3 series or 2 series?

**Bandit1** · 03-03-2007, 02:47 PM

hey whats up all can anyone tell me the difference between a 3 series and 2 series. also a buddy of mine has a 97 v6 maro and wants to do gears whats the best to go with for a m5? thanx all

**01Z28M6** · 03-04-2007, 08:36 AM

The 2 series carrier is for 2.73:1 and possibly 3.08:1 gears while the 3 series is for 3:23:1 and up. I might be wrong about the 3.08:1 ....

As for the 2 vs 3 series rear end - A 3 series differential is shorter from the gear flange face to bearing end on the long side. The 3 series ring gear is thinner than the equivalent gear in a 2 series differential set up. For instance, to use a 3 series ring gear with a 2 series carrier a 5/16" spacer on the flange face is required. This is really hard to visualize without pictures or actually seeing them side by side. If you are looking for performance you will probably want to go with a 3 series. The 2 series is for tall gearing and low rpm, high speed cruising.

**Bandit1** · 03-04-2007, 08:40 AM

ok so if i wanted to put 3.73's on i would go with the 3 series carrier? my car has the crapy 2.73's it came with from the factory so it has a 2 series carrier?

**01Z28M6** · 03-04-2007, 08:49 AM

Originally Posted by Bandit1

ok so if i wanted to put 3.73's on i would go with the 3 series carrier? my car has the crapy 2.73's it came with from the factory so it has a 2 series carrier?

You would want a 3 series carrier, correct. I know Richmond makes special 3.73 gears to work with your 2 series carrier so you can check into that if your 2 series is still in good shape and you are on a budget.