I was wondering if the Tach and speedo feed off of each other in any way via the speed sensor or anything with the computer, reason why I was wondering is I just got my car back with the 3.23 gear swap and I know the speedometer is wrong but it still reads the same RPM as is did with the 2.73 at 70 mph and I know I should be turning more and then sometimes the tach reads way above what it should be I am confused. I have ordered the gears to fix the speedo by the way.

 

If you still have the stock speedo gears in the trans the rpm's/and speed will be the same. The output shaft from the trans is still spinning at the same speed at a given rpm as before. The only change is the speedo is off It probably reads 70 when going 60-65 something like that.

 

Your speedometer is fed off the VSS in the tranny which uses 2 gears to turn it. These gears are color coded and it takes the right colors to match you rear gear ratio. If you changed rear gears and left the same VSS gears in, then the speedometer will be off.

The tach is fed from an entirely different system, and unless you tach is bad, those ARE the RPM's your turning.

 

Is that 70mph from your incorrect speedo, or are you actually going 70 when you check it? My guess is that you are using your incorrect speedo reading. The speedo reading comes from the rpm of the output shaft of the tranny, which is directly related to the rpm of the engine. Until you change the speedo gears, the engine rpm and speedo reading will be 'in sync' with each other, regardless of gear ratio, tire size, etc...

 

Thanks guys, on the way to work this morning I slapped myself in the head for using the wrong speedo to check my RPM's, 82Camaro hit it right on the head.