wstar's Journal

wstar

TWS Recap!

I did a Red-group check-ride Saturday and got myself into Red w/ Driver's Edge. It wasn't as scary as I thought it would be. I thought they'd be running me down all session and I'd have my arm hanging out the window the whole time, but I'm actually on pace with them pretty well (although certainly not in the faster half of the group). The simple corner passes I'm pretty used to now, but I can tell it will take a while to learn how the rules of "etiquette" work in a pass-everywhere group.

For example, in the "pass on straights only" groups, usually if I see a car closing on me fast in the corners but he's still not quite on my bumper, and I know he's not as fast in the straights, I'll lift for him on the straight so he doesn't get stuck behind me for a 1/3 of track in the next twisty section. It seems like the opposite social rules apply here: if they're not on your bumper coming into the straight (*and* faster than you on the straight), go ahead and stay in the throttle and pull away, because when/if they do catch you in the next twisties, you can always let them pass there as well. No point in losing laptime over trying to be pointlessly-polite.

Also, I broke my car this morning. As I laid into the throttle for a pass, the car went into some kind of limp mode and I had no real revs or power left. I coasted down through the next corner and then eventually pulled off the side of the track. Tried to restart the engine, but it was running rough and limiting at like 2K with a SES light on, so I gave up and let them tow me in :/

SES was for a faulty Crankshaft Position Sensor. Restarting it in paddock, the engine seemed to run ok at idle and very low RPM, so I doubt there's any internal damage (well, it was a little rough, but I think that's probably the limp mode's un-tuned timing and/or lack of good sensor input, etc). There was a funny rattle off and on though, and it sounded like it was coming from the bellhousing area. Jacked the car up and pulled the crankshaft sensor, and it has some physical scratches and wearmarks on the tip of it like the flywheel nicked it. With the sensor back in I was able to drive it back up into the trailer at least, with that bad rattle sound.

At this point my best guess is a cracked flywheel/flexplate, or maybe a flywheel<->torque converter bolt backed out, or both. Parts cost on the sensor and flywheel is pretty cheap, but it will be a bitch to drop the trans to install the flywheel. Next events are June 21-22 and 28-29, so I need to figure this out relatively quickly. Tomorrow I'll pull the access covers/plates and/or the starter motor so I can actually look at the edge of the flywheel or tap it with a hammer and see how it sounds or something. I may just call a Nissan place too and see what they'd do. The shorty lift in my garage doesn't have open access under the trans, so I know I can't (easily) drop it here.

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7AT Track Car!
Journal thread / Car setup details

Eagle

I hit the track on Sunday and the car was running fine as long as the RPM's were above ~1K. So during my session i was fine as long as I didn't come to a stop, so sure enough when i finally got off the track and stopped, the car died.

If I was below 1K and in drive or reverse, the car would bog down and stall. I thought I was gonna have to have the car towed home, but I managed to get the car rolling by revving to 4k and 5k in neutral and then dropping it into gear. The momentum got the car moving, RPM's stayed high enough to prevent the car from stalling. Shifting, especially downshifting manually seemed to aggravate the transmission and would cause the "stalling" symptom to return. I was able to reproduce the problem on demand, all i had to do was drive it like a manual

Anyway, dealer has my car...says they're gonna replace the transmission under warranty. They haven't said what the problem is and I doubt they are going to diagnose it to figure it out. I want to prevent this in the future but I don't know if this is my flex plate or something else. So I'm hoping your experience might help point me in the right direction so i can spend my money wisely on this.

This is actually my second transmission, the 1st one got replaced Sept 2013. The way this is going, I'm sure it will happen again.

I pinged Megan370z and he seems to be in the same boat with the 7AT, except i think he's gonna throw in the towel on fixing it and just swap it out for a 6MT.

I called GTM about the flex plate seems it's just checmically treated to better withstand the heat, I ahve no idea if it will fix my problem or if I need their torque converter or maybe something else.

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ZeN

Heh, i had the same problem before, it's the torque converter welded itself. Try applying throttle while braking like doing a launch, you'll hear something crack. That will fix it temporarily, you still need to change your TQ converter because it will come back. You must had a good run then come to a stop suddenly.