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Tuning Guide
Where do you want to go?
When looking at any car, the first thing you must look at when tuning is what do you want your car do. Is it ¼ mile? Track racing? Autocross? Or Canyon Racer… Because depending on this, the parts necessary can differ a whole lot and the more you tailor to one specific area, the more incompatible your ca will become for the other… It’s also important to keep in mind what you want your car to become…definitely not what your accessories shop or friends want it to become, right?
Looking at the stronger side of AE92, your target is most likely mini-track racer or downhill canyon special. But, rushing into this area, you often spoil the delicate balance of this car and, it’s easy to ruin your enthusiasm as well as break your budget. You likely chose a Corolla to keep things inexpensive… This said, you should first try to find what characteristics you like and work toward increasing the potential for where you are going… Of course, the basic idea of suspension and engine tune applies to all areas of work, so let’s take a look at some streetable light modifications first.
Engine:
The AE92 Corolla GTS, AE82 FX-GT, and various front drive Corollas has (or can transplant) a 4A-GE. Needless to say, this is what we like about the cars. Some of you might know that first AE92’s and the FX came with the 120ps 4A-GE and the latter ones in 140ps 4A-GE. Rather than aiming for too much power, let’s take a look at what makes us feel good…the best trait of a 4A-GE is in it’s response and total balance. So we’ll keep this in mind and work towards lighter tune to keep torque curves pleasant for street and sweepers.
The exhaust system on a light tune AE82/92 4A-GE should use between 55~60mm diameter pipes. This will keep the smooth torque curve, which should be the main concern for any street 4A-GE owners. The lack of torque can really make a car a dog to drive in town. With a funnel type (mushroom) air cleaner, like the HKS Power Flow, the intake will be stable and responsive to the throttle modulation. For a little more time and money, one can install 264 degree cams from HKS offering great drivability and higher peak. This is great for front drive...not too difficult in mid-corner throttle and quick at the exit.
Once the breathing is prepped, the next step should be in obtaining lightweight flywheel to bring out the best of what the 4A-GE does…rev… Raising the rev limit another 750rpm is another way to produce a nice 4A-GE too. This should be plenty for modifications and you should now try to tune the engine so it’s at it’s maximum potential the way it sits… Timing, Throttle Position Sensor, compression, oil and fuel pressure, filters, injectors etc…should all be checked.
You want more? Let’s cover that later…Just do these first carefully!
Suspension:
As you all know, the AE82/92 is a front wheel drive car. What this means is proper suspension setting is crucial for getting around turns effectively, especially at the front where most of the work is done. First thing to keep in mind here is that your suspension must stroke for it to turn quickly. True, lowering the car will create lower center of gravity but there should be plenty of suspension travel for you to shift the car’s weight to each wheel.
It’s also notable that the AE82 uses McPherson struts so lowering too much will create negative roll center and will act to tilt the car when lateral force is applied. In theory, you should have enough stroke to not bottom when your tires are at their maximum adhesion…when it’s squealing and just before it howls and smokes. The springs should be soft enough to easily transfer the car’s weight by brakes and throttle, and stiff enough to not let the suspension fully stroke and upset the tire's contact patch. Oversteer and understeer should be easily induced and should be an option to the driver. Front springs of 5~6 kg/mm are best for radial tires and rears from 3.5~4 kg/mm. Use adjustable rate oil shock absorbers for fine tuning for conditions and stages. Gas shocks ride nicer but can get twitchy at the limit and during transfers.
Just as important as spring rates and damping are alignment… To make your front wheels trace where you want to go, you should first set your rears to do one thing… That is, make it stay put until you want it to let go. Rear end alignment should first be set to original specs. That way, you can concentrate on the front suspension. The AE92 OEM front stabilizers (sway bars) are quite nice for occasional blasts, so you should just change the bushings to start. In fact, as mentioned in most of my other writings, replacing all the suspension bushings are the best investment for proper handling. Do it on any car over 5 years old...before you try anything else. OEM is fine but TRD makes some really nice sets that you can still use on the street. They will keep your wheels in place during hard driving. Stay away from using too much pillow-ball joints unless its track only car… They can really cause problems with vibrations and harsh jolting at the mounts.
TRD Bushing Kit and Techno Pro Coil-Over Struts
Its also important for you to choose the proper tire size and wheels. Corolla is a light car so it does NOT need anything wider than 205mm tire width. Ideally, you should equip your car with higher-grade tires such as Yokohama R032 or AVS Intermediates. Stay between 14~15x7” rims so it’s easier to control lower profiles are less forgiving.
When you have better understanding of car dynamics, you can invest in some coil-over systems for your car. This will allow infinite height adjustments to corner-weight your car. And, as added bonus... springs are cheaper and available in smaller rate increments.
Tom's Racing Group A
If you are considering serious cornering control and exit speeds, invest in a Limited Slip Differential. (See LSD section in Tech Talk). You can also invest in ball-jointed camber plates at the top of front struts to improve turn-in response. These two pieces can be costly but a must if you are serious and use coil-over suspension systems.
Brakes:
The Corolla has plenty of braking equipment, as not much is needed to stop a light class car. To fight fade and increase cornering control, swapping pads for a street performance grade is a cheap and effective idea. Grex by Greddy had nice all-around performance and excellent front-rear balance. You can also specify many rates and materials available from Endless, Image, and many other companies in Japan. Steel braided lines and master cylinder stopper increases response and modulation feel. Slotted/ Drilled rotors are not required and can break if you live in cold or wet climates. They are only necessary when you consistently brake from 100mph repeatedly as in race tracks. Also, stay away from racing grade brake pads as they need lot's of heat before they start to work...it's actually really scary on the street because they never heat to proper temperature.
Interior and Exterior
Dog Fight Pro Body Kit
The biggest attraction to AE92 owners is the car’s good looks. The best-looking Corolla of them all, I just had to mention this side of the fun. Decoration possibilities for the exterior of the AE92GTS are infinite. Many body kits are still available and choice can be boggling.
Bomex Aero Kit
As for the interior, there are important elements in choosing the right driving environment. Full bucket seats are almost a must for serious driving and can actually improve driver awareness and controls. Steering wheels and shift knob are matters of personal choice but be careful as this has an effect on driver control too. The AE92 shifter has a long stroke so cutting the shift lever to fit your liking or replacing it altogether with short-stoke shift kit is recommended.