Gear ratio change?

[Dathaeus]

This may be something totally dumb as someone who loves to drive hard but has never raced professionally or messed around with cars much internally....

But I always thought my gear ratios were not "pleasing to me"... even worse than my old 1997 328i. I didnt think much of it before I read this

Project E46 330i ZHP

Shortening the ratios would really feel like something I think I want... I hardly approach high RPM's in 6th so I wouldn't care about that. Shifting is definitely my weakest driving skill, but this is worth a try only if I dont have to spend thousands on parts... is it just settings that can be easily modified under the hood or should I just let it be? I am sure someone here has done something like this........ ya?

[az3579]

Gear ratios involve a differential swap. You can change to an open diff which is cheaper, or you can get a LSD, which runs a few grand.

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[Hermes]

Gear ratios involve a differential swap. You can change to an open diff which is cheaper, or you can get a LSD, which runs a few grand.

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This... It's not gonna be a cheap and easy under the hood fix. You can try to find a finned shorter ratio open from an auto, it will be cheaper than a LSD but will still cost you multiple hundreds and require getting under the car to install

[Vas]

So where is the best place to get a 3.46 rear end ?

[JupiterBMW]

So where is the best place to get a 3.46 rear end ?

+1


iPhone 5S. Tapatalk Pro. BOOM

[derbo]

OP,

Having shorter gear ratios, mean you shift MORE through the gears as the gears have a smaller range of mph.


If you still want a shorter gear ratio, a 3.46 from the auto 3series (nonZHP) is the most popular. SalvageYards, forums are common places to find these differentials. The input flange and the output flanges may need to be exchanged with your existing ones to match your half-shafts and driveshaft.

[wsmeyer]

As far as I can tell no 330i's came with the 3.46. 325i's, 325xi's, and 330xi's came with the 3.46 rear end but are the internals interchangeable?

[derbo]

As far as I can tell no 330i's came with the 3.46. 325i's, 325xi's, and 330xi's came with the 3.46 rear end but are the internals interchangeable?

Oops, I'm sorry. 323/325i were the ones with the 3.46. Thanks for the correction.

330i autos came with 3.38.

[BCS_ZHP]

The input flanges are different from a 325 to a 330, 4 bolts vs. 6 bolt to attach to the driveshaft. I have been told changing that input flange can be troublesome, save yourself the headache and look for a 3.38 vs. the 3.46, the gear ratio difference is negligible. The output flanges you can reuse from your existing differential, they pop right out with a little leverage to the side of them. And then don't forget to procure a couple of output shaft seals as you don't want to have to do this twice to replace the $5 seals.

[wertyu78]

This... It's not gonna be a cheap and easy under the hood fix. You can try to find a finned shorter ratio open from an auto, it will be cheaper than a LSD but will still cost you multiple hundreds and require getting under the car to install

I picked up a Z4 3.64 differential with finned cover for $25. I did have to swap the flanges, but no issues at all!