[SF335]

I am planning to put an LSD into my 2011 335i 6MT and am debating whether to change the final drive ration from the 3.08 to a 3.46. It looks like doing the 3.46 is about $800 cheaper, which is quite nice. The car is my DD but will see a lot of track time.

I would love to get some input from those who have done this, how you use the car, and whether you would do it again/recommend it.

Thank you.

[feuer]

The reason why 3.08 cost more than 3.46 isn't the ratio. MT are welded and require more work to install LSD. Cut the main gear, mill it, drill it, tap it.....I have been tracking my 335i MT too and don't recommend changing the ratio because it will introduce the need for additional shifting and use of 5th gear. Now I use 3rd and 4th almost exclusively. Every additional shift will induce extra stress on the whole drive train. Also more work for me. So my vote is no.

[Ozzie335i]

4th gear at 3000 rpm is 60 mph, 6th gear at 3000 rpm is 80 mph. I am no feuer racerguy, but still I like it and would do it again.

[rich_mane]

I swapped a manual transmission into my factory automatic car and kept the AT 3.46 diff. I happen to like the shorter gears. Gets up and goes real quick in 2nd and 3rd but my car doesn't see the track, it's just my daily. For a lot of tracking then I'd go with what the feuer said, the less you shift the better.

6th gear 80MPH cruising is about 3200RPM for me.

I'm wondering if it's completely necessary to change the "Gear Ratio Calculation" in the tune itself. I've been running the MHD OTS Stage 2/E30 tunes and haven't asked Twisted Tuning to change it for me. No faults or DSC problems yet, 12k miles into the swap.

[maxslug]

Better late than never, I did some maths on this one...
https://www.1addicts.com/forums/show...php?p=30588519