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I thought i might just post a guide for people that have the AX4S in their bull. Some basic information about it and what they should know.

Encyclopedia link (technical information): http://www.ford-taurus.org/taurusinfo/Engine/Trans.php

1.Difference Between AX4S and AX4N

The AX4S is a synchronous transmission, in simple terms, it must go through each gear before reaching its desired gear.

(First, Second, Third, Fourth *Overdrive*)

This is not an issue during daily driving. However, when slowing down from 3rd gear (45mph roughly) to a stop (stop sign, red light) you may notice a small nudge that indicates the transmission has switched from (3) into the *(2)* gear and finally reached the desired gear (1).

Upon acceleration, you may feel a slight nudge when pushing the pedal to the floor. (1) then to *(2)* and finally to (3).

These slight nudges should be no more than a thud and a slight slowdown, if you experience a large thud with a sever slowdown, you may have an issue.

The AX4N (The more efficient AX4S, which is mated primarily to the 24V Duratec) is a non-synchronous transmission and can skip gears to achieve the highest efficiency when changing gears and keep the transmission cooled down. It is said that it shifts smoother, but this is noticeable mainly when slowing down or speeding up because the transmission can skip the intermediate gear and can directly go from (3) to (1) or (1) to (3).

Another hot topic is Overdrive or the *(D)* on your gear selector.

Overdrive simply gives you a fourth gear that your tranny will switch into whenever you reach highway speeds. Instead of keeping it in (3) and letting the RPMs rise and reduce your MPG, it will simply shift into another gear to keep the RPMs lower and the efficiency higher. It will also eliminate engine braking and let your car glide easier, which most of the time helps with efficiency. Some people will say to keep your car in the regular D, and some will say keep it in Overdrive. If your going to be cruising at 60-70Mph, keep it in OD. If your driving in stop and go traffic or city driving, you may want to keep it in D. I keep it in the regular D because i get better performance as the tranny lets me reach the RPM band that houses all of the Vulcan power. However, when i reach 60-70 and i reach the top end of the (3) RPMs, ill switch it into OD to maintain the speed and help efficiency. Its your call, but either one is safe.


2. Maintenence

The killer for our Taurus transmissions is overheating and lack of lubrication. Both of these tend to be a problem with the AX4S. Because the AX4S has to "touch" each gear and cannot skip gears, it tends to generate more heat than the AX4N and can be problematic under heavy stress conditions. To help this problem, you may install a transmission cooler, which will keep the transmission at a safe operating temperature, and prolong the life.

Another basic thing to do is a pan-drop. This should be done every 30K miles, or whenever the transmission fluid smells burnt, or is not red in color. There is an excellent guide on here by Breeves02 (http://www.taurusclub.com/forum/98-solutions-common-problems-how-articles/176149-gen-4-trans-pan-drop-filter-change-ax4n.html)

The tutorial is for the AX4N/Duratec combo, but it is still the same idea as the AX4S and AX4N are very similar.

Another good thing to do is to engage the parking brake most of the time. Leaving the car in park at any incline will put stress on the tranny pawl, and will put unneeded stress on your tranny. If you put your car only in park its like lodging a sandstone rock underneath a boulder on a hill and expecting it to stay still. If you put your parking brake on, it will drastically reduce any wear on the pawl.

3. Driving style

Well, assuming that you have the Vulcan engine, you probably drive it like a granny car, or push it to its limits to compete against barebone Impalas. Either driving style can be harmful for this vehicle. Driving this car like its a boat and keeping the car at the "transmission shift point" will wreak havoc on the tranny. When i say shift point, i simply mean the speed at which your car usually switches gear. For me, the (2) to (3) shift point is around 40Mph, this simply means that the car is at the neccesary RPM to shift into the next gear. If you keep the car at that speed/rpm, the tranny may shift sporadically into both the (2) and (3) multiple times as it tries to understand whether you intend on moving faster or slower. I've made this mistake, and it does not feel good.

The other driving style is "race car" and basically means driving the car like it actually has power. The Vulcan is a reliable engine and it does have "some" power, but its not a Ferrari and should not be driven like one. If you push the pedal to the metal on the AX4S, the transmission will quickly switch gears and generate alot of heat. Its like starting the car and immediately pressing the gas, its not good for the car or your wallet when you need to repair your tranny.

I drive a bit aggressive, usually driving quickly in (2) and (3) and i always let the vehicle accelerate at around 3000RPM. Its a Vulcan, they are reliable when not being pushed to the limits.

Finding an appropriate driving style is not hard, it just requires you to pay close attention to your RPMs and shift points.

4. Conclusion

Many people will tell you, you have the weaker tranny. In simple terms, you do. But its not because its not a good performer. Its because of the reliability issues that result from the added heat that is generated. An AX4S will perform on par with a AX4N when it is well maintained and in good condition. However, if you dont take care of it, it will live up to its "slushbox" moniker.

Enjoy your bull, and remember, the tranny was the worst part of these cars, just because you have the AX4S, doesnt mean you have a disadvantage. :)

(Mods can feel free to edit. Im not a transmission expert. This is just a write up of all i know.)
 

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The other driving style is "race car" and basically means driving the car like it actually has power. The Vulcan is a reliable engine and it does have "some" power, but its not a Ferrari and should not be driven like one.
:lol2: Oh, the Vulcan owners are going to love that...
 

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Excellent write up, I am the very proud owner of a vulcan and I have no complaints or issues with it, sure it doesnt have very much balls but its got the perfect amount for me! Havent had a single problem other than CSS and squeaky serp belt!
 

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Discussion Starter #4
:lol2: Oh, the Vulcan owners are going to love that...
Ive accepted the fact that its slow, but I enjoy the Vulcan engine :)

"Its got half the balls and twice the life." As my friend likes to say.

And thanks for the support Zinger. :p
 

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Good write up! Very informative. This should be stickied, if it isn't already.
 

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i got a 99 taurus se with the AX4S transmission. i can tell a big diffrence between the ax4n and ax4s. i liked the ax4n in my 96 taurus better than i do than my ax4s in my 99. i fell the ax4n had a more power than my ax4s does.
i do feel the small thud when coming to a stop, but u say thats nothing to worry about?
 

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Discussion Starter #7
Its normal that the car jolts a bit when coming to a stop. Its not as serious as it may seem. Just an operational thing. If it is an extremely powerful jolt, you may want to take it to a shop.

The AX4N and AX4S only select gears in which the car shifts in to, they do not determine power. It seems to me you may have had a Vulcan/AX4S and a Duratec/AX4N.

(Edit: Maybe someone can enlighten me on Gear ratios. I believe both the AX4N and AX4S had a 3.77 ratio, but im not 100% sure.)
 

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Its normal that the car jolts a bit when coming to a stop. Its not as serious as it may seem. Just an operational thing. If it is an extremely powerful jolt, you may want to take it to a shop.

The AX4N and AX4S only select gears in which the car shifts in to, they do not determine power. It seems to me you may have had a Vulcan/AX4S and a Duratec/AX4N.

(Edit: Maybe someone can enlighten me on Gear ratios. I believe both the AX4N and AX4S had a 3.77 ratio, but im not 100% sure.)
Same ratio. Only the 3.4L SHO had a different one.
 

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Its normal that the car jolts a bit when coming to a stop. Its not as serious as it may seem. Just an operational thing. If it is an extremely powerful jolt, you may want to take it to a shop.

The AX4N and AX4S only select gears in which the car shifts in to, they do not determine power. It seems to me you may have had a Vulcan/AX4S and a Duratec/AX4N.

(Edit: Maybe someone can enlighten me on Gear ratios. I believe both the AX4N and AX4S had a 3.77 ratio, but im not 100% sure.)
its a small nudge, and it dont do it all the time. i was just a little worried because my ax4n didnt do that and my moms ax4n didnt do that.


i know ax4s's have some problems and i tried to to get one but for $2150 @ 97k it was a good deal.

when i dropped the pan and changed the filter and fluid the metal magnet had barley anything on it, so it looks like the tranny is in good shape.
 

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Discussion Starter #10
The AX4S will serve you well if taken care of. My car has a very slight nudge and is mostly unnoticeable. If you take care of your car, it will take care of you. And besides, the Gen 3/4 transmissions were ALOT better than the original AXOD. :p

Its like comparing a Ferrari (AX4N) and Porsche (AX4S), and then comparing those two to a Toyota (AXOD). The Porsche and Ferrari dont look so bad when compared to the Toyota.
 

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The AX4S will serve you well if taken care of. My car has a very slight nudge and is mostly unnoticeable. If you take care of your car, it will take care of you. And besides, the Gen 3/4 transmissions were ALOT better than the original AXOD. :p

Its like comparing a Ferrari (AX4N) and Porsche (AX4S), and then comparing those two to a Toyota (AXOD). The Porsche and Ferrari dont look so bad when compared to the Toyota.
oh i always take care of my transmissions. i drop the pan and change the filter and fluid every 30k because i kno if you dont take care of these transmissions they can fail fast.
 

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Discussion Starter #12 (Edited)
Yours should last you a while then.

Id like to add though, If your AX4S does end up going out on you, there is still the possibility of swapping the Tranny for a AX4N, but there tends to be alot of work for that to be accomplished correctly.

If you'd rather rebuild, im pretty sure there are shift kits available that will make the transmission stronger.
 

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Yes, if it ever goes kaput you should stick an upgraded Dacco torque converter in along with other goodies.
 

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Discussion Starter #15 (Edited)

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The torque converter is not problematic on the 4S. The stator is. When that wears into the torque converter seal, you loose trans fluid.

The 03 and up AX4N is known to strip the splines out of the torque converter. And like any Taurus, repeatedly locking and unlocking the torque converter is going to wear it out faster if you drive like that.

Swapping out an AX4Sfor a 4N is no small challenge. A matching PCM, correct wiring harness and pinout matching, subframe (at least for 3rd Gens) and Y pipe (at least for 3rd Gens, and even then, it's really just some mounting tab differences), CV axles...
Not sure why one would go to this trouble unless your parts vehicle has everything you need/want.
 

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Discussion Starter #17
The torque converter is not problematic on the 4S. The stator is. When that wears into the torque converter seal, you loose trans fluid.

The 03 and up AX4N is known to strip the splines out of the torque converter. And like any Taurus, repeatedly locking and unlocking the torque converter is going to wear it out faster if you drive like that.

Swapping out an AX4Sfor a 4N is no small challenge. A matching PCM, correct wiring harness and pinout matching, subframe (at least for 3rd Gens) and Y pipe (at least for 3rd Gens, and even then, it's really just some mounting tab differences), CV axles...
Not sure why one would go to this trouble unless your parts vehicle has everything you need/want.
Thank you for the insight. I wouldnt attempt a 4N swap unless i had a full donor car with everything i would need. And im going to run this 4S until it leaves me on the side of the road.

And on the topic of the TC, that was more of a observation from the posts about transmission problems on here. :p
 

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The torque converter is not problematic on the 4S. The stator is. When that wears into the torque converter seal, you loose trans fluid.

The 03 and up AX4N is known to strip the splines out of the torque converter. And like any Taurus, repeatedly locking and unlocking the torque converter is going to wear it out faster if you drive like that.

Swapping out an AX4Sfor a 4N is no small challenge. A matching PCM, correct wiring harness and pinout matching, subframe (at least for 3rd Gens) and Y pipe (at least for 3rd Gens, and even then, it's really just some mounting tab differences), CV axles...
Not sure why one would go to this trouble unless your parts vehicle has everything you need/want.
100% with you until the part about the Gen3 subframe. Are you sure
there are different subframes for the two transmissions? I thought
they used the same frame but the frames were generic with
different mount points in them for both engines and trannies.

One CV is the same, one is different. I think its the long one on
the passenger side thats different between the two trannies.
 

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All DOHC came with the A4XN/4F50N. 19 bolt pan.
 
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