The Differential Is In! (pics Too)

[woobiee]

more photos http://gallery.fightwitharms.net/02-05-05

The day has came and went; we finally installed the 3.46 differential i purchased 3 weeks ago. Got it from Reno Auto, a salvage yard. The 3.46 was from a 323i with 14,000 miles on it (less than my car). Sold for $325

The total time was 4 hours to install. We had two problems through the process; 1) my car was too low to get onto the lift lol (not a big problem tho) and 2) we raped the bolts that went from the rear L/R axles to the differential flanges. I had to go out and get new ones at the dealer which were $3.68 each! x 12 of them. Luckly Tischer BMW in Silver Spring Maryland are awesome guys and got me 20% off without hesitation.

The drive is spetacular! My car just feels 'lighter' to drive. It revs much faster and wtihout much hesitation. I cannot believe this is my car. This thing pulls and pulls without end. Every gear was improved. On the highway, i can pass people without downshifing to 4th...stay in 5th and go.

RPMs have changed...a bit higher, 12% increase about.
In 4th gear at 50mph, i was at 2550rpms, now with the 3.46 im at around 2950. 70mph at top gear is around 3100rpms

I recommend this mod to any 323/325 manual cars. BMW should have kept the 3.46 diff on the cars!

[Slvr e39]

Nice work woobie...did you put those wheels on just for the shop? or are they winter wheels or what?

[storme]

so this is a mod for which car,,i know e46 but which some/all
and what does it do??
and will it work for all??

[woobiee]

Slvr e39 - yea they are my winter set (stock) i hate them.

storme - sorry for not informing you about it. The rear differential is basically a gear on a bicycle. When you ride a bike up a hill, youll want to select a speed (gear) that will be easy for you to pedal up that hill. Well if you were going downhill in that same easy gear...youll prob wont go very fast because you'll have to pedal super fast...youll have to switch gears for something more slower to gain speed.

In a sense this is what i did to the car. I took out one gear (the one that goes fast downhill) to a slow but easy gear (to go up hill). By doing so, my overall top speed decreases but like i said above, it is easier to pedal; which means my accelerationi time is much faster.

I had a 3.07 and now a 3.46. This means i have about a 12.7% increase in both HP/TQ to the wheels. With the GruppeM and differential, im somewhere around 190-200hp and 200-210 ft lbs of torque. The torque force is equal and in some areas more force than a 330!

The differentials are all interchangable. A 323/325/328 will work without a problem. 330s have different flanges so youll have to swap out the flanges. But other than that, its a direct swap. There are many OEM differentials available, from a 2.93 (high top speed, low accerlation) 3.07, 3.15, 3.23, 3.38, 3.46, 3.73...and so on. The higher the ratio, the faster the car will get to redline in each gear but the top speed will decrease. Vice versa.

This is why 90% of all AUTOMATIC E46 3 series come with a 3.46. All convertibles comes with 3.46 as well. The reason because is since automatics are slower than their manual counterparts and the convertibles are heavier, they need the more aggressive gearing to compensate for their faults. Manual E46 do not come with the 3.46 since they are already faster than the autos. I just married the two; the manual tranny + the aggressive gearing 3.46.