So I have a freshC4 Trans with stock 300 gears in the rear. I want to change to a posi , what would be a good set of gears to install. I don't do alot of highway driving maybe 55 to 60 mph tops. I just wanting to know high to goand what RPM to expect with the gear changes. I was thinking 355 . The motor is a 289 ,mild cam, with headers , 600 Carb.So if anyone has any suggestion I would Like to hear them.Thanks

 

3.55 - 3.73

you would be pretty happy with a 3.00 to 3.55 increase and you wouldnt be killing your RPM's either

 

A good compromise is 3.25.Good performance around town but OK on the freeway.

I pull about 2400 rpm at 55.

 

Thanks, thats what I was looking for , what the RPM would beat 55mph with what gears.Thanks

 

Here, check out these calculators. More info here than you could ever use.
Cheers.
http://www.wallaceracing.com/Calculators.htm

 

heh i'm running 3.08 and it's a dog. going to 3.73s since i do a lot of town driving


as of now i probably pull 28-29 at 60 or so

 

I ran 3.55's when I had a c-4 and would rev about 3000 -3200 with a 25.5" tall tire @ 65.

 

Im going to put in 3.55s or 3.73s in my car with either a Detroit locker or a Detroit tru-trac. It is an 8 inch axle. Im not sure which of the two I will pick, but I have 29 inch tall tires as of now (not for long, next set will be a size shorter). So I will probably go with the 3.55s since I don't have overdrive.

 

hell i was gonna go to a 3.80 gear with my C4[8D]

 

I went with 3.55's with my car. I think you will notice the difference, but with 3.25's you won't get as big a bang for your buck? Did that make sense to ya?