S13 vlsd swap issue

[my 1 88 u]

A couple of weeks ago I swaped out my 92 240sx diff and cover for a s13 vlsd and s13 5lug diff cover. Now my speedometer reads higher speeds than I am acually going. It will read 90mph when I'm only going 83mph, 105mph when i'm really going 90mph.

Why?
How?
What to do?

[TX Drifter]

I might be wrong but I think that its the speed sensor. JDM read in Kilos. US in miles. But like I said, I might be wrong. But is the speed sensor on the diff.?

[GRiDRaceTech]

Dude, it's saving you from bigger fines for speeding. Leave it.

Or, have your speedometer calibrated.

[nissanguy_24]

on the S13 the speed sensor is on the driveline. maybe you messed it up? that or you swapped in a turbo Z32 diff instead of a S13 or NA Z32 diff the turbo diffs have a different rear end.

Also i believe the turbo JDM S13s have a different gear ratio then ours by a small number. any of it could be throwing you off.

[my 1 88 u]

what can i do about it?

[180fan]

the speed sensor's at the back of the transmission. If you messed it up, get a new one at a yard. There should be one or two 10 or 12mm bolts holding it in. I'm I'm not mistaken it should be one 10mm.

The diff you got, got any pictures of it? If you look around on the cover, do you see a designation saying R200? Does your acceleration really suck bad? If it doesn't say R200, you don't have an s13 diff pumpkin. Then the next logical thing to look for is the acceleration. If that's way slow, you've got a turbo R280 pumpkin and should get rid of that. If your acceleration is still about the same, you should check the speed sensor instead. If all your other instruments are still reading properly I doubt it's an electrical problem anywhere else unless your speedometer is going out just as a coincidence with the diff change.