M35X Transmission slams when manually upshifting. [SOLVED - burned fluid, replaced trans]

[rtucker1004]

My 07 M35x is a dream. I love everything except the upshifting under torque. When I manually shift from 2nd to 3rd moderately heavy on the throttle, the drivetrain SLAMS into gear. It's as if the motor mounts are busted.

Has anyone else experienced this issue?

RT

[AG-M35]

Does it only happen when it's cold or after it's warmed up also?

[p28driver]

My M35x does exactly the same thing (jerks between manual 2-3 shift under power), no matter warm/cold. To avoid, you have to back off the throttle just the right amount at just the right time during the shift. All the other transitions are perfectly smooth no matter what you do with the throttle. I'm planning on bringing it up at the next service, but I'd be very interested how common this is and if anyone has had it fixed.

Dallas

[AG-M35]

Mine's been doing that when it's cold and only if you get on itl. If you pull away slowly, it's fine. After it's warm, no problem. I never use the manual mode, so am not able to comment on that side of it..

[exbmwdude]

My 2006 M35 Sport does the same thing. I think the transmission is calibrated for "firmer" shifts in manual mode. It's a shame really - I think they had the shifts calibrated perfectly in auto mode. I just want to be in control of when it shifts and to do that means enduring the overly harsh manual programming.

Just another reason to dislike this transmission and hope Nissan gets a proper 6-speed unit in there....

exbmwdude2006 M35S

[jgoodman]

Mine does it too. I'm afraid I'm going to bust the transmission. Is this bad for it?

[AG-M35]

From my experience, transmissions that shift, without you knowing it are 'slipping the clutches' with a slowly applied servo. This luxury car feature can wear out the clutches faster. A firm shift, in my opinion is much better, in terms of component life and your ability to know what's happening. A slam shift can't be too good, as it can degrade the clutch facings and put unnecessary strain on the other drivetrain components. Since mine doesn't do it warm, my logic is that a seal may not be flexible enough to do the job, in colder temps. Definitely a warranty issue. Whether or not Infiniti will own up to it is another matter.So, that's three posts in a few days. I'll be there's a lot more out there...

[rtucker1004]

I'm embarrassed to be coming back this post after so many years and seeing your friendly replies. So, let me tell the story. In 2014 the transmission was completely shot at 62k miles. I've been religious to have my 15k increment services to the drive train. August 2014 I had the transmission serviced at 60k miles. Two weeks later the car was barely drive-able. I lost all torque in reverse, and 2nd to 3rd was slipping (slightly over-revving between gears). The dealer had the car for 3 weeks to tell me the transmission was "shot". Well, DUH! "Sir, your fluid is completely burnt." Really? I just had it serviced two weeks ago! How could my fluid get burnt that fast? The dealer was doing a drain and fill, not a flush. "Sir, a drain and fill replaces only 25% of the fluid, so the new fluid was contaminated by the 75% bad fluid still in the transmission." Oh, so 2 weeks ago, you took burnt fluid out of my transmission and said nothing! You buttoned it up and put me back on the road! One call to Infiniti US Consumer Affairs and a look at my service records and I had a replaced transmission for $zero, out of warranty. My mileage is up 2mpg (avg 19.5mpg), the shift points feel different, and I no longer get a banging shift point from 2nd to 3rd in the winter. Clearly, these transmissions have design issues.

[rtucker1004]

Does it only happen when it's cold or after it's warmed up also?

It would happen while manually upshifting 2>3 under torque (power), warm or cold.
It would happen while auto upshifting 2>3 not under torque, when cold (in winter).

[rtucker1004]

From my experience, transmissions that shift, without you knowing it are 'slipping the clutches' with a slowly applied servo. This luxury car feature can wear out the clutches faster. A firm shift, in my opinion is much better, in terms of component life and your ability to know what's happening. A slam shift can't be too good, as it can degrade the clutch facings and put unnecessary strain on the other drivetrain components. Since mine doesn't do it warm, my logic is that a seal may not be flexible enough to do the job, in colder temps. Definitely a warranty issue. Whether or not Infiniti will own up to it is another matter.So, that's three posts in a few days. I'll be there's a lot more out there...

JGoodman, see my belated update to this post. Infiniti replaced my trashed transmission out of warranty. They would not openly admit that there is a problem with the 5speed, but since they were replacing it for no cost, I did not press the issue.

[rtucker1004]

My M35x does exactly the same thing (jerks between manual 2-3 shift under power), no matter warm/cold. To avoid, you have to back off the throttle just the right amount at just the right time during the shift. All the other transitions are perfectly smooth no matter what you do with the throttle. I'm planning on bringing it up at the next service, but I'd be very interested how common this is and if anyone has had it fixed.

Dallas

p28- I agree. It takes finesse to back off the throttle at the right time to the 2>3 upshift. Other shift points don't require this soft handling. See my belated update of what happened.

[EdBwoy]

Well, thank you for updating us either way. I think we have had some posts on transmission issues here recently, but again at 10 years, they seem very few and far in between.
Glad it worked out for you in the end.

[gavnator]

Ditto on my M35X. It has 82,500 on it and the transmission has be flushed twice since original fluid. It slams when up shifting 2nd and 3rd. I don't typically shift manually although it suppose to be safe to do so. I'm wondering if this has more to do with being an M35X and specifically the ATTESA E-TS system more than anything else.