Originally Posted by mykal335xi
Joining the group-buy guys, looks like it may fall short but I'm in anyway.
I ended up keeping my 335xi because the wife likes it so much. I doubt I'll race it again, but I will likely get the Cobb installed on it and a pro-tune for E85. If things don't progress much then I may get back into this myself when I get my second car (E39 M5), and run progressively more power and traction until something breaks.
A couple of notes for those non familiar with my car:
- Ran 490whp / 550wtq on nitrous + meth + race gas (no nitrous in 1st gear though, no point really without more traction)
- 350+ brake boost launches from 1st gear
- 100+ brake boost launches from 2nd gear, then the clutch packs for that gear were done, 2nd gear launches in the 335xi are NOT recommended by me for this reason
- Power transfer to the front wheels is a bit jerky when engaging at full power (rear wheels spin briefly before all 4 start spinning)
- Ran Pilot Sports initially, but just on tune only, all high power runs were done on Conti DWS, with this setup I hit a 1.57 60' time with copious amounts of wheelspin
- Wheelspin in my setup may be what saved my drivetrain from breaking, according to all the drivetrain experts I talked to traction is the #1 killer of drivetrain components
- No transfer case issues, or front diff issues thus far (knocks on wood)
Originally Posted by Jack M.
I'm sure it would be very easy to manipulate the motor which controls the LSD action in the t-case, but the problem is the ECU will very likely freak out if it was unable to control the LSD in they way it wants to. Is there a way to shut that OFF, so the ECU is not monitoring the unit? If so, I can very likely design and build a circuit which will allow the driver to control the LSD manually by either going full ON or full OFF.
Full ON would be nice for drag race use. Full OFF may be a bit tricky and I'll have to take a closer look at the clutches to be sure they will not be damaged if you were to run the car in a way where the front or rear wheels would move independently for extended periods.
I know the ACD unit in the EVOs will burn up the clutches if you have the wheels turn at a different rate for too long, even if the system is OFF and no pressure is applied to the clutches.
This was my thinking, If the ability to control the transfer case is capable through cobb or JB4 then i think alot of the warm gear issues will go away. Doing some research i see that as mykal335xi said, the rear wheels slip then all 4 slip. This to me sounds like (front/rear %) at a stop, the system is disengaged 0/100 when you accelerate and the system sees wheel spin it then uses the warm gear to transfer power to the front. Under heavy load (track launch) the gear cant handle it, and when you increase the tq thats more force that gear has to work against causing failure.
To me the easiest thing to do would to control the module like the evo 9's can do "snow mode" and sets a 50/50 delivery of power.
once you reach the middle of second gear or third you are able to transfer back to a less friction mode of say 20/80.
tldr; hack the transfer case module for 50/50 power delivery