Rear subframe reinstallation - piece by piece, or preassemble

[divedoc]

I'm in the middle of a rear subframe refresh - bushings, diff seals, etc. Everything is off the car and disassembled. I was initially going to put everything back together on the ground before jacking it into position under the car, but I've seen some people do it piecemeal. Is there an advantage to doing it one way vs the other?

[sapote]

I would preassemble the whole thing as you have more room for the upper control arms nut/bolts.

[BMWahba]

Definitely preassemble and raise the whole thing in. Way easier.

[Ramo]

I followed this video when I refreshed my rear end.

https://www.youtube.com/watch?v=mKNPI5KTUK8&t=2704s&ab_channel=FCPEuro

[heinzboehmer]

+1 to preassembling

[FBloggs]

Off the car assembly makes all fasteners more accessible.
Use an ATV jack as a stable lift.

[divedoc]

Preassembly makes more sense to me too. Then I saw FCP’s video series on the rear refresh, and I wondered why they’d put it all back in that way.

Thanks for the advice. I have a few more things to do first, like finish the diff work and try to extract the brake line bracket bolt on the right trailing arm. Someone snapped off the head in the past, I found the bracket held in place with a zip tie.

[AussieE46M3]

I personally like to assemble the car piece by piece as I generally change every bushing/bearing so it's apart anyway. I do loosely fit the upper arms prior to fitting the subframe.

Little things to keep in mind, torque the inner arms rubber bushes with the wheel at it's desired position to not pre-load the rubber. This also applies to RTAB's and lower shock bolt if you run rubber.

You also need to put the arms on before the diff goes in as it blocks the bolts from coming out or going in.

There's no benefits in doing it either way, jus whichever is easier for you.