ZDan

Compliant tread and sidewall are generally better for rolling resistance, this is hinted at in part of the text you snipped above^^^
A tire tread and sidewall with very low bending stiffness doesn't resist deforming as much and generates less heat (lost energy). Think of how a radial tire bulges out at the bottom vs a much stiffer bias ply tire. The radial is more compliant and has much lower rolling resistance.

Back to the idea of dialing in more front toe so that it goes to zero while driving:
Each front tire on a 3000 lb S2k (w/ driver + fuel) will see a drag force of ~1000 lb under 1g braking. How much toe out do you reckon that 1000 lb induces? I don't know, but surely it's not more than 1degree. Even if the front tires are generating 50 lb of drag just freewheeling (at zero toe, I bet it's less than 15 lb, there's just no way RS3 RR coeff is .07), that would net you on the order of .05degrees if 1g braking gives1 degree.

Food for thought... Still betting that zero front toe will give you greater tire life than .16 degrees toe-in!

Gernby

I really do appreciate your input on this thread, and I'm seriously rethinking my position. Since I've had several arguments with people about the torque loss from the RS-3's, I've been struggling to separate that argument from the one that pertains to this thread (change in toe from rolling resistance).

Since I do CAN Dyno pulls in 3rd gear, but do DynoJet pulls in 5th, it seems the difference in tractive effort could explain why the CAN Dyno shows greater loss than the DynoJet. I will definitely try to squeeze in some testing with different combinations of tires with various levels of toe-in. The rear toe isn't as easy to set without an alignment rack, but I think I can work out some sort of system. I did really well calculating everything while installing and setting up my suspension last week, but spent $350 on my current alignment and corner weight check.

Gernby

To answer this question, I would guess that 1000 lbs wouldn't deflect the bushings all that much more than 100 lbs. I would expect the suspension bushings to be VERY exponential in rate.

SpitfireS

Yeah, my bad, I was looking at the posted jpeg.
Maybe I need a new monitor - or better glasses, or both

Well... the max in UK-spec would be 0°40" and not 1°20" (= 1,33 degree, right?)
And, the rear toe in UK-spec is at the minimum OEM setting, as if they agree with your less-toe-is-always-better statement but didn't want to recommend a setting out of OEM specs.

Is there any change the MY'00-02 AP1 chassis will react differently to less than UK-spec rear toe in?
With the build-in rear toe change at suspension compression to "help" cornering?
And the build-in snap-oversteer when you lift mid corner?
(I know one should not lift mid corner but if the rear steps out and you're not kinda waiting for it or expecting it one may get confused and lift, making it worse...)

ZDan

Max spec UK toe is 0°40' (thats 40', arcminutes, not " which is arcseconds. UK spec is screwed up in more ways than one...) *per side*. 1°20' total (or 1.33°).

I inadvertently ran in the MIDDLE of the UK spec range at 1.05° (.5 + .55) and the result was well nigh undriveable and wore out rear tires ALL the way down in 3000 miles. So even that amount is RIDICULOUS. 1.33° is just INSANE. Or maybe just stupid...

My theory: They didn't properly transcribe the US/rest-of-world spec range. US spec was 0.32° to 0.64°, UK spec is exactly double that. I think they took the TOTAL US toe spec and accidentally applied that PER SIDE in their document. Then when EVERYBODY who ran that spec got AWFUL handling and truly ABYSMAL tire life, instead of fixing it they just said to use the small end of their ABSURDLY inflated spec range!

As far as I'm concerned, the MINIMUM US spec of 0.32° total should be the MAXIMUM. So to me, the minimum end of the UK spec is about TWICE the max I would recommend.

My car is an '01, so I'm dealing with the same toe-change-with-bump issue.

That's exactly right, don't abruptly lift when things start to go wrong! Hang in there! My first track event in the S, I ran the max US spec rear toe, or 0.64°, because I was running close to no tire stagger (which, it turns out, isn't that big a deal anyway) and I knew the car's reputation for evil handling characteristics. AT that level of rear toe, I must say it lived up to that reputation. The car was a blast to drive, but handling could get a little spooky/weird/non-linear. Nothing at all like my 240Z, which even when set up to oversteer like mad was always linear and predictable in doing so. After my second event, the rears were corded and I knew I couldn't deal with the wear rate, so I asked the shop for the min spec, 0.32° total, 0.15° per side. INstead they gave me 0.15° *total*. I was concerned that the cars sorta spooky behavior would get worse, but found that it actually handled more predictably with the toe tremendously reduced! And tires lasted 2-3x longer! Win/win.

Only once have I gone back to BIG rear toe, and that was inadvertently and unbeknownst to me. But the handling steadily got worse and worse (more EVIL), and tire wear went CRAZY (see above).

Anyway, fear not running MINIMAL toe. EVERYTHING gets better! Handling, tire life, mileage.

IMO it's HUGELY unfortunate that so many have tried to "cure" the AP1's weird handling with more toe, which to me makes it WORSE! And also kills tires. And mileage...

Hence my crusade against running a lot of toe. Maybe I should write a treatise on it and get it stickied...

SpitfireS

You've got me - again - on the ' or ".
Degrees / arcminutes / arcseconds = ° / ' / ", I hope I've got it right now.
Nevertheless, in the UK-spec that I posted I see 0°20' per side, 0°40' in total, for rear toe.
Or maybe I'm having a Stan March - I don't get it moment.....
I should rephrase my question, knowing one can feel the difference in 0,1/0,2 bar of tyre pressure.
So I'm sure I would notice a difference with another toe setting, would it be a positive one, even in an AP1?
Going by your enthousiastic crusade against toe-anywhere I guess the answer is: Yes, 100%.

Btw.. how would you explain the huge difference in opinion between your toe recommendations and others posted in this thread?
I have no reason to doubt - and I don't - about what you are saying, but the same goes for the others.
You can not both be right... right?

One explanation could be this:
I've posted more than once the Torsen diff play's a huge role in handling of the car.
And diff oil changes the behavior of the diff.
1+1=2, diff oil changes behavior.
Not that many people have actually agreed with me or even noticed the same.
Making me - sometimes - think I'm just imagining it all.
But I know I'm not, I know what I feel in my seat when taking a (tight) corner under throttle.

Do your "Toe sucks" statements sometimes make you feel like Don Quichot?
"Why, for the love of Pete, doesn't anyone else notice what I did?"

ZDan

UK spec range you posted (first sheet) is 20' per side to 40' per side, 40' to 1°20' total. Which is 0.67° to 1.33° total. No doubt after a slew of customers got undriveable cars and 1/10th normal tire life, they decided to recommend the lowest setting in that range (second sheet). Which is still absurdly high.

Obvi!

In the end it's up to you to figure out what really works and what doesn't, for *you*. But I've only seen you and one other advocate for a lot of rear toe-in in this thread.

SpitfireS

Well.. the way I interpret the UK-spec sheet is that the first sheet is/are the OEM settings.
In the pdf copy of a (US) service manual, and my copy of a Honda ESM they do not state the rear toe in degrees, just in millimeters/inch.
I don't know what 6mm of rear toe will be in degrees, I'm guessing it is half a degree, the middle setting.
Using OEM you're right, you could get it to 1-1/3 total rear toe.
Using UK-spec the max rear total toe is 2/3.

You call this absurdly high, so far I would not call my car undrivable with this setting, on winter tyres and AD08's.
Actually, I did - last year - drive on winters well into the spring, just to wear them out, get all the life out of them and get new ones next season.
And the rears just would not wear, I was expecting high temps and some spirited driving would wear them out quickly.. but it didn't.
But if less=better, that's better
We'll see, I have to look for a good shop to have this done.
I hope to get a printout to scan& post.
Hmmm... I don't think so.
I did post the picture of my fronts after running them with 0 toe and -1,xx camber showing not a whole lot of inside-camber-wear.
On rear toe I have no opinion, yet.
Other than: UK-spec is not undrivable.

ZDan

And for whatever reason, they got it WRONG by a factor of 2X vs. any remotely reasonable range. Just try running the middle of that range, 1degree total, and see how that works for you! Total disaster. I know, I've inadvertently run that much. Car was well nigh undriveable at the track or on the street in the wet, and the back end would be all over the place over bumps/undulations.

The US manual states 6mm +/-2mm. Simple trig to get the angles. Tire diameter is 25" (close enough), so toe angle is sin-1(6mm/25.4)/25" = .54 degrees, +/-.18degrees. So US spec range is 0.36 - 0.72 degrees (I was a little off with 0.32 - 0.64, don't remember exactly where I got that from, I just know that the 0.64 degrees total I originally went with was based on the max end of the US spec range).

Again, that spec range is only in the UK manual. And it MUST be in error. Again, just try running the mIDDLE of that range for a few thousand miles (1 degree total) and see how that goes!

We just established that the UK spec max is 1-1/3 degrees total.
What happened: Alignments got set based on the ERRONEOUS 2/3 to 1-1/3 degrees total spec, and cars drove like absolute crap and tire wear was anywhere from 1/2 to 1/10th normal. So somebody figured out that the ONLY way to get reasonable handling and tire life AND stay within their (again erroneous) spec range was to specify the MINIMUM end of that range: 2/3 or 0.67 degrees total. Which is REALLY supposed to be the MAXIMUM rear toe.

I said it was absurdly high, I didn't say it was undriveable. 1 degree, now THAT'S undriveable. 0.67degrees is driveable for a little while. I wore out my track tires so quickly, though, that I found myself on cords for the time trial at my 2nd event on them.

THat's you're impression, but I'm not seeing any data. When I went from 0.64 degrees total to 0.15 degrees total, track tire life and street tire life increased by 2-3X (~3 1hr track days to 8+, street life from ~8-9k miles to 20-24k).

In my experience, more than ~0.4 degrees is what I would call excessive. For sure running less than 0.67 degrees is going to be *better*, for every single aspect of performance. Personally, I run 0.2 degrees total, which is below the minimum of the US spec range, no problems with instability even trail-braking like mad all the way to the apex.
Show me the other posts in this thread advocating for 0.67+ degrees total rear toe.
The greater part of the ERRONEOUS UK-spec range for rear toe is undriveable, unsafe, and will give totally unreasonable tire life. The very minimum end of the UK-spec range is "driveable", but is still costing people in terms of stable predictable handling and tire life as well.

UK "recommended" setting is based on their getting the REAL Honda spec range wrong by a factor of 2x. If they'd gotten it right, their range would have been 20' (0.33degrees) TOTAL to 40' (0.67 degrees) TOTAL, and not per side.

And IMO even the Honda-intended range is well on the high side, I recommend 0.2 - 0.3 degrees total.

SpitfireS

IMO, the UK-spec alignment is ONLY the bottom part, where it says: Honda (UK) recommended optimum specification.
Where the max total toe is 2/3 of a degree, without a range.
Based on the mm>degree conversion you showed: yes.
Measuring a toe-in at the tire is kinda strange though, where do you measure?
What if I'm running a different tyre, the OEM S-02's rears have pretty square sidewalls.
And where do you take the 0-line?
It would make more sense to get a solid fixed point to measure, to avoid faults.

This is the alignment tool they show in my ESM and the measuring point is at the rim, not at the tire.
It does change the mm>degree conversion a fair bit.
6mm at 16" will give you 0,85 degree total.
Agreed, this is still no where close to the workshop manual specification in the posted bulletin.
Data:
Bought a set of 4 (205/225) Continental TS810 on 11-2007.
The fronts have about 45000km on them now and I will use them next winter - profile depth is 4mm or so.
The rears lasted for 32000km, with 3,5mm profile left (but no point running bald winters and they would not really wear quickly at high temps, as I mentioned before, to feel better replacing them)
On 12-2010 I bought a second hand set of TS810 rears with 6.5mm left, I put around 13000 on them, I don't know the profile depth right now.
32k km on a set of rears is not that bad, IMO.
With less rear toe I would have gotten twice that?
That would be nice.
Point taken.
If saying "I like how the car drives with UK-spec" is the same as advocating... then yes: guilty.
You show me (us) a fool-prove, beyond reasonable doubt way to convert the OEM 6mm to degree.
Honda sure doesn't give any hint on how to do this.
What do the modern alignment computers / equipment in the US say about S2000 rear toe-in?
Is the setting in the database in mm or degrees?
Is what most will see as the UK-spec.
Still, I think my car is not unstable and the handling is not bad, certainly not unpredictable and rear tire life is not extremely low.
I'm going to give this a try and I'll let you/everyone know.