sryth

I was going over all of my current options to do some ¼ mile testing at home when I realized that, using a computer and a speed sensor, I could build a better system than the gtech and even the AP22.

I figure that if I could add a speed sensor to a rear wheel, I could accurately gauge distance traveled, and as a result...speed. This data could be used for all acceleration tests.

This data could also be graphed in a similar fashion to that of a dynometer (the concept is very similar), provided that you keep the weight/track conditions consistent. I think this would yield more accurate results than a dyno, as they would be real-world results as the car would actually be moving (real wind instead of fans).

Any ideas as to how I could connect a speed sensor to a rear wheel? I’d tap into the sensor that’s in the tranny, but then wheel spin would spoil the data.

Any help/comments appreciated...

-Sryth...
__________________________________________________ ____________________________
'98 SE 5spd, Pebble Beige, PRCAI
Pacesetter STS, Stillen Y, Stillen FSTB and ACT Clutch on the way!

Vyrus

iTrader: (4)

What about when you slam it off the line and your tires spin? And unless the sensors (wheel and whatever else you mount it on) are perfectly times everything will be off by as much as a wheel.
-Cyrus

Whitemax

Well, he was talking about installing the sensor on the rear wheel, so there should be no wheelspin

pblaze

I think ABS is a standard option on all 4th gens. The rear spindle carrier should have a through hole and a tapped hole for a tab type Hall effect sensor. I can email you an exploded part drawing if you'd like. The sensor points at the back side of the center hub of the brake rotor. The easiest way to start would be to buy an ABS wheel sensor from Nissan. If there are special rotors for ABS equiped vehicles, get one too. Or, you could roll your own setup, but that would involve selecting a Hall effect sensor, and possibly machining the rotor.


How are you planning on acquiring and processing the signal?

Vyrus

iTrader: (4)

It would have to be wireless though, so you would need a sensor and a projector right?
-Cyrus

sryth

I would definitely be interested in the exploded drawing, and any more information you have on the sensor itself. I have a ’98 SE, and it came without ABS (I’m told it was an option for this year). Since it was an option for my car, should I be able to mount the sensor with no modification? If this sensor points at the actual hub, I have a feeling that there are special wheel hubs for ABS equipped vehicles.

How does the ABS speed sensor work? Simply put, I need to count rotations of the wheel. As for acquiring the signal, I was thinking that I could strobe a pin on the parallel port for each revolution of the wheel. Then I will write software to poll that line on the parallel port and timestamp it. The graphing can be done with excel, gnuplot, or whatever. That will be the easy part.

Finding the right sensor is going to be the hard part.

-Sryth...
__________________________________________________ ____________________________
'98 SE 5spd, Pebble Beige, PRCAI
Pacesetter STS, Stillen Y, Stillen FSTB and ACT Clutch on the way!