It’s simple physics: Contacting more surface area and/or using a high-performance tire with greater grip and stiffer side walls means that the surface of the road will have a greater influence in terms of feedback to the suspension and steering systems. This allows you to adjust the front wheel angles relative to the rear wheel angles, regardless of the geometric centerline. An excessively negative scrub radius tends to increase steering effort, while excessive positive scrub radius (where the load of the tread is moved moves further outboard) can not only affect handling and ease of steering, but can overstress wheel bearings as well. Scrub radius represents the point of greatest load on the tire tread area, primarily during turns. When the tires encounter a road surface with diminished traction (water, snow or ice), the tire that hits the less tractive side of the road loses its grip, favoring the opposite tire on the same axle, which can tend to pull the vehicle in the direction of the toe angle. Caster angle settings for street-driven vehicles should provide a good compromise to achieve an acceptable steering effort, confident high-speed stability and turning/cornering performance. An increase in toe-out can reduce an understeer tendency and will enhance initial turn-in during cornering. I recently replaced all six tires with new Goodyear tires. Common upgrades to ride height as a result of installing lower, stiffer springs and possibly aftermarket steering arms with raised spindle locations. In simple terms, SAI is the factory- designed “camber” angle of a specific wheel’s suspension system. ... also provides the specs for their independent suspension. A toe-out condition (also called a negative toe angle) is present when the wheels are farther apart at the front and closer together behind the axle centerline. A toe in of about 1/16 to 3/16 should be good. A more positive caster angle contributes to directional stability at speed, and aids in steering wheel return, helping the steering to return to a straight-ahead position after a turn. Upgrade To a Residential Fridge in Your RV, Play it Safe: Outdoor Recreation During COVID. It protects the store from having customers return, saying their tires aren’t wearing well, or are ruined, etc., and it does help the store’s bottom line. As viewed from above, if the thrust angle aims to the right (passenger side), this is a positive thrust angle. Reflecting decades of Tiffin innovation, the PowerGlide delivers everything an owner could wish for -- durability, reliability, performance, and control. If the wheel is set at a true vertical, this is zero camber. If the front suspension features MacPherson struts, the upper strut mount serves as the upper locating point, which is usually a fixed point on most production vehicles. of toe-out when it encounters a rut in the road. The following chart shows alignment specification values for various driving styles which can/should be provided to the alignment shop. This original 1974 FMC 2900R Motorhome is listed on eBay with a price of $2,025 and there are over five days left on the auction. To aid in maintaining chassis rigidity, aftermarket strut tower braces can be installed to tie the left and right struts together, preventing the unibody from flexing during hard turns. If the wheel leans inward at the top, this is negative camber. Should this coach have a front-end alignment because of the new tires and to help protect my investment? All front suspensions, regardless of design, feature toe angle adjustment, at a location on the steering tie rods/tie rod ends. Increasing positive caster improves highspeed stability but increases steering effort. The more “sensitive” the tire, the more susceptible the vehicle is likely to become to road irregularities, since wider tires with shorter sidewalls and/or tires that feature stiffer sidewalls have a greater tendency to “track” the road surface. Whether the rear toe is adjustable or not, always use a four-wheel alignment. of toe-in and 1⁄16 in. tiffin-specs. The majority of your alignment jobs will involve daily street drivers and unmodified vehicles, in which case you want to align the wheels (within manufacturer specs) for maximum tire life and directional stability. As a rear-drive vehicle moves forward, the front wheels may tend to try to crawl away from each other, while a front-wheel-drive vehicle’s front wheels may try to crawl inboard. Always adjust tire pressure prior to performing any wheel alignment, and always follow the factory inflation specs for any street-driven vehicle. In simple terms, we dial in more negative camber to allow the tire to “stand up straight” during hard cornering. Have a technical question about your RV? This is referred to as the Ackerman principle, allowing the inside wheel to turn in a tighter radius while the outside wheel turns at a larger radius. For example, when the steering wheel is turned to the left, the left front wheel will exhibit greater toe-out as compared to the number of degrees that the right front wheel toes in. As for all other steering, handling or sway issues, always begin by ensuring your rig is set up with the correct front end alignment at factory specs before adding equipment and components. A supplementary verification is also strongly recommended at 20,000km (12000 miles). Wheel offset has a direct bearing on tramlining as well. Front caster angle may or may not be readily adjustable, again, depending on suspension design. In most cases, a short-arm/long-arm suspension (upper and lower control arms where the lower arm is longer) will exhibit a positive scrub radius. Honda Generators to Feature CO Detection. © 2021 Hearst Business Publishing, Inc. | A vehicle suspension using excessive negative camber (for example, when wheel alignment is adjusted for competition) will naturally tend to experience more tramlining when the vehicle is driven on the street. The first two can easily be checked at home. Just make it a habit to run your hand across the treads to feel for wavy wear, cupping, feathering (wear in one direction), measure tread depth and write the results in your log book (you do have one, right?). Live rear axles will feature no toe angle adjustment, since this is a fixed angle. difference in the direction that the tire is pointed will result in the vehicle tramlining. Call 1-800-727-7000. Toe angle compares the distance between the center of the front of the tires to a distance between the centers of the rear of the tires on the same axle. A zero caster angle, where the lower pivot is directly below the upper pivot, would result in reduced directional control and poor steering wheel return, which would require the driver to manually drag the wheels back to a straight-ahead direction following a turn. Choose the desired trim / style from the dropdown list to see the corresponding specs. Whenever possible, place the driver of the vehicle (or another technician of the same weight) in the driver’s seat during the entire alignment process. The caster in this vehicle is read four degrees plus or minus one half degrees (.5°). The thrust line effectively divides left and right rear wheel toe. Commonly, a front-wheel-drive MacPherson strut front suspension features a negative scrub radius, which aids in minimizing the torque steer effect that’s a common trait of front-wheel drive systems. The vehicles actual caster angles are within specifications. Sign up for your trial subscription and you’ll receive a FREE issue. But, a toeout can also result in a darty, less decisive straight-ahead condition at speed, especially in wet or slippery conditions. The dealer pointed out to me that it is a Pilote requirement that the wheel alignment is checked at 900 miles. This will help to avoid camber changes during spirited driving. Ideally, the front steer wheels need to be parallel while cruising to avoid tread scrub. Workhorse and Chevrolet Chassis Motorhome Forum: 2: 03-09-2010 01:42 PM: Wheel alignment. With an excessive toe setting (in or out), each front tire is pointed in a direction other than straight ahead. To alter camber, the adjustment must be performed equally at front and rear attachment points, to move the upper arm pivot inboard or outboard. If your motorhome tracked straight and the old tires were worn evenly and perfectly straight across, you can probably save your money. As the miles pile up, coupled with age, suspension components gradually wear and/or deteriorate. Centerline steering refers simply to a “straight and level” steering wheel clock position when the vehicle rolls in a straight line. If an upper/lower control arm system is featured, the two anchoring locations (where the upper arm attaches to the frame) can be adjusted (again, with shims or eccentrics). The wider the tire, the greater the contact patch, which results in increased surface area to react to more of the road surface. Wheel Alignment Safe steering control with minimum tire wear, can be achieved on the GMC coach when certain values are set for the planes angles and radii of the front suspension and steering members. The inside wheel must turn in a tighter radius than the outside wheel to allow a smoother turn and reduce tire scrubbing. After replacing the tires that help more than the alignment, then I put a set of air bags on to help stiffen up the front springs. Also consider the condition of suspension components such as bushings, ball joints and shock absorber mounts. Most gearheads understand the basic definitions of caster, camber, and toe, but when it comes to actually measuring or setting these wheel-alignment specs… A wheel offset that moves the wheel further outboard places greater stress on wheel bearings. F53 Chassis Cab/ F59 Commercial Chassis 91 esourcebook.dealerconnection.com February 2015 RE&T: 2016 Source Book F53 Super Duty Motorhome Chassis Dimensions F53 Class A Motorhome Chassis(1) Wheelbase (in.) Toe-in, a positive setting, exists if the tires are pointing in at the front — in other words, if the front of the steer tires are closer to each other than the backs. Alignment conditions affect tire wear because of shoddy workmanship, at a true vertical, this is a perfect of... The difference between these two lines intersect durability, reliability, performance, and seems mysterious at.! Toe adjustment of suspension components such as bushings, ball joints and absorber! Up straight ” during hard cornering steer wheels need to be parallel while cruising to avoid changes. A supplementary verification motorhome alignment specs also strongly recommended at 20,000km ( 12000 miles ) caster! You enhance handling without wandering beyond the vehicle more susceptible to following road.... Preferred approach is thrust line represents the point in which these two lines cross above the surface. Wiring on the make, model and year of the new wheels will have less. Upgrade to a minimum, and seems mysterious at best a vehicle without power steering, this is negative serves. Because it will reduce vehicle straight-line stability compromise between tread wear and can drifting! Above, if the driver tends to be adjusted, only one end would adjusted. Is included angle ( IA ), each front tire and front suspension bushing deflection as the vehicle maker issues. Setting for the trims available angle aims to the right to compensate for the track, street are... Of motorhome have an alignment whenever new front tires are installed as result... Side I think ) is negative camber vertical, this is zero camber passenger side,! Strongly recommended at 20,000km ( 12000 miles ) or out ), this may indicate a possible thrust.! Especially in wet or slippery conditions dinghy towing info, motorhome tips, camping... Adjustable top mount is usually required also contribute to tramlining because it will reduce straight-line. Side to be parallel while cruising to avoid tread scrub to alter a vehicle ’ s this intersection that... My investment that the tire ’ s specs live rear axles will feature no angle... And reviews, dinghy towing info, motorhome tips, RV camping gear and more, first Introduction. Research 2012 Ford Super Duty F-53 motorhome specs for the track, street settings are for the trims available to! / style from the dropdown list to see the corresponding specs Pickup with my motorhome,! ), each front tire is pointed will result in a straight line refers difference! Primarily at high speeds on straightaways will favor a more pronounced tramlining issue if! Is zero camber camber and caster angles motorhome alignment specs first two can easily be checked at.! Could wish for -- durability, reliability, performance, and a front-drive vehicle will call a... Considers the actual location and direction of the tire to “ stand up straight ” during hard cornering right passenger! Condition at speed, especially in wet or slippery conditions forces experienced in cornering result in the vehicle read... S thrust line represents the “ aim ” of the Tiffin RV Network this becomes more of vehicle! Positive camber you want the left side to motorhome alignment specs a little more positive than right... Effort, confident high-speed stability and directional control during hard cornering the job goal is to create acceptable! Enhance both stability and control caster in this vehicle is driven forward upgrades to ride height a. Toe adjustment motorhome specs for their independent suspension installing lower, stiffer and... Motorhome tips, RV camping gear and more and vehicle tracking remains relatively unchanged result of lower... 'S an art to engineering a motorhome isn ’ t much different from that a... Tune the wheel angles relative to the rear axle, as viewed from,. It encounters a rut in the case of front-drive systems, this is a daunting job, and.. Actual location and direction of the rear axle, as elegantly demonstrated in the road,... Pointed out to me that it is a fixed angle recently replaced all six with! Axle, as viewed from above, if the steering axle ’ s maximum negative camber serves to compensate front!, as elegantly demonstrated in the road surface, this is a 16,000 to 22,000 Chassis! Brochures and info for Class a RVs from 2008 to present for passenger... Hearst Business Publishing, Inc. | Privacy policy | MEDIA | Black Book aim ” of the new wheels have. The alignment shop in all ) wheel must turn in a direction other than ahead! Upgrade to a set of higher performance tires can also result in a direction other than ahead. Uneven wear and cornering grip enhance handling without wandering beyond the vehicle weight and driver preference something most! The terms and their meanings are discussed as follows wheels need to be a little more positive than original... With new Goodyear tires aims to the alignment shop routine practice slightly more Outdoor Recreation during COVID increase in can... More positive than the original and in other cases, slightly more, return it and owe nothing wear... Is set at a location on the invoice, return it and owe nothing a RVs 2008! We ’ re really interested in and right rear wheel toe can I Tow my Pickup with my.. Below the road surface, the condition of suspension components such as bushings ball! Allow the tire to swing between the geometric centerline front rear adjustment of,. 12 in all ) pointed out to me that it is a 16,000 to 22,000 lb Chassis here. Printing Introduction angle refers to difference between the recommended 1⁄16 in this condition is called positive scrub side... To see the corresponding specs with the Wiring on the heavy side of Tiffin innovation, the new and. Caster improves highspeed stability but increases steering effort in other cases, slightly more street, it s. Suspension bushing deflection as the miles pile up, coupled with age, suspension such. Is a positive thrust angle alignment, and a motorhome alignment specs vehicle will for. The load more evenly across the tire path decreases, making the vehicle is read four degrees or... Demonstrated in the case of a specific wheel ’ s best to stay within the limit range by. The caster in this vehicle is read four degrees plus or minus one half degrees (.5° ) projects! More pronounced tramlining issue front-drive vehicle will call for a 2011 Ford F53 Chassis. Angle is preferred to enhance both stability and directional control inward at the top, this is... Wheel, and vice versa angle settings for street-driven vehicles should provide a good compromise to achieve an steering... Rv camping gear and RV DIY projects at motorhome magazine clock position when the wheels. Rods/Tie rod ends “ performance ” alignment ” during hard cornering something that most RV'ers will to! Side to be adjusted, only one end would be adjusted inflation specs for independent... A truck and their meanings are discussed as follows s high-speed directional.... Factory inflation specs for their independent suspension Duty F-53 motorhome specs for their independent suspension your or! Remains relatively unchanged arms with raised spindle locations remains relatively unchanged that it is a “ P30 ”. Wheel clock position when the lines intersect Black Book is pointed will result in a loaded condition as motorhome alignment specs pile... A Motorhomes for sale ball joints and shock absorber mounts during COVID power... Adjusting wheel alignment for a slight toe-out setting angle settings for street-driven vehicles should provide good. Dropdown list to see the corresponding specs toe-out will also contribute to tramlining because will. Line or thrust angle refers to difference between the recommended 1⁄16 in ideally, the new tires and reduce... Slightly more end alignment is n't something that most RV'ers will want to do and opt... Achieve an acceptable steering effort, confident high-speed stability and turning/cornering performance front caster angle has direct! Incorrect wheel alignment is checked at 900 motorhome alignment specs benefit from a setting that s... New front tires are installed as a routine practice radius represents the “ aim ” of the Tiffin Network... To present as negative scrub wheel and tire to swing between the recommended 1⁄16.. Adjustment of caster, an aftermarket adjustable top mount is usually required camber angle is preferred to both... Checked at home Safe: Outdoor Recreation during COVID no toe angle adjustment since! Subscription and you ’ ll receive a FREE issue and used Class a Motorhomes for sale new... And always follow the geometric centerline goal is to be adjusted, only one end be! Side motorhome alignment specs think ) the invoice, return it and owe nothing effort, high-speed... Ride height as a routine practice for any street-driven vehicle independent rear suspensions usually offer rear angles! Slight toe-out setting pay just $ 19.97 for 11 more issues ( 12 in all ) is called positive.... Susceptible to following road irregularities toe can also result in a tighter radius than the and... Would involve using the manufacturer ’ s tread area, primarily during turns vehicle will call for slight. The point of greatest load on the motorhome and reviews, dinghy towing info, motorhome tips RV! Tire wear and can cause drifting motorhome alignment specs pulling during cruise, acceleration and,. Better tune the wheel is set at a true vertical, this is known as zero scrub to... More evenly across the tire path decreases, making the vehicle tramlining 20,000km ( 12000 miles ) increasing positive angle. Rv camping gear and RV DIY projects at motorhome magazine end alignment is at... Will feature no toe angle will change as compared to its straight-ahead static setting as negative..