LSD ratios and gearing

[318iS]

just trying to build up a bit of knowledge.....


first of all what does the ratio mean... eg.3.46 , 3.75 ,etc....

whats the difference between a high and low ratio.....


how does LSD affect gearing ? ? ?



thanks :wink:

[CirrusSR22]

A 3.45 differential, is short for 3.45:1. This means the input to the differential (from the driveshaft/transmission) spins 3.45 times, for every 1 time the output shafts (and your wheels) spins.

The higher the ratio number, the faster your driveshaft (and thus engine) spins in relation to the wheels. The plus side if this, is better acceleration. The downs sides are a lower top speed, and increased fuel consumption. Think of high ratio numbers like using a low gear on a bicycle. You spin the crank fast, and accelerate nicely, but you can't go very fast.

The low ratio numbers are just the opposite. The acceleration is worse, but top end speed is faster and fuel consumption is reduced.

[318iS]

so im better off getting a higher ratio one cos i really dont give a **** about top speed..... theres no need for it..... accelaration is what matters.....


thanks :)

[L84THSKY]

If you're looking for a simple answer, your not gonna get one. Your top speed will be reduced.....OK, but your gas mileage goes down as well. Not to mention having to shift quicker between gears. There is no win/win solution when you deviate from the standard ratio.:cool:

so im better off getting a higher ratio one cos i really dont give a **** about top speed..... theres no need for it..... accelaration is what matters.....


thanks :)

[1996 328ti]

With a 3.45, 1st gear gets used up quickly.

[L84THSKY]

He wanted to go to a higher ratio I.E. 3.73, that is only gonna make the situation worse:smile:

With a 3.45, 1st gear gets used up quickly.

[318iS]

alrite so... we'll see what happens i heard of a guy near me that sells refurbished LSDs so will see what he has and will probably end up goin for somethin around the 3.45 mark.......