Where is the speed recorded from?

[Jeff240sx]

In an s14 KA, where is the speed recorded from? Is it tire revolutions, diff, tranny revs?
Just kinda wondering, since my tires are 11% larger than stock. Same thing about odometer reading.
-Jeff

[mrmephistopheles]

the transmission. I'm amazed you didn't know that.

[projectRDM]

Motorsports sells different pinions to calibrate the speedometer when using taller/shorter tires.

[Jeff240sx]

the transmission. I'm amazed you didn't know that.

So.. my car at true 70 will read 63, correct? And 1 true mile will click the odo .9 miles? With the aforementioned 10% taller rear and 11% taller front tires?
-Jeff

[aznpoopy]

i believe so. my s14 always reads the speed a bit lower then it actually is. way back in the day when i first got my car and mounted slightly larger new tires, i drove following my gf and we talked on cell phone to confirm it.

[knightrider]

imo the nissans suck at the speedo accually being acurate, even with stock sized tires, my speedo was off 5mph, they are notoriously inaccurate. but yea its in the tranny, near the back, little cylinder hanging out the passenger side

[mrmephistopheles]

So.. my car at true 70 will read 63, correct? And 1 true mile will click the odo .9 miles? With the aforementioned 10% taller rear and 11% taller front tires?
-Jeff
Since it's basing it's measurement off the tranny, the true difference will be between the trans and rear tires. You can have 20" blingblangs in front and stock in back, and you'll be reading stock speedo numbers. Nissan speedos are notoriously inaccurate.