'98 VVTi rear sway bar upgrade

[fastegg]

I'd like to quicken up the steering, reduce body roll and reduce understeer on my '98 LS. To do this everything ive read and asked about surgest putting a larger dia rear sway bar but i'm not sure how bigger to go. I'm thinking 2mm bigger. Everything on the car is stock apart from heavy duty Bilstien shocks.
I need new tyres soon and was think of going from 225/60/16 to 225/55/16. Two reasons are firstly to give it a bit more grunt out of corners and 2nd is quicken the handling up..... any surgestions ?

 

[EyesofThunder]

In the US here large sports sedans will see upwards of a 38mm rear bar, which is pretty fat (Herb Adams). The key isn't just the thickness, it is the lever, the shorter the lever the stiffer the bar. My 80 Turbo Trans AM has the Rancho Challenger GTIII bars and they are adjustable ends, so I can shorten the lever based on track conditions or tire traction. Factory I have seen 36mm front bars on the 3rd and 4th generation Camaro/Firebirds before they died off.

For comparrison on the front, Herb Adams and HO Racing market a 35mm front bar (solid) and it is approx 550 lbs/in deflection rate. My Rancho bar is only a 31.75mm bar, but due to the adjustability, I can set between 400ish lb/in to 900 lb/in deflection rate. Stiff is an understatement. But handling it does well. So well it ripped the bar to frame bracket bolts out of the frame. Do NOT underestimate a race stiff bar on a street car at least with potholes like we have here!

So what I am saying is don't neglect the length of the lever, you might be able to simply figure out a way to shorten the lever and very effectively stiffen the bar up without replacing it.

I have seen holes drilled in them (use extreme caution!), but my Rancho's have an adjustable sliding bracket, which is often easy to turn sideways and needs a lot of maintenance (should be splined really to prevent it from turning).

I'd like to quicken up the steering, reduce body roll and reduce understeer on my '98 LS. To do this everything ive read and asked about surgest putting a larger dia rear sway bar but i'm not sure how bigger to go. I'm thinking 2mm bigger. Everything on the car is stock apart from heavy duty Bilstien shocks.
I need new tyres soon and was think of going from 225/60/16 to 225/55/16. Two reasons are firstly to give it a bit more grunt out of corners and 2nd is quicken the handling up..... any surgestions ?

 

[EyesofThunder]

You always want to keep the car in balance, typical US spec cars are usually set to understeer before they get to oversteer. Adding too large rear bar can upset the balance and make it oversteer in a corner when not under power, which is very dangerous. But you do want to have enough rear bar that the car is more neutral and then when you are under power you get to the point of oversteer and you can manage it with throttle and steering correction. Thus you have a FUN car!

Don't forget too, rear springs are often a culprit (again, here in the states where the car companies think we WANT crap handling cars that are mushy and ride poorly), so the rear springs are under sprung and under dampened, and then we have a car that is just crap all the time.

My Lexus GS400 is pretty good, but it still needs rear spring rate increased some, I feel that is better than more bar at this point, but more bar is still also needed. The shocks are spec'd well, I like that dampening rate so far....

 

[fastegg]

'98 LS400 rear bar

Hi Eyesofthunder.
Yeah, I went from a 22mm hollow to a 24mm solid. The guy that made it says its 160% stiffer than stock. When stock, the car understeered badly, particulally in the wet, when I pushed it (in the wet) It'd lose the steering easily, and what was worse, it always felt like the steering was about to go south. After i fitted the new bar, in the wet, the car now feels like it wants to 4 wheel drift, like instead of losing the steering, it feels like the whole car wants to slide... which is good i think as i'm activly looking for a Torsen 2 diff centre out of a mk4 1996 or newer Supra so there's none of this one wheel spinning rubish... once i get the Torsen in it, we should see some serious oversteering. The car has a set of HD Bilsteins fitted but i would like to fit slightly heavier springs, maybe 10-15%... If i had the $$$ i would put a set of custom coil overs but i'm an unemployed parasite and can't afford such luxuries!!! I acctually feel i could have gone to a 25mm rear bar instead of the 24mm but since nobody over here has done any suspension work to a '98 LS i'm the guinea pig.... Its all good fun...
By the way... do you guys use Purolator Pure One oil filters ?
Suposed to be heaps better than stock ones...