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SNAP oversteer or Reducing dynamic toe changes

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Old Aug 28, 2019 | 05:38 AM
  #21  
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Originally Posted by rpg51
Yes, the bad old tires definitely played a major role in my experience described above. But, so did the CC. Also, so did the idiot behind the wheel.
I feel you there. When leaving Track Night in America a few weeks ago and seeing the torrential storm coming AND knowing my tires were toast, I shoulda stopped for a burger like a lot of the others at the event did. But NO, "I am going to head 50 minutes home to get some other stuff done" and kept driving. Visibility went to near zero quickly, people pulling off all over and as I looked for the next overpass (thinking hail was coming next) I found myself in a 45 degree drift down the middle of the highway skiing along on top of the standing water Got it straightened out and pulled over and sat under a bridge until it passed! I should have known better, but you know how that goes sometimes.
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Old Aug 28, 2019 | 06:14 AM
  #22  
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A buddy put his new-to-him 2002 car "in the cattails" in the Metro Parks soon after acquiring it 4 or 5 years ago He's a strong believer in "snap oversteer." Since then he's retrofitted the OE suspension and acquired OE 17" wheels and tires and hasn't reported a recurrence.

Honda modified the suspension in 2002 and dialed out some of the oversteer but you already have this system so before I'd diddle with the suspension (assuming it's OEM) I'd look at tires. Wider rear tires will reduce oversteer. As will narrower front but who wants that!? Not sure what's available in 16" but the "CR-spec" 17" tires are 215F/255R (vs 215F/245R). Reproduction 17" AP2V1 wheels (good reviews here) and "CR-spec" tires will bolt directly to the car without modifications. This may be all you need and is as simple as putting the car on jackstands and swapping out the wheels/tires. 30 minute job and you don't get dirty.

-- Chuck
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Old Aug 28, 2019 | 08:31 AM
  #23  
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Originally Posted by Car Analogy
The problem with cc and rain is that on many cars the driven wheels are not the wheels that are used to measure vehicle speed.

When you hit a puddle, car immediately slows a bit due to the extra drag at the tires. So the car senses its slowing, and thinking its a sudden steep hill or something hits the accelerator. But driven tires are in a puddle, so just spin. Car doesn't speed up, so cc thinks whoa, steeper hill than I thought, hit the gas more and more! Things snowball and car spins out of control.

.
True, I have been along for that ride once early in my s2000 career and learned my lesson, also bought a new pair of underpants to celebrate keeping it out of the ditch.

Last edited by s2000Junky; Aug 28, 2019 at 08:34 AM.
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Old Aug 28, 2019 | 08:42 AM
  #24  
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From: Illnoise. WAY downtown, jerky.
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Originally Posted by clubhopper
I just did this swap earlier this season.

the only thing that is different is the upper control arms. Everything else is the same...you don’t need AP2 knuckles as they are identical, or the lower control arm, everything else transfers over from your AP1.

The only other thing was the brake hard line bracket is slightly shifted rearwards on the AP2 subframe because of the thicker upper control arms by about 1cm. It’s not a big deal as you can bend the line slightly to get it in place on the ap2 sub.

eh? AP2 knuckles are different af.

The ball joint location is different...which aids the anti-bump steer geometry.

AP1 knuckles will fit. AP2 knuckles are needed to complete the AP2 geometry.

The ABS wire brackets attach to the UCA. Which hard line are you talking about?

As others have stated...OP....you're driving the car in a way that the back will step out. Fixing that is free.

Aftermarket BSK's have some cons:
-You're using aftermarket chassis parts
-You're putting a significantly higher stress on the knuckle.

The AP2 subframe is more pricey (maybe) and labour intensive...but its a better, more complete solution.

Last edited by B serious; Aug 28, 2019 at 08:44 AM.
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Old Aug 28, 2019 | 08:51 AM
  #25  
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Man searching for the below information was like pulling teeth! Lots of info about AP1 and a bunch of other good reading material but not a whole lot of concrete information about the AP2. Finally found the info what I was looking for and thought I'd bring it back here.

AP1 - toe changes are quite dramatic and has been consistently reported at ~1/8" per 1" compression. Also read through portions of the MASSIVE STR Prep thread and found a graph of the AP1 toe curve

AP2 - Little to no toe changes
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Old Aug 28, 2019 | 09:32 AM
  #26  
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Originally Posted by zze86
Man searching for the below information was like pulling teeth! Lots of info about AP1 and a bunch of other good reading material but not a whole lot of concrete information about the AP2. Finally found the info what I was looking for and thought I'd bring it back here.

AP1 - toe changes are quite dramatic and has been consistently reported at ~1/8" per 1" compression. Also read through portions of the MASSIVE STR Prep thread and found a graph of the AP1 toe curve

AP2 - Little to no toe changes
Yep, it is the toe curve that does it. But ... only if you do something you shouldnt Lifting mid corner will definitely cause it. It will cause less traction in ANY car though, but will be more noticeable in an AP1 vs AP2 because of the toe curve. So it is a combination of driver error in a car more susceptible to driver error and not just an issue with the car. After one event in Bstreet in the car I started learning that behavior and it became a plus, since I could use said behavior to help in some instances. After a bit i just became normal to me and actually made me a much smoother driver by speeding up my fixing of bad habits from autocrossing FWD cars previously.

You can feel the behavior if you are in a normal turn and add/remove throttle slowly. You will actually feel the rear steer a bit due to this compression/rebound movement.

STR setup pretty much removes it for the most part. Still there relative to an AP2 but a LOT less noticeable. But not everyone wants to prep to that level for a DD of course. But take it to an autox and spend some seat time learning it and you should tune out the error that induces said "Snap" oversteer.
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Old Aug 29, 2019 | 06:12 AM
  #27  
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Er, sorry for thread derailment, I'm enjoying reading about the AP2 rear subframe and other stuff swap, I'll ask my fellow S2kers who have done this about more details when I'm at Watkins Glen next week. For sure if/when I get another S2000, I'd like an AP1 with AP2 rear geometry. Best of both IMO...

But to continue the aside regarding cruise control in the rain:

Originally Posted by rpg51
Like you I have always used CC in the rain without troubles. But, on this occasion my S nearly spun off the interstate. I was in CC going about 70mph. Moderate rain. Some standing water. Old worn rear tires.
OK, this is clearly a situation when you shouldn't be using cruise control! Like I said before:
That's not to say that I think it's a good idea to use cruise control if there's a lot of standing water, but in those conditions it should be obvious that you'll have to constantly modulate speed depending on whether you're driving through a small pond or not...
Even with new full-tread-depth tires. And of course not with old worn rear tires! I use cruise control in the rain all the time, including in heavy(ish) rain, but *never* with standing water. It takes a LOT of rainfall to generate standing water on most highways, nevermind interstates...

From your experience, I think it's an overreaction to conclude: "NEVER use cruise control on wet roads." If you can see well enough to perceive standing water well in advance of reaching it, *and* you are paying close attention to driving and the road ahead, cruise control usage is fine. For me this is true probably 85% of the time while driving in the rain. If you can't see well enough ahead to cancel cruise in advance of reaching possible standing water, of course you shouldn't be on cruise control.

HA! This article pretty much exactly my reaction when I saw a similar, maybe the same story a long time ago. BULLs**t!
I mostly agree with where that article is coming from, but I disagree with the notion that CC necessarily diverts attention from driving. On the contrary, when conditions allow its use, CC allows the driver to use *more* of his attention to maintaining situational awareness since he/she isn't having to devote any attention to maintaining constant speed.
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Old Aug 29, 2019 | 06:43 AM
  #28  
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In his excellent book on high performance motorcycle riding, Keith Code uses an analogy about attention required for specific tasks. He compares your total amount of attention to a dollar amount, and how you spend it.

Say your total attention span is worth $10. When you first learn to say, drive stick, like $9 and change is required just to take off from a stop without stalling or burning up the clutch. Leaving precious little leftover for anything else, like not getting in an accident.

But as you get better, that number quickly goes down. Soon its below maybe $.50 worth of attention to take off from a stop.

So while I agree cc reduces amount of extraneous demand and leaves more money on the attention span table for other aspects of driving, the dollar amount of attention to maintain speed isn't really all that high. Especially in a car like this where engine rpm (which equates to highelway speed) can so easily be audibly discerned. On a lonely stretch, with no other traffic to pace with, you'll know if speed starts creeping up.

I find being engaged in the driving experience helps keep more of my $10 on driving, less on mind wandering. So I think the amount saved not having to pay attention to speed is more than offset by the amount lost to being less engaged.

But I will say that for long stretches, tbe ergonomic benefit of cc is a real gift. Being forced to constantly hold the same leg position in a cramped car that doesn't offer many alternatives for keeping your foot on the pedal takes a real toll on my aging body (whose size already stretches the boundaries of fitting in this car). For that reason, its worth it...
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Old Aug 29, 2019 | 06:55 AM
  #29  
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Originally Posted by ZDan
Er, sorry for thread derailment, I'm enjoying reading about the AP2 rear subframe and other stuff swap, I'll ask my fellow S2kers who have done this about more details when I'm at Watkins Glen next week. For sure if/when I get another S2000, I'd like an AP1 with AP2 rear geometry. Best of both IMO...

But to continue the aside regarding cruise control in the rain:

OK, this is clearly a situation when you shouldn't be using cruise control! Like I said before:
That's not to say that I think it's a good idea to use cruise control if there's a lot of standing water, but in those conditions it should be obvious that you'll have to constantly modulate speed depending on whether you're driving through a small pond or not...
Even with new full-tread-depth tires. And of course not with old worn rear tires! I use cruise control in the rain all the time, including in heavy(ish) rain, but *never* with standing water. It takes a LOT of rainfall to generate standing water on most highways, nevermind interstates...

From your experience, I think it's an overreaction to conclude: "NEVER use cruise control on wet roads." If you can see well enough to perceive standing water well in advance of reaching it, *and* you are paying close attention to driving and the road ahead, cruise control usage is fine. For me this is true probably 85% of the time while driving in the rain. If you can't see well enough ahead to cancel cruise in advance of reaching possible standing water, of course you shouldn't be on cruise control.


HA! This article pretty much exactly my reaction when I saw a similar, maybe the same story a long time ago. BULLs**t!
I mostly agree with where that article is coming from, but I disagree with the notion that CC necessarily diverts attention from driving. On the contrary, when conditions allow its use, CC allows the driver to use *more* of his attention to maintaining situational awareness since he/she isn't having to devote any attention to maintaining constant speed.
I have a MY00 with AP2 rear sub/UCA/spindles/swaybar.

The first outing on track with setup and I could tell there was a MASSIVE decrease in corner entry oversteer. Also mid-corner oversteer over bumpy surfaces. The car feels locked down and very confidence inspiring. Ohlins with 12K/10K and HR RCA's front and rear. It's really REALLY nice to drive.

Anyway...about CC in the rain...its generally a bad idea. You're not taking into account the human aspect. 99.99999999% of people don't hover over the brake/clutch pedal or cancel button with CC on.

The car accelerates for you.

People also tend to relax and let their guard way down.

With all this put together, a reaction to hydroplaning is delayed.

Idk where you live...but lots of highways can collect standing water even in light rain. Not easily visible dips in the road can collect water. And sometimes a drain blockage will cause spill-over onto the road surface.

There are also other factors that occur during rain. Most people around you will drive more eratically. Your car may be harder for other drivers to see. etc.

Lots of factors. CC isn't a great idea in the rain.

Your owner's manual states the same. Something like, "do not use CC in inclement weather".

Last edited by B serious; Aug 29, 2019 at 06:58 AM.
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Old Aug 29, 2019 | 07:00 AM
  #30  
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Originally Posted by Car Analogy
So while I agree cc reduces amount of extraneous demand and leaves more money on the attention span table for other aspects of driving, the dollar amount of attention to maintain speed isn't really all that high.
From what I've seen as a side-seat passenger and as a sharer of public roads, it requires entirely more attention than most people can give it!

Especially in a car like this where engine rpm (which equates to highelway speed) can so easily be audibly discerned. On a lonely stretch, with no other traffic to pace with, you'll know if speed starts creeping up.
IMO, not really. Over time you're going to drift. Wouldn't it be great if there were a simple device to maintain speed for you so that you NEVER had to look down and take your eyes off the road?..

I find being engaged in the driving experience helps keep more of my $10 on driving, less on mind wandering. So I think the amount saved not having to pay attention to speed is more than offset by the amount lost to being less engaged.
For me, very much the opposite. I find that not having to worry about maintaining constant speed frees up more attention for maintaining awareness of vehicles around me and road conditions. Any time at all spent looking down to check your speed (which you should be doing every minute or so without cruise on), is time where something could be happening/changine *out there*.

But I will say that for long stretches, tbe ergonomic benefit of cc is a real gift. Being forced to constantly hold the same leg position in a cramped car that doesn't offer many alternatives for keeping your foot on the pedal takes a real toll on my aging body (whose size already stretches the boundaries of fitting in this car). For that reason, its worth it...
Also, it prevents speeding tickets. AND it prevents you from inadvertently getting into speed competitions with other drivers.

I'm a motorcyclist, even raced for a few seasons (won my class 2nd year!). Never read the Keith Code book but I found the video (VHS!) in the bargain bin many years ago, and honestly I couldn't get through it! He spent way way WAY too much time and effort on the whole "dollars and cents" attention analogy and I totally lost the plot...
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