Transmission slipping on steep uphil

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labsy
Posts: 289
Joined: Sun Nov 02, 2014 9:26 am

Transmission slipping on steep uphil

Postby labsy » Fri Sep 11, 2015 12:35 am

Hey,

I wonder if you could help me pinpoint the issue, probably with automatic transmission, maybe gears, transfer or even final drive.

I like to go off-road occasionally and few days ago in a forest I followed really steep log skidding trails uphill, quite long (maybe quarter mile long). It was not slippery, so traction was good.
I went in 4LO, ESP off and I made it to the top.

What was weird was how it went. It's hard to explain, but a dozen of feet it went normally (say, 3-4 wheel revolutions), then I heard like rear end would slip for 1 wheel revolution and vehicle movement nearly stopped. After few seconds, when I was afraid vehicle would totally stop, it kept moving for next few feet, for next few wheel revolutions...then everything repeated.
And so it went up to the top, repeating the above described behaviour regularly like in prescribed intervals all the way up.

I checked tires, pressure, with OBD2 for DTC codes...nothing wrong. Also wheels were not slipping.

As my understanding, what could slip is only torque converter, as this is the only component in drive chain which is not geared. Everything else is gear transmission and AFAIK cannot slip.

I have R51, 190.000km, ATF changed once few years ago and last year I changed 4 quarts of ATF (as that's what I had in my garage).
Any idea?


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labsy
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Joined: Sun Nov 02, 2014 9:26 am

Postby labsy » Fri Sep 11, 2015 4:52 am

UPDATE: Today I mounted little flags out of duct tape on all wheels, so I can see from driving position whether they are turning or not. Then I went up that hill again.
Under steady RPM again the same symptoms, going smooth for 15-20 seconds, then decreasing power for few seconds, until it grabs power again and pattern repeats all the time up the hill.

Then I tried all the same in 4LO, but this time shift lever not in D, but pushed it into Manual 1st gear. Went up hill without any hiccups.

Hmmm...seems like he was trying to shift from 1st to 2nd gear while climbing that hill, and as he did not succeed due to high torque requirements, he landed back in 1st gear for next few feet.
Interesting to know how it behaves :)

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Thupertrooper
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Postby Thupertrooper » Fri Sep 11, 2015 5:18 am

Nice detective skills lol thanks for sharing. I usually go in to 1st gear when I'm in 4lo since its a lower gear and normal Drive when in 4Hi

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labsy
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Postby labsy » Fri Sep 11, 2015 7:40 am

Thupertrooper wrote:Nice detective skills lol
Yes, Sherlock Nissan :roll:
...but I'll change oils regardless. Final drives and transfer just bought, so to let my Pathy go paths for some time :D


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