I don't think the failure is really 7AT-related, but I guess the answer to that question is a matter of opinion.

Keep in mind nobody's opened up the engine or even the bellhousing yet, this is all based on an experienced, trustworthy 370Z mechanic's opinion that a main bearing is spun based on the sound, and that the flywheel is damaged by looking through the bellhousing access holes. I 99% trust he's right on both counts.

Given the audio data from the datalogger late Saturday (where the engine was operating fine in terms of revs and performance, but there was a buzzing/grinding noise), I think the flywheel failed first, and then the imbalance/drag from that affected the crank and caused the eventual spun crank bearing within a couple sessions after the flywheel got bad. The flywheel *is* different on the 6MT and the 7AT, obviously (the 7AT has a "drive plate" that the torque convertor bolts to, it's a different part number than the 6MT flywheel). I've seen reports of cracked driveplates on 7AT's elsewhere (e.g. Megan's here: http://www.the370z.com/engine-drivet...wner-look.html ). The 7AT itself is supposedly still in good shape right now, but perhaps there's a weakness in the 7AT-specific driveplates under heavy loads at the track.

BTW, Option 1b with a salvage block is in the ballpark of $7K installed (~$5K of that in parts). Better than ~$11-12K for the new block, but still a lot of cash, especially for an engine of unknown durability going forward. Next thing I want to look into is what an engine rebuild shop would charge to rebuild mine and make it stronger, and how long the process would take assuming no unexpected parts damage.

I think I might be able to find a cheaper salvage engine than they did. The plan that's starting to form here is throw a cheaper salvage engine in for right now, maybe get the cost down to ~$4-5K installed, and I could still make my June events (one of which is expensive and non-refundable). Then keep my old engine and work on tearing it down and rebuilding it slowly as a stronger replacement for down the road when the salvage one dies.

How about $700?
2007 Infiniti G37 Engine

2009 infinity g37 parts

Saw your car at Baker today hiding in the corner.
I think you can find the engine plus parts for a lot less used, I think the salvaged engine plus re-building the current in spare time is the best option.

Something fishy about that. The VQ37HR first came in the 2008 G37 Coupe. 2007 should have been a VQ35HR.

I found an engine! It's from a wrecked 2013 370Z w/ 7AT (so I get the flywheel too) from a local salvage lot. Only 5K miles on the donor car and it's (probably) not damaged from the wreck. Assuming everything goes smoothly (which should be obvious right off the bat and covered by the salvage lot's parts warranty), it's damn near a brand-new engine. Just a hair under $3K after tax and delivered.

The block should get dropped off at Baker sometime Monday, and Jason will be dropping it in and moving over the various bolt-ons next week. Then it will need a quick dyno-tune to make sure my UpRev settings are ok on the new block (not sure where yet), and I'll need to put it on my mini-lift and go over everything carefully to make sure I'm comfy trusting the car, and then hopefully back on track for June 21-22 @ MSR-Houston and June 28-29 @ COTA.

What were you down there for? :) Did you get to see the cage in the car? I don't think you've seen it since then.

Damn that's a good deal! Lucky man! :)

Glad to hear you'll be back up and running soon and for what is relatively very little in terms of cost! Your thread and Megan370s has served as some good inspiration for me to track my 7AT. I just got my car back and the next steps for me are going to be to figure out what I need to do to ruggedize this transmission so i can enjoy quarterly track days without sending it back to the dealer every 12 months.

I'm possibly looking at GTM's torque converter, an upgraded transmission oil cooler, maybe the GTM flex plate and whatever fluids will be best to help this thing soldier on.

The first thing I'd do is make sure you have good cooling on the trans fluid. I'm now running a Setrab 19-row Series-6 width cooler for my trans fluid, and I believe it's enough to keep from cooking the fluid under pretty extreme conditions. Most of the kits from the vendors have smaller cores than that. Somewhere deeper in my journal there's some posts about that (e.g. don't buy Stillen's kit, just buy a completely different set of adapters and hoses anyways, because their lines are too large to clamp onto our trans fluid fittings securely - not sure about GTM's).

Keeping the rest of the car cool (e.g. radiator upgrades, uprev fan settings, large engine oil cooler, maybe vent the hood near the front of the engine block, etc) is critical as well, since all temps on the car are somewhat interrelated.

I haven't ever done any trans-parts upgrades aside from cooling. I passed on the GTM valve body job for now because I couldn't get any reliable information on how it behaved from a road-racing perspective (i.e. whether it makes the upshifts too "shocky" for breaking traction on upshifts during trackout (or downshifts while trailing in) - I imagine some street guys and drag racers might actually like that behavior, but I sure wouldn't). I've never even considered touching the torque convertor or anything like that, although after this incident the HD Flex Plate is a little tempting.

Upping 7AT line pressures just a little bit via UpRev is worth it, but don't go too far. ~10% bumps across the board worked well for me with boltons. I also ended up switching my fluid to Motul Multi-ATF, which is one of the very few aftermarket fluids that's rated for our trans from a reputable company. I think it's at least as good as the stock fluid at handling the stress, anecdotally, and I've had it in for a couple of change intervals now. But if you care about dealership warranty issues, who knows if they might balk about using anything but official Nissan Matic-S. GTM has a couple of different PDFs on 7AT fluid swaps and recommended change intervals based on trans fluid temp. Putting in a trans fluid temp gauge (in the side of the pan) is worth it, especially one with a peak hold to find out your high-temp marks for the day. Check out this one: http://www.gtmotorsports.com/Manuals..._Procedure.pdf

At 4 track days a year, you'll be long done with that car before you've put as much wear on it as I have on mine, so you're probably going to be ok if you're reasonably cautious. I was reviewing my records on this stuff a couple months ago, and me and this car have been through about 38 track days in just a little under 3 years (or ~19x full track weekends if you prefer to count it that way). So that's a rough average of a little better than one weekend every two months for the whole 3-year period, plus another ~40K of street miles from back when this car was dual-purpose. Track miles are hard on any car. Having a major failure by this point is not completely unwarranted :)

Getting a quick oil change and spacers put on the wife's Z.

Jason sent me a pic of my flywheel. Yup, definitely something wrong with the flywheel :p

https://googledrive.com/host/0B9O2uT...MlE/image.jpeg

that's a bit worst than my first one ....




Just as a reference,
This is my second flex plate after not even 5000 kms and 1 track day and half.

http://www.the370z.com/members/megan...15-000-kms.jpg

Got the car back today. It would've been done much sooner, but we had various minor scheduling and parts issues (not the least of which was figuring out very late in the process that the flywheel on the donor motor was distorted and had to be tossed). I've only done a quick testdrive 1 block down the road from the dealership before I loaded it all back up on the trailer, but everything seems perfect. The guys at Baker Nissan did an exceptional job, pretty happy with them (again). Jason is an awesome mechanic :)

I need to fire it up a few more times here and basically triple-check everything for the usual gotchas like minor leaks, but I don't expect any real problems. That and re-check my alignment, which I was due for anyways. First real abuse test will be at MSR-Houston down in Angleton next weekend (June 21-22). I decided to skip wasting $500+ on a re-tune for now after talking it over with Jason as well. All the bolt-ons are unchanged anyways, and whatever minor variance there might be between blocks, the ECU should be able to adapt to that fine.