Bleach

I run 225 width on all four corners in my 280ZX 2+2 (yes, a totally different suspension and size of car) and it seems to have just a bit of understeer. I suppose that's the safest for street driving...

lww

If I add more camber, it'll make the back end even MORE tail happy.

There's no factory camber adjustment on the rear of these cars so the only thing you can do is add more camber to the front... ;(

Believe me, the car is setup as well as possible for the track without going to coil-overs.

Bleach

Just cut your springs and SLAM it! That'll give you camber.... oooh ya, you'll be cool then. Oh and paint a rising sun on your hood. Gotta have that!

SHADY280

hey i gotta q now that were on the subject. my car pushes really bad at slow speed, bleach can atest to this, hes seen it, i got 255's all around, it handles great at speed, just not slow speed, how can i correct it?

lww

Like, slow speed under acceleration? Or you're just turning around a casual residential corner at 25 mph and the front end pushes out?

SHADY280

under accel, and if i really push it at slowish speeds, like 30-50 kph around a 90 degree turn on the street. i got slightly positive camber, would that not help much at the moment (i havent got around to cutting the springs down yet) and the big sway bars 1/1/8 front and 7/8 rear

lww

Under acceleration, you should get slightly positive camber.

But I'll bet it's that big front sway bar. 1" front and 7/8" rear will help get the rear end around.

On FWD cars, because they have such big understeer problems, they usually go with over-size rear sway bars.

lww

I was running -3.5 deg on the front of my Honda with the stock sway bars. When I went to the over-size SI sway bar on the rear, I pulled over 2 deg. out of the camber and got it down to -1.25 deg with the same corner handling characteristics.

SHADY280

so if i lower the front just a little, it would stay more negative, therfore creating less push, plus i need to correct the back, i think im aboot +2 deg camber

RodMoyes

I was thinking about this, because I have noticed the same thing with my car since putting on the massive/sticky/wide tires...

I have a lot of negative camber on the rear too, which doesn't help. The camber on the front is perfect because I have the bump steer spacers in there.

So, we all forgot the easiest and cheapest way to get rid of some of the cars tendancy to push at lower speeds...

Drop the air pressure on the front
Raise the air pressure on the rear

This is soooooooooooooooooo overlooked and can make MASSIVE differences in handling.

Just think of how much NASCAR and CHAMP and FORMULA 1 teams play with different air pressure settings on those cars to achieve the results they want...

I'm gonna play with my air presure a little and I'll let you know the results.

Now granted, this is not a "Cure all" but it's probably something that will make a huge difference. Idealy, you would still want to correct any camber or other alignment issues that you have as well.

Rod.

Dorifto

In addition to Rod's suggestions about tire pressures, etc., I'd consider an alignment. Sounds like a toe problem. That has, at least in my case, been the culprit of low-speed pushing.

Think of it - toe-out improves cornering, and toe-in improves high-speed stability. Therefore, if you've got excessive toe-in, you'd have great high-speed stability and the like, but rather poor low-speed handling. On the opposite side of that dime, if you've got excessive toe-out, your car will handle very responsively at low speeds, and become very squirrely at higher speeds.

The following link describes what I'm thinking flawlessly. http://www.ozebiz.com.au/racetech/theory/align.html

lww

Tire pressure is an excellent short term solution, but you absolutely need to get your alignment setup properly so you can run the correct tire pressures for your tires to maintain proper heat range and tread wear.

Get the car to an alignment shop and have them check the straightness of the body. If your body is tweaked, it'll make it really hard to get the right alignment to begin with.

You can adjust your rear alignment in several ways like cutting coils to lower it and add more negative camber, slotting the shock tower mount bolt holes or slotting the rear control arm's to adjust the position of the mounts to compensate for weird alignment issues.

Worst case, you can have ArizonaZCar.com fab you up a set of custom adjustable control arms...

PooFlinginMonke

I've found that going with higher profile tires goes a long way toward low speed grip in these types of situations in which nobody has changed the geometry of the suspension to the point of relocating pick up points.

The hard part is getting used to the wallowy feel of the higher profile tires and the finesse required to make a wallower handle (think 300zx in Improved touring).

Many a 240z can pull 1.0g on the skidpad with some good 225/60s.........no need for crazy low profiles that cause wheels to die through normal driving.

This is why most of the front running IT cars still run 60 series tires......well that and the fact that you cannot change diameter from stock.

SHADY280

how does sloting the top of the REAR shock towers help? it wouldnt really effect anything, on the front this is true, but not the rear, and yeah my car is aligned properly, i had it done with all new componants, and i havent hit anything since i had it done, i really need to get rid of that positive camber in the rear, and maybe try the air thing, but im also interested in permenently fixing this. i also find it interesting that others have this problem and its not just me. i never had this prob when i had 225/60/r14 on it. what size are yours now rod? and could it be because our cars weigh so little, the weight is spread across such a vast distance of tire? less psi on the roads surface?

RodMoyes

First, slotting the rear strut mount points can make a HUGE difference by allowing you to adjust camber by "leaning" the top in or out. Rear alignment problems are the least recognized and least understood, and can create WICKED poor handling problems if not corrected.

My tires size now is 245/35/ZR18 ... they are some wide, sticky sonsabitches!

I have A LOT of negative rear camber / \ and because of that, the rear wants to stay PLANTED at slow speeds a lot more than it would with... ZERO l l or Positive \ / camber.

L-Dub is on the right track

Rod.

Dorifto

Keep in mind though, that your rear suspension camber is completely independent of the shock ... it's an A-arm mounted to the body, with a spring holding it up. The hub is mounted directly to the A-arm, not the shock. Moving the shock's top mount won't do much on a ZX.

lww

Think about how the A-arm moves throughout it's travel and what controls that travel. It doesn't move straight up and down. It's on an inside pivot point and the outside travels in an arc.

By moving the angle of the 'at rest' position of the shock, in essence the pre-load on the spring, in or out will change the at rest camber of the car and more importantly, the camber under suspension compression as it moves through it's arc of travel.

RodMoyes

Yeah!
Damn Skippy!

That's what I was sayin'

Rod.

lww

........

260DET

Thanks for the video. Nothing like a day at the track, looks to be a fast one too, plenty of flow. There is a video around of a Z32 at that same place.