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mattfwalters · 08-29-2017, 02:20 AM

I've owned a 2006 Z4MC in Sepang Bronze Metallic over Sepang brown extended leather interior for a little over 4 years now. I bought the car in Vancouver, BC with around 50k km on the odo - today it has a little over 82k km (51,000 mi) and is in many more pieces than most people would consider "normal" or "healthy". Apologies for starting this thread mid-build; I've been documenting it elsewhere, but on a private forum, since initially this was going to be a pretty mild build. Now that this has turned into something of a monster, I figured it was time to make a thread in a public forum so that I can take advantage of more peoples' knowledge of the cars, and get more input on the build, process, thinking, time, sweat, blood, and tears that are going into my coupe.

Here's how it looked before any of the modification began:

After my first track session with the car, it became immediately clear to me that it was a fantastic chassis, but that there was lots of room for improvement. I loved (and still love!) the S54's power delivery, but found the car to understeer badly when pushed, to be fairly poor at managing weight transfer despite the obviously high stock spring rates and meaty sway bars, and to have brakes that just weren't up to track duty in opposition to the wonderful insanity of the S54. These judgements are relative, of course - the Z4MC is so damn good on the track, but it tells you the whole time how it can be better. "I just need a little more rubber, and a little more suspension, and a little more power, and a little more brake, and I'll be perfect for you" is what it whispered in my ear the whole time.

The first round of modifications were: Ground Control coilovers with 550lb front and 700lb rear springs, GC front camber plates, rear sway delete (well, disconnect), stud conversion, 18x9.5" ET35 Apex EC-7s on all four corners (12mm spacers in the rear) with some 200AA A Kumhos, ECS floating front rotors and fresh BMW rotors in the rear, and Hawk HP+ pads. Back at the track, the results were... somewhat positive (fast lap starts around 4 minutes ):

That 2:02 lap was around 12 seconds faster than my previous best at the Ridge. As you may be able to tell from the video, I was pretty happy with it.

And then I put my foot on the slippery slope and started ordering more stuff. The parts shelves when I started the "mild" build contained:

AP Racing CF front splitter / rear wing
Evolve CF CSL-style airbox / Alpha-N tune
Schrick 288/280 degree cams and DLC cam followers
Brembo 4-pot calipers from Porsche 996 turbo (also newer Boxter / Cayman S) front / rear with RallyRoad adapters, RallyRoad lines, and Hawk HP-10 pads
eBay exhaust headers
Beisan VANOS seals, rattle fix, and oil pump

So, naturally, the first thing I did was to install the rear wing, because... reasons. It's sexy as hell, ok? See:

A wise fellow on the other forum said "This build is bonkers. I see it as 'put on a ridiculous wing and build the car to, by God, live up to that ridiculous wing.'", which basically says it all.

So then I did the brakes:

And holy hell, this is how these cars should have come from the factory. Solid pedal, assertive brake action, I simply couldn't make them fade no matter how hard I tried. So naturally I ordered some Castrol SRF to flush them when it's actually track time.

So, come end of May, I booked a couple of days off of work so I'd have a five-day window to get all of the bits installed, install the Evolve Alpha-N base map, and get the car to a nearby dyno and baseline it.

Late in the game, I decided to order the Bimmerworld rod bearing / ARP bolt kit, just to be safe. So you can imagine how this went.

I made a list:

Set up the engine support:

Target of opportunity: pulled the exhaust headers while I was mulling over how to deal with the subframe and balljoints. Getting at a few of the bottom nuts on these is bloody awful and made me want to throw a wrench across the room more than once.

Finally just said "hell with it" and pulled the subframe with the control arms and steering rack attached. It's not as heavy as I feared, but was heavier than I'd hoped. Unfortunately I screwed up a couple of the balljoint boots trying to separate the control arms and tierods, and was pretty pissed about it. Ordered some generic silicone boots to replace them, still haven't done it.

Finally the oilpan is exposed!

Looked up at the guts. The oil pump needs to come out before the rods are accessible.

Set up for bearing / bolt replacement:

Art shot of one of the conrods, highlighting the split-cap construction (for the unaware: they're forged as single units, and then split with liquid Nitrogen to create the cap / rod separation. It means that each rod is unique, caps aren't interchangeable, and are also directional). The colour of the crank doesn't come through in this photo, it's a really lovely deep blue.

Finally, the bearing shells that came out. Lots of copper showing there, I was very glad I decided to do the rod bearings. Spoiler alert: this was about 1/2 of what caused the build to go from mild to "I hate my wallet".

Next day, I got serious about the top end, and things went sideways early on. I'd done the shims twice before, so wasn't surprised by most of the prep. But then I added a new entry on my "stuff to not forget" list:

Of course, the nut being in the sump was literally the best-case scenario. It could have been anywhere along the cam chain channel, in the main timing gears... ugh.

Then, of course, I realized that the rocker shafts simply cannot come out of the head while (1) the head is in the car, or (2) the rad support is installed. I decided to pull the head, because I didn't want to pull the engine. Spoiler alert: that's the second half of the build derail. I used the DIY "back off each cam bearing cap nut 1/4 turn, in series, at a time" method for cam removal, and it went smoothly. Being way behind schedule, I totally bailed on building my own exhaust system behind the headers and ordered SuperSprint catless section 1, non-resonated X-pipe, and race cans.

Happy fun top end time:

Pulling all of the VANOS bits:

A small pile of take-offs, including a bag of 27 cam journal cap nuts

Mostly-stripped head:

Stuff that came off:

The note I left myself at the end of the day:

So then I carried on to pulling the head off. It was pretty straightforward at that point.

The 28th nut:

This is where things got fun. Since the head was off, it didn't make any sense to me to put it back on without a refresh. A bit of research later, I ordered SuperTech valves / springs / retainers, and Achilles guides / seals, from the fine folks at Achilles. When I dropped them off at the machine shop (which, I found out, builds a tonne of Spec E46 and race S54 engines), they asked me about the rod bearings. I cheerfully explained that I'd done the Bimmerworld treated bearings and ARP rod bolts, so all was well. They responded by asking me a bunch of questions about things like roundness, clearances, bolt stretch, rod length, piston height... and I realized that I'd made a huge mistake.

Welp.

Since the block was coming out for a torque-plated 0.5mm overbore / rotating assembly balance / etc., I ordered Molnar rods, ARP main studs, VAC main bearings, JE +0.5mm pistons, VAC coated rod bearings, Clutch Masters aluminum flywheel, Clutch Masters FX300 clutch kit and mentally set the new engine's redline to 9,000RPM.

The next time I think to myself "self, this would be easier if you just pulled the bloody engine out of this thing", I'm going to listen. Pulling the engine is honestly cleaner than dropping the front subframe to get at the bottom end, and it isn't that bad of a job with the Z4M's huge engine bay - even leaving the transmission in place.

Next time I think the engine is going out the bottom, since I had to drop the front subframe to get it out without smashing the hell out of the oilpan (sigh).

At this point, things came fully unhinged. I ordered a Radium fuel rail (note! Despite claiming E85/E86 compatibility for their S54 kit, modification to either the kit or the Z4M's fuel system is required to use it), CSF aluminum radiator, Achilles power steering cooler, Setrab 650 (double stack 50-row) oil cooler, a bunch of -10AN fittings and hose, Earl's oil thermostat, Technica internal oil thermostat defeat, AEM X-Series oil / fuel pressure + oil / water temp + wideband AFR gauges, Moroso 1.5qt accumulator, EGR / heater core block-offs, and probably a bunch of other stuff I'm not thinking of right now. Sent the injectors off to RC to be cleaned and balanced. Only god and Visa know what else I spent on stuff for the car during that period of time.

Prepped the shortblock to go to the machine shop:

There was coolant everywhere in the bottom end. Next time I pull it, it's coming out in one piece so I can be sure the water's out before cracking the head and dumping it into the oil passages / sump. Ugh.

Off to the shop:

Some snaps of the shelves / floor around the shop at that time:

Pulled the rest of the front end apart to make life easier for myself:

Found more damage under the car than I'd expected / hoped:

At this point, I learned that removing the engine and most of the nose of the car makes the distribution... not 50/50. I can lift the front of the car off of the front lift arms with one finger. Not great. Pretty spooky.

So then I got a shortblock and a ported / deshrouded head back from the machine shop:

Assembled head:

SuperTech springs / retainers / valves:

Combustion chambers:

New intake ports (phwoooooaaaaarrrrrr):

Ported exhaust:

Cleaning up parts to re-install:

Re-installed the oil pump, pickup tubes, chain, and tensioner (yes, 25N-m and Loctite red):

Did the VANOS re-seal / rattle repair:

..and this is nearly up to date. Next post: getting the Schrick cams installed on the bench to set the 0.25mm clearance specified by Schrick (spoiler alert: this is harder with stiffer valves and higher-duration cams), and to make sure that all of the shims are taller than the tops of the spring caps...

08-29-2017, 02:20 AM	#1
mattfwalters Second Lieutenant 226 Rep 223 Posts Drives: 06 Z4MC (Sepang/Sepang/insane) Join Date: May 2014 Location: Vancouver, BC iTrader: (0)	Watch me ruin a Z4M Coupe: build thread I've owned a 2006 Z4MC in Sepang Bronze Metallic over Sepang brown extended leather interior for a little over 4 years now. I bought the car in Vancouver, BC with around 50k km on the odo - today it has a little over 82k km (51,000 mi) and is in many more pieces than most people would consider "normal" or "healthy". Apologies for starting this thread mid-build; I've been documenting it elsewhere, but on a private forum, since initially this was going to be a pretty mild build. Now that this has turned into something of a monster, I figured it was time to make a thread in a public forum so that I can take advantage of more peoples' knowledge of the cars, and get more input on the build, process, thinking, time, sweat, blood, and tears that are going into my coupe. Here's how it looked before any of the modification began: View post on imgur.com After my first track session with the car, it became immediately clear to me that it was a fantastic chassis, but that there was lots of room for improvement. I loved (and still love!) the S54's power delivery, but found the car to understeer badly when pushed, to be fairly poor at managing weight transfer despite the obviously high stock spring rates and meaty sway bars, and to have brakes that just weren't up to track duty in opposition to the wonderful insanity of the S54. These judgements are relative, of course - the Z4MC is so damn good on the track, but it tells you the whole time how it can be better. "I just need a little more rubber, and a little more suspension, and a little more power, and a little more brake, and I'll be perfect for you" is what it whispered in my ear the whole time. The first round of modifications were: Ground Control coilovers with 550lb front and 700lb rear springs, GC front camber plates, rear sway delete (well, disconnect), stud conversion, 18x9.5" ET35 Apex EC-7s on all four corners (12mm spacers in the rear) with some 200AA A Kumhos, ECS floating front rotors and fresh BMW rotors in the rear, and Hawk HP+ pads. Back at the track, the results were... somewhat positive (fast lap starts around 4 minutes ): That 2:02 lap was around 12 seconds faster than my previous best at the Ridge. As you may be able to tell from the video, I was pretty happy with it. And then I put my foot on the slippery slope and started ordering more stuff. The parts shelves when I started the "mild" build contained: AP Racing CF front splitter / rear wing Evolve CF CSL-style airbox / Alpha-N tune Schrick 288/280 degree cams and DLC cam followers Brembo 4-pot calipers from Porsche 996 turbo (also newer Boxter / Cayman S) front / rear with RallyRoad adapters, RallyRoad lines, and Hawk HP-10 pads eBay exhaust headers Beisan VANOS seals, rattle fix, and oil pump So, naturally, the first thing I did was to install the rear wing, because... reasons. It's sexy as hell, ok? See: View post on imgur.com View post on imgur.com View post on imgur.com A wise fellow on the other forum said "This build is bonkers. I see it as 'put on a ridiculous wing and build the car to, by God, live up to that ridiculous wing.'", which basically says it all. So then I did the brakes: View post on imgur.com View post on imgur.com View post on imgur.com And holy hell, this is how these cars should have come from the factory. Solid pedal, assertive brake action, I simply couldn't make them fade no matter how hard I tried. So naturally I ordered some Castrol SRF to flush them when it's actually track time. So, come end of May, I booked a couple of days off of work so I'd have a five-day window to get all of the bits installed, install the Evolve Alpha-N base map, and get the car to a nearby dyno and baseline it. Late in the game, I decided to order the Bimmerworld rod bearing / ARP bolt kit, just to be safe. So you can imagine how this went. I made a list: View post on imgur.com Set up the engine support: View post on imgur.com Target of opportunity: pulled the exhaust headers while I was mulling over how to deal with the subframe and balljoints. Getting at a few of the bottom nuts on these is bloody awful and made me want to throw a wrench across the room more than once. View post on imgur.com Finally just said "hell with it" and pulled the subframe with the control arms and steering rack attached. It's not as heavy as I feared, but was heavier than I'd hoped. Unfortunately I screwed up a couple of the balljoint boots trying to separate the control arms and tierods, and was pretty pissed about it. Ordered some generic silicone boots to replace them, still haven't done it. View post on imgur.com Finally the oilpan is exposed! View post on imgur.com Looked up at the guts. The oil pump needs to come out before the rods are accessible. View post on imgur.com Set up for bearing / bolt replacement: View post on imgur.com Art shot of one of the conrods, highlighting the split-cap construction (for the unaware: they're forged as single units, and then split with liquid Nitrogen to create the cap / rod separation. It means that each rod is unique, caps aren't interchangeable, and are also directional). The colour of the crank doesn't come through in this photo, it's a really lovely deep blue. View post on imgur.com Finally, the bearing shells that came out. Lots of copper showing there, I was very glad I decided to do the rod bearings. Spoiler alert: this was about 1/2 of what caused the build to go from mild to "I hate my wallet". View post on imgur.com Next day, I got serious about the top end, and things went sideways early on. I'd done the shims twice before, so wasn't surprised by most of the prep. But then I added a new entry on my "stuff to not forget" list: View post on imgur.com Of course, the nut being in the sump was literally the best-case scenario. It could have been anywhere along the cam chain channel, in the main timing gears... ugh. Then, of course, I realized that the rocker shafts simply cannot come out of the head while (1) the head is in the car, or (2) the rad support is installed. I decided to pull the head, because I didn't want to pull the engine. Spoiler alert: that's the second half of the build derail. I used the DIY "back off each cam bearing cap nut 1/4 turn, in series, at a time" method for cam removal, and it went smoothly. Being way behind schedule, I totally bailed on building my own exhaust system behind the headers and ordered SuperSprint catless section 1, non-resonated X-pipe, and race cans. Happy fun top end time: View post on imgur.com Pulling all of the VANOS bits: View post on imgur.com View post on imgur.com A small pile of take-offs, including a bag of 27 cam journal cap nuts View post on imgur.com Mostly-stripped head: Stuff that came off: The note I left myself at the end of the day: So then I carried on to pulling the head off. It was pretty straightforward at that point. The 28th nut: This is where things got fun. Since the head was off, it didn't make any sense to me to put it back on without a refresh. A bit of research later, I ordered SuperTech valves / springs / retainers, and Achilles guides / seals, from the fine folks at Achilles. When I dropped them off at the machine shop (which, I found out, builds a tonne of Spec E46 and race S54 engines), they asked me about the rod bearings. I cheerfully explained that I'd done the Bimmerworld treated bearings and ARP rod bolts, so all was well. They responded by asking me a bunch of questions about things like roundness, clearances, bolt stretch, rod length, piston height... and I realized that I'd made a huge mistake. Welp. Since the block was coming out for a torque-plated 0.5mm overbore / rotating assembly balance / etc., I ordered Molnar rods, ARP main studs, VAC main bearings, JE +0.5mm pistons, VAC coated rod bearings, Clutch Masters aluminum flywheel, Clutch Masters FX300 clutch kit and mentally set the new engine's redline to 9,000RPM. View post on imgur.com View post on imgur.com The next time I think to myself "self, this would be easier if you just pulled the bloody engine out of this thing", I'm going to listen. Pulling the engine is honestly cleaner than dropping the front subframe to get at the bottom end, and it isn't that bad of a job with the Z4M's huge engine bay - even leaving the transmission in place. View post on imgur.com View post on imgur.com View post on imgur.com Next time I think the engine is going out the bottom, since I had to drop the front subframe to get it out without smashing the hell out of the oilpan (sigh). At this point, things came fully unhinged. I ordered a Radium fuel rail (note! Despite claiming E85/E86 compatibility for their S54 kit, modification to either the kit or the Z4M's fuel system is required to use it), CSF aluminum radiator, Achilles power steering cooler, Setrab 650 (double stack 50-row) oil cooler, a bunch of -10AN fittings and hose, Earl's oil thermostat, Technica internal oil thermostat defeat, AEM X-Series oil / fuel pressure + oil / water temp + wideband AFR gauges, Moroso 1.5qt accumulator, EGR / heater core block-offs, and probably a bunch of other stuff I'm not thinking of right now. Sent the injectors off to RC to be cleaned and balanced. Only god and Visa know what else I spent on stuff for the car during that period of time. Prepped the shortblock to go to the machine shop: View post on imgur.com View post on imgur.com View post on imgur.com There was coolant everywhere in the bottom end. Next time I pull it, it's coming out in one piece so I can be sure the water's out before cracking the head and dumping it into the oil passages / sump. Ugh. Off to the shop: View post on imgur.com View post on imgur.com View post on imgur.com Some snaps of the shelves / floor around the shop at that time: View post on imgur.com View post on imgur.com View post on imgur.com View post on imgur.com View post on imgur.com View post on imgur.com View post on imgur.com Pulled the rest of the front end apart to make life easier for myself: View post on imgur.com View post on imgur.com View post on imgur.com Found more damage under the car than I'd expected / hoped: View post on imgur.com View post on imgur.com At this point, I learned that removing the engine and most of the nose of the car makes the distribution... not 50/50. I can lift the front of the car off of the front lift arms with one finger. Not great. Pretty spooky. So then I got a shortblock and a ported / deshrouded head back from the machine shop: View post on imgur.com View post on imgur.com View post on imgur.com View post on imgur.com View post on imgur.com View post on imgur.com Assembled head: View post on imgur.com View post on imgur.com SuperTech springs / retainers / valves: View post on imgur.com Combustion chambers: View post on imgur.com View post on imgur.com New intake ports (phwoooooaaaaarrrrrr): View post on imgur.com Ported exhaust: View post on imgur.com View post on imgur.com Cleaning up parts to re-install: View post on imgur.com View post on imgur.com Re-installed the oil pump, pickup tubes, chain, and tensioner (yes, 25N-m and Loctite red): View post on imgur.com Did the VANOS re-seal / rattle repair: ..and this is nearly up to date. Next post: getting the Schrick cams installed on the bench to set the 0.25mm clearance specified by Schrick (spoiler alert: this is harder with stiffer valves and higher-duration cams), and to make sure that all of the shims are taller than the tops of the spring caps...
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