[QUOTE]Originally posted by WestSideBilly
[B]Couple quick points...

Jason & Nick: Having spent some time at G-man, and knowing my approximate lap times, along with those of several other S2000s, what kind of lap times have you been turning?

 

Hi Everyone-

FYI-

The bumpsteer is very easy to identify once you undestand what is happening...

Let's start off with a quick overview of the suspension system and what Honda seems to have done to "correct" handling problems.

1. Digressive shock valving from the factory. This means the shocks are very stiff under small hits, but "blow" the shimstack under big hits. The net effect is, if the road surface is smooth, the shocks are very progressive, but if the surface is not, the resulting suspension action is more active, and has less control.

2. Honda used narrower than specification 205 tires up front, and wider than specification 225 tires in the rear. We've documented the OEM 225 width as being as wide as an aftermarket 245 or even 255 size, and the 205 being narrower than almost all the other 205 sizes on the market. What this tells me is that Honda recognised the traction problems in the rear, so they "hedged".

3. Honda engineers designed bumpsteer into the suspension. This is a fact. We don't know why they did this, we don't know what this is for. What we DO know is that it creates handling problems...

So the combination of all of the above causes this very problem- under high cornering loads on less-than-smooth surfaces, the OEM struts will be overloaded and blow the shimstack, resulting in uncontrolled suspension action (dictated by the OEM springrates and stiction in the system). This "action" results in the chassis corkscewing motion- usually from one rear corner to the opposite front corner, weighting and unweighting the corners. When this happens, the only thing that will stop it is easing off the corner, slowing the car down, and re-engaging the corner. IF the driver doesn't calm the chassis down, the resulting snap oversteer is only his/hers to blame, since the more the chassis corkscrews, the more the tires are overloaded (which usually results in loss of grip).

I think Honda designed the car the way they did was their way to "dumb down" the fabulous car they had for the public. If they had made the car the way I wanted it to be (only basic suspension differences, no content changes) the car would have ridiculously high thresholds- not the best thing for a mass produced open top roadster that costs well within the reach of most enthusiasts (as opposed to a Ferrari 550 Spider). These high thresholds would be absolute- but at the speeds that the driver would have to attain to get there would make it downright dangerous for most, and require high levels of skill to maintain it there. Instead, they marketed a car that slides around abit, requires some (not a bunch of) skill to manipulate at legal speeds, and makes the driver feel very involved. A fun car to drive, but not necessarily a fast car to drive. The flip side to that is, if the driver is not attentive or experienced enough, this "involvement" is the worst thing to drive... Another thing that Honda was sure to think about was the fact that their sales channels are not the best at doing due dilligence when informing customers what exactly they are buying. Heck, most of them don't even know what makes it so special...

Keep in mind that my car has several "fixes"- a bigger front swaybar to control some of the cross weight shifts and oversteer, progressive shocks on higher rate springs, and the King front bumpsteer kit that eliminates most of the front problems. The biggest problem seems to be the rear of the car- it loses traction first AND it has bumpsteer. As soon as our friends at King decide on a course of action on eliminating the rear bumpsteer, I will have it done to my car (and go testing again!).

And about people attacking Bieg-

Lay off him. I think he's trying to be as nice as he can be here, like I am too.

Sorry for the long post...

 

[QUOTE]Originally posted by dlq04
[B]

I'm not trying to speak for them, but the last posts I saw I'm pretty sure they were turning 1:39xx with street tires on a cold track and they lowered that to 1:36xx with worn race tires.

 

Justed checked, sorry I'm off on the "P" cars (memory is a terrible thing to lose)... they are generally best lapping in the 127 - 129 range per PCA web site.

 

[QUOTE]Originally posted by Jason Saini

 

Mike,

I've read about a decent number of S2K's that came improperly aligned from the factory. Did you check to see if yours met specs when you had it aligned?

 

Strike,

Yes. Here are the numbers after driving the car two weeks. I think everything was in spec except for too much front toe out:

front camber -0.2d, -0.7d
front caster +6.1d, +6.0d
front toe -0.07", -0.06"
rear camber -1.3d, -1.6d
rear toe +0.18", +0.12"

I am currently running the following:

front camber -2.0d
front caster +5.7d
front toe -0.06" each side
rear camber -1.5d
rear toe +0.03" each side

I added more front negative camber to increase cornering grip and reduce wear on the tire's outside edge. In order to get that much front camber I had to reduce front caster. I left front toe unchanged because I liked the car's turn in response. I reduced rear toe in to help reduce understeer. I left rear camber at the factory setting because pyrometer testing showed no change was necessary.

 

A couple things... first, the 1:27's and 1:29's are very high hp porsche 911's at a very high state of tune. The day we were at Gingerman, we were one of the fastest cars on the track other than a Formula Ford that was lapping at 1:27. We also believe that with some more tweaking and fresh tires we can lap in the 1:33 range. I'm sure we'll get a chance to test with fresh tires before the bump-steer kit is ready for the rear.

Also, for Mike... It's a completely stock version that I am talking about. And you are not the first person on the board to complain about consistent understeer. I can make no explanation for this, as I have driven 5 or 6 different examples and they all behaved a little differently. Maybe your car is different? For example, I cannot get more than -1.2 degrees LF and -1.4 degrees RF..... yet you are running -2.0 on both? Our chassis must be different, or your alignment gear is optimistic. I have to drop to +3.6 caster just to get that piddly camber I have!

I will say that I have cannot even begin to understand why there are some people that experience such pronounced understeer, as Mike isn't the first I have heard of. It's just not a factor in any of the versions I've driven. Maybe you just like your cars REALLY REALLY loose, Mike?

 

Oh why thanks! Hehe.

Jimmy

 

Originally posted by Triple-H
Posted by West SideBilly
Maybe you are not familiar with sarcasm.

This thread goes from constructive to pissing contest to constructive to pissing contest to constructive to pissing contest. The facts are hard to sort out from the fiction because there is so much, well you know, pissing going on.