Suspension Upgrades

If you've just bought an AE92 GT-S, one of the first things you'll probably notice is the excessive amount of front end dive when braking--you don't even have to slam on the brakes to get it all wallowy. If anything, the suspension doesn't inspire confidence when pushed to its limits. I also noticed a tendency for the wheels to lose traction on uneven surfaces when getting on my then-stock brakes--the stock struts were shot, but I've ridden in other GT-S's with the same problem. After checking out some video captures f/ a few autox events, I realized that body-roll was a big problem.

After ordering and paying the entire amount upfront for Koni Sport strut inserts, I had to wait 6 weeks since no one in the U.S. stocked these Koni's--they had to be shipped by sea in a pallet. These Koni's are inserts. That means you have to use your old struts' housings. I had to saw off the tops of the rear struts, drill a hole in the bottoms, slip the rear Koni inserts in, and bolt it down. For the front struts, I had to find the OEM-type strut housings since the previous owner of my car bought some crappy struts--these weren't rebuildable with a screw top like the OEM's were. After some furious junk yard searching, I decided to try the OEM strut housings off an AE82 FX-16 GT-S--perfect fit! =)

Currently, with the Koni strut inserts, Ground Control coilovers, and front and rear TRD anti-swaybars, my car handles beautifully. The difference is like night and day! I was surprised at how much higher the limits are. If I get the suspension dialed in right, I can enter turns with a hint of understeer, let off the gas for an instant, get the rear end to rotate nicely, then get on the gas again! Ahhh... Handling Heaven! =)

Suggested suspension upgrades (in order) for the AE92 GT-S:
1. Proper Alignment Settings
   Effect: With a few twists and turns of the suspension bits, you can change your car's handling from tame to watch-out-cuz-I'm-outta-control. For a car that spends 90% of its time cruising on the highway, you'll want the least amount of toe-out at the front to keep the car from wandering a lot and minimize tire wear. If you tend to drive hard, do a full autocross season, and appreciate a better handling car, dial in more toe out up front. Keep the rear toe as close to zero as possible--too much and the car will be scary during quick transitions unless you have adjustable rebound struts. The more camber, the better--but, you'll have to watch out for uneven tire wear. If you have a dedicated track car, the sky's the limit!
2. Tire Air Pressure
   Effect: Yes, changing the tire pressures can affect handling. The general rule is that the more air a tire has, the more load it can take and keep its traction. Since the AE92 GT-S has more of its weight up front and inherently drives like a FWD car (i.e. understeers), you'll want the rear end to be more "loose" to decrease the amount of understeer. So, raise the tire pressure for the front and decrease the tire pressure in the back.
3. Better struts
   Effect: Keeps the chassis' movements under control (due to any springs' propensity to release stored energy from the compression stroke). Daily drivers that see no track time will be fine using Tokico "blues" or KYBs. If you want to maximize your suspension performance, you'll definitely want to have adjustable rebound valving. The Koni Sport strut inserts are perfect for this. Be warned that as you start increasing the spring rates (anything more than twice the OEM rate which is 120 lbs/in), the strut will be under-valved and will prematurely wear out. The best solution is to get strut inserts that can be custom-valved to match the car's weight and spring rates. The Tein HA suspension setup and Koni inserts can be custom valved for additional money. For all-out racing without compromise, look into the double adjustable (compression and rebound) "Advance Design" race inserts--you can custom valve and rebuild them all by yourself. This upgrade should be done along with springs; it's cheaper and more time efficient.
4. Stiffer coil springs with a drop of no more than 2"
   Effect: Stiffer ride, more controlled cornering, no more front end brake dive (I found out that the springs were a major source of the amount of brake dive on the AE92. This upgrade should be done along with new struts.
5. Plus-size wheels
   Effect: Increase your car's contact patch with the road surface. Just try to stick with tire sizes that'll keep the same overall rolling tire circumference so the speedometer isn't thrown off. I know people run a 17" x 7" wheel combination on their GT-S's with no problems. The trick? Get a wheel with a 38-40mm offset, or for less ambiguity, no more than a 5" backspace. But, don't go thinking to yourself, "Hey! Now I can throw on those 18-inchers on my GT-S!" No!!! Don't do it! As you progressively increase the tire/wheel size, the weight will start to add up. You'll be trading off straight-line acceleration for slightly better lateral acceleration, i.e. cornering. Plus, all of that extra weight will add up to the unsprung weight in your suspension system. What does that mean? The springs and struts will have a harder time controlling the heavier suspension bits. It all boils down to picking a tire/wheel size that isn't ridiculously big. I'd suggest sticking with a 15" wheel for a daily driver.
6. Stiffer Anti-roll Bars in Front and Rear
   Effect: Aside from dramatically decreasing the terminal roll angle, they'll help bring neutral handling to the car. The AE92 GT-S will start to behave more like a RWD car, rather than a FWD car. You can opt to also install the stiffer rear bar, but it'll be more "nervous" on the road. Just a word of caution... Getting used to a FWD car that oversteers at your will takes some getting used to! The front TRD bar is 27.5 mm in diameter and 50% stiffer than stock while the rear is 19.35 mm and 67% stiffer. Click here to see a comparison of the rear OEM and //TRD anti-swaybars.
7. New or Polyurethane bushings
   Effect: Brings the suspension specs back to STD and reduce tire wear due to misaligned parts.
8. Crash or Camber Bolts, Camber Plates
   Effect: If you've just started thinking of how to improve the AE92's suspension, you most likely noticed that the caster and camber are both unadjustable from the factory. Solution? You can try using crash bolts from the dealership. These replace the hub-to-strut bolts on either side with smaller diameter bolts to allow for "play." If you plan on running large amounts of negative camber (> -3.0° in front, > -2.0° in back), do the proper thing and get camber plates to replace the strut tops.
9. Offset Bushings
   Effect: If crash bolts aren't for you, try using the bushings from Whiteline Automotive. The bushings allow for front camber and caster, and rear camber adjustments.
10. Coilover kit
    If you want even more adjustments (i.e. spring rates), look into getting a kit from Ground Control. They're probably your best bet--they're under $400 and you have the option of picking the spring rates that suit your particular needs. You will need to keep the original strut housings, so if you haven't upgraded your struts, then now would be a good time to do so. After a detailed and long discussion w/ some fellow autocrossers and personal experience, I'd recommend running rates of 350-400 lb/in up front (depending on how balanced you want the car to be; higher front rates will decrease the oversteer tendency) and 175-225 lb/in at the rear. These rates should give a decent compromise between track and road driving. If you want stiffer springs, try to maintain the 3:2 spring rate ratio (in kg/mm). Fine tuning will be accomplished by means of struts with adjustable rebound damping and tire pressures.
11. Longer wheel studs
    Effect: If you're running with alloy rims, they may actually be thick enough at the hub seat so that the wheel nuts don't fully thread on. With longer wheel studs, you are assured of a better fit and peace of mind. Click here to compare the OEM and longer Land Cruiser wheel studs.
12. Wheel Spacers
    Effect: By increasing the tire track (width) of a car, you can help lower the suspensions' roll center. What does that mean? To put it simply, you can balance out your car the way you want it to suit your driving style. Believe it or not, H&R (the famous suspension company from Deutschland) actually makes a set of spacers for the AE92! They start at US$69 per pair and include longer studs and 2 alluminum/magnesium alloy spacers. Choose from 5, 15, 20, and 25 mm thicknesses.
13. Stickier tires with stiffer sidewalls
    Effect: Helps you get the most out of your improved suspension setup. Supposedly, the "time gap" between Hoosiers and Kumhos is negligible in FWD cars. Hoosiers may be worth a tenth of a second. Kumhos run approximately $100 while Hoosiers run $150+. Be advised that at the very least, you'll need to run -2.5° of camber to improve tire life and performance. Too little camber and the outside shoulders will just scrub themselves to death.
14. Custom-built Strut Housings with Race Inserts
    Effect: The limiting factor in how far you can drop the AE92 GT-S is the strut housing height. This is especially important up front. If you drop the front end height so that the lower arms are parallel to the ground, you'll only have 0.75"-1.25" of compression travel depending on your suspension setup. Custom-built housings to fit so-called "short stroke" inserts are the proper solution. Short stroke struts have the advantage of having shorter bodies. That, in turn, means you can cut approximately 20mm off the top of a strut housing and gain that extra 20mm of compression travel. You get to pick the compression and rebound valving to match your vehicle's spring rates, corner weights, and anti-swaybar stiffness. Expect to pay $1600-$2000 for a complete race setup.