What causes the RE4R03A transmission to shift "SLOWLY"

[Infinitiguy19]

lyI would like to know what makes it shift so slow like everyone says?

Is it the TCU that tells the ECU to retard timming during the shift

Or is it just the internal parts and design of the transmission that make it slow shifting?

[qship96]

Define "slow"? At 231,707 on my original transmission I would not describe the shifting as "slow".....not neck jerking fast and harsh like a modified 1960's musclecar,but comparable to any of my friends new luxury cars.

[mtzgr777]

I'd like to find out the same thing....

By the way qship96, have you had to replace the knock sensors on your Q?Mines at 140,940 and I think its about time for me to have it done, but I'm going to hold off for a bit 'till I get some $$$.

[MinisterofDOOM]

Define "slow"? At 231,707 on my original transmission I would not describe the shifting as "slow".....not neck jerking fast and harsh like a modified 1960's musclecar,but comparable to any of my friends new luxury cars.

Mine has less than 40k miles on it and it has always shifted the same: slow and mushy. It is definitely not comparable to any modern automatic I've driven. Heck, it's not even comparable with other autos from the early 90s. Just like the trashtastic RE4F in my Maxima, the Q's transmission constantly frustrates.As far as neck-jerking...shift speed shouldn't be a factor. They can be RELATED, but one does not invariable cause the other. You can have smooth fast shifts, jerky slow shifts, and any other mix.

The 5 speed auto in the 6th gen Maxima is a billion times better than the crap trans we got in our Qs. Shifts are incomparably smoother and quicker.

The sad fact is that JATCO didn't have a clue what they were doing when it came to auto transmissions until the turn of the century.

[maxnix]

If you have slow transmission shifts, it might pay to go back and read the early Q45tech articles on his transmission maintenance regime.

You definitely have a problem.
Modified by maxnix at 10:44 AM 8/13/2009

[Q45tech]

A good way to measure the TCU commanded shift time is to view the ignition advance cut signal to ecu in 0.03 second increments.

AS the clutches and components [pump] wear the pressure cannot keep up and timewise it slows down.

I have a trimode tcu which changes the pressures and makes for really fast [compared to stock tcu] shifts BUT even then you can feel the progressive declines after 100,000 miles.

The RE4R03A is undersized for a Q45 especially one with a ECU reprogram as the engine torque output can get to ~ 330lb/ft vs 290 stock!

You can play with the values of the shunt resistor on the presure solenoid to restore some of the sharpness.

The 1994-96 vesion was even slower and softer than 90-93 transmission.

You can change viscosity of ATF by using Redline High Temp ATF in warmer climates at your own risk. But below 50F it gets interesting and stressful on internals.

The new RE5 has a higher torque limit 333 lb/ft to match the revised engine.The even newer 7 speed is rated for 380 lb/ft.

[MinisterofDOOM]

I would kill for a trimode TCU. I really do think that would eliminate a lot of my issues with the trans. I also need to get the J30 speedo gear on the car to get the shift points back where they're supposed to be in relation to real-world speed...I think that would probably help with some of the car's indecisiveness. But then again my Maxima's trans was slow to act as well, and it was stock (later had an upgraded valvebody).

You can change viscosity of ATF by using Redline High Temp ATF in warmer climates at your own risk. But below 50F it gets interesting and stressful on internals.

That's really tempting. But we spend easily 4+ months of the year below 50*F here. Do you think it'd be worth the risk, particularly on a newer, less worn transmission like mine? I've kept on top of maintenance (true fluid exchange about 8k miles ago, in addition to "the usual), though it has been subjected to the increased torque as you noted.

I'd like to think I don't have to worry too much about killing the auto in this car since ideally I'll just replace it with a 5 speed if it does die. But I'm not eager to rush it, either, as I don't have a second car to drive while the Q is down for the work.

[maxnix]

Will a moderator consider chaning "slow" in the title to the proper adverb slowly?

Are adverbs no longer studied in today's English classes?

EDIT: Thank you Mr. Moderator!
Modified by maxnix at 6:17 PM 8/15/2009

[Q45tech]

Why not acquire electronic pressure sensors and connect to supplied ports [see FSM] and view driving pressures in real time.

Start with accurately measuring and graphing the 1st > second shift, since 2nd is good to 94-100 [depending on redline] .

0.5 second improve is 0.5 second improvement in quarter mile like adding +50 lb/ft and +50 HP to engine.

[Kiven422]

My 1993 Q45 has always had a slow 2nd-3rd gear transition.

As I test drove the 1994 Q45, I quickly noticed snap-shifts like a late 90's model BMW 3-Series. Snap-shifts and before you knew it... right under your foot, at the lowest RPM possible. All gear transitions gave the same quick snap-shift.

I think the transmission started the laggy shifting after I started to smash the pedal.

Though I can control the speed and feel of the shift through pedal control.

Also, you guys may bash me but its 100% true and not exaggerated... Every time I fill Arco AM/PM Premium, its impossible to actually "feel" a shift. NICE!

I also like how after 40MPH 2nd and 3rd gear as the TCC LOCKS... the car torques off and you slightly give it gas, no over-rev.
Modified by Kiven422 at 12:20 AM 8/15/2009

[txQ45]

It's all in the design to have a smooth shift nothing harsh from the factory.. By increasing the pressure and the controls on the valvebody, modulators you can have a very sharp shift. Try HttP://www.aaa-hiperformanceauto.com

They have "Built Transmissions" for the Q, Nissan NA, and TT.. from mild to over 1000hp capabilities

[Q45tech]

After miles/years the seals inside transmission cross leak and reduce peak internal pressure to drive the shift. After awhile only a rebuild will tighten things up to near new.

In Summer you can use a hightemp ATF version which is too thick for cold weather and probably gain 0.2 - 0.3 seconds or more in quarter mile [2 shifts] at the expense of some life.

http://www.redlineoil.com/prod...cid=9