Tag Archives: MFactory

BMW N54 Clutch Upgrade: SPEC Stage 3+ with MFactory SMFW

If you’ve been following my website, you probably read my detailed post about installing a 335is/550i clutch after my OEM clutch wore out. However, with MMP Stage 3 turbos on the way, I knew the 335is clutch wouldn’t hold as I turned up the boost. With a goal of 700whp, I decided to replace it with a SPEC Stage 3+ clutch and retain my MFactory single mass flywheel.

SPEC Stage 3+ Clutch

Since I just installed an MFactory SMFW about 20k miles ago, I decided to reuse it because I knew it was in good condition.  All I had to do was purchase a SPEC Stage 3+ clutch with OEM or MFactory flywheel configuration so it would mate up properly. If I didn’t already have the MFactory flywheel, I probably would’ve bought a SPEC flywheel to go with the clutch. However, I’d rather save some money when possible!

Since the transmission was going to be removed, I wanted to refresh a few things at the same time. I noticed my shifter developed some side-to-side slop so I decided to upgrade the bushings. The car has almost 120k miles and still has the OEM transmission mounts, so I knew those could be replaced. I’ve also never servied the rear differential and noticed it was seeping a tiny bit of fluid. Might as well replace the rear pinion seal and flush/refill the fluid!

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BMW 135i – 335is/550i Clutch Upgrade

2017 Update: This 335is/550i clutch setup held up great for 22k hard miles! I have absolutely no complaints. In June I decided to upgrade to MMP Stage 3 turbos and chase 700whp. I knew this clutch setup wouldn’t hold, so I removed it and replaced it with a SPEC Stage 3+ unit.


After adding my aggressive E85 flash last summer, the factory clutch started to slip. I decided it was time to upgrade so I could enjoy the car to it’s full potential this summer. From Spec to ACT, there are plenty of aftermarket options available. Then I found the 335is/550i clutch upgrade on ECSTuning, so I started to do some research.

This clutch comes factory in the F10 550i, which puts down 443 tq and weighs a whopping 4552 lbs. DINAN doesn’t offer a clutch upgrade for their different stages of 550i’s, so apparently they feel that it is adequate. Their Stage 3 550i puts down 580 tq and they kept the factory clutch. Also, someone on the forums is using this clutch and claims that it is holding at over 620wtq on aftermarket turbos. To me, it sounds like the clutch is severely underrated.

My 135i won’t see more than 500 tq anytime soon. I’d guess that it is currently around 420whp/465wtq, but only weighs 3300 lbs!

I decided to give it a try. Here is my parts list from ECSTuning:
Continue reading BMW 135i – 335is/550i Clutch Upgrade