You Can Has A Custom Title!!
Join Date: Nov 2002
Location: UMBC, Maryland
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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.