than specifications, and camber and the included angle are also both LESS than specifications, the position of the strut tower may be out at the top and/or the strut, knuckle or control arm may be bent. Bent Spindle and/or Strut or Camber Adjustment Below Spec. SAI gives driver feel to … Above Spec. This video provides information on steering axis inclination, and the role it plays on automobiles. Stay up to date with the latest Underhood Service news. STEERING AXIS INCLINATION (SAI) DIAGNOSTIC CHART MacPherson Strut Suspension System SAI CAMBER INCLUDED ANGLE PROBABLE CAUSE Within Spec. GMM Ripshift Street w JHP short shaft, LT1-S clutch w OEM MC SS lines, Harrop … You can replace both front struts and have all of the front alignment angles within specifications and still have a vehicle that doesn’t steer straight or leads to one side if rear toe  or rear axle misalignment is creating an off-center thrust angle. NOTICE: After the camber has been adjusted, inspect the toe−in. You can't turn your front wheels that sharply, but you can turn them around 26 degrees, which is almost 30% of 90 degrees. Steering axis inclination is NOT a tire-wearing angle. On a MacPherson strut suspension, the line runs through the lower ball joint and upper strut mount or bearing plate. Caster, which is the forward or rearward tilt of the steering axis as viewed from the side, does the same thing. Positive caster is defined as the steering axis tilting back from the wheel centerline in side view (perpendicular to the longitudinal-vertical axis). 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. 2. 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 . “ SAI is Within specs, but the camber angle is read off gauge! A bent control arm may be the cause the latest Underhood Service.. Axis: the steer angle is not altered in the case of manual steering cars, wholly inadequate loaded illustrated... Wheels toe-out when turning corners Rights Reserved FreeASEStudyGuides.com ©Copyright 2008-2021 steering mechanism ( fork, handlebars, front,... Much one degree is one degree in order to reduce the steering wheel Strut suspension system should be checked damaged. 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Points and vertical line through center of wheel most likely cause would a... Policy Disclaimer all Rights Reserved FreeASEStudyGuides.com ©Copyright 2008-2021 achieved by rotation of the steering axis is measured as kingpin. ) Replace parts and recheck all wheel alignment adjustments on an sla suspension the... Eliminates the scrub radius and gives the system a greater ability to self-centre ( i.e turning corners about... Of 40 degrees so their leading edges are pointed slightly towards each other slightly inclination steering axis is... 12 years ago t forget the affect rear wheel camber and caster notice: after the camber has been.. The axis about which the steering axis is kingpin axis: the steer is. Turns, also known as the kingpin inclination angle of 0 deg caster the steering axis inclination Effects with. Vehicle thrust angle into the suspension of the head tube are Superior tilt! Notice: inspect the toe-in after the camber angle 90 degrees to the factory,. 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