AE86 Control Arms for Rear SuspensionBattle Version / Club 4AG
There are many items in the process of restoring the AE86 for use in sporting activities. While most people only consider the suspension as springs and shocks, and perhaps an anti-roll bar or two, at Club4AG, we'd like to talk about more specific things... That is…the role of control arms and various under-pinnings to the suspension itself. While most people are unfamiliar with the role of these items, no one can ignore it's apparent availability in catalogs and articles. It is a given to consider it's modification in the world of racing, but it is not a concern for many people with normal cars. In this article we will look at the rear control arms, and it's functions and effects in a brief manner. The rear control arms on the AE86 consist of 4 link longitudinal arm design and supported by a 5th lateral link support. The 2 upper control arms and 2 lower (longer) control arms, tied longitudinally on to the chassis, hold the differential housing (the axle assembly) , while the 5th lateral link holds the suspension against lateral loads (the side to side force loads.) Because of this design, the differential case will move fore/aft and side to side throughout the stroke of the suspension as the links pivot in an arc, though not loose at any given point. Of these the lateral rod's side-to-side movement is sometimes a problem even for show cars as different height suspension puts the rear axles in different location laterally and offsets the wheels against the fenders differently. In race conditions, this also changes the thrust angle alignment of the car slightly. Thus, in most instances, people replace this lateral rod (also called Panhard rod) to correct the static location of the differential on height corrected cars, and in effect centers the axle housing in a static stance.
My old 'Revolver' brand adjustable Lateral rod just behind and parallel to the differential axle housing
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Lower control rod from axle ends to the bodyThe replacement usually consists of bushings and a special lateral rod with a length adjustment. On lowered cars, the lateral rod will position itself more horizontally and OEM lateral rod, being too long at that height to center, will push the rear wheels to the left. Adjustment is usually made shorter to compensate. Vice versa for lifted cars for use in off-road rally. The bushing is usually replaced to give more positive feedback for the driver with less road noise and vibration isolation properties, but in case of the AE86, it's simply done because of it's age...it's usually loose fitting, cracked and basically dead, causing unnecessary alignment changes too easily. In many race fields solid, ball jointed ends are fitted in place of the bushing to give extreme feedback to the driver with minimal isolation from harsh vibrations, but such items will put enormous stress on the body and sometimes creates cracks in the uni-body of the AE86. Needless to say, this is not an ideal condition for daily driven cars or cars used on the street...not to mention the rattles and jiggles the car will exhibit with no isolation point for vibration. But since all links have joints on BOTH ends, we can replace the floating side (one that is not attached to the body) with a rigid mount while keeping the body-mounting side, rubber or urethane bushing. This way it would be somewhat of a in-between setting for occasional racers who wish for more feedback at expense of some road noise and driveline noise. The longitudinal 4 link is replaced for similar reasons. In the race field, much of the fore-aft traction characteristics of the car is determined by small changes in the 4 link alignment. By changing the tilt and sweep of the rear 4 link’s support and alignment, we can increase or decrease according to driver preference, the traction levels of the car.
Battle Version / Club4AG Control Arms
Battle Version (A. Pfeiffer of San Francisco) developed a nice setup and is for sale now. It consists of all five rear links with adjustability for length. All links have high tensile alloy beam construction with reverse threaded ends. This type of threading on ends facilitates adjustment of the lengths without removal of the rods. One simple unlocks the lock nut on both ends and center rod will turn in a 'turn buckle" style to shorter or longer setting. The prices are shown at the bottom of this article... and will be available shortly from Club4AG.The links also consist of high-strength Delrin (tm) polyurethane-rubber bushings on one end and solid bearing joints on the other. And installation was somewhat more involved than I expected. It was more a problem with removal of the old, aged OEM rods that took a couple of hours on the rack to complete. Once the OEM rods were out, the new adjustable bars were worked in with excellent fit onto all the body and differential mounts. Even the Delrin bushing on the lateral link fit the OEM differential's mount very snug and with absolutely no play...or I shall say 'perfectly...'It's a very precise fit and finish with alloy portion of the unit anodized in pleasant purple color, and in my opinion was better in materials than the comparable pieces from Cusco brand.AND...for those wondering how it affect performance...Well, for those replacing them from OEM setups (especially with those with dead, old bushings) it will make the car much more responsive to steering, throttle and braking inputs and will make your car feel much more solid. I do have to forewarn the street users that these links will make significantly more noise and will transmit much more vibration than one would be accustomed to for a road car. There are more whirring sounds from the differential and brakes as well as thumps and knocks from road irregularity...(not a real pleasant characteristic for dating or car-audiophiles) Hey, but who are we talking about anyways?! This is Club4AG! Live with it!... OK, for those who have to listen to AM band traffic reports in your daily commute, no need to apply here...More experienced drivers will notice that the throttle application will directly feedback in car's attitudes and traction (as well as noise). This also means that novice drivers will make more mistakes as rough throttle inputs will directly upset the car's balance in a more dramatic manner. Simply put, as in all suspension changes, that driver skill must follow any modifications for the car to become more peaky in nature. (I'm no Andretti, but I have had some share of practice...so bear with me here...)I mounted the all links in OEM lengths with the exception of the lower control link. By extending the lower links by 10 mm over OEM length, I aimed towards stabilizing higher speed corners. With the 4mm extended wheelbase I gained from 10 mm adjustment, my car exhibited slightly more understeer initially than with standard length, but at the same time made the rear transitions more composed in lateral sweeps. It may have also reduced the fore-aft traction levels a slight bit due to the differential's additional forward tilt, in exchange for slightly more forgiving throttle control.In my first outing in a tight autocross, I immediately noticed that rear of the car was very informative in nature and responded very predictably. Frankly I was expecting more trashiness, but was pleased to learn that the rear stayed manageable and ready to act upon driver inputs. Once the car pitched loose at limits with slight lift throttle oversteer into 80 km/h reducing radius corner in 2nd, the gradual transition of rear end was predictable and managed with throttle and with light counter steer. (not faster, mind you, but more informative and reactive).. I don't want to mislead here so I will note that it is still much more peaky and unforgiving to those who are just learning to throw the rear end around so be cautious about jumping into this setup. Overall in autocross, I did generate faster laps than before with predictability causing less number of mistakes, yet at the same time I did make more excessive errors when I did make them (overshooting apexes with 4 wheel drifts among few others, making my runs less consistent. I guess more skills and practice will cure that to an extent. Overall the feeling was simply awesome! And that it is a dramatic change to replace them.
| Battle Version / Club4AG - rear 4 link setup with lateral rod | $700 US |
| Battle Version / Club4AG - rear lateral rod only | $200 US |