S2Kman

On the digital unit, adjustment wouldn't really be quite the same.

Adjustment would work like this:
1. Use a GPS or other external speed sensing device to drive a pre-determined speed (say 20 MPH) You would ignore what the speedo was reading at this point.
2. Once you had reached this pre determined speed you would hold this speed for 20-30 seconds and simply press the button on the thing and it would calculate a conversion factor, and immediately start applying it.
3. Your speedo should instantly jump to 20 MPH when you press the button in step 2.
3. You are all done!

As for multiple settings, it would probably require a change in the design because there isn't currently a way to indicate which setting is active. An led would have to be added, or at the very least, a toggle switch to switch from setting 1 to setting 2. However, it would be so easy to calibrate I can't really see a need for it, especially since I can't imagine folks changing wheels/tires on a daily basis. It seems to me that having two settings would only encourage folks to use the device to 'save mileage' illegally.

Also, for lag, the digital device shouldn't introduce any more than a few microseconds of propogation time to the incoming signal, so I agree that there really couldn't be any lag with it that could be discernable to a human. It's actually a really simple circuit, and the ASM code for it wouldn't be very complex either. Pretty much just a loop that counts incoming pulses, multiplies it by a conversion factor and continously outputs pulses with the conversion factor applied.

Keep in mind that by cutting this wire in the Honda harness in your car, you MAY have serious implications with your warranty if Honda discovers that you have been tampering with the input signal to the speedometer. If you can find a way to install it WITHOUT cutting a wire (Can't you pop the pin out of the harness?) DO IT and then you can put it back to stock if you need to.

My own personal CYA: If anyone decides to use any of the information I have posted to do anything in the real world with any of this information, I am not responsible. I have only posted ideas and thoughts for curious minds, I am in no way suggesting that anyone should do any kind of modification to their car. If you do it, good luck and I warned you that you might be causing yourself a big problem.

If anyone decides to build and sell the unit, I'd recommend two things:

1. To the seller: Write up a release of liability form (or get a pre-made one from an office store or legal supply shop) that says that you sold the product to them for educational purposes and that it is not intended to be installed on a vehicle, and that you are not responsible for any problems caused by the use/misuse of this device for any purpose, yada yada, and make people sign it before you sell it to them.
2. To the seller and the buyer: It's probably not a good idea to post/advertise the fact that you sold the mod/installed the mod in the public forums. Honda frequents this board and the information could be used against you if you need to make a warranty claim. It also seems possible to me that if you ever decide to sell your car, posts on this forum could be used as evidence of odometer tampering and mis-reporting of mileage at sale time.

Also: Modifry Did you receive the PCB layout I sent you?

S2Kman

To address temperature/environmentally induced drift/accuracy, the digital unit will still be subject to some amount of drift. It will function by counting clock cycles and the a crystal is used to determine the frequency of the clock. The crystal I used in this design is rated at 50 ppm accuracty from 0 C to +70 C. I think this translates to +/- 50 clock cycles out of a million which is about 200 cycles/second (there are about 4 million cycles/second). This means it could be off by +/- 100 uS over this temperature range in the measure of a second. So I guess what I am saying is that it could vary by as much as 1 millionth of a second, which is pretty accurate, but it DOES drift. If my calculations on this are off, please correct me.

mingster

I'd be interested in either forwarding my customers to you or buying it from you as a package to be sold with the J's Racing final gear setup. Please let me know any details you may have.

1Randyc

Yes, I would like to be in this. I need this more than anybody.
I have secondary tranny and ring/pinion gear change done long time ago.
And suffered speedo/odo error long enough.

I applaud who came with solution to this.

Thank you.

cmnsnse

Meeee Toooo! Ill take one . ..

s2oooboy

I would be interested in that package deal with the Js 4.3 Final gears......I would more than likely go with the digital version please....

modifry

I think having you sell them to gear change customers is really the way to go. That way we all know they are being used for valid speedometer correction for *off road* use. (you bought the different final gears for off road use, didn't you?)

Once s2Kman and I get a digital prototype going, we'll get someone to test it, and go from there.

I also think we should include a wire/pin to make the connection to the speedo input. You could also do it with a connector pair at the C101 connector in the driver's footwell, but it's a big connector with a lot of wires, and would probably double the cost. But some may be willing to pay the freight for an easier and almost plug-n-play fix (you'd have to connect a ground wire, but the rest of the connections would be in the C101 connector pair).

Who knows where to get Honda connectors cheap? And pins too?

CRX 18

RWD_RKT got pins and connectors somewhere for the VAFC harnesses. He may be the person to ask.

SUis1

I'm interested, the speedo issue has been the hold back on changing gears!!!!!! Great work guys!!!!

BAD S2K

I am very interested in this mod. The digitial solutions sounds best; but, I will buy whichever you make. I'm installing the 4.44 gear in the next 2 weeks and I'm running 265/35/18 wheels in the rear. I'm looking for a 8-9% correction.