Made a video from datalogger recordings on the flywheel thing. Youtube desc copied for embed: Audio comparison of "normal" and "something's wrong" engine sounds from Saturday. That "something's wrong" sound
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05-19-2014, 06:42 PM | #781 (permalink) | |
A True Z Fanatic
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Made a video from datalogger recordings on the flywheel thing. Youtube desc copied for embed:
Quote:
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05-22-2014, 09:10 PM | #783 (permalink) | |
Track Member
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Location: South Orange County, CA
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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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05-22-2014, 10:51 PM | #784 (permalink) |
A True Z Fanatic
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Honestly, I have no idea what's wrong with your transmission, sorry! This is the only AT I've ever owned, and I know next to nothing about the internal mechanisms of one (at least, not enough to diagnose based on symptoms like that).
My trans has been fine so far, and it's been through a lot of abuse. I basically never used the normal "D" mode even when it was a street car, and at the track it's M-mode and high revs all day long. I don't *think* my trans is currently broken, just the flexplate. Worst case, could be related issues at the pilot bushing and/or torque convertor (e.g. loose bolt), but who knows at this point. I'll know more once the guys at Baker starting looking at the car. The only non-standard things I've done with my 7AT really is up the line pressures slightly via UpRev, and switched fluid to Motul Multi-ATF. I've done a mostly-complete fluid swap on this trans twice now with the Motul. Hot track days can really destroy fluid pretty quickly, and bad fluid could lead to all kinds of problems. There's a PDF chart from GTM somewhere about trans fluid temp vs miles-to-change... I'll probably put a stock flexplate back in mine for now, assuming that's the main thing that's broken. As long as the first one lasted, I'm sure something bigger will break before another one does. |
05-23-2014, 01:11 PM | #786 (permalink) |
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Sorry don't mean to thread jack your journal. I called the dealer and they confirmed it was the torque convertor, they said it was actually coming apart
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05-25-2014, 03:43 AM | #788 (permalink) | |
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05-26-2014, 04:06 PM | #789 (permalink) | |
A True Z Fanatic
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05-26-2014, 04:08 PM | #790 (permalink) |
A True Z Fanatic
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Also, while the diagnostic investigation over at Baker North probably isn't complete yet, it's looking like more than just a flywheel+sensor on my car. There's a good chance there's damaged crank bearings or something along those lines. I'm not sure how sure they are yet as to cause and effect. Looks like the 7AT may have outlived the engine! I'm sure I'll know more in a couple of days.
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05-27-2014, 02:01 PM | #791 (permalink) | |
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Quote:
After dropping him off I left the engine idling and didn't shutdown the car, probably for 5 to 10 minutes at least. I also left the hood up so it could ventilate a bit more Sent from my SPH-L720 using Tapatalk
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05-27-2014, 06:50 PM | #792 (permalink) |
A True Z Fanatic
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So, it looks like I did spin a crank bearing (in addition to (probably as an after-effect of) having flywheel damage). Nissan won't warranty the engine, of course, but I can hardly blame them on a car like mine. Even asking was mostly a shot in the dark.
So, I've got some heavy thinking to do on options here. The factors in play are money (of course!) and time (two events I really wanted to make in the latter half of June, not blowing the rest of the schedule for the year, and in general not spending months off the track with fading skills). The first routes that come to mind and/or are useful for comparison:
Last edited by wstar; 05-27-2014 at 06:57 PM. |
05-27-2014, 07:21 PM | #793 (permalink) |
A True Z Fanatic
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Man that's a tough spot. If it were me I would probably go with option 3. It's far cheaper to buy a built car than to build one yourself and having a car you can write off without such a big loss is nice (I wrecked my 350Z race car this weekend and still managed to smile for a photo of it in the trees since I don't have nearly as much in it as my 370.).
Option 4 might be the wisest but at least in my case I don't think I could give up racing. That Peter Egan quote - "Racing makes heroin addiction look like a vague wish for something salty" says it all. |
05-27-2014, 07:28 PM | #794 (permalink) |
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I would do 2A. You already have a track car that you know well, and have top shelf parts in it. You'll end up with having a bullet proof VQ motor.
Buying another track car. Who knows what you might get in to with it. It could be more $$$ then you think in the long run. Doing the GM motor swap. Sounds good when you talk about. But it will take time and $$$ to finish it. And you could lose your feeling for the sport while doing the swap. You will never get you money back out of it when selling your parts. And time you've put in to it also. Unless you want out of the sport all together. You and everone else that tracks a car should know that broken parts is part of the game. You always hope that it will never happen to you. But when it does. Be prepared to bit the bullet.
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05-28-2014, 03:14 PM | #795 (permalink) |
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Forgive my ignorance, but was the failure due to the AT transmission? Do the same issues exist with the 6MT? I just haven't heard of many Z's with engine failures.
I'm sure you could quickly source an engine and transmission. Nissan Unlimited usually has stock. (Near 290 and Beltway 8) So my vote is 1b. If it was my car I'd do that. You are a better man that me if you can walk away from this sport without some kinda rehab program. On the flip side, owning a miata is cheap you can probably sell off your Z stuff and use a fraction of it on a built miata. |
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