[DialedIn]

I have a 325i with a manual trasmission, and I never get to use the 6th gear, not even at 130kmph/80mph. It seems to me that the car is too high geared.

Has anyone swapped in an automatic rear differential with 3,73 final gear ratio instead of 3,23?

Will this improve drivability and allow me to use the full range of gears? Are there any downsides to this?

[Biginboca]

Yes a bunch of us have done it. Search will turn up threads about it.

In my opinion, this is the best bang for the buck mod you can do. Used diffs can be had for $200-250 delivered if you are patient on eBay.

You will not be disappointed... just do it!

[desertman123]

https://www.1addicts.com/forums/show....php?t=1418770

[Eins Suchtig]

I did it and love it!

[DialedIn]

Originally Posted by Biginboca

You will not be disappointed... just do it!

Okay, I just ordered one!

[desertman123]

When it was cold out (50° is cold for Florida!!) And my prirelli summer tires were at the end of their lives, the 3.73 would roast them apart if I hit it in first

[DialedIn]

Originally Posted by desertman123

When it was cold out (50° is cold for Florida!!) And my prirelli summer tires were at the end of their lives, the 3.73 would roast them apart if I hit it in first

Did you roast them with an open diff or do you have an LSD?

[avocet]

Originally Posted by DialedIn

I have a 325i with a manual trasmission, and I never get to use the 6th gear, not even at 130kmph/80mph. It seems to me that the car is too high geared.

Sounds like you are a perfect candidate for regearing!

If I were to do alot of highway commuting I might feel differently about the 3.73, but I don't. One of the best mods!

[bigdonny]

At risk of sounding dumb I must ask: Is this mod doable for an AWD? My instincts tell me with the front transfer case being set at a gear to work in tandem with the rear diff, this would be an issue.

I ask because I have a 2010 328i xdrive. This is my second BMW but my first straight-6
and I've been generally disappointed with the lack of performance in the car. my last two manual cars I've owned had much shorter gearing and I certainly preferred that.

[Biginboca]

Originally Posted by bigdonny

At risk of sounding dumb I must ask: Is this mod doable for an AWD? My instincts tell me with the front transfer case being set at a gear to work in tandem with the rear diff, this would be an issue.

I ask because I have a 2010 328i xdrive. This is my second BMW but my first straight-6
and I've been generally disappointed with the lack of performance in the car. my last two manual cars I've owned had much shorter gearing and I certainly preferred that.

I would think a manual x drive could swap the diffs (need front and rear) from an auto x drive.

[desertman123]

Originally Posted by DialedIn

Did you roast them with an open diff or do you have an LSD?

Open diff, stock E-LSD.

These cars WILL lay down 11's - I've tested it.

The DSC unit will apply brakes to whichever wheel is spinning faster to get both of them to spin at the same speed. Obviously this isn't perfect but it works.

[DialedIn]

Originally Posted by desertman123

The DSC unit will apply brakes to whichever wheel is spinning faster to get both of them to spin at the same speed. Obviously this isn't perfect but it works.

I have an early model year, and thus I don't have the E-LSD. I am contemplating installing a Torsen differential and new bearings and seals while I am at it. But the LSDs are super expensive! lol

[DialedIn]

The differential is mounted on the car! I'm just waiting for the sealant to dry so I can fill her up with oil and take it for a test drive.

I removed that damn CDV at the same time.

[Biginboca]

Originally Posted by DialedIn

The differential is mounted on the car! I'm just waiting for the sealant to dry so I can fill her up with oil and take it for a test drive.

I removed that damn CDV at the same time.

Nice Job! I did my cdv when I did my diff also lol

Why did you have to seal the diff... Did you do the vented cover too?

[DialedIn]

Originally Posted by Biginboca

Nice Job! I did my cdv when I did my diff also lol

Why did you have to seal the diff... Did you do the vented cover too?

I don't think I will miss the CDV. Without even driving it the clutch pedal feel is instantly better!

Removing the differential cover gave me a chance to inspect the gears for wear and measure the backlash and I learnt that the ring gear is bolted on and not welded. - Making it a perfect candidate for an LSD.

But this was a whole lot of work and I'm not ready for an LSD install for a while.

The new diff painted red and mounted:


The old diff looking nasty:

[DialedIn]

After test driving the new diff I was pleasantly surprised.

The new diff (although it was the cheapest one available on eBay) appears to be in very good condition and the CDV delete was a nice addition. The car feels more mechanical without the CDV.

It's much more fun to be able to use the full range of gears now, but It's gonna take some getting used to having to shift at different speeds.

[bimmer_mopar_harley]

hey guys rather new to forums as far as posting anything read allot but never asked a question i have a e90 328i i call her Frankenstein!! she has parts from many different chassis. today i swapped out my final drive assembly with a e83 4.44 lsd tallest gears bimmer offers at least from the factory,i think, could be wrong, only problem i didn't for-sea happening was axles binding, i had to raise the stance up about in by adjusting the coil overs i tried throwing it on the alignment rack and adjusting camber way positive and then way negative didn't seem to help much plus its not the fix im looking for! anyone no of any good solutions? perhaps a shorter axle from another chassis? has anyone done a simliar swap and ran into any issues?

[hassmaschine]

if the diff housings are the same you probably just need to swap the output flanges with your old diff.

[bimmer_mopar_harley]

The Diff Housing Were Different, The Front Ears For Mounts Were Much Higher On The E83 Diff Where On The E90 There Centered With Output Flanges. Output Flanges Were The Same But The Rear Cover Had To Be Swapped I Had To Fabricate The Front Diff Mounts.

[hassmaschine]

ah, if you've fabbed stuff yourself (good for you, seriously), I don't know of an easy answer. Perhaps the E83 CV shafts are a little shorter? or maybe you can piece together a set of shafts from the E83/E90?

Did the E83 really come with an LSD? BMW has gone weaksauce for a long time, no LSD on anything except M cars. It might be the one mod I'd be willing to spend money on for my 330i...

[bimmer_mopar_harley]

yes it is a lsd the e83 awd with n52 had it. ill shoot a video of wheels moving with it on the lift tomorrow when i get to the shop, nice thing about being a tech this time of year is it slow at work and i can work on my own stuff without having to stay late.

[Bufalo]

I seem to recall that my '07 X3 did have a true limited slip, it was pretty unstoppable in low traction situations and not just from electronics.