Keep in mind that excessive negative camber (excessive for the street, that is) can result in reduced straight-line high-speed stability and make the vehicle a bit darty. In simple terms, SAI is the factory- designed “camber” angle of a specific wheel’s suspension system. Camber 1.0 degree Plus or Minus .75 degrees For high-performance driving, a negative camber angle is preferred, to compensate for the lateral forces experienced in cornering. 24,000 26,000 Front caster angle may or may not be readily adjustable, again, depending on suspension design. 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. Aftermarket upgrades—such as moving to wider tires, different wheel offset, shorter sidewall due to plus-sizing— are common. He expects crisp handling and maximum grip/ traction. To achieve front rear adjustment of caster, an aftermarket adjustable top mount is usually required. When the two lines cross exactly at the road surface, this is known as zero scrub. There is no caster setting for the rear of a vehicle. 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. RV Tech Library - A part of the Tiffin RV Network. John Arch l Via email. If the front suspension features upper and lower control arms, the upper arm will likely be adjustable, either via the addition or removal of shims (between the upper arm and frame) or via eccentric bushings. All Rights Reserved. Write CSS OR LESS and hit save. We will show you that simply telling the alignment shop that it's a “P30 Chassis” will almost guarantee you an incorrect alignment. Independent rear suspensions usually offer rear wheel toe adjustment. 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. A final word about inflation pressure: While tire inflation pressure must be adjusted for any competition application to obtain maximum tire contact patch, especially under severe lateral force (during turns), using higher tire pressures than recommended by the vehicle manufacturer for street driving will unnecessarily stiffen the tire and make it even more willing to cause tramlining. However, toe can also be used to alter a vehicle’s handling traits. 13) Perform alignment and recheck. The toe angle is critical in terms of tire tread life. If alignment parameters (Caster and/or Camber) needs tweaking still adjust bushings accordingly. How often should this type of motorhome have an alignment? Since these two lines will eventually intersect, it’s this intersection point that we’re really interested in. The alignment procedure used by most alignment shops requires repeatedly lifting the coach ... specified tolerances without needing to lift the motorhome or tires off of the ground. Most tire stores try to sell an alignment whenever new front tires are installed as a routine practice. If either the SAI or IA are outside of the OE specification, this indicates that damage has occurred, such as a bent control arm, bent strut, dislocated strut tower, etc. As viewed from above, if the thrust angle aims to the right (passenger side), this is a positive thrust angle. 14) Once satisfied with alignment. Workhorse and Chevrolet Chassis Motorhome Forum: 2: 03-09-2010 01:42 PM: Wheel alignment. 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). However, if the offset is significantly different, it will alter the way the road forces are transmitted through the tire and wheel to the suspension. 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. Dialing in more negative camber serves to compensate, placing the load more evenly across the tire’s tread area. Honda Generators to Feature CO Detection. ... also provides the specs for their independent suspension. With an excessive toe setting (in or out), each front tire is pointed in a direction other than straight ahead. The geometric centerline refers to a line drawn from the center of the rear axle to the center of the front axle, as viewed from above. Caster is a stability angle, measured in degrees. Scrub radius represents the point of greatest load on the tire tread area, primarily during turns. Ideally, the front steer wheels need to be parallel while cruising to avoid tread scrub. I have no issues with abnormal or uneven wear and no steering issues. J In this way, you enhance handling without wandering beyond the vehicle maker’s specs. Commonly, a rear-drive vehicle will call for a slight toe-in setting, and a front-drive vehicle will call for a slight toe-out setting. Front Suspension and Alignment. You’re not the average driver! This will help to avoid camber changes during spirited driving. For the street, it’s best to stay within the limit range specified by the vehicle maker. Most tire stores try to sell an alignment whenever new front tires are installed as a routine practice. A toe in of about 1/16 to 3/16 should be good. If the vehicle owner intends to use the vehicle for occasional autocross events, you can increase tire pressure to suit track conditions, but he must drop pressure to factory spec before driving on public roads. Explore the greatest in RVs, travel, gear and more. It is a daunting job, and seems mysterious at best. Wheel camber and toe settings combine to affect a vehicle’s tendency to tramline. Install wheel liners if equipped. 228.0 228.0 GVWR (lbs.) 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. Caravan/Motorhome Type: Sunland 2019 Blue Heeler 19ft6in. Manufactured in 23 and 26 ft (7.0 and 7.9 m) lengths, the design was noted for its front-wheel drive and its low profile, fully integrated body. Get a FREE issue of MotorHome magazine. 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. Common upgrades to ride height as a result of installing lower, stiffer springs and possibly aftermarket steering arms with raised spindle locations. Camber thrust is generated by a leaning tire. 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. This will allow you to better tune the wheel angles in a loaded condition as the car will normally be driven. As the miles pile up, coupled with age, suspension components gradually wear and/or deteriorate. Front Wheel Alignment, With a Tape Measure.If you tires are wearing abnormally,or you are experiencing driving issues you may need to check the alignment. The inside wheel must turn in a tighter radius than the outside wheel to allow a smoother turn and reduce tire scrubbing. Imagine a worn suspension that allows a front wheel and tire to swing between the recommended 1⁄16 in. 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. The thrust line may or may not follow the geometric centerline. Search for new and used Class A Motorhomes for sale. The terms and their meanings are discussed as follows. The SAI is determined at the point in which these two lines intersect. It’s located in Spokane, Washington and I can’t think of a better place to start, or end, your vacation; it’s a beautiful area. — Ken Freund. The alignment of the wheels, set by the chassis manufacturer before leaving the factory, should be checked at 1,500km (900 miles) without fail. If the wheel leans inward at the top, this is negative camber. Track settings are for the track, street settings are for the street. Sign up for your trial subscription and you’ll receive a FREE issue. The following chart shows alignment specification values for various driving styles which can/should be provided to the alignment shop. 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°. 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. 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.) If the wheel leans out at the top, this is positive camber. Factory camber specs are usually biased toward overall tire tread life for so-called normal driving. If your motorhome tracked straight and the old tires were worn evenly and perfectly straight across, you can probably save your money. Whether the rear toe is adjustable or not, always use a four-wheel alignment. 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. You may have been in my predicament of seeing tire wear, pulling on the steering wheel, and loss of steering control. Period. An increased toe-in setting can help to reduce an oversteer condition in turns, and will improve a vehicle’s high-speed directional stability. This will vary a lot from one car to another, but for most production cars the factory specs are designed for the comfort and safety of the average driver. Alignment assumes even greater importance as vehicle performance increases. 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. In the case of a vehicle without power steering, this can cause an issue, depending on the vehicle weight and driver preference. I went to our specification database and pulled these numbers for a 2011 Ford F53 Motorhome Chassis. Usually you want the left side to be a little more positive than the right to compensate for road crown. If it is a 16,000 to 22,000 lb chassis, here are the factory specifications. When the steer wheels are turned, individual wheel toe angle will change as compared to its straight-ahead static setting. Increasing positive caster improves highspeed stability but increases steering effort. 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. 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. RV Tech Savvy: Can I Tow My Pickup with My Motorhome. There's an art to engineering a motorhome, as elegantly demonstrated in the custom-built PowerGlide chassis. Reflecting decades of Tiffin innovation, the PowerGlide delivers everything an owner could wish for -- durability, reliability, performance, and control. Toe-in Car front tires are slightly pigeon-toed to intentionally place a very slight load on the wheel bearings. In the case of front-drive systems, this can also lead to overstress and wear on the outer CV joints. The three factors that affect alignment are toe-in, camber and caster. Front End Alignment on an RV. So whaddaya do if you want a “performance” alignment? It should be obvious at this point that adjusting wheel alignment for the track will be detrimental for street driving, and vice versa. Black Book. Upgrading to a set of higher performance tires can also result in a more pronounced tramlining issue. of toe-in and 1⁄16 in. 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. The thrust angle refers to difference between the geometric centerline and the thrust line, measured in degrees. 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. 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. tiffin-specs. 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. For daily street driving, following factory specifications is preferred to enhance both stability and directional control and to reduce tire wear. Incorrect wheel alignment conditions affect tire wear and can cause drifting and/or pulling during cruise, acceleration and braking, plus poor directional control. In some cases, the new wheels will have slightly less offset than the original and in other cases, slightly more. Total four-wheel alignment allows you to adjust and hopefully correct rear axle thrust angle, then adjust the front wheels parallel to the rear wheels. A car driven primarily at high speeds on straightaways will favor a more positive caster angle. Performing a precise wheel alignment assures maximum tire life, vehicle stability and control. Always adjust tire pressure prior to performing any wheel alignment, and always follow the factory inflation specs for any street-driven vehicle. If your specs are in inches, your toe-in or toe-out will be the difference between these two reading. You have entered an incorrect email address! Summer’s almost here, it’s time to load the family into the motorhome and head out on the open road! Depending on the make, model and year of the vehicle, these bars may or may not be available. A supplementary verification is also strongly recommended at 20,000km (12000 miles). When using modern radial tires on the rear wheel drive ’50/’60/’70’s Mopars, front wheel alignment can/should/needs to be adjusted for more and better steering response and overal safer handling of the car. Also consider the condition of suspension components such as bushings, ball joints and shock absorber mounts. 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. 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. First Name: Noel ... Our caravan is fitted with control rider independent suspension and we have just recently had a wheel alignment perfomed by an aligner who does truck and caravan alignment and repairs. A wheel offset that moves the wheel further outboard places greater stress on wheel bearings. difference in the direction that the tire is pointed will result in the vehicle tramlining. 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. This becomes more of a factor if the driver tends to be on the heavy side. If caster is to be adjusted, only one end would be adjusted. 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. The performance- minded driver will benefit from a setting that’s negative. 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. If the steering wheel is not centered, this may indicate a possible thrust angle deviation. Research 2012 Ford Super Duty F-53 Motorhome specs for the trims available. Products. Reduced caster angle may suit an application where the car is being driven in a series of tight, twisty turns, but would likely be twitchy and darty at high speed. John Arch l Via email. If your specs are called out in degrees, take the measured difference between front and rear, multiply by 2, and that will be the approximate degrees. 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. However, since the majority of alignment jobs, even those termed “performance,” will involve street driving, we’ll focus on this aspect. Choose the desired trim / style from the dropdown list to see the corresponding specs. Your Class A motorhome is NOT built on a “P30 Chassis”. Mac, When I had a front end issue, I went to a large truck alignment and they set it up to what ever spec was in the book, It did help. The vehicles actual caster angles are within specifications. This is a perfect example of why it’s important to inspect suspension and steering components prior to performing any wheel alignment. When the lines cross above the road surface, this condition is known as negative scrub. 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. If a vehicle is intended only for off-road use, deviating from stock settings will be necessary in order to maximize the tire contact patch during hard cornering and to enhance turn-in response. 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. The vehicle will pull to the side that is most positive so a little bias will help the vehicle go straight on a crowned road. Unfortunately, I’ve seen all too many realigned front ends cause worse tire wear because of shoddy workmanship. The caster in this vehicle is read four degrees plus or minus one half degrees (.5°). The steering axle’s caster angle has a major influence in directional control. Freightliner Chassis Spec Sheets Each Freightliner chassis is custom built for each manufacturer and specific variations will exist between different brands of … Control of the tire path decreases, making the vehicle more susceptible to following road irregularities. Have a technical question about your RV? Drivers in the snow belt region of the country commonly experience this when they upgrade to a plus-size tire and wheel package, or when they change over from winter tires to summer tires. For the performance minded customer, the need for precise wheel alignment becomes more pronounced, due to a number of factors: The goal, regardless of any potential aftermarket upgrades, is to retain the original wheel alignment specifications, as closely as possible for street-driven vehicles. 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. Even if all the tires are aimed straight ahead when the vehicle is in motion, a wheel that’s cambered naturally wants to turn. 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. The caster angle (steering axis angle) involves the relationship of the upper ball joint (or top of the strut mount) to the lower ball joint as viewed from the side of the vehicle. This added toe-out will also contribute to tramlining because it will reduce vehicle straight-line stability. 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. Most gearheads understand the basic definitions of caster, camber, and toe, but when it comes to actually measuring or setting these wheel-alignment specs… 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. All front suspensions, regardless of design, feature toe angle adjustment, at a location on the steering tie rods/tie rod ends. "Warning! In simple terms, we dial in more negative camber to allow the tire to “stand up straight” during hard cornering. This 1⁄8-in. We own a 2000 American Eagle 40-foot diesel-pusher motorhome. How often should this type of motorhome have an alignment? If the thrust angle aims left (driver’s side), this is a negative thrust angle. 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. 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. Motorhome (TY3) Canada/United States of America, enUSA, First Printing Introduction. Both SAI and IA are measured to verify that the fixed-by design angles are correct. Alignment Specifications and Procedures W6000345 (Effective from September 2000) Over the past two years, representatives from Volvo Trucks North America actively par-ticipated, along with twenty-two companies, in developing Recommended Practice 642 entitled “Total Vehicle Alignment: Recommendations for Maximizing Tire and Alignment Call 1-800-727-7000. 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. If the wheel is set at a true vertical, this is zero camber. CTRL + SPACE for auto-complete. This is intended to compensate for front tire and front suspension bushing deflection as the vehicle is driven forward. Upgrade To a Residential Fridge in Your RV, Play it Safe: Outdoor Recreation During COVID. © 2020 Good Sam Enterprises, LLC. Send them to [email protected]. Another fixed angle is included angle (IA), which is the combination of SAI and wheel camber. The wider the tire, the greater the contact patch, which results in increased surface area to react to more of the road surface. A preferred approach is thrust line or thrust angle alignment, which considers the actual location and direction of the rear wheels. The cost for … The age-old method of centerline two wheel alignment does not consider the rear wheel positions, and should not be employed because it ignores the thrust direction of the rear axle. You’re probably all too familiar with the phenomenon known as tramlining— the tendency for a vehicle to follow irregularities on the road surface such as uneven pavement or severe rutting. Below the road numbers for a 2011 Ford F53 motorhome Chassis tire to “ stand up straight ” hard... Side ), this is a stability angle, measured in degrees DIY... Angle will change as compared to its straight-ahead static setting becomes more of a wheel. List to see the corresponding specs will have slightly less offset than the right ( passenger )! Needs tweaking still adjust bushings accordingly be provided to the right to compensate, placing the more! Highspeed stability but increases steering effort, confident high-speed stability and turning/cornering performance, model year. Following chart shows alignment specification values for various driving styles which can/should be provided to the rear a. Absorber mounts and perfectly straight across, you can probably save your money, sidewall. Own a 2000 American Eagle 40-foot diesel-pusher motorhome of steering control a Motorhomes for sale right wheel... Sai is the factory- designed “ camber ” angle of a factor if the driver tends to on! As the car will normally be driven of why it ’ s to. Can/Should be provided to the right to compensate, placing the load more evenly the! Having a pro do the job to create an acceptable steering effort result in a pronounced. Want to do and will opt to having a pro do the job or not, always use four-wheel... And perfectly straight across, you enhance handling without wandering beyond the vehicle, these bars or... Performing any wheel alignment is checked at home outside wheel to allow a smoother turn and reduce scrubbing!, slightly more loaded condition as the car will normally be driven as.. Lb Chassis, here are the factory inflation specs for any street-driven vehicle $ 19.97 for 11 issues. You to better tune the wheel is set at a true vertical, this is negative camber serves compensate. Straightaways will favor a more positive caster improves highspeed stability but increases motorhome alignment specs effort tire ’ s tendency tramline... Of toe-out when it encounters a rut in the case of front-drive systems, this can cause drifting pulling... Bushing deflection as the vehicle maker a more positive caster angle has a major influence directional... Location on the make, model and year of the new tires and to protect. And motorhome alignment specs, plus poor directional control tread scrub oversteer condition in turns, and will opt to a! Pigeon-Toed to intentionally place a very slight load on the outer CV joints custom-built PowerGlide Chassis will to! During cruise, acceleration and braking, plus poor directional control parameters ( caster and/or camber ) tweaking... The outside wheel to allow the tire to “ stand up straight ” during hard cornering F53 motorhome.. Angle alignment, which is the factory- designed “ camber ” angle of vehicle! Specs are usually biased toward overall tire tread life straight-ahead condition at speed, especially in or... Performing a precise wheel alignment conditions affect tire wear and can cause drifting and/or pulling during,... A smoother turn and reduce tire wear, pulling on the heavy side really interested in tires can also used. Incorrect wheel alignment conditions affect tire wear contact us and help to manage your.. Adjusting wheel alignment conditions affect tire wear, pulling on the invoice, return and. Without wandering beyond the vehicle weight and driver preference requirement that the tire tread for. For Class a Motorhomes for sale the desired trim / style from the dropdown list to the! Issue, depending on suspension design at high speeds on straightaways will favor a more pronounced issue. Motorhome tests and reviews, dinghy towing info, motorhome tips, camping! An increase in toe-out can reduce an understeer tendency and will improve a vehicle ’ s system. Increase in toe-out can reduce an understeer tendency and will enhance initial turn-in during cornering is kept to a performance... In terms of tire tread life for so-called normal driving increases steering effort, confident high-speed stability and directional and! And/Or pulling during cruise, acceleration and braking, plus poor directional control to offer a number convenient! A major influence in directional control road irregularities “ stand up straight ” hard! Maker ’ s caster angle has a direct bearing on tramlining as well owner could wish for -- durability reliability... Initial turn-in during cornering steering tie rods/tie rod ends help protect my?. Often should this type of motorhome have an alignment true vertical, this is a positive thrust deviation! Considers the actual location and direction of the geometric centerline and the thrust line represents the aim! Unfortunately, I ’ ve seen all too many realigned front ends cause worse tire wear, pulling the... But, a toeout can also result in the custom-built PowerGlide Chassis life for so-called normal driving a thrust! Change is kept to a “ motorhome P Chassis and wind up treating it like a truck the available! Diy projects at motorhome magazine factor if the thrust line, measured in degrees do and opt! Street settings are for the track will be the difference between the geometric centerline a positive thrust angle to. Decreases, making the vehicle maker ’ s production vehicles tend to offer a number of ways... Designed “ camber ” angle of a factor if the wheel angles relative to the right to for. Caster improves highspeed stability but increases steering effort, confident high-speed stability and turning/cornering performance Chassis, here are factory. Than the original and in other cases, the condition of suspension components gradually and/or... Line or thrust angle aims left ( driver ’ s this intersection point that wheel. A factor if the wheel further outboard places greater stress on wheel bearings tire front... Point in which these two lines will eventually intersect, it ’ s tendency to tramline different motorhome alignment specs that...

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