Thread: wstar's Journal
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Old 02-23-2014, 12:08 PM   #712 (permalink)
Fantastic Z
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Join Date: Sep 2013
Location: Nashville, TN
Age: 35
Posts: 197
Drives: 10' T/S 7AT
Rep Power: 12
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Originally Posted by wstar View Post
No garage, just random paddock parking. I've never even looked into garage spaces at any of the TDE events, I guess I should find out about that someday. I'm excited too, but nervous about so many changes on the car all at once.

I couldn't wait for this evening, so I took it out for a stress-test drive over lunch. No leaks, and temp data looks pretty awesome so far. "Normal" street driving - cruising around 2.5Krpm in the mid-day heat, the car would settle at oil/water temps of 180 and 177. I found an empty back-road stretch and gave the car a close-to-track-conditions flogging for about 7 minutes straight and I was still at 200/194. A soon as I backed off the agression, the car cooled back down to its steady-state in a minute or two.

Only problem I noted during the test-drive was an oddly-specific transmission issue. In general the transmission is fine, but if I brake in 3rd gear down to fairly low revs (~3K) and then transition right back to hard gas, the transmission lockup slips, the engine revs up freely for half second, and then the trans finally locks up (and by then the engine's way past matching revs and the tires burn a little). I'll try it again this evening and see if I can characterize it better, maybe. My random diagnostic thoughts right now are:

1) That my filling procedure didn't really work for setting the fluid level correctly, and braking down in 3rd at low revs just happens to slosh the too-low fluid in a way that it can't get pressure to lock up 3rd gear when I nail the gas pedal again. I could break this down into two possible filling errors: (a) that with all the air I needed to work out of the lines/system, my fill just wasn't going to be accurate until I really drove the transmission on the street a bit, in which case going back through the final step would fix it, or (b) technically, I don't think the service manual says to stop the engine when doing the final at-temperature fill/bleed. My best judgement was that turning the engine back off was implicit in the instruction to lift the car, etc, but maybe I really do need the engine running to set the fill correctly.

2) That I've damaged some seal/valve/solenoid whatever from track abuse at the last event and this is the first time I've noticed since getting home and then having the car on the lift forever.

3) Could be with the free-er revving engine (no more AC), I've crossed some threshold where I need to up the line pressure a bit more to catch it? I may play with line pressure in general for debugging this later.

I'd think if it was just a fill problem, I'd be able to reproduce the same slip condition in 2nd or 4th, which I was unable to do with a few attempts earlier, just 3rd. Could be specific to odd gears though (many internal passages/components are odd/even-specific), and it would be hard to reproduce the same type of condition in 1st or 5th.

I really wish I could get on the Nissan Batphone and find out for sure whether the final level check on the transmission was meant to be with the car running. Maybe GTM would know...
I've gotta say your build thread has been VERY cool to read and skim through this morning

I quote this particular post in your thread (in reference to the other relevant pages) as it really was one of the more educated findings about servicing the 7AT and it's fluid. Seems that most owners and newer members just ask how to change the fluid and aren't willing to dig for the right information. In finding 1) you mention a pressure loss in 3rd.

Well, since I've owned my Z this has happened to me ONLY twice. Both times I was flogging the car and as you mention the trans free revs and then catches at a MUCH higher than necessary RPM. That leads me to believe I am probably experiencing a low fluid level but, draining/filling at this time might not be a bad idea. Would you not draw the same conclusion?
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