i have a 1973 240z with the stock rear end and 4 speed tranny. i have upgraded to a 15x7 wheel with a 205/60/15 tire. my speedometer is reading at least 10 to 15 mph faster than it should. what's the best fix for this?

If all the parts are truly stock (rear end and speedo gear), then the spring inside your speedometer itself must be weak. Because the tire size you are running is basically stock height as well. I'm betting that the odometer is pretty accurate.

There's only a couple of options here. One would be to change the speedo gear to compensate, but that will throw off the odometer. The other is to repair or replace the speedometer itself.

hey thanks for the info! there's a place here in town that repairs speedos. i'll give them a call.

i noticed that the speedo needle isn't very steady while driving.