[Mineral_///M]

In the process of a high horsepower Single Turbo DCT 335is build and I have a few questions that I can't seem to find answers by searching. I'm looking at doing a m3 rear end conversion (Diff, axles, Driveshaft) because its beefier and more cost effective than a drop in option. Problem is I keep reading about anything higher than a 2.56 gear ratio and you get DCT slip codes. So my questions are

1. Has anyone swapped a DCT 335is I've found a few manual ones that were swapped but no DCT cars?
2. Can I get away with the 3.15 ratio?
3. Is this a good route to go or should I just go with a MFactory unit or another company?

Thanks in advance.

[mweisdorfer]

Originally Posted by Mineral_///M

In the process of a high horsepower Single Turbo DCT 335is build and I have a few questions that I can't seem to find answers by searching. I'm looking at doing a m3 rear end conversion (Diff, axles, Driveshaft) because its beefier and more cost effective than a drop in option. Problem is I keep reading about anything higher than a 2.56 gear ratio and you get DCT slip codes. So my questions are

1. Has anyone swapped a DCT 335is I've found a few manual ones that were swapped but no DCT cars?
2. Can I get away with the 3.15 ratio?
3. Is this a good route to go or should I just go with a MFactory unit or another company?

Thanks in advance.

I would not go to the trouble of installing an M3 differential.

If I wanted to install an LSD, I'd look at one of three companies, Mfactory, Wavetrac, & Quaife.

[LMB335IS]

I've done the complete conversion (diff, axles, driveshaft) along with the M3 GWS with center console and working drivelogic, M3 GTS TCU flash, M3 KOMBI and M3 DSC/SZL. You're going to have a mismatch with the 3.15 FD and the 335is TCU software and conversely I had a mismatch with the M3 software and the 335is 2.56 FD. I switched to a 2.81 gear in my M3 diff because the 3.15 is just too low for our N54 powerband and rev limit but will work within the limits of the M3 software, no errors, no funky shifting.

The beauty of this setup is not only do you get the beefier drivetrain and LSD, but you also get the M3 launch control, no brakes involved, adjustability of the launch rpm, and no DSC/DTC interference. For the basic conversion you'd need the M3 GWS, shifter boot and knob, center console top trim piece with drivelogic switch, and a couple different electrical connectors for the GWS and drivelogic repinning, maybe $500-$600 total from Ebay.

With the big case 210mm diff there's a few gearing options depending on the direction you take. Options are 2.65, 2.81, 2.93, and 3.07 at the higher end. Which one you use depends on the DCT software you use but I've found that the 2.81 splits the difference and will work with either software version.

Most people entirely overlook the benefit of the upgraded axles and driveshaft, not to mention the diff, all of which are far stronger than the mediocre factory 335 axles and driveshaft setup. There's far more to it than just a simple LSD in terms of gains.

[AWSAWS]

Originally Posted by LMB335IS

I've done the complete conversion (diff, axles, driveshaft) along with the M3 GWS with center console and working drivelogic, M3 GTS TCU flash, M3 KOMBI and M3 DSC/SZL. You're going to have a mismatch with the 3.15 FD and the 335is TCU software and conversely I had a mismatch with the M3 software and the 335is 2.56 FD. I switched to a 2.81 gear in my M3 diff because the 3.15 is just too low for our N54 powerband and rev limit but will work within the limits of the M3 software, no errors, no funky shifting.

The beauty of this setup is not only do you get the beefier drivetrain and LSD, but you also get the M3 launch control, no brakes involved, adjustability of the launch rpm, and no DSC/DTC interference. For the basic conversion you'd need the M3 GWS, shifter boot and knob, center console top trim piece with drivelogic switch, and a couple different electrical connectors for the GWS and drivelogic repinning, maybe $500-$600 total from Ebay.

With the big case 210mm diff there's a few gearing options depending on the direction you take. Options are 2.65, 2.81, 2.93, and 3.07 at the higher end. Which one you use depends on the DCT software you use but I've found that the 2.81 splits the difference and will work with either software version.

Most people entirely overlook the benefit of the upgraded axles and driveshaft, not to mention the diff, all of which are far stronger than the mediocre factory 335 axles and driveshaft setup. There's far more to it than just a simple LSD in terms of gains.

How did you change the final drive ratio?

I'd like to do the same.

[LMB335IS]

Originally Posted by AWSAWS

How did you change the final drive ratio?

I'd like to do the same.

Do you have the M3 diff?

[whyzee125]

IMO no reason to go M3. It's beefy but the LSD is inferior to the quality aftermarket offerings and you can always get upgraded axles if you need them. I'd go either Mfactory, Quaife, Wavetrac, Drexler etc. OR you could do the Ford 8.8 rear conversion from SeemsLegit. They have some strong axles and you can get the gear ratio you like. My preference would be for the stock diff housing as you can keep your OEM driveshaft that way.

[rbryantaz]

Originally Posted by Alohadrive

Aloha
I am new to this forum. I may end up being a regular. But first issue first. I have an e90 335i with upgraded twins, all bolt ons including inlets, outlets and we recently installed the complete rear end out of an e90 m3. We used the entire subframe, with diff axels and brakes. Everything seems awesome at first but after a few hundred miles I had a front caliper sieze up. I took it apart cleaned and put back together because I couldn’t find a problem. The car sat a bit but next drive it seemed as though the rear brakes were dragging. Can anyone tell me if there is a problem with running the front 335 brakes and rear m3 brakes. Maybe incompatable ASB module or brake booster or master cylinder? Any advice would be appreciated.
Mahalo

The e90 M3 uses the same front brake pads as the 335i but...

The M3 has a 60mm caliper front piston with 360mm rotor vs 57mm/348 for the 335i. The pad being mounted farther from the hub center gives it more leverage and more braking force. It isn't a HUGE difference but it is a bit more front braking.

Running 335i fronts and M3 rears will give more rear bias but I don't think it is a major problem. I would probably run the upgraded front pads and less aggressive rear pads to even it out... It might be worth considering the M3 master cylinder of the pedal stroke seems longer than stock but that also probably isn't really needed

The easiest upgrade to make it better would be to run the F30 front brakes with the e90 M3 master cylinder. The f30 brakes can fit on the 335i front spindles where the e90 M3 versions do not. Those calipers are not cheap though...


-Rich