If you are interested in making the car quicker through changing the final gear ratio there is a problem with continued use of the OEM vehicle speed sensor (vss) as posted by 1Randyc in response number 22 of the following thread:

http://www.s2000online.com/forums/showthre...?threadid=20274

The stock gear ratio is 4.1 and J's racing is offering three upgrades; 4.30 street, 4.44 track and 4.77 autocross. The higher the ratio the quicker the car becomes (ex. 0 - 100) BUT you will loose some top end (maybe from 160 to 145)

Randy's problem has become an inacurate speedometer/odometer reading from the vss. I think you will agree this car handles like a dream and what it needs is the throttle response which can be cost-efficiently achieved from the gear ratio change. I ask all of you interested in this modification to join me in leaving no stone unturned in finding an accurate vss solution. Ideas & Input PLEASE!

 

Anybody know if its possible to reporgram/calibrate the ECU? Or is it a seprate system that needs a gear change. Possibly an adaptor can be fabricated so a cable/sensor can be 'plugged in'

 

please, someone figure this out. I want to change the gear ratios, but I don't want to get excess miles on the odometer or have a bad speedometer. Help!

 

You should have three choices.

1. Change the speedometer "drive" gear in the tranny. In the old days this would drive a mechanical cable. Today, it's some sort of toothed wheel (or even an actual functioning gear) that a sensor reads and then outputs a series of 5v pulses to the ECU. However, this would be a real pain (require opening up the tranny - suppose you could do it when you install the new gearing).

2. Intercept and alter the pulses. The VSS is a simple connector, and easily accessible under the car. So it wouldn't be tough to snip a wire and intercept the signal. You'd need a small circuit that would alter the pulse count. For example, if the pulse count is currently 10/mph and you went to a 4.30:1 gear you'd need to change to 9.5/mph. Since its a simple 5v logic problem, you could probably buy an off-the-shelf chip from Radio Shack that would allow you to compensate (once you determine the pulse rate, which can be done by reading the sensor with a multimeter while turning the rear wheels by hand).

3. Alter the ECU. Once companies like Hondata crack our ECU, changing speedo/odo functions should be easy. However, this will take time.

All in all, #2 sounds very reasonable. In fact, maybe I'll take a look at it this week if I have a chance.

UL

 

UL, let me know how it goes. I want to do this mod, but I don't want my odometer and speedometer all screwed up. Thanks

 

I was told by the Honda service manager that the S2000 speedo can be recalibrated if needed. Call your dealer and ask them if it's possible. Or try this: http://www.nu-metrics.com/pages/01enite.html. The product you're interested in is the Nitestar. You probably don't want the complete unit but they can help you modify the existing speed sensor to make it accurate.

 

[QUOTE]Originally posted by Eze8199
[B]please, someone figure this out. I want to change the gear ratios, but I don't want to get excess miles on the odometer or have a bad speedometer.

 

[QUOTE]Originally posted by Utah S2K
[B]

You already do! He's a quote from the only S2000 in the Nevada Silver State Challenge in May:

Silver State Road Race results:

 

Got an e-mail back from Yasu at Racing Craft and after speaking with his supplier J's Racing, "J's agree's there is an 8% faster speedo reading and odometer readout but at this point has no parts to correct it".
Yasu also contacted ATS who agrees to a 10% increase with no parts to rectify".
Talked to the service department at my Honda dealership and they said their manual shows no way to calibrate the speedometer/tachometer.
My Helms shows no calibration application.
This leaves the Ultimate Lurker who will stay at a Holiday Inn Express and visit Radio Shack - Good Luck, we're behind you all the way.

 

Well, its been a while since I did circuit design, so I pulled out some of my reference texts today. Found plenty of square wave generators (pretty simple op-amp circuit), but nothing to do a frequency shift. Don't worry though, the circuits exist, I've just forgotten how to create one from scratch.

I'll be checking some more sources tomorrow and hopefully we can measure the output of the sensor this weekend.

UL