Yes, the flywheels are the same. The clutch disc will have different splines based on if it's mating to a 5 or 6 spd.

Hello. I just picked up a 6-speed. With a leaking rear main seal. The clutch was replaced recently and I suspect the tech that did this didn't do it correctly. Which has happened to me before, they are kind of hard to do. We'll see

I have a free 550i clutch from a return. This was a really nice upgrade over the stock 340i clutch. So the X5 has a stronger pressure plate, but how does the disc compare to the 550 disc?

I eventually want to supercharge this thing, like 7-10 psi. 15psi. The 550 disc should probably be good for that.

Would the 550 disc with the stock pressure plate work? It sounds like it based on what I'm reading. I'm guessing the pressure plates in fine shape and the disc probably has some oil on it. I hope it has an oem pressure plate and I can just use this disc for a nice upgrade. 10 psi. And the cams.

I'd bet that the tech was simply not paid to do the rear main. Did they even pull the flywheel? No reason to pull it if you're just doing a clutch swap.

The real question is what size input shaft the 550i clutch has? I would not assume that the disc is interchangeable without checking.

Edit: Also, I assume that you've checked this, but make sure that the valve cover gasket isn't leaking at the back. I've seen so many cases of people thinking that the rear main is bad when it turns out that the valve cover gasket was improperly installed and leaked badly at the back.

I have it and the alignment tool in hand and will measure and count the splines.

Anyone have an old X5 clutch laying around and can measure? It'd be pretty cool if they're the same. 550 disc with X5 pressure plate would be great on this car and great on most of the three series.

The 550 fits many of the three series. Really as far as I have found so far pretty much all the clutches are interchangeable. But I don't know, you never really know. I doubt they all are interchangeable.

Back of the valve cover looks clean unfortunately. The oil pan is seeping, it looks like the o-ring for the half shaft bracket may also be seeping, and that little inspection port for the flywheel, the cover is missing and unfortunately it's wet in there and there's a drop a fresh oil on one of those small hex heads for the rear main cover. Not 100% though I cleaned everything and it's only one tiny drop overnight. I have to check again it'll take a few more days to be sure.

Tonight I have the sunroof cassette on the workbench trying to figure this damn thing out.

Oh and by the way that reinforcement plate with the nuts is a pain in the ass. The f30 those nuts are just captive welded to the subframe so you just gun the bolts in and out in 2 seconds. This is a royal pain in the ass getting a wrench in there. I couldn't find any other way to do it on the ground apart from pulling the wheel off. I don't know how to weld yet but I would like to weld an appropriate nut on there and get a high grade bolt.

They aren't the same size according to what I found:

550 clutch:
Clutch Diameter (IN) 11-3/16"
Clutch Disc Diameter (IN) 9-7/16"
Clutch Disc Spline Quantity 26
Clutch Plate Facing Outer Diameter (IN) 9-7/16"
Input Shaft Diameter (IN) 1-3/8"

X5 clutch:
Clutch Diameter (IN) 11-1/8"
Clutch Disc Diameter (IN) 9-7/16"
Clutch Disc Spline Quantity 22
Clutch Plate Facing Outer Diameter (IN) 9-7/16"
Input Shaft Diameter (IN) 1-1/8"

Please correct me if I'm wrong but I cross reference Luk clutch kits and came up with this