Member, P400 Sport, DSC On (>550)
Join Date: Jul 2011
Thanked 93 Times in 65 Posts
Has anyone on here actually put the 4.10 diff on their 6spd M5? I've researched for months and the best I've found is they know someone who knows someone who installed one. I love my 08 IB 6SPD M5 but have been pretty disappointed for daily driving with it. I have a pulley, Corsa sect 3, and Brentune (which helped quite a bit actually, and great customer service!).
My main problem is just the lack of low-mid end power, primarily when taking turns at normal speeds. On ramps at 40mph used to be a blast in my E39 M5, E36 m3, and my 335I with JB4. In this car/gearing though it's just not in the powerband. Yes, we all know the E60 M5 can't be touched on a long straight highway. That's not where I get the most pleasure out of my driving.
My last hope before selling to get an M4 or similar would be the 4.10 diff in to get more use out of the RPM range. I hear good things about the 3.91 but don't think it will be enough of what I'm looking for. Can anyone chime in the good and bad of 4.10? Does it kill the highway practicality? Thanks!
I have a bit of previous experience with this matter. I tried to install a 4.10 ring and pinion in my '10 SMG E60 (BEFORE Turner said it wouldn't work) and indeed it wouldn't meaning the ECU and TCU wouldn't let it work.(Check Turner's website and if they currently say it will work on a 6-speed E60 then you should be good.)
So I returned the 4.10 in exchange for the 3.90s and they worked fine although the installation is a little tricky and time-consuming. I am told by some tuners that they can make the computers accept the 4.10s in an SMG car with some coding but that remains to be seen. My 3.90s did make a significant difference and either gear will make a difference for you as well, however a couple of things you should be aware of before you pull the trigger. The gears have to be broken in and as I recall it was something like 1000 miles or so to do it right. I also had a slight whine at certain rpms that couldn't be tuned or adjusted out though this is not uncommon when you swap out a ring and pinion. What might be a bigger issue for you is the increased rpms at cruising speeds. I don't recall the increase but Google "Wallace Racing" and check out the calculators there. You can play around with them but in general it's a linear relationship so going to a 4.10 from a 3.62, about a 13% change, should bump the rpms up the same 13%.
For reference my 3.90s cut my 1/4 mile ETs (11.50s at 123.6; 151 in the 1/2 mile) by a little over 0.3 seconds but check out my video on Fluidmotorunions's YouTube section to see how fast it got through the gears-with 8,400 redline shifts I think I was in third gear in a little over four seconds, the other mods notwithstanding. Point being, you will definitely feel how well the car responds to the gears.
2010 BMW E60 M5 SMG Carbon Black/Black
Evolve Tubular Headers w/SwainTech ceramic coating
FluidMotorUnion Custom Tune
FluidMotorUnion Custom Exhaust Dumps
FluidMotorUnion Custom Velocity Stacks
RPI GTS Exhaust Sections 1,2 and 3
RPI Oil Cooler
3.91 Ring and Pinion
ESS SMG Upgrade
ADV10 DC Wheels 20x10.5, 20x9
Michelin PSS 295/30-20, 255/35-20
Voltphreaks VPH900 Battery
Hoosier 315/30-18 Drag Radials, Hoosier 245/45-18 A6
Apex Arc-8 18x11, 18x9.5
"I don't care if the door gaps are straight. When the driver steps on the gas I want him to $#!? his pants."...Enzo Ferrari