Keep in mind that trailing arm angles can become excessive if the rear of the chassis lifts a lot during acceleration. We've The variation of height for the right-rear trailing arm is very small. 122. On asphalt, do not make large changes to components that influence rear steer. The amount of rear steer due to body roll is regulated by the height of the front mounts of the arms, which are always mounted lower than the rear point of rotation (the axle). change. Ben from AFCO Racing is an expert in multiple aspects of race cars including cooling and set up. One theory related to having the attitude of the car sideways involves the use of the aerodynamic aspects of the car. Your DS length will dictate your lower link length. minor relative to the overall handling improvement that is realized by corners. New info from @Fabman on RLCA angle: 3 to 5 degrees downward slope . . Trailing arm bushings come included (part No. extremely short links change their angles radically whenever the This bolt on upper trailing arm mount is designed to allow use of a quick change into a stock GM metric chassis. If the Panhard bar is mounted on the right side of the chassis and level to the ground, the rear end will be pulled to the right, and will steer to the left when the chassis moves during cornering. Pinion angle is measured between the pinion gear flange and the driveshaft. This is your problem, (sprung v. unsprung) your rear lower control arms (body mount to axle mount) must be in a 2.0-3.0 degrees (max) downward slope to the rear axle. 2023 Physics Forums, All Rights Reserved, Car lift using suspensions as lift points, Calculation of the reduced stiffness of a simple suspension, Suspension location for suspension pedestal, Bearing race diameter inequality question. forward(L.S.) They constantly introduce new products to their lineup. This produces quite a bit of rear steer to the right, moving the rear of the car to the right, just like when we used to throw the car sideways. When you find the correct amount of rear steer, stay there and tune the handling with the other components. . We can see the effect of the Sprint Car wing in the turns-as the cars actually roll left due to the pressure differential developed on the flat wing sides-as the cars go sideways at a high speed. Just as bad, some of the top-mount arms (ones that physically raise the upper trailing arm location on the rear end housing) have a tendency to hammer the trunk floor when you get on the throttle. If you dont do anythinig else. This produces a motion ratio that causes the spring to move less than the chassis per degree of roll and/or inch of squat. There are four types of rear suspensions used in most dirt cars that are significant to study regarding rear steer. #2. pat the angle of the trailing arm wont really effect anything that much. Wehrs Body Braces. Distance from link mounts to transmission output and 3'rd yoke will dictate mount position. How Much is Too Much? I was looking for more info on stock rear 4 link trailing arm angles. My car was level, As the chassis loads the RR in the turn you want it scribing an arc in one direction only. Mike Kojima says: July 15, 2019 at 4:38 pm . Adjustable trailing arms will allow you to set the static pinion angle. Hes authored five how-to books and written over 4,500 tech articles that have appeared in sixty different high performance automotive, motorcycle and aviation magazines worldwide. One fix is to position the links so that the It seems not being an Irak/bu . clamp brackets are used in front of the axle, axle wrap-up during BMS Racecars - Winning's not just a goal it's a tradition! The 4-link is a relatively complex rear suspension that is very For more than 50 years, A & A Manufacturing has worked closely with racers and chassis fabricators. Brand new Stamped steel, C-channel arms are strong and sturdy Improve the handling of your '78-'88 GM Metric rear suspension by replacing twisted or worn out rear control arms 11" center to center Sold each IMCA Approved. 1-15 How Important is it to Bump the Left Front? What effect would this have on roll center and other aspects of rear geometry for a road race application? Designed for the Hobby stocks, these trailing arm brackets have the lowest mounting hole position possible. Decrease the Pre-Load on the Stabilizer Bar. The sideways attitude of the car does two things: 1) it helps to slow the car down on entry much like an air brake on a Lear jet, allowing deeper entry and 2) it may also help to produce a left-side, lateral force that resists the opposite centrifugal force that tries to take the car to the fence. An anti-roll bar can also be mounted on the rear axle housing. NOTE: If installing on a Frankland quick change, the bracket will need to be modified and reinforced to fit. Big Chevy Impala and Caprice 1980 to 1994 casting number is 369056 for right side and 396055 for left side and if you can not locate these I can send you info on other substitutes. it feels as a plank over nude bearings on the road .. Replacing the worn out rear trailing arms and bushings will reduce wheel hop and axle wrap that occurs during racing. Lower the front LR trailing arm mount. So, teams need to take this rate difference into account. The setup is balanced when the LF and LR tire temps are similar. When the rear links are too short forward bite and cause a gas pedal push. AA-175-D. Rear steer can either tighten a car or make it very loose. here a simple Q as life for you: owning an base malibu sedan 81 and had changed coils (some, new and used), and new gabriel stock shocks, Im banging my head on the paviment as this car has absolute no suspension. In the past, drivers would set up the car for exit off the corners, throwing the car sideways by breaking the rear tires loose. Not only does the condition of rear steer affect the entry and middle handling balance, it affects handling under acceleration due to the thrust angle of the rear end being either right or left of the centerline of the car. the 60 in the low 50s have 505hp 350 460fpt car weight 3400 what is your take on the pinion angle? My trailing arms are stock triangulation. I do have a few questions though: Are you running the car with an Anti Roll Bar or at the least, with a sway bar on the back? The technology related to rear steer for asphalt and dirt are somewhat different. Be aware that trailing arms angled uphill too steeply can hold the With this design, lateral movement of the rear end causes rear steer. Then this NEW trailing arm bracket kit is a must have. I use the H&R parts stuff anti roll bar Part No. just ordered the adjustable lowers Looking for increased forward bit and traction? Joe Garrison of GRT Race Cars and Mark Richards of Rocket Chassis both said having rear steer capability in a dirt car was critical. birdcage rotates or "indexes" on the axle tube whenever the The upper arms is where many very in opinion. 4. preceding paragraphs should help you understand why. No more than 10-15 pound difference, excess split makes car tight. $15.75. Realize that you can increase forward bite on any type of rear Dave is the owner of Hammond Motorsports. The entry is more important to design for than the exit as far as rear steer is concerned." And have fun at SIR! Adjustable arms allow easy rear suspension . Use this kit to build your own custom rear end. Description : General Motors 64-67 "A-Body" Adjustable/Indestructible Rear Control Arm Upper Cross Member! A level panhard bar ( same mounting height on both sides) means force is vectored laterally to the tires. sub frames in these cars move a lot when the car lifts at the front changing the pinion angle.. front sub frame is not tied These new Superior 28 or 31-spline axles feature screw in studs in a 55 wheel bolt pattern, , thick heavy duty bearing retainer plates, and tapered wheel bearings pressed on. Anti-squat is a concept used to determine how much the rear of a chassis will squat under acceleration as a result of the rear geometry. 4.0 drop trailing arm brackets slotted to accept offset slugs. How to find roll centre in anti-dive or anti-squat double wishbone suspension, where upper and lower arms are at angle (side view)? All driving train actually repalced with Moog components.. A well designed 4-link provides good forward bite and the proper These trailing arm brackets use common offset slugs (sold separately) to allow you to change the amount of lead or trail in the rear end. ~ index. These tips are for an independent a-arm front suspension and 3-link rear suspension type of car, but may apply to other types of suspensions as well. everything is a compromise. AA-384-B and AA-384-C), made from 3/16-thick steel, sit on the back of the lower trailing arm mounts. We do not necessarily need to know the exact amounts of rear steer our cars are subjected to, but we do need to have a solid understanding of what produces rear steer and what effect rear steer has on the handling in our cars. If not, no amount of adjustment will get the thing down the track properly. Under the right conditions, rear steer can be beneficial and enhance performance. JavaScript is disabled. at least 3" of rebound movement for the left The bushed end has a Teflon-lined QA1 stainless steel spherical bearing (rod end) with a stainless steel spacer. A triangulated four-link puts the instant center (I/C) locationthe imaginary point of where the rear suspension components intersect, and the point theyrotate around in a given (instant) positionway out front, often close to the engine. Now available value added Metric Rear Control Arm . Great info! There are a few similarities, but many differences in how we evaluate and use rear steer for each group. This one is made by Hotchkis for GM A-body cars. Truth!^^^^^. Some forward bite may be lost when Rear steer in a circle track race car is a condition caused by suspension movement. A & A Manufacturing makes a similar trailing arm mounting kit for racers using Ford 9 rear ends in GM Metric chassis (part No. Tubular arms are constructed of 1 1/4" diameter .120" wall steel tubing, which offers increased strength over other designs and also has the added advantage of lighter weight. These tapered profile spring cups are manufactured from high strength steel and are designed to minimize any stretch and bending while still being lightweight. Anytime you are acting thru an angle, this force is diminished and is not as effective as it could be. chassis. the bottom of the bottom link arrangement of illustration 2C on the left side and the Another option are the double adjustable UMI upper and lowers available at Summit Racing (Part Number 402717-B or 402717-R). With the trailing arms toed in at the front you can use the J-Bar mounting angle to help steer the rear end through roll. clamp brackets. On most flat- to medium-banked tracks, the left-rear moves very little. clamp brackets during acceleration will be accompanied by an Not sure if there are any big "Tricks". shortened bottom link. It consists of a regular trailing arm and two links for controlling the camber throughout the suspension travel and for carrying the lateral loads. 3. Wayne The adjuster is at the front of the bar. Seems that more of an angle equals more traction bit, less angle (ie flatter) more stability in the turns and under braking. This clamp on trailing arm mount is for the GM metric chassis lower bars. Masters added, "Any time we can press air against the sides of the car, we can help the car to turn." if u could move trailing arm mount on chassis with the uppers as close to the rearend housing as can get and the lowers 2.5 away from housing. A lot of guys take that to extremes.". $149.99; 149 - Reward points. These systems only steer to the left and have a limited amount of steer. shortening the lower links, is a reduction in loose roll steer. what wold be the best angles to be at for most foward bite along with handling four all four links ? You can play with all of these a little to work on plunge/roll steer. Simply replace the LR bracket and have increase drive and adjustability. Decrease Upper Control Arm Angle on the Rearend. That saved the factory some money. LR bracket is 7 from axle tube to center of bottom hole, but still conforms to the 7.5 max length rules. 2). Specifically designed to increase LR drive off the corner and corner entry adjustability with multiple hole adjustments on the RR. LATE MODEL SUSPENSION FRONT-REAR; LATE MODEL DRIVELINE-WHEELS; . The bottom of the left side Lower the front LR trailing arm mount. attention to how the lower link adjustments change the paths traveled by Wehrs Modified Valance Support Weld On Clevis. Photo courtesy of BMR. The advantage of this system is that it keeps the rear end squared up and the thrust under acceleration straight ahead, if that is what is needed. The bearing allows for smooth movement without the binding a rubber bushing can cause. $ See all 6 photos. Semi-trailing arm suspension, handling and stability performance, non-linear vehicle model, Bees algorithm Date received: 17 November 2011; accepted: 3 February 2012 Introduction These arms are longer then stock to help lessen pinion angle changing during suspension travel. A 1/2 inch height change from level can make significant handling changes. The Z-link rear suspension, or swing arm as it is also known, is another system used on dirt cars. AA-175-B) are constructed from stout 5/8-thick steel. wood, aluminum strips, etc. sensitive to adjustments. The live class took place January 22-23, 2022. If you want to insert bushings with a press rather than a mallet, opt for part No. Heres a better look at a trailing arm mounting brace. Looking for some help / opinions on the optimum lower control arm angle for 05+. Everything needs to be free to move or you will chase crazy problems and never figure it out. Also pinion angle with stock bushings. efforts, will provide you with an advantage. loose roll steer tendency caused by the steep angles of the upper links. with the very soft chassis meaning floppy front subframe is 4.5 enough? if the left rear of your chassis hikes up during cornering, loose roll Raise the front LR trailing arm mount. very stiff. This bracket is also built heavy, weighs 7.5lbs (with slugs) to help increase LR rear end weight. There are reports from the past of a team winning a race using four 400-pound springs on a Z-link type of car. You can see how this adjustment works in illustration 2B. This induces rear steer when the car squats on exit.
