I bought a used rearend that was suppose to have a 3.73 gear in it. Well I installed it and went to the track this weekend. With the factory 3.42s I was crossing the traps at the top of 4th, now Im shifting to 4th about 50 to 60 ft from the traps. My times were down from 13.80@102 to
13.95@101 and I was running the car harder this time and have gone from shortie headers to long tubes. I had the same 60' times. Ill have a video up later of the run. Is there an easy way to tell what gear is in it without opening up the rear?

 

You can always try the inaccurate spin-and-count method lol

 

Hows that work?? I dont believe its as low as 2.73 maybe 3.23s.

 

The idea is you jack up the diff and count how many rotations of the driveshaft it takes to spin the tires once. Of course both tires must be kept completely in phase (locked together).

 

Sounds like You do have a 3.73. The engine is now reving through its powerband quicker than it did with the 3.42's. That is what's forcing You to shift into 4th gear before Your through the traps. The long tubes might be another slight contributor to the faster reving. You may have to go to a taller tire if possible.

 

Ive SLOWED DOWN! I was running 13.80@102 with 3.42s with the same 60's.

 

Maybe it was the top of 3rd I used to finish in, Ill have to try and find a video. Im going to post a link to the vid of this run, it just seems like I fall on my face after the 1/8th

 

Video of the run is here http://www.youtube.com/watch?v=XzDzn21G4vg