Well, 3 1/2 years and 1 pandemic later, the subframe is finally in!! I'm not going to go into the detail of how it's done since there are several write ups and YouTube videos to help get you through it. Actually, on paper, it's very simple: drop exhaust and driveshaft, disconnect parking brake and hydraulic lines, remove 4 subframe bolts and your done. Just like that, no sweat. I you look at Spencer's video on YouTube that exactly how it went for him. Great, I'm ready: did my homework, took notes, got all sorts of internet bookmarks, let's go.
Yeah, not so much. In theory, it's exactly as you'd expect. In actuality, the gremlins had a field day. I'm only going to go over the gremlins here since it really is a straight-forward job.
I'll mention some very helpful resources for doing the final bolt up. Between these and NewTIS.info you'll have everything you need:
https://www.m3post.com/forums/showthread.php?t=1330067 great resource for M3 spec torque values. Just about every torque value needed is listed here.
Spencer's rear subframe video
https://www.e90post.com/forums/showthread.php?t=1117936 good subframe swap thread
http://www.onelapx1.com/blog/how-to-...w-actually-fun coding out the diff nannies. Don't forget to do this when you are done.
Here's basically how it went.....
1. remove underbody shields. Great confidence builder since pretty much nothing can go wrong here. Just make note of any missing fasteners so you can order them when done.
2. making great progress, let's take the exhaust down. This became gremlin number one when 3 out of the 4 studs snapped when trying to back off the nuts. I ran off to Harbor Freight for an air hammer, air saw, and 25" breaker bar, and some other stuff. ALL got used in this project. I knocked off the 4th stud with the hammer, finished removing the exhaust, and decided I would return to this at the end. You'll read about it further down.
3. drive shaft out. Front bolts easy after removing tranny support and placing jack under tranny. No big deal. Rear 50mm nut was unreal. This was gremlin #2. I had read that for some this came relatively easy, for others it was a bear. For me, it took everything I had and the 25" breaker bar to get this sucker moving. After over an hour of wrestling with this, I called in my 16 year old son, added the floor jack handle to the breaker bar and it was still a huge job getting the rear shaft nut completely loose. Major time drain. Two tips on this: a) look at the picture below, place a solid object at the center drive shaft joint to prevent it from turning b) when looking towards the rear of the car, turn the big nut clockwise to release it.
4. release brake lines. Gremlin #3 was waiting for me. I went to remove the rear rotors in order to release the parking brake cables. I guess 105k miles on the original brakes gave them a chance to really settle in on the drums. I could not remove the rotors as they were hung up on the brake shoes. I knew something was wrong because I'd been experiencing an intermittent scraping sound from the rear. I chose to ignore that since this job was coming up. It took Thor's Hammer (look at my previous posts) and a piece of 2x4 to knock the rotor off. It took so hefty hitting. Fortunately, rebuilding the parking brakes was on my to-do list from 3 years ago and I already had the parts. Gremlin 3-2 had to do with the hard brake lines on the chassis. These connect to the rubber inner lines that jump over to the subframe. I had a stainless line kit ready to go disconnecting all of the points was on the list. Well, one of the chassis tubes/pipes started to twist when I tried to back off the nut on the line. Looks like the nut had fused to the metal brake line. I snugged it all back up and figured "I'll get back to that." You'll see later.
5. final steps before dropping the frame. Since I was working alone I figured I'd remove a lot of the big components to make this lighter and easier handle. I disconnected the inner axle flanges then removed all control arms from the hub carriers and out came the axles and hubs. Bottom nut on shock absorbers were also removed. Calipers and rotors had already been removed. Pull the 4 bolts and down comes the subframe. Piece of cake. No gremlins here.
6. new frame goes in. Simple since I had made cradle to hold the fully assembled subframe. This this is easily over 300 lbs fully assembled and I'm working alone. Line up the cradle, drop the car onto the subframe, and pop in 4 bolts. Sweet, just like on TV Sunday morning shows or How It's Made.
7. control arms. Not so easy. I had not tightened anything on the subframe since the control arms need to be torqued with the hub at ride height (13 3/4" as per my friend's 7k mile full stock 1M). Here things got interesting. Seems that the combination of M3 rear sway bar and M3 rear spring make for a very stiff suspension. So stiff that jacking up the lower control arm at the hub ends up lifting the whole car without compressing the suspension. Curse, think, curse, re-think. Alright, remove the shock bolt, support the control arm, remove control arm bolt, remove spring, replace control arm bolt, don't connect shock, and now I can lift the lower arm. Great. Now to get at the bolt on the top two control arms and apply 74 ft-lbs torque. More fun. Eventually got all the arms done on both sides then had to re-install the springs and and shocks and settled for just torque them down wherever they were. I'll be taking the car in for an alignment so getting to the lower arm bolts at ride height on the alignment rack will be easy. This all took the better part of a day. Too much back and forth and tight spots and cursing.
7a. inboard axle flanges. I'm a do-it-once-do-it-right, spend-the-money-on-good-parts, while-you're-in-there kinda guy. The manual calls for new bolts on the axle flanges (and guibo and rear drive shaft CV joint) and I had not ordered any of those way back when. I went off to my local dealer to order all of the above. Drive shaft was about $60 for bolts. Axle bolts was $14 per bolt x 12. I bought the drive shaft bolts since they were going to get buried under layers of stuff and because these were all torque +degree bolts. The flange bolts I passed on because of expense, easy accessibility down the road, there was no +degrees after the 89 ft-lbs, and besides, I'd re-used flange bolts on several track cars with no problems. Besides that, my son said "There's 12 of them, how many are going to fail?" Good logic. I went with that.
8. brakes. Parking brakes is something I'd only done once before and using a generic tool for those damn return springs didn't make this job any fun. Simple but full PITA. Rotors and calipers I could do with my eyes closed. The calipers I had rebuilt a couple of years ago so I knew they were ready to drop in. No gremlins, just nasty return springs.
9. drive shaft. I used a brand new 1M shaft so no drama to be expected. This comes with brand new guibo, center bearing, and rear CV so there should be many miles of trouble free driving. No big deal to hang this up but I did get lost in what I thought was a problem. I put the shaft up and pushed the guibo bolts through after removing the cross brace. The bolts were hitting part of the tranny. Curse, think, curse, internet major research, try again. Seems that the shaft was tipped slightly and the bolts ran into interference. There's not much wiggle room in there. When everything was bolted up there was 2-3 mm clearance between the tip of the bolts and the tranny. Another time drain.
10. exhaust. I've had the PE exhaust in place for 4 years but never did the Y-pipe because I had a downpipe on the shelf and was waiting to see how that sounded before I cut off the resonator. The DP never went in and it probably won't now that I'm running JB4 w/BEF and a PS1 and because NJ is very strict about that sort of thing. There's an upward looking camera that the car gets driven over during DMV inspection and I rea lly don't want to hassle with DP bolts again. Yes, the gremlin at step 1 was back to haunt me: snapped DP studs. I did a lot of research and tried heat but I only have a propane torch. This might as well have been a Bic lighter. No good. I tried the air hammer. No good. Liquid Wrench soaking over several days did nothing. I had a ball joint tool that I thought I could use to push on the studs but it was too big. In the end, thank goodness I had a brand new drill bit set and I just went at it. I used 7 steps of bits with lots of lube. The key is to run the drill dead slow and let the tip of the drill bit bite its way through. As soon as you build rpm you get no bite and lots of friction and heat resulting in a dead drill bit. This was a solid 4 hours if not more for drilling. Fine, bolt up the exhaust, replace all the shields.
11. final testing. Car still on lift. Start the car. Yeah, gonna have to do the MHD cold start delete. Sounds fine after 30 seconds but loud before that. Good thing I didn't do the DP and Y-pipe. Put the car in gear, get the wheels spinning. No noises of any kind. Both wheels turning in same direction. Good. Test brakes. Hmm, pedal drops slowly. Stop car, get out, and look at brake fluid on the ground. Right, that brake line from a few days ago. Yeah, there had to be a final gremlin.
12. brake line. Curse, think, curse, research. I ordered a flare tool to make proper bubble flares, I also ordered a couple of unions, and I'll put them all to work. Access to the brake connection is way "in there." I've tried getting in to tighten the one nut but everything is just flexing and the nut isn't turning. The plan is to remove one control arm that is in the way, cut the hard brake line, and use the long steel pipe off the subframe I took off in order to repair the bad section. Fine, that's another couple of hours. Wait, better allow the better part of a day.
In all, I put 8 long days into this project. Not quite the slam dunk Spencer experienced. Why so much trouble? I think it comes down to an 8 year old car with 105k miles in the northeast with super salty winter roads. The DP studs and brake line are definitely attributable to that. The rear drive shaft nut? who knows? It wasn't rusty so maybe it was a gremlin.
If you think you want to do this it doesn't take a lot of skill but it does take a wide range of tools and you need a lift. I have a 36" lift and that was fine for clearance. However, a lot of it would have been much easier with a full lift. You are constantly looking for the right tool and being able to not have to roll and crawl out each time would be great.
Still to do: brake line, tranny and diff fluids, alignment, new summer tires. How about those front camber plates to be changed out? That'll have to wait. I'll live with the noise for now.