How Much Toe-out?

[sopwith21]

Hi everybody. We're still working like maniacs here trying to win a championship later this month. We've not yet checked the toe-out on the car (from the previous owner) but it looks like it has a LOT. Probably over a quarter of an inch... maybe more.

We run on an 11-turn, 2-mile road course with top speeds around 120, low speeds around 40 and average around 72 mph. I have a '74 260z with 23x9x15 Goodyear R430's, with recently installed coilover kits, Tokicko adjustable struts and a welded rear end. It handles pretty well, but we're still dialing the chassis in.

What do you guys suggest for toe out? Thanks!

[dspillman]

HI Sopwith,

Run as little as possible on both ends...zero in the rear...fronts just enough to make it turn in. Replace all the mushy bushings with poly or delrin...check bearings. dragging wheels around is sure way to go slower in a straight line.

david

[PrOxLaMuS©]

Let me get this right.....

Toe-In ( / \ ) improves turning and braking and acceleration

Toe-Out ( \ / ) improves stability but acceleration and braking is a bit skiddish and turning is a tad more difiicult

[sopwith21]

Right. And toe out can turn you out of a corner or switch directions quickly. Since turn-in is not a problem on my car, I can afford to go with a slight toe out and see if it helps. Trouble is, the previous car owner had LOTS of toe out. Doesn't look right to me at all. I'm thinking of squaring up the car completely.

[Brett240]

nononono hang on a sec.

Toe in / \ gives improved high speed stability, decreases turn in ability but will help more mid-corner once the weight has transfered to the outside tyre. acceleration will suffer (marginal- not noticebly) compared to zero toe.

toe out \ / helps initial turn in but thats it. once the cars weight is on the outside tyre its of no help. stability suffers - makes the car wonder.

[PrOxLaMuS©]

ahh had em almost swapped around

[jmortensen]

I used to work in a shop with an alignment rack, so I tried a BUNCH of different alignments. The fastest rear toe setting for me was 3/16 total toe in. I like 0 or a little toe out in front, usually 0 on a big track and toe out at autox.

I hear people talking about "dragging tires" and I don't know what to make of it. I think that school of thought comes from ITS where guys are trying to get the most out of their 190bhp, and given their rules maybe you can't blame them. I run 3/16" total toe in the rear on slicks and can get a full season of autox and maybe 3 or 4 track days out of them, so it's not like that little amount of toe burns them off the car right away. When I was telling people about my toe settings on hybridz a lot of them assumed I would be going thru tires like crazy, but the reality is not at all. I usually replace them because they've been over heat cycled, not cause they're down to the cords either. 3/16" total is WELL within the factory alignment specs also IIRC.

My best guess is this has to do with the 2 basic styles of race car set up. As John Coffey has explained it on Hybridz, the "East Coast" setup uses very stiff springs, smaller sway bars, stiffer springs in front. The cars tend to understeer more. Apparently this works well due to the very smooth surface of tracks back east. The "West Coast" setup uses softer springs and bigger bars and tends towards a little toe in in the back, and the cars tend to oversteer. Our tracks are not so smooth and this works better according to the theory. I like my car set up West Coast style I guess, but I came up with my preferences way before I knew that they fit a pattern.

Bottom line is I'll do whatever is FASTER, and for me that is toe in on the rear.

[Walter Moore]

Ok, really stupid question...

Are you guys using those aftermarket coil-over rear suspensions to achieve toe in/out adjustment, or is there something that I missed when I put my rear suspension back together?

I didn't see anything that looked even remotely adjustable on the entire rear suspension.

[dspillman]

You can use eccentric bushings where control mounts.....could also use other means, but eccentric are easiest.

david