S2000_rider

Hey guys,

I would appreciate if you could help me determine what the phuck is wrong with my S2K...

I don't know if anyone else is experiencing the same problem, but when travelling in jam packed area's where the car never gets out of first, at speeds at around 6-9 mph, the car suddenly begins to rock back and forth. It's not like it's going to stall, but it's like someone is continuously bliping the gas and letting off, bliping the gas and letting off, repeatedly. This only occurs in 1st gear at low speeds (6-9 mph).

What do you guys think it could be???

Thanks!

xviper

[QUOTE]Originally posted by S2000_rider
[B]Hey guys,

I would appreciate if you could help me determine what the phuck is wrong with my S2K...

I don't know if anyone else is experiencing the same problem, but when travelling in jam packed area's where the car never gets out of first, at speeds at around 6-9 mph, the car suddenly begins to rock back and forth.

RedY2KS2k

Most cars with manual transmissions will do this to some extent. I think that it's much more pronounced on the S2000 because of the extremely low gearing and the high compression ratio.

RT

you have extremely low gearing? trade ya

Incubus

It is driver induced. I have experienced this.

It's because your throttle foot is not steady. Don't believe me?


Your car rocks a bit, and this makes your foot move into or out of the pedal. At first it's a little bit, and then it just gets out of control. It starts off slow and just gets worse until you put in the clutch or give it gas.
For me, simply knowing the cause stopped the problem.

Hope this helped...

philipf22

[QUOTE]Originally posted by Incubus
[B]It is driver induced.

outoforder

There's a video around of the April 25, 1992 YF-22 accident... Basically the same problem, the aviation safety folks call it Pilot Induced Oscillation.

http://books.nap.edu/books/0309056888/html/26.html

It's a basic control system problem. When you push down on the gas, the car accelerates, and pulls your whole body including your foot backward, off the gas. Let off the gas, and the deceleration pushes your whole body, including your foot, back onto the gas.

This is just negative feedback. If there was no delay, there would be no problem... you would just find it harder to push down the gas pedal in first gear than in sixth. The problem is that there is delay, and the delay allows your body to gain momentum and change position.

The solutions are many. Take your pick:
- Reduce the weight of the driver
- Increase the drag of the drivers butt against the seat.
- Increase the internal resistance to shear between butt and seat (pucker up or get into better shape).
- Decrease delay between gas pedal down and acceleration (Note: Honda has already done a fair bit here)
- Increase rate of gas pedal spring
- Drag your foot against right hand side of footwell while on the gas.
- Tighter seatbelts
etc.

I find just treating the gas pedal as an on/off switch while in first gear eliminates the problem. Plus, it adds to the challenge of parking.

Incubus

Parking like that sure is fun. It makes a cool sound from the tires. Makes you look like a beginner driver though.

F1_Rules

...

RT

Some things can make the problem more pronounced. If the Golf drivers are retards, then maybe VW is installing some sort of damper to alter the natural frequency of the "system".
You ever seen vids of the Tacoma Narrows Bridge?