Hey guys. I'm new to the forum. I've been using the search button and doing a little reading. I just picked up a 1994 Z28 with the 4L60E and 2.73 rear gears. I really like the car and it's in nice shape with only 128,000 miles, and the price was right at $2,000. However I hate the 2.73 rear gear ratio. I really want to do a 4.10 swap, but I've been reading both good and bad reviews. A lot of folks recommend the 3.73's instead. I intend on doing quite a bit of modding to the car in the future, so I want to get a gear ratio I can grow with. It will mostly be used for street driving, occasional strip, and little highway driving. I have a couple questions, and would like some input from some people who have already done gear swaps and can give me an idea what to expect.

Will I absolutely hate the car with 4.10's, or will I still have plenty of usable power with a sticky tire? Are 3.73's really a much better choice, or maybe something in between like a 3.90? Also, while searching Summit for ring and pinion sets, I see that there is a series 2 and a series 3. From what I understand, the series 2 gear sets are made to work with 3.08 and numerically lower carriers, and the series 3 are made to work with 3.23 and numerically higher carrier assemblies. Please someone correct me if I'm incorrect. So as I understand it, if I order 3.73, 3.90 or 4.10 Richmond gear sets they will fit my carrier as long as I get the series 2 (thicker) gears. Correct? Or will I need a spacer? I don't want to replace the stock posi carrier with aftermarket, so I'm scratching my head trying to figure out what all I will need to make this work.

Any advice would be helpful. I really appreciate it guys.

 

3:90s FTW!

 

The problem with increasing ratio numerically, the pinion becomes smaller and ring gear becomes thicker.
This design has the installer grinding on the new parts for fitting differential pinion gears inside the carrier.
This shaft has to come in/out of carrier so axles can be pushed in releasing the clip for axle removal and installed for axle retention.
The thinner the ring gear, the less to be ground off. 3.73:1 would be good.
But, I'm not a professional mechanic.

 

342 or 373 will work better with the auto trans.

 

Thanks for the replies guys. I appreciate the help. I ended up ordering 3.73's and have an appointment to have them put in on Feb 5th. The 500 mile break in process is going to be slow and tedious, and it's gonna take all of my self control not to let it rip.

 

fair warning, aftermarket gears will whine.