rearend gear questions
 

i finally got my new wheels/tires and drove my car for the first time. i cant go over 45 mph in 4th gear without tach climbing over 3 and sounds like im in a lower gear?? my car was set up for drag racing i think? could it be rearend is geared for that or transmission messed up?? it shifts fine but seems like the tranny gears are very low, my budddy says its probally the rearend is geared like 485 or something like that, any help??

Sure sounds like very low rear gears to me. If you have a LSD/Posi rearend, jack both tires off the ground, spin one wheel 1 full revolution, and count how many times the driveshaft turns. If you have an open diff, jack only one wheel off the ground, spin the tire 2 full revolutions, and count how many times the driveshaft spins. As an example, if the driveshaft spins approximately 4 times, you have 4:10 gears, etc. I'm betting you have more like 5:13's in there. Also, your relationship between speed and rpm's is assuming the speedo has been calibrated for your gears. Without changing the speedo gear, low rear gears like that is going to make the speedo read way high, so it must have been "fixed".