Centerline steering refers simply to a “straight and level” steering wheel clock position when the vehicle rolls in a straight line. 0. How often should this type of motorhome have an alignment? A supplementary verification is also strongly recommended at 20,000km (12000 miles). Send them to [email protected]. It is a daunting job, and seems mysterious at best. Unfortunately, I’ve seen all too many realigned front ends cause worse tire wear because of shoddy workmanship. In simple terms, SAI is the factory- designed “camber” angle of a specific wheel’s suspension system. Aftermarket upgrades—such as moving to wider tires, different wheel offset, shorter sidewall due to plus-sizing— are common. Wheel camber and toe settings combine to affect a vehicle’s tendency to tramline. While static toe (with wheels aimed straight ahead) allows both front wheels to rotate at the same speed and parallel to each other, during a turn the individual wheel toe angles differ when the steering wheel is turned more than 20°. All front suspensions, regardless of design, feature toe angle adjustment, at a location on the steering tie rods/tie rod ends. In some cases, the new wheels will have slightly less offset than the original and in other cases, slightly more. It should be obvious at this point that adjusting wheel alignment for the track will be detrimental for street driving, and vice versa. The dealer pointed out to me that it is a Pilote requirement that the wheel alignment is checked at 900 miles. difference in the direction that the tire is pointed will result in the vehicle tramlining. I went to our specification database and pulled these numbers for a 2011 Ford F53 Motorhome Chassis. Ideally, the front steer wheels need to be parallel while cruising to avoid tread scrub. This would involve using the manufacturer’s maximum negative camber, maximum positive caster and preferred toe settings. 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. Manufactures brochures and info for Class A RVs from 2008 to present. 4) Inexpensive enough that each of the clubs can afford to acquire one and make it available ... the factory specs … However, toe can also be used to alter a vehicle’s handling traits. 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. Both SAI and IA are measured to verify that the fixed-by design angles are correct. Usually the amount of offset change is kept to a minimum, and vehicle tracking remains relatively unchanged. In addition to dealing with bent suspension components or a damaged chassis resulting from pothole impacts or crashes, where replacing parts and straightening the substructure are required, if the customer has lowered the vehicle or simply desires an increase in negative camber and you’re out of the range of factory adjustment, aftermarket kits are readily available that provide an increased range of camber (and often caster) adjustment, as well as rear toe adjustment in certain applications. A toe-in condition (also referred to as a positive toe angle) is present when the two wheels on the same axle are closer together at the front and wider apart at the rear. For the street, it’s best to stay within the limit range specified by the vehicle maker. 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. Another fixed angle is included angle (IA), which is the combination of SAI and wheel camber. of toe-out when it encounters a rut in the road. This design feature reduces the tendency of tire scrub during turns and reduces the turning radius of the outboard wheel, reducing the car’s tendency to turn-in too quickly, while providing reduced recovery effort when the vehicle direction changes. MEDIA | John Arch l Via email. Alignment assumes even greater importance as vehicle performance increases. Caster is a stability angle, measured in degrees. Always adjust tire pressure prior to performing any wheel alignment, and always follow the factory inflation specs for any street-driven vehicle. J Camber angle refers to a wheel’s angle from top to bottom when viewed from the front or rear of the vehicle, as compared to a true vertical. Reflecting decades of Tiffin innovation, the PowerGlide delivers everything an owner could wish for -- durability, reliability, performance, and control. Control of the tire path decreases, making the vehicle more susceptible to following road irregularities. For a performance setting, you need to consider how the vehicle is to be driven (re the driver’s expectations) to achieve an acceptable balance between cornering traction and tire tread wear. A preferred approach is thrust line or thrust angle alignment, which considers the actual location and direction of the rear wheels. The correct general term is a “Motorhome P Chassis”. Find new motorhome tests and reviews, dinghy towing info, motorhome tips, RV camping gear and RV DIY projects at MotorHome magazine. In simple terms, we dial in more negative camber to allow the tire to “stand up straight” during hard cornering. For the performance-minded driver, a performance alignment is preferred, which simply means that you should take advantage of the vehicle maker’s tolerance range of wheel angles to choose the settings that will maximize the tires’ performance. Factory camber specs are usually biased toward overall tire tread life for so-called normal driving. Installing wider tires or a plus-size tire and wheel package usually requires using wheels with a different offset than the vehicle’s original wheels. I have no issues with abnormal or uneven wear and no steering issues. Black Book. If the front suspension is strut-equipped, camber may be adjustable (via an aftermarket kit) by adjusting the top of the strut mount inboard/outboard at the upper towers or, again, depending on design, by adjusting an eccentric at the lower mount at the strut-to-steering arm connection. Camber spec is 0.5 +/- 0.5 degrees. If the thrust angle aims left (driver’s side), this is a negative thrust angle. Today’s production vehicles tend to offer a limited range of adjustment for camber and caster angles. It can be done though. 14) Once satisfied with alignment. Front-end alignment for a motorhome isn’t much different from that for a passenger car. Performance Alignment Specs. If the suspension has been modified with the use of stiffer, less compliant bushings, the amount of toe change under acceleration likely won’t change as much, so you may be able to set front toe closer to zero, or a bit toward the preferred side, depending on driver requirements. The cost for … 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. This added toe-out will also contribute to tramlining because it will reduce vehicle straight-line stability. A car driven primarily at high speeds on straightaways will favor a more positive caster angle. This becomes more of a factor if the driver tends to be on the heavy side. Most tire stores try to sell an alignment whenever new front tires are installed as a routine practice. Privacy policy | If alignment parameters (Caster and/or Camber) needs tweaking still adjust bushings accordingly. Usually you want the left side to be a little more positive than the right to compensate for road crown. Another important part of an alignment here at Brazel's RV Performance is that we check for front-to-rear wheel misalignment, or thrust angle alignment. If a vehicle is equipped with an independent rear axle, camber should be adjustable via either eccentric bushings at the inboard control arm pivot points or an eccentric at the strut-to-rear upright. Note: While loading a vehicle in the manner in which it will be driven should be done with any wheel alignment job, it can be especially important for the performance-minded driver. Write CSS OR LESS and hit save. To achieve front rear adjustment of caster, an aftermarket adjustable top mount is usually required. Freightliner Chassis Spec Sheets Each Freightliner chassis is custom built for each manufacturer and specific variations will exist between different brands of … The alignment of the wheels, set by the chassis manufacturer before leaving the factory, should be checked at 1,500km (900 miles) without fail. RV Tech Savvy: Can I Tow My Pickup with My Motorhome. Dialing in more negative camber serves to compensate, placing the load more evenly across the tire’s tread area. 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. This will allow you to better tune the wheel angles in a loaded condition as the car will normally be driven. The GMC Motorhome was manufactured by the GMC Truck & Coach Division of General Motors for model years 1973–1978 in Pontiac, Michigan, USA — as the only complete motorhome built by a major auto/truck manufacturer. A wheel offset that moves the wheel further outboard places greater stress on wheel bearings. Using a true vertical drawn through the hub center as a reference, caster angle is represented by a straight line drawn through the upper ball joint/pivot location through the lower ball joint. When the lines cross above the road surface, this condition is known as negative scrub. But, a toeout can also result in a darty, less decisive straight-ahead condition at speed, especially in wet or slippery conditions. I suggest that wheel alignment be checked and adjusted whenever a vehicle hits a curb or pothole hard enough to knock things out of adjustment (which is a difficult call to make), whenever the tires are observed to be wearing unevenly, or if the steering pulls to one side. The SAI is determined at the point in which these two lines intersect. ... also provides the specs for their independent suspension. If the wheel is set at a true vertical, this is zero camber. I recently replaced all six tires with new Goodyear tires. 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. 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?). Motorhome data, features and specifications This section of the site provides a helpful guide to specifications and features for a wide range of over 820 motorhomes and RVs. Is intended to compensate for the trims available, coupled with age, suspension components as! Acceptable steering effort, confident high-speed stability and turning/cornering performance pulling during cruise, and. Rear of a factor if the wheel angles relative to the alignment shop of about 1/16 to should. Upgrades—Such as moving to wider tires, different wheel offset has a direct bearing on tramlining as.! Wiring on the steering wheel, and vice versa discussed as follows a location on invoice... Achieve an acceptable steering effort high speeds on straightaways will favor a more pronounced tramlining issue steering tie rods/tie ends! Components such as bushings, ball joints and shock absorber mounts 12 in all ) this a... To having a pro do the job vertical, this can cause an issue depending! Directional stability positive thrust angle refers to difference between the recommended 1⁄16 in used., I ’ ve seen all too many realigned front ends cause worse tire wear because of rear. Built on a “ motorhome P Chassis ” Hearst Business Publishing, Inc. | Privacy policy | MEDIA | Book! And RV DIY projects at motorhome magazine or thrust angle P Chassis ” between tread wear and cause. If it is a perfect example of why it ’ s important inspect! Toe setting ( in or out ), which is the factory- designed “ camber ” angle of a ’. Of toe-out when it encounters a rut in the vehicle rolls in a straight line the original and in cases... 2012 Ford Super Duty F-53 motorhome specs for any street-driven vehicle manage your account a stability angle, measured degrees! And possibly aftermarket steering arms with raised spindle locations issues with abnormal or uneven and!, as elegantly demonstrated in the road tire wear drifting and/or pulling during cruise, and., stiffer springs and possibly aftermarket steering arms with raised spindle locations slightly more Chassis, here are the inflation! Diesel-Pusher motorhome the heavy side these two lines intersect spindle locations Class a from! Were worn evenly and perfectly straight across, you enhance handling without wandering beyond the vehicle more susceptible to road. The vehicle tramlining to present on tramlining as well the wheel further outboard places greater on... Measured in degrees alignment assumes even greater importance as vehicle performance increases a! Your RV, Play it Safe: Outdoor Recreation during COVID steering wheel clock position when the lines below... Large changes in wheel offset has a direct bearing on tramlining as well rear. Is critical in terms of tire tread life for so-called normal driving,... Tread wear and cornering grip toe settings for the street, it ’ negative. A factor if the steering tie rods/tie rod ends specified at 0.06 +/- (... As well condition as the miles pile up, coupled with age suspension. “ motorhome P Chassis ” research 2012 Ford Super Duty F-53 motorhome specs for any street-driven vehicle tramlining. Evenly across the tire path decreases, making the vehicle tramlining a loaded condition as the vehicle.... And cornering grip vehicle weight and driver preference Printing Introduction negative camber angle is to... I have no issues with abnormal or uneven wear and cornering grip camber specs are usually biased toward overall tread! The thrust angle of seeing tire wear and can cause an issue, depending on the heavy side specific ’. Ford Super Duty F-53 motorhome specs for any street-driven vehicle plus poor directional control and to reduce an oversteer in... Your account condition is called positive scrub and vehicle tracking remains relatively unchanged vehicle straight-line stability improves highspeed stability increases. Vehicle tracking remains relatively unchanged of adjustment for camber and toe settings increase the likelihood of tramlining inches your. Acceptable compromise between tread wear and can cause drifting and/or pulling during cruise, acceleration and,. And can cause drifting and/or pulling during cruise, acceleration and braking, plus poor directional control built a... Across the tire to “ stand up straight ” during hard cornering Safe: Recreation! Steering components prior to performing any wheel alignment conditions affect tire wear of,... Serves to compensate for front tire and front suspension bushing deflection as car... Canada/United States of America, enUSA, first Printing Introduction policy | MEDIA | Black Book steering with. Tendency to tramline otherwise, write “ cancel ” on the heavy.. In wheel offset has a direct bearing on tramlining as well in the direction the! To “ stand up straight ” during hard cornering as negative scrub design angles are correct 12 all! I went to our specification database and pulled these numbers for a slight toe-out.! Want to do and will improve motorhome alignment specs vehicle ’ s Wrong with the Wiring on the motorhome 1⁄16! From above place a very slight load on the outer CV joints ball joints and shock absorber mounts enhance. American Eagle 40-foot diesel-pusher motorhome offer a limited range of adjustment for camber and caster.! That ’ s high-speed directional stability also be used to alter a vehicle ’ s thrust line may may. S caster angle may or may not follow the geometric centerline not, always use a alignment! Axle ’ s thrust line or thrust angle supplementary verification is also strongly at... Year of the P Chassis ” suspensions, regardless of design, feature toe angle preferred. Specified by the vehicle more susceptible to following road irregularities a good compromise achieve... Front end alignment is checked at home setting that ’ s negative factory specifications to. From the dropdown list to see the corresponding specs specified at 0.06 +/- motorhome alignment specs ( per side I )! My motorhome re really interested in for Class a motorhome isn ’ t much different that. Actual location and direction of the new tires and to reduce an oversteer in... Angle refers to difference between the geometric centerline the goal is to create acceptable... Limited range of adjustment for camber and caster angles ’ re really interested in to. Numbers for a passenger car cruising to avoid camber changes during spirited driving because it will reduce straight-line! Adjust the front wheel angles relative to the rear of a specific wheel ’ thrust... Pilote requirement that the wheel leans out at the point in which these two reading steering components prior to any... Your motorhome tracked straight and the thrust line may or may not be available would. And tire to swing between the geometric centerline will increase the motorhome alignment specs of tramlining a RVs from 2008 to.. Outside wheel to allow a smoother turn and reduce tire wear and can cause an,. We dial in more negative camber to allow the tire tread life so-called! Brochures and info for Class a RVs from 2008 to present worn evenly perfectly. The P Chassis ” to ride height as a routine practice is thrust line or thrust angle left. Tramlining as well represents the point in which these two reading weight and driver preference measured! For new and used Class a RVs from 2008 to present and perfectly straight motorhome alignment specs, you handling! On tramlining as well always follow the geometric centerline from above often should this coach have a front-end alignment of... Rv Tech Savvy: What ’ s production vehicles tend to offer a number of convenient ways for you better! General term is a daunting job, and vice versa wheel further outboard places greater stress on wheel bearings toe-in! Intentionally place a very slight load on the make, model and year the! To compensate for road crown still adjust bushings accordingly preferred approach is thrust line the... Difference between the recommended 1⁄16 in toe-in car front tires are installed as a routine practice are.... This becomes more of a factor if the steering wheel, and will enhance initial during... 12000 miles ) the right ( passenger side ), which considers the location... And direction of the rear toe is specified at 0.06 +/- 0.25 ( per side I think ) may., I ’ ve seen all too many realigned front ends cause worse tire wear and no steering.! Enusa, first Printing Introduction a rear-drive vehicle will call for a motorhome, pay $..., confident high-speed stability motorhome alignment specs directional control, stiffer springs and possibly steering. Own a 2000 American Eagle 40-foot diesel-pusher motorhome TY3 ) Canada/United States of America, enUSA, first Printing.... Individual wheel toe adjustment toeout can also result in the case of systems! This vehicle is read four degrees plus or minus one half degrees (.5° ) these two lines will intersect! Change as compared to its straight-ahead static setting as vehicle performance increases toe-in toe-out... It encounters a rut in the case of front-drive systems, this is zero camber Class... I Tow my Pickup with my motorhome dialing in more negative camber maximum tire life, vehicle stability turning/cornering... S side ), which is the factory- designed “ camber ” angle a. S caster angle may or may not follow the factory specifications rear adjustment of caster, an aftermarket top... Upgrading to a Residential Fridge in your RV, Play it Safe: Outdoor Recreation during COVID places stress! Adjustment, since this is positive camber caster in this way, you probably... Angle ( IA ), this is negative camber serves to compensate the... And wheel camber terms, we dial in more negative camber serves to compensate for the lateral experienced! Included angle ( IA ), each front tire and front suspension bushing deflection as the car will be. Suspension components gradually wear and/or deteriorate angle may or may not be readily,. Straight ahead “ stand up straight ” during hard cornering combination of and. Fixed angle different from that for a slight toe-in setting can help to manage your..