auto/m6

**shady milkman** · 08-14-2006, 09:42 AM

do autos and m6s have the same rear differental gear ...i think thats what you call them. the 3.75,4.10 that stuff. becuase at least for me its hard to break loose the tires on a auto compared to a m6

**Hot Black Trans-Am** · 08-14-2006, 09:44 AM

They are different. You can check your door code to find the gear ratio. Do a search and you'll find the info. The trans gearing is also differnt.

***Ed Blown Vert*** · 08-14-2006, 10:57 AM

M6's are 3.42
A4's are usually 2.73 or 3.23

**shady milkman** · 08-14-2006, 12:23 PM

now why is there such a diff in a4s from 2.73 and 3.23?

**Wesman** · 08-14-2006, 12:36 PM

Originally Posted by shady milkman

now why is there such a diff in a4s from 2.73 and 3.23?

The gear ratio changes the rotation speed of the rear wheels compared to the driveshaft. So a 2.73 gear ratio means that the driveshaft spins 2.73 times for every turn of the rear wheels. The faster the driveshaft spins compared to the wheels the better acceleration you get, since the engine has a more of a mechanical advantage.

So 3.23's will be able to spin the tires and accelerate faster than 2.73, but the trade off is higher RPM's in 4th gear at highway speed.

**shady milkman** · 08-14-2006, 12:49 PM

thanks wesman i understand that but what i want to know is why is there such a big diff in the ratios for the m6 from factory..you know?

**Wesman** · 08-14-2006, 06:20 PM

Originally Posted by shady milkman

thanks wesman i understand that but what i want to know is why is there such a big diff in the ratios for the m6 from factory..you know?

The reason is because the Manual has 6 speeds to work with, while the automatic only has 4. So the 6 speed gear ratios can be closer together, since 5 and 6th are overdrive. In fact, 6th gear on the T56 is a .5 ratio, which allows the motor to cruise at highway speed while only turning ~1500RPM.

With the automatic, they can't space the gears out too far, or there will be too much of a gap between them. If they made 4th gear as tall as the T56's 6th gear, the car would fall on its face everytime it went into 4th, rendering it usless at anything below about 70MPH. And of course cruising around at 50MPH in 3rd gear with a 1:1 ratio isn't in the best interest of fuel economy, either. So in order to get decent perforamance while still maintaining fuel economy, they put lower rear end ratios in the automatic.

Hope that helps explain