Anyone swapped an xDrive auto 3.46 to manual 3.08 final ratios?

[typedRew]

Really considering doing this swap, wanted to see if there was anyone with experience doing it, even if it was just a rwd car that went to the longer manual ratios.

My car is stock twins, and plans to stay that way, possibly upgraded twins at some point so my goal is maximize time in the meat of the power.

I really like a nice broad torque range with long legs and I feel like the manual final drive would give me what I want. Right now im always hunting for the right ratio and it seems like the car is always shifting. Especially affected is my 60-130 time which requires 2 shifts(3-4-5) and i'd like to change that.

Id also like to trap about 10mph higher without needing to find 5th gear and right now im near my limit at 118 in fourth nearing 6500rpm, so adding power will require another shift, and i think it will negate the added power and ultimately not show improvements on et or trap. And if it does it will be minimal.

Anyway. Just wanted to see if anyones gone to the trouble, especially considering the effort needed to swap the front diff.

 

[doublespaces]

I have gotten lost with all the swaparoos, pretty sure I've seen it the other way on non xDrive vehicles so I'm curious to see if anyone has done this as well.

 

[Coupes66]

I installed a M3 diff which had 3.25 gears fitted into my auto 335i. The reason for changing the gear ratio was to get through the traps in 4th gear at 6,500 rpm (129 mph). It achieved that goal successfully. The only issue has been that when driving around town in drive, I find 5th gear is too tall as the revs are at 1,200 at 60 kph. Put it into manual in 4th and it feels good. Highway driving is great with 1,800 rpm in 6th at 100 kph. With 3.08 ratio, even 4th may be too tall around town.

 

[typedRew]

I installed a M3 diff which had 3.25 gears fitted into my auto 335i. The reason for changing the gear ratio was to get through the traps in 4th gear at 6,500 rpm (129 mph). It achieved that goal successfully. The only issue has been that when driving around town in drive, I find 5th gear is too tall as the revs are at 1,200 at 60 kph. Put it into manual in 4th and it feels good. Highway driving is great with 1,800 rpm in 6th at 100 kph. With 3.08 ratio, even 4th may be too tall around town.

did you do any programmingafter the swap or did the car seem to take the change without issue

as far as low revs around town I don’t mind, my only specifc goals for the swap are listed in the main post Any downsides I’ll just live with

 

[Coupes66]

did you do any programmingafter the swap or did the car seem to take the change without issue

as far as low revs around town I don’t mind, my only specifc goals for the swap are listed in the main post Any downsides I’ll just live with

I didn't have to make any programming changes. Speedo reads ok.

 

[typedRew]

I didn't have to make any programming changes. Speedo reads ok.

Appreciate your info