Gernby

iTrader: (1)

I couldn't agree more. I don't want to try and turn my 350 into a track monster, but I would like to tune the suspension for a little more nuetral handling. If this comes from changing tire stagger, spring rates, sway bars, or alignment settings, that's what I'm going to do.

BTW, where did you find that the rear tow-in is so high?! Is anything other than toe adjustable on this car?

lobuxracer

iTrader: (2)

I checked it all out on TIS. No adjustments other than toe on the 350. The 250 AWD has a nice cam setup for adjusting front camber, but none of the 2WD cars got it. It makes me wonder if it could be retrofit. [EDIT] Just so we don't waste time, it is not possible to use the 4WD components on the 2WD without a complete suspension swap - the control arm is different, the shock mounting is different, and everything associated with these parts is different - sorry already thought of that one.[/EDIT]

FWIW, here are the complete alignment specs:

2WD Front

Toe - 1.0 +/- 2 mm (0.04 +- 0.08 in.)

Sport suspension camber: -0°36' +- 45' (-0.6° +- 0.75°)
Sport suspension caster:8°04' +- 45' (8.07°+-0.75°)
Sport suspension SAI: 10°55' +- 45' (10.92°+-0.75°)

Normal suspension camber: -0°23'+- 45' (-0.38°+-0.75°)

Normal suspension caster -
16" wheel: 8°07' +- 45' (8.12°+-0.75°)
17" wheel: 8°11'+- 45' (8.18°+-0.75°)
18" wheel: 8°04'+- 45' (8.07°+-0.75°)

Normal suspension SAI: 10°41' +- 45' (10.68°+-0.75°)

4WD Front

Camber; -0°25' +-45' (-0.42°+-0.75°)

Caster: 4°38'+-45' (4.63°+-0.75°)

SAI: 11°16'+-45' (11.27°+-0.75°)

2WD Rear

Toe in (total): 3 +- 2 mm (0.12 +- 0.08 in.) (This is a LOT of toe in).

Sport suspension camber: -1°14'+-45' (-1.23°+-0.75°)

Normal suspension camber -
17", 18" wheel -1°14'+-45' (-1.23°+-0.75°)
16" wheel -1°1'+-45' (-1.02°+-0.75°)

4WD Rear

Camber: -0°50' +- 45' (-0.83° +- 0.75°)

Left-right error: 30' (0.5°) or less

As you can see, there is very little camber on the front, and a lot in the back. Just the right prescription for understeer. Also, the rear toe is adjusted with a cam, not a threaded rod, so there may be issues with lowering the car and not being able to adjust the toe correctly. Personally, I would set it to minimum spec (1mm), the same as I did with my Supra after I ate up a set of Dunlop D40M2s in 11,000 miles on the inside edges. Never had another problem with it after that even with -1.5 degrees of camber on all four corners. A degree and a half negative in the front did wonders for front end grip too.

Also FWIW, I took the IS around a corner I know very well last night with a couple of tCs in tow, and I got exactly what I expected - lots of understeer and complete loss of grip at the bump in mid-turn with a small slide toward the concrete barrrier. Predictable, expected, and a lot slower than my other cars. Still, not all bad, just not like a fast car at all.

lifeisgood

For what it's worth, I had the same question when I was trying to improve the handling characteristics of a 66 mustang that I was restoring. The advice I got was that a thicker front sway bar and adding a rear sway bar would help improve handling--less body roll. A few people warned me that the trade-off of putting a rear sway bar was that it could create oversteer, in the worst case the back end of the car would swing out without warning. I don't drive my car at the track--so I felt the risk was low. I added both the front and rear sway bar to the Mustang and it handles much better than stock.

I like the handling of the IS but would consider a minor upgrade in the swaybar area if that would reduce the slight body roll.

Gernby

iTrader: (1)

lobuxracer,

That' not nearly as much rear toe-in as I thought you were saying. I guess I was thinking 3 degrees of toe-in. My previous car (Honda S2000) needed AT LEAST .25 in of toe-in PLUS a big front sway bar to be nuetral on the track. Of course, the only people that I know that got much mileage out of their rears were those that did mostly highway. I never got to the 10K mark even with corded tires.

lobuxracer

iTrader: (2)

That was the best fix for the problem? Wow. That doesn't sound like a well designed chassis at all, and isn't consistent with what I've been told about S2Ks. I don't have any personal experience with them though, so I'm just surprised you'd need that much toe. Did you already have 3 -4 degrees of negative camber in the front? Oops - probably should be a PM...

Gernby

iTrader: (1)

Don't get me wrong. It handles AWESOME in stock form. It just has an oversteer issue. Honda totally revamped spring, damper and bar rates every 2 years trying to get it under control. With a HUGE front sway bar and plenty of camber, the car is absolutely amazing!

BTW, stock spec for rear tow-in on the S2000 is 1/2"!