Navara V6 V9X STX550 Torque Converter Slip

[Supermike]

Hello all,

I've had this issue for a while and I kept meaning to get a video of it to try and help describe the issue. Well that's even if it is an issue. Fellow V6, V9X and STX550 owners (ok maybe not STX550 as I'll explain below) do you get the same thing and it's maybe not an issue???

So I have noticed, when the gearbox oil is cold, not measuring temperature, just that it's been sat overnight and the ambient temperature is low (this might be why STX550 owners might not be able to help as Aus temps). When I first set off I get this "slip" in all gears (more noticeable in higher gears) and in all modes (D, DS and Manual)

The Nav revs to around 3K if your putting it under higher load and stays at around 3k even when manually flicking up through the gears. If in manual I can rev it above 3 too but obviously don't like doing this when it's cold. When when I let off the accelerator the revs drop to idle, then when I go back on throttle the revs come up. The only way to get it to act how I think it should is by being very gentle with the throttle and putting little load on the engine and through the gearbox.

As soon as the Nav has been running for 10-15 mins and the gearbox oil has warmed up it's acts like I think it should. You can knock it into manual at 1.5k revs, mash the throttle and it just pulls but revs don't spike, they rise with the speed (like a manual box). So I have changed the gearbox oil and I used compatible Millers oil as I noted this had to be Nissan S Matic or equivalent, I think from memory???

So I did the procedure as per manual, drain, full, run, repeat until gearbox oil comes through clean. The old oil didn't look that bad either, no signs of "burnt" oil and didn't smell "burnt". The only thing I couldn't do was check actually gearbox oil temp when checking oil level, I used an infrared temp gun on the gearbox casing at around 35DegC. I thought I should factor in a few degrees for heat soak....

Probably worth pointing out this "issue" existed before and after gearbox oil change and I don't think it made a difference either way.

I hope it's ok sharing YT link as I couldn't get the video to upload here.

 

[landmannnn]

There's a noticeably different transmission map when the transmission is cold, I really only notice it on hills where it revs a bit higher.

Good that your oil looked in decent condition, that would suggest nothing wrong with the gearbox.

 

[Supermike]

There's a noticeably different transmission map when the transmission is cold, I really only notice it on hills where it revs a bit higher.

Good that your oil looked in decent condition, that would suggest nothing wrong with the gearbox.

I did wonder if it would behave differently when cold so not to damage anything or to prevent people from kicking the crap out of them when cold. Yes might is really noticeable going up hill when cold

 

[landmannnn]

I read this the other day, not that relevant to your situation, but interesting



RE7R01A Transmission / JR710E / RE7R01B Transmission Overview
First introduced for the 2009 model year in the Nissan 370Z, InfinitI FX and Infiniti G series, the RE7R01A transmission is a 7-speed automatic manufactured by Nissan’s transmission subsidiary Jatco. Also known as the Jatco JR710E transmission, this gearbox features 4 planetary gear sets, 3 multi-plate clutch packs, 4 multi-plate brakes, and 2 sets of one-way clutches.


Unlike many transmissions, the Nissan / Infiniti RE7R01A transmission uses partial torque converter lockup between gear changes to reduce harshness. To achieve this, the RE7R01A / JR710E modulates the applying pressure with the torque converter clutch control valve and torque converter clutch solenoid (they refer to this as Smooth Lockup Control). To further enhance the smooth operation, the line pressure behind each clutch is adjusted to match the engine force and vehicle speed

RE7R01A Transmission Features
RE7R01A Adaptive Shift Control – The TCM can automatically change the shift program from Standard, Power, Uphill and Downhill depending on the gas pedal position, engine RPM, braking and other parameters. In the Uphill shift program, the transmission will stay in 4th, 5th or 6th to prevent it from “hunting for a gear”. In the Downhill program, the TCM will automatically downshift to provide engine braking.

Nissan Rev Matching – Jatco calls this feature Synchronized Revolution Control, and it reads the various vehicle speed, braking and RPM parameters to determine whether a downshift is about to occur. It can then tell the ECU to briefly increase the engine RPM to provide a smooth heel-and-toe like downshift.