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Why is my 4N shifting like my old 4S? I thought the whole N part meant it wasn't synchronous shifting, but if I let off the gas after punching it, I can feel it shift from 1-2, 2-3, 3-4. If I'm in overdrive and punch it, I can feel it downshift 4-3, 3-2. I thought it was supposed to jump to the necessary gear. If that's the case, what's going on? If that's not the case, then have I misunderstood the difference between the tranny's?
 

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I don't think that is the meaning on "N".
Non-sync is reffering to the rpm's. If you drive with some speed and lift the foot from the gas (or put the transmission in N) you will see that the engine rpm's drops to iddle with the "N" transmission. While on the "S", the rpm's are kept by PCM at a higher number ("right" value in sync with transmission for that speed).
Now, I never felt a double down-shift in mine at hard acceleration. Maybe I didn't try hard enough :)
 

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I don't think that is the meaning on "N".
Non-sync is reffering to the rpm's. If you drive with some speed and lift the foot from the gas (or put the transmission in N) you will see that the engine rpm's drops to iddle with the "N" transmission. While on the "S", the rpm's are kept by PCM at a higher number ("right" value in sync with transmission for that speed).
Now, I never felt a double down-shift in mine at hard acceleration. Maybe I didn't try hard enough :)
I have 2 AX4N tauri and none fall down to idle when you lift.
 

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AX4N (1994-2006)

Type:

Automatic Transaxle 4-speed Non-Synchronized
VIN Tag ID:

First Letter: X (1994-2005)
Only Letter: N (2006)
(More Info)
Ratio:

1st: 2.771 2nd: 1.543 3rd: 1.000 4th: 0.694 Rev: 2.263 Final: See VIN Tag
Fluid:

Dexron III/Mercon ATF (1994-1998)
Mercon V (1998+)
Notes:


(Pop-Up)
This transaxle was stronger and better than the "AX4S". It was used on all Duratecs and V8 SHOs and most 2000-2006 Vulcans. The V8 SHO version of this transaxle was slightly different internally (mainly different final drive ratio, higher stall torque converter, and more clutch packs) than the non-SHO version. Some 1994-1999 Vulcans got this transaxle although there was no reason why and they were pretty random. This transaxle is also known as the "4F50N".

The "AX4N" has a different pan than the "AX4S" because the two transaxles have different bolt patterns. This transaxle has 19 bolts that hold the pan on.
 

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That blurb from wiki doesn't explain what "Non-syncronized" mean.
 

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Non-synchro means it can drop gears in pairs, basically go from 4th straight to 2nd. It shouldn't drop into 3rd.

AX4S - Synchronous Example 1: Cruising at 25mph (3rd gear), you floor it, it downshifts to 2nd gear briefly, then into 1st.
Example 2: Full throttle acceleration from a stoplight to 35mph or so, then let off the gas. The transaxle will up-shift to 2nd gear very briefly, then finally into 3rd gear where it needs to be.
In other words, it has to shift in order 1-2-3-4 and 4-3-2-1
AX4N - Non-Synchronous
Example 1: Cruising at 25mph (3rd gear), you floor it, it skips second and downshifts directly to first.
Example 2: Full throttle acceleration from a stoplight to 35mph or so, then let off the gas. The transaxle will upshift directly to 3rd gear, skipping second.
In other words it can shift how ever it wants 1-3, 3-1, 2-4, 4-2, etc..
The AX4N is a more efficient transaxle. The ability to skip un-needed gears helps reduce wear and tear. Mechanically, the AX4S and AX4N are very similar, but hydraulically, they are not.
 

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My experience:

Drive with constant speed, gas pedal sligthy depressed. I have "X" rpm's.
Lift the foot from gas - speed stays the same (for a while), engine drops instantly some 3-400 rpm (let's call it "X-300"). Engine and transmission are not in sync anymore.
Now, I floor it - rpm's jump to the "X" for a fraction of second and after that jumps to some 4-5000 rpm.

Is that your experience?
 
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