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.
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 (https://www.taurusclub.com/forum/98-s...ange-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.
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.)