How is toe in measured

Also, an off-center steering wheel can sometimes be corrected by adjusting one tie-rod more than the other. Steering wheel position has no effect on your final alignment. Camber Camber is the measurement of tire lean in degrees. If the top of the tire tilts inward, the vehicle has negative camber; outward lean is positive camber. Most newer vehicles have slightly negative camber to improve stability and handling.

Two indicators of camber problems are the vehicle pulling to one side the one with more positive camber or possibly less air in the tire and uneven tire wear across the tread. Camber is easy to check with an angle finder and a straight edge, ideally one that's the same length as the wheel diameter so that tire sidewall bulge doesn't interfere with the straight edge. Many front-wheel-drive cars don't have camber adjustments, and out-of-spec camber here often indicates bent or worn parts.

On vehicles that have adjustable camber, the job can involve adding shims between the control arms and frame and turning cam bolts. Many people prefer to let an alignment shop make these adjustments, particularly if their car has independent rear suspension.

Caster Caster is the angle of steering pivot in degrees. Just as water-skiers lean backward for stability, most vehicles are designed with slight negative caster — the upper ball joint is to the rear of the lower ball joint similar to the front wheels on a shopping cart.

A clue to caster problems is the vehicle pulling to one side the one with less positive caster. Heavy steering and wheel hopping over bumps are signs of too much positive caster, and light steering but excessive wander are clues of too much negative caster. Aligning to spec usually involves repairing or replacing chassis parts, so the average motorist is probably better off leaving caster corrections to the pros.

Taking a few minutes to check your alignment will make your tires last longer and your vehicle handle better. Even if you choose to have a shop align the vehicle, you'll have a better idea of the problem — and knowledge normally equals power. Irregular tread wear signals alignment problems. A saw-tooth pattern left indicates a toe problem, and beveled wear right points to camber problems. Courtesy Hunter Engineering.

Toe is the fore-and-aft difference in tire distance. Most vehicles are slightly toe-in for a lighter steering feel and to keep a slight pre-load on wheel bearings.

Post by: paddy » Sat Jan 17, pm. Post by: alan71 » Sun Jan 18, pm. Post by: twincamman » Sun Jan 18, pm. Post by: stuartgb » Sun Jan 18, pm. Post by: paddy » Sun Jan 18, pm. Post by: twincamman » Sun Jan 25, pm. This website is supported by the contributions of our members. To review the Contributing Member Benefits. If you would like to keep this website up and running, please consider contributing:. This feels like a really stupid question but when measuring toe in where do you measure, is it at the rim diameter or the tyre diameter.

Also what would you guys recommend I set the toe in to? Many thanks Andy. Works great.. Tony Vaccaro www. Andy, I've just done my car this week having reconditioned and modified the rack for wider wheels. The seating table being movable in at least a transverse direction of the vehicle or a rotational direction of the seating table as viewed in plan with respect to a predetermined base member. The measuring unit further comprising a measured member having a vertical measurement surface extending outwardly from the seating table, and a pair of distance measuring means for measuring respective distances from two positions which are spaced from each other by a predetermined distance, to the measurement surface with respect to the base member.

The measuring unit further comprising a toe angle calculating means for calculating the toe angle based on measured values from the distance measuring means. The measurement surface of the measured member is oriented at an acute angle with respect to the transverse direction of the vehicle as viewed in plan at least when a measurement is made.

As described above, the measurement surface of the measured member extends outwardly with respect to the wheel or the mount for the wheel, and is oriented at the acute angle with respect to the transverse direction of the vehicle as viewed in plan.

Therefore, a large displacement of the wheel or the mount in the transverse direction of the vehicle is converted into a small displacement of the measurement surface in the longitudinal direction of the vehicle. Consequently, even if the installed position of the vehicle is greatly displaced from a standard position, the distances can be measured reliably and highly accurately, and the toe angle can be measured without the need for limiting the attitude of the vehicle.

The toe angle is determined by measuring the distances with the distance measuring means disposed in the two positions spaced by the predetermined distance.

If the measuring unit is provided at each of four wheels of the vehicle, and the distance measuring means of the measuring units simultaneously measure the distances to the corresponding measurement surfaces, then distances can be measured efficiently. The measuring unit may include a moving unit for moving the measured member into abutment against a side face of the wheel or a side face of the mount for the wheel.

The moving unit allows the measured member to be held in a position slightly spaced from the vehicle when no measurement is made. When the measured member is held in abutment against the side face of the wheel or the side face of the mount for the wheel, the distances can be measured reliably and accurately.

According to the present invention, a toe angle measuring method of measuring a toe angle of a wheel of a vehicle comprises the first step of seating the wheel or a mount for the wheel at a fixed position on a seating table which is movable in at least a transverse direction of the vehicle or a rotational direction of the seating table as viewed in plan with respect to a base member.

The second step is of urging a measured member having a vertical measurement surface extending outwardly from the seating table and oriented at an acute angle with respect to the transverse direction of the vehicle as viewed in plan at least when a measurement is made, against the wheel or the mount for the wheel.

The third step is of measuring respective distances from two positions which are spaced from each other by a predetermined distance, to the measurement surface with respect to the base member.

The fourth step is of calculating the toe angle based on measured values from the third step. As the measurement surface is oriented at the acute angle with respect to the transverse direction of the vehicle as viewed in plan, a large displacement of the wheel or the mount in the transverse direction of the vehicle is converted into a small displacement of the measurement surface in the longitudinal direction of the vehicle.

The toe angle to be corrected is determined by measuring the distances with the distance measuring means disposed in the two positions spaced from the measurement surface by a predetermined distance. The toe angle to be corrected can be used as a basic value for calculating a toe angle. An apparatus for and a method of measuring a toe angle according to an embodiment of the present invention will be described below with reference to FIGS.

As shown in FIGS. Of the four measuring units 18 , the two rear measuring units are disposed on rails 21 for sliding movement in the longitudinal direction of the vehicle depending on the wheelbase of the vehicle The vehicle 14 is basically fed to a position intermediate between the left and right pairs of the measuring units With the above structure, the seating table 46 is smoothly movable on a horizontal plane in the transverse direction of the vehicle 14 , the longitudinal direction of the vehicle 14 , and in the rotational direction, and is held in a so-called floating state.

The rod of the main cylinder 30 , the rod of an auxiliary cylinder 54 to be described later, and a push rod 56 can be extended and contracted by the controller The measuring unit 18 also includes a seating base 48 disposed substantially centrally on an upper surface of the seating table 46 , a slider 50 mounted on the seating table 46 by a stay 46 a , and a hub side face presser 52 which is guided in the transverse direction of the vehicle by the slider The measuring unit 18 further includes an auxiliary cylinder 54 mounted on the stay 46 a for actuating the hub side face presser 52 , a push rod 56 mounted on an end of the second base member 36 for actuating the horizontal movable plate 40 in the transverse direction of the vehicle, and two laser-type noncontact distance sensors distance measuring means 62 a , 62 b mounted on two stays 60 extending upwardly from a bracket 58 which extends from the end of the second base member The seating base 48 has a recess 48 a see FIG.

The hub side face presser 52 includes a connector 64 fixed to an end of the slider 50 and extending upwardly, a hub presser disk 66 connected to an upper portion of the connector 64 and disposed in facing relation to the hub 16 , and a measured member 70 having a measurement surface 68 which extends outwardly from the connector When the hub side face presser 52 is moved by the auxiliary cylinder 54 , the feelers 66 a are brought into contact with the side face of the hub 16 that is seated on the seating base The measured member 70 is of a triangular shape with a distal end having an acute angle as viewed in plan see FIG.

The hub side face presser 52 has a hole 70 a defined therein for reducing the weight thereof. The measurement surface 68 is a vertical surface facing rearward in the longitudinal direction of the vehicle, and is elongate horizontally.

The measurement surface 68 is oriented at an acute angle with respect to the transverse direction of the vehicle. In FIGS. The seating table 46 is rotatable as viewed in plan, and the measurement surface 68 may have an acute angle with respect to the transverse direction of the vehicle 14 at least when measured.

The two noncontact distance sensors 62 a , 62 b are disposed in facing relation to the measurement surface 68 at respective positions that are horizontally spaced from each other by a certain distance y 1. The noncontact distance sensors 62 a , 62 b are arrayed such that the noncontact distance sensor 62 a is positioned outwardly and the noncontact distance sensor 62 b inwardly.

This layout of the noncontact distance sensors 62 a , 62 b allows them to measure respective distances x 1 , x 2 along lines normal to the measurement surface 68 from the two positions in a noncontact fashion. The measured distances x 1 , x 2 are supplied to the controller The measuring unit 18 shown in FIGS. A right measuring unit for use with the right front wheel or the right rear wheel is symmetrical in structure to the left measuring unit, and will not be described in detail below.

As shown in FIG. The above functional units are realized when the CPU reads a program and performs software processing in coaction with the storage units, etc.