[Atom Ant]

Great input, thank you! The only thing i don’t like on my 340i M6, that the engine speed is high at freeway, especially bugging problem in Hungary as we drive between 160-180Km/h. I believe fuel consumption could be significantly lower with lower engine speed. I also would like to enjoy more the gear box, because shifting not often necessary as the 6th gear is mostly good from 60km/h already.
I am curious for your experiences since you did the rear differential change, because I kind of scared to do such mods.

Originally Posted by RumDomRum

I just did the diff swap today.

I have a 2019 440i Coupe MANUAL. It came with a 3.23 rear differential and an 0.845 6th gear.
I also own a 2019 440i Gran Coupe xDrive with the Auto. The auto came with 2.81 rear diff and a 0.634 8th gear.

At 90mph with the GC Auto my RPM is 1950. With the manual at only 80mph it was running 3100 RPM. I don't remember what it is at 90, but I think it was around 4k. I HATE the difference between the two because honestly, I liked getting almost 40mpg in the auto and hated getting only 29mpg in the manual.

So I purchased the M-Performance LSD diff in 2.81 (PN: 33108659989) and put it in the manual 440i.

Verdict: It's great.

Now at 80mph I'm at 2500rpm. It's never going to be as good as the auto since top gear is such a different ratio, but I'm enjoying every gear more. Now, if I lose grip on a hard accel, both rear tires go and the car doesn't do the side to side shimmy that is sometimes terrifying. The car is much more predictable and feels better planted.

The swap was straight forward and everything fit. All you need is a 50mm wrench (I purchased one from Harbor Freight) and normal BMW fitment tools (couple torx, 10, 13, 16 and 18mm).

Only issue I have discovered: RevMatch is now non-functional. I'm guessing I need to find some way to tell the DME the ratio is different. No fault codes, no lights, no drivetrain malfunction indicators, nothing. Speedo is still correct, as well.

[bradsm87]

Originally Posted by SpencerC_6MT

I don't have ISTA, but I recently bought ProTool, which supposedly has most the same capability. Where did you find this under? I'm going to see if I can work it out to cure the "clutch slip" codes.

It is an automatic TCM function. The Manuals are handled by the ratio information in the DME/DDE ROM and needs a flash.