Valkyrie

Can someone suggest a good baseline alignment for a fairly light (1100 kg) track car with 235/255 17" street tires (Direzza ZIIIs), no aero, a single turbo (300-350 HP), and coilovers?

I asked the shop to give me 0.2 degrees in the rear, and they ended up giving me 0.2 MILLIMETERS (per tire). That's... not going to work. And left/right caster was off by over a degree. Now I'm out $150 for a **** alignment....

evo_koa

iTrader: (2)

track car as in autox or road racing?

Valkyrie

Road racing. You know... on the track.

ZDan

front camber: 3°
front toe: 0°
front caster: 5° - 6.5° (I run 5° but some people think that more is always better... That may have some validity to a point for autoX, but IMO not so much for track usage. Personal preference/driver feel thing)

rear camber: 2°
rear toe: 0.1° total (1mm total, 0.5mm per side)

I wouldn't worry about the toe too terribly much, lots of people run 0° rear toe with these cars which is essentially what you have now. Then again if you asked for 0.2° (total, I presume?) and they gave you 2x0.2mm total, or ~0.04° you could ask them to fix it. But you might just try it first. I run 0.1° total, for me I would consider 0° to 0.2° total to be a good minimum to maximum range.

I wouldn't worry about caster being different by half a degree, but over 1° difference, yeah, you might ask them to fix that...

Valkyrie

Supposedly they couldn't get the caster within one degree while also keeping the camber the same. Not sure how much I beleive it....

0.2 degrees translate to about 4 mm total toe-in.

Do people really run so little rear toe-in? That seems like a recipe for disaster for a relatively high-powered rear-drive car. You might end up going toe-out during hard braking.

I got -2 degrees camber in the front and 1.5 in the rear, and I'm OK with that for the time being.

A friend of mine actually suggest slightly toe-out in the front for less understeer.

I for one could use a little more caster since the steering actually feels very light for me, having come from an MR2 (power steering, but HEAVY power steering).

ZDan

Depending on what tracks you go to, might be worth trading some camber symmetry for caster symmetry. I.e., if you only do counterclockwise tracks you could probably stand to lose some right-side or gains some left-side camber without losing (possibly gaining) overall handling performance.

0.2 degrees per side = 0.4 degrees total ~4mm total toe-in (4.4mm for 25" or 635mm diameter tire)
IMO that is way more toe-in than you want.

What does power level have to do with anything under hard braking?! Nothing evil necessarily happens when/if you smoothly go from slight toe-in to slight-toe-out under dynamic conditions.
FWIW I have about 550 crank hp and I just looked at my alignment and I'm at 1.5mm total rear toe-in, or 0.75mm per side, ~1.5 degrees total. It's fine...

Too much rear toe in sucks. Bad for turn-in responsiveness, bad for straightline stability in grip-challenged conditions, and very bad for rear tire wear.
I no longer subscribe to the conventional wisdom that more rear toe-in is "more stable", after excessive-rear-toe experiences with the S2000 and 240Z (intentional and unintentional), I've found that excessive rear toe is way way worse than near-zero rear toe.

More would be better... I run more on my STREET car (that I take to the track)

I've never had to resort to toe-out up front, but would be willing to try it. But IMO for "less understeer" you're better off minimizing rear toe first, and trying that with zero or near-zero front toe. Setup with excessive rear toe-in and big front toe-out to try to fix the understeer is not a good place to start, IMO...

Dunno what people have against "light" steering as long as it's responsive and communicative. Everybody always seems eager to add in as much caster as possible for more steering weight/resistance though... In my experience, too much caster can add heaviness to the steering that can actually mask feel rather than enhance it. But again, it's a personal preference thing.

billyboy

If you're running stock toe links (and trailing arm bushing to a certain extent), the norm here for a circuit car would be 4mm toe. Powering the car on and off throttle on a hoist shows the compliance in the system....and it goes the way you don't want it to in the off position.

ZDan

Again, if you get some toe-out under dynamic conditions, it's not necessarily the end of the world. I know because I get toe-out at the back of my AP1 S2000 in every braking zone at the track. That car has a lot of toe change with bump, more than 6mm or 0.6° total rear toe-out from the static setting for every inch of droop travel under braking.
After trying 0.6° static rear toe-in (per "expert" recommendations), after two track events I knew I couldn't live with it just based on tire life. Also, the handling was not ideal, kinda nonlinear and spooky.
So I took it back to the alignment shop and asked for half that, or 0.3° total, 0.15° per side. Instead they gave me 0.15° *total*. I was a bit concerned with running that little rear toe-in vs. 0.6° given recommendations of "experts" and the weird handling behavior of the car. But whaddya know, the car handled *better*, more predictably, with improved turn-in. And rear tire life more than doubled!
Note that with 0.15° total static rear toe-in on that car, rear toe is definitely going into the toe-out range in the braking zone to the tune of at least 0.45° toe-out (probably more than that). But it's not a problem.

Anyway, this might also sorta fall into the "driver preference" category, but I strongly encourage anyone to try running minimal toe-in values and see what you think. I have intentionally and unintentionally tried big toe vs. little toe on the S2k and 240Z, and for me, running minimal rear toe-in is MUCH better for handling linearity, turn-in responsiveness, straight-line stability in the wet or over bumps/undulations, and way way way better for rear tire life. Literally no downside for me.

FWIW it looks like the FD spec is for 2mm or ~0.2° total rear toe-in, with an allowable range from -1mm to +5mm (0.1° total toe-OUT to 0.45° total toe-in).

BLUE TII

iTrader: (9)

Caster is nice because it provides camber as you turn the wheel.

So it provides more camber in low speed high steering angle cornering (like a tight corner you just stood your car on its nose with the brakes for).

Still, like ZDAN said, I maxed my camber with regards to keeping the caster the same on each side (yes, this is a limit to the FD suspension adjustability).

The only difference I see on my auto-x set-up compared to track set-up really is that I run minimum rear camber for maximum grip accelerating as I am squirting out of corners in 2nd (lots of torque through gearing).

My FD auto-x, street, kart track, hillclimb alignment-

Front ride height: about 25.25" to top of fender arch
(ride height is a tiny bit off side to side because of corner balancing)
Front Aero: Stock R1 front lip
Front Camber: -2.4
Front Caster: -6.7
Front Toe: 0

Rear ride height: about 25.5" to top of fender arch
Rear Aero: Top Fuel spoiler
Rear Camber: -1.2
Rear Toe: 1.5mm toe in per side

Ohlins DFV 11K/11K
295/30-18 DOT-R
18x11 +45
Poly front bushings
Poly rear upper arm bushings only

I found adding the rear spoiler helped settle the rear over 90mph, a GT wing would have even more effect.

If you have loose bushings or stray far from stock offset you can get some sketchy braking behavior.

Valkyrie

Did you actually graph your bump steer? Six millimeters for the first inch of droop is a metric ****-ton of bump steer.

If your car isn't wickedly unstable under hard braking, I suspect you aren't actually getting toe out under braking.

Unless you're driving something like an EVO that has a lot of electronic controls, driving a car with rear toe out is akin to riding in a shopping cart.

ZDan

At the track, the difference in camber gained in low-speed corners for 7° vs 5° caster is ~0.3°, and for higher-speed corners the difference becomes negligible. You can run slightly more static camber (like a tenth or two) to compensate for this if you run low caster.

IMO caster is more of a "driver feel" thing for track usage, more is not strictly better or worse for objective cornering performance.

For autoX, with much greater steering angles, it becomes a more important setup parameter for performance. But there's still going to be a limit to "more is better"...

If camber-limited and you can trade caster angle for more static camber, that might provide a positive performance benefit at the track.

ZDan

I didn't measure it, but this guy did: https://www.s2ki.com/forums/s2000-ra...ck-ap1-817939/
He measured 0.42" of toe change with 3" of compression travel, on one side of the car! Yeah, a metric f**k-ton...

It could be that the toe-change curve is less severe on extension, but the guy reports that it was quite linear on the compression side.

I do not subscribe to the idea that rear toe-out necessarily results in wild instability anyway. Sure, significant rear toe-out will give rise to instability, but nothing evil instantly happens when you go into modest amounts of dynamic toe-out.

BTW a shopping cart with fixed rear wheels and castered fronts is very stable! I've driven a fair number of shopping carts and there are seldom issues with stability, if anything they're *too* stable and require a lot of input at the helm to turn when loaded...

Anyway, I've tried running a lot of rear toe-in and much more modest numbers and in my experience, on the road and especially at the track, running static toe nearer to zero is infinitely better for all handling characteristics and for tire life. I think it is a better idea to start at the small end or at least at the midrange of factory toe spec than to start at the maximum end of the very wide factory spec range.

You can have your rear tires working against each other by running a lot of rear toe-in, and try to compensate for the understeer by pitting the fronts against each other in the opposite toe-out direction. But IMO not the best use of tires...

Valkyrie

Seeing as Honda is a pretty competent designer of suspensions, I assume that either 1. the guy measured it wrong 2. his car is slammed (or something is installed/adjusted wrong), or 3. yes, it

I do not subscribe to the idea that rear toe-out necessarily results in wild instability anyway. Sure, significant rear toe-out will give rise to instability, but nothing evil instantly happens when you go into modest amounts of dynamic toe-out.

[/quote]

A smidge of dynamic toe-out might be acceptable, but stastic toe-out is a no-no if you want a driveable car.

BTW a shopping cart with fixed rear wheels and castered fronts is very stable! I've driven a fair number of shopping carts and there are seldom issues with stability, if anything they're *too* stable and require a lot of input at the helm to turn when loaded...

[/quote]
....wait, are you talking about shopping cars, or those little buggies fat people ride around on? Also, if you have a car with rear toe out that's jacking the inner rear wheel up, that car is going to inherently oversteer.


Sure, more is less in many ways, but that doesn't necessarily mean better lap times. I like a planted rear even if there's a little understeer, especially under throttle.

ZDan

You didn't finish here, but it has been widely established that the AP1 S2000 does indeed exhibit big toe change with travel. This guy's absolute measurements may not be 100% on but the "toe-in with bump/toe-out with extension" behavior is very real and due to non-parallelism of the toe link with the control arm. This was fixed in the AP2 generation.

Actually the Japanese manufacturers have made this same damn mistake repeatedly. FC RX-7, early 2nd-gen MR2, and then the AP1 S2000. The idea being to provide progressively more toe in with bump to give more understeer under increased cornering load to "help" the uninitiated. BAD idea, but one that some otherwise brilliant car designers have repeated for no good reason...

First off, it causes handling behavior to become non-linear and inconsistent with suspension travel.
Secondly it actually PUNISHES the uninitiated as when they get into trouble cornering they LIFT off the gas, rear suspension extends, outside rear toes relatively outward and they get additional oversteer above and beyond the natural oversteer they get from unloading the rears and loading the fronts. And around she comes...

Yeah, that's the "rule" I was told and that you've been told. But again, it's not like you go into magically evil territory when you cross zero. I would rather try 0.1° static rear toe-OUT in my S2000 than go back to 0.6° toe-IN. There's going to be a fairly broad range of acceptable rear toe and handling behavior will become less acceptable moving further away from optimal, and I know that 0.15° is well within the sweet spot and that 0.6° is well outside it.

When Mazda developed an acceptable range of static rear toe-in for the FD, they arrived at a range from -1 to +5mm, or 0.1° total toe-OUT to 0.45° total toe-in. So obviously they found that slight toe-out was not a disaster for handling.

No. A shopping cart is stable. It will keep going straight until you act to cause it to turn. A standard U.S. shopping cart with fixed rear wheels and castered front wheels, anyway.

No, if you have static rear toe OUT, the INSIDE wheel in a corner is actually giving more understeer, while the much more heavily loaded outside rear is giving more oversteer. But, AGAIN, as static toe is reduced there is nothing BIG and MAGICAL that happens when you go from small toe-in to small toe-out. Despite the fact that well-meaning people have told you and I that. They're wrong.

You asked for a STARTING point. As someone who has tracked a number of cars at a bunch of tracks over a long period of time, I gave you one. If you already know the answers, why'd you ask the question!

I'm just trying to save you some time here, ultimately you have to find your own way anyway...

In my experience, the FD with ~0.1 - 0.15 degrees total rear toe-in (0.5mm to 0.75mm per side) is totally stable on corner exit even out of 2nd gear corners with 550hp applied. For what it's worth...

Valkyrie

Doh, I meant to suggest that the S2000 might have enough anti-dive/anti-squat that it doesn't droop much during braking of when letting off the throttle, but it sounds like the AP1 does have a fairly problematic rear suspension.

Shopping carts here have four caster wheels, so they aren't stable.

I only have 0.2 mm total toe, so I will try to get at least 1 mm. I wonder how many turns of my toe links that is...

billyboy

Not quite sure what the Honda has to do with the FD really. The Zed is a stretch too, have a mate who professionally fixes the suspension, at least within what various rules allow, for clients around the world for historic competition use....there's quite a bit to fix!

I can't speak for road tyres - which sort of defeats the purpose of a track car to my mind, but at least in R comps and slicks, which I expect he'll get around to eventually, tyre life implications seem to be nil in any decent brand. You'll heat cycle them out long before wearing them out....if he was every day driving as well, yes, there's cause not to run that toe.

ZDan

I made mine quick enough with fairly minor mods...
Exactly the same as the FD? No. But not totally unrelatable or irrelevant either.

??? So you don't care if you get 3 events or 6 events out of a set of tires?

Totally depends on the tire. There are plenty of track-only R-comp tires that have usable grip down to the cords.

Anyway, you gave your input and your reasoning (which I disagree with).

I'll stick by my recommendation for a *starting point*. Don't see any reason to start with a lot of rear toe. Resorting to a lot of rear toe-in for "stability" and to reduce oversteer is a misguided approach...

In my opinion!

j9fd3s

iTrader: (3)

its not problematic, its meant to feel really responsive, which it does. arguably it gets too responsive, but that is opinion. we had an AP2 out at the track a few weekends ago, and at 5/10ths it was fine, but 8/10ths it was amazingly tail happy.

not to turn this into a car review, but overall i was disappointed with the S2000, on the street its ponderous. it makes the Rx8 feel like a supercar.

j9fd3s

iTrader: (3)

may i suggest a little test?

so if you have zero toe in the front, mark the tie rods, and give yourself a flat (of the hex) of toe out on each side, and run a session. then go back to where it was, and do another session. if you have time, try a flat of toe in.

the right setting is the one that works the best

Valkyrie

Just in the front, or the rear too? I assume you mean a 1/6th turn.

I don't really have enough to say about the front except that it kind of understeers, but I suspect that's not an alignment issue to begin with.

The best way to describe the way it hands in fast corners is that the front of the car tends to trail behind the direction I'm steering rather than point straight at it. Does that describe push understeer?

I suspect my handling problems might have to do more with a lack of rear stroke and rebound damping than anything else. These shocks are SOFT for the spring rate, which in turn is too soft for how little stroke they shocks have.

ZDan

That's really the only major flaw with the car. That and soft top, really wish they'd made it a coupe...
Here's mine braking for turn 1 at New Hampshire Motor Speedway:


Rear is definitely extended at least an inch, which would put me well into the toe-out range based on bump curve, but not taking into account bushing deflections (which probably toe it out further). Front dive is somewhat disguised by the fact that tires are 205/45-16 instead of stock 205/55-16...

Do you think if you take it back to the alignment shop they'd work with you? Front caster being a degree out is certainly driveable but not ideal, would be good to have that addressed as well.

Valkyrie

Probably not. Also, I'd still have to pay the person who trucked it over to the alignment shop since it's not street legal. I heard some mumbo-jumbo about them not having enough adjustment available to fix the caster or the toe... although I think it was BS and that they simply didn't realize I had specified degrees per wheel instead of millimeters.

I bought a paint pen and marked my cam bolts and tie rods so I don't lose the alignment I have.

It's actually closer to 1.4 degrees off, in terms of caster...

Turns out my rear shocks only have 2.36 inches of stroke from full droop to full bump. That's.... not good. My fronts have twice as much stroke.

I'm probably going to have to buy different coilovers.

adam c

iTrader: (2)

Maybe I missed it, but I dont see what year your car is. My car is a 94. I had some understeering issues that went away when I swapped out the stock 94 rear sway bar for a 93 oem bar. The 93 bar is slightly stiffer, and induced enough oversteer to make a really nice difference.

Valkyrie

It's a JDM 96 Type R (base model).

j9fd3s

iTrader: (3)

just the front to start with, its very simple.

for the handling problem, if its bottoming out, raise it up. its very very easy to overthink a setup, and if its a new(ish) to you car, it is better to under think things.

lower it, until it bottoms out, and then raise it up. set toe to zero, initially.

set camber to something negative, -2 and -1.5 is fine to start with, the actual amount you run depends on the tire. for example, we run a 205/50/15 on the miata, and we started with the R6 hoosier, it liked about -3.5 degrees of camber. we have since switched to the S&M7 or whatever, its just a newer Hoosier, and it only wants -2.5 or so. the new tire is WAY faster.

castor, like Dan says is up to you. for a road race car it won't make any difference, except the driver (thats you!) might like a certain setting. the FD is a PITA to adjust at the track. for starters i would just make it even. this is almost the last thing to play with, in road racing.

shocks. soften them all the way, and go for a drive. then go all the way stiff and go for a drive. then try half way. at this point, your butt dyno should be calibrated enough to know if it wants to be stiffer than half or softer than half.

if you have adjustable sway bars, try them! thats what its for! if you don't, try unhooking the rear, see what you think.

for tire pressures, just set them all to something, hoosier has a chart of tire size to vehicle weight, just use that and then don't touch em. tires are springs.

i realize there is a big time investment in this, we actually keep a log, putting a white board in the trailer was really the best thing we've done in years.