Automatic Transmissions Ultimate Guide

[moyea]

For discussing the Automatic Transmissions in Nissans only, please.

Please do not post any remarks disputing the A/T vs. M/T. No "swap it for a manual" or the usual unhelpful replies. I will make comparisons to the M/T in the post but don’t think it is an attack. Let’s just stick to the capabilities of the automatic. I jumped in this post because time after time the A/T has never been properly represented on the 240sx. I will list a few reasons to stick with the A/T and other reasons not (with some tips to bring out the asskicker in automatic):

History: Did you say I have a Skyline transmission?

Jatco being a leader in import transmissions for years, have made trannys for about every Nissan (and other JDM) cars on the market today. The links explain it better than I can >

http://www.jatco.co.jp/ENGLISH....htmlh ... /L...sions

Let’s get to the technical: http://auto.howstuffworks.com/...n.htmh ... verter.htm

Mechanically speaking the M/T is the better of the two. A/T uses several smaller clutches, gear sets, bands, and other crap to work. Very heavy and very complicated. As opposed to the beefy, manly M/T gears and clutch. M/T's can take a hell of a beaten under load but to a point. In this respect your A/T will most likely not out last the M/T but even the stock M/T is not built for the stress we put on our cars. OEM A/Ts and M/Ts are built for the daily drivers often using modulators, resistors, or boosters to ease the shifting of gears. A/Ts are especially victim to this due to the torque converter, Transmission Control Unit (TCU the A/T brain), Valve body, solenoids, resistors, etc. The factory didn't even come close to the potential of quality components and as you can see their are many things you need to upgrade. The cost of these upgrades are easily twice of M/T upgrades. Don’t be discouraged because the results can be twice that of an M/T.

The Slowmatic: Did you know the fastest 300zx in the country is an A/T?

The perceived slowness of the A/T is mainly due to a few culprits: Mechanical > Torque converter (TC) and valve body (VB)Electrical > Transmission computer (TCU)FLUID!!!!!!!!!!There are other things but these are the easiest and cheapest to upgrade.

OEM TCs straight suck. Replacing this unit with one built tuff and with a higher stall. This is a matter of preference and application though. http://www.converter.com/q1.htm and http://www.importperformancetr...shtml are good sources. Simply stated, aftermarket TCs provide better acceleration and higher power to ground output.

The Valve body is basically the heart, not the brain as some people call it, responsible for the hydraulic systems of the A/T. This is a very complicated system dealing with pumps, valves, fluid pressure, etc. In short, OEM A/T VBs don’t do their job as efficiently as an aftermarket unit. A good unit can improve shifts, durability, and fluid transfer to name a few things.

The TCU is the brain of your A/T! The TCU is essentially the same as the ECU/ECM for your car. It takes in various inputs ranging from vehicle speed/rpm to fluid temp. The OEM TCU is usually set to allow comfortable shifts and low torque output (compared to what it can do). This is where the A/T beats out the M/T. For me to make an adjustment to the vehicles transmission on an M/T, would require mechanical changes usually involving removing the transmission and adjusting gear ratios. A/T requires much less work for adjustment. With an aftermarket TCU I can adjust every aspect of my transmission all on a laptop. I can change shift points, line pressure, coolers, trans brakes, lockup, it just keeps going and going (nothing outlasts the Energizer bunny). This provides infinite possibilities for transmission control. And when I say total transmission control I mean everything, even manual shifting. This by far the best reason to stick with automatics. It’s also the second most expensive thing to upgrade. http://www.bigstuff3.com/index2.htmlhtt ... shift.com/

Fluid is by far the most important thing in the A/T. Just like oil is the life blood of your engine, ATF is the same for your transmission. ATF is needed for everything your A/T operates, low ATF or oxidization means no line pressure and no lubrication. This means your clutches won’t lock up right or worse yet break. This is the first thing and cheapest to upgrade on an A/T. Just like motor oil, not all ATF is created equal. Synthetic is they way to go here because it provides a much higher resistance to oxidization and heat.

http://www.amsoil.com/StoreFront/atf.aspx

Tips and facts: Did you know 4RE401A is the most widely used transmission in the Nissan line up?

Where to start?

Change the fluid, gasket, and filter. Some times the filter cannot be replaced, usually not the case, but with a good cleaning (parts cleaner) and having the fluid flushed (twice) it’s a good start. Check or ask to inspect the fluid and filter removed from the car. This is a good indication to mechanical problems. Metal parts, shavings are signs that the transmission will need to be rebuilt in the future, for now keep on trucking.

Next step is to get a temp gauge. http://www.autometer.com/cat_g...sid=4 Being able to monitor the abuse you’re putting on the A/T is crucial, I would never race a car without some sort of monitoring device. (Tip: You can use an oil pressure gauge to monitor ATF pressure too/ not needed if you have an aftermarket TCU which has an output for it).

Then get a transmission cooler, preferably one with a fan mounted to it, I found this out after I had already bought one without. After some hard runs or drifting ATF heats up, the fan allows you to maintain temps at low speeds or idle. But any cooler is better than nothing, the stock cooler is mounted on or in the radiator which doesn't help to bring temps down. The best place to put the aftermarket cooler is in front of the radiator. (or on the hood ).

Shifter is next. I have yet to find aftermarket shifters for the 4RE401A but if you own a domestic your in heaven. http://www.bmracing.com/index....cat=2Three types to work with ratchet, gate, detent. The type in the 4RE401A is a detent but don’t quote me on that. The key thing to look for is reverse lock out, preventing you from killing yourself. I prefer a ratchet style because it works like a sequential shifter on M/Ts, every pull of the shifter changes gears then returns the shifter back up. This is very sick! Once again you have now taken away one of the main reason people switch to M/Ts. And yes.....you can downshift.

Tip: You can use your stock stick to shift but become very familiar with the gears and the rpm in which you can upshift and downshift (it’s in the FSM). 1=1st, 2=2nd, D w/o OD= 3rd, OD=4th. Don’t be confused with M/Ts 5th is like OD for them. DO NOT hold your finger on the shift button you may push it into neutral or reverse!!! Only press the shift release when downshifting, it will slide freely when shifting up to Drive.

After that it’s really up to you. I think aftermarket VBs and then a transmission build should be done in that order. The reasoning behind this is if you do blow your transmission it will most likely be one of the clutches or bands so you can salvage your aftermarket VB and put it in another A/T. Then when you get the money for a bulletproof A/T rebuild your all set. Transbrakes are also something to consider.

I threw the torque converter last because selecting a TC is matched with the output of the engine (amongst other things). If you plan on putting out 400lbs/tq you don’t want to buy a TC that’s built for 250. So you can wait until your finished with the power adders or just get a slightly higher stall TC (500 1000 more rpm over stock).

Mind over Matter: TCU vs. Man http://www.visualexpert.com/Re....html

(Do NOT Try This) How many times have you been laying down rubber with your boys and every run you do you best them? I hear all kinds of excuses like "I missed a gear" or "You got lucky off the line". The truth is this; a comparable M/T cannot shift as fast as the A/T. I know some M/T guys can relate to this fact. Driver reaction time and accuracy is something that plagues the M/T world, footwork is a desirable and valuable skill. A/Ts do not face this problem because of the TCU taken' only a fraction of a second to change gears.

DVD Extras and Theory: "If you’re just going to swap it, can I have it"?

The 4R01 is hands down the most available import transmission out there. Just think back at all the time you went to the Pick N' Pull. So what does this mean for you? Options!!! If you burn out your transmission who cares?! There’s like 600 of them at the yard going for as low as $300. There is always somebody trying to get rid of them for swaps. I had two in my garage last year! And you can just swap aftermarket parts to another transmission. Here's some theory for you: Did you know your A/T is in the SR20DET? In fact, the Silvia A/Ts are actually beefier than yours because of additional clutch plates and higher stall to accommodate the turbo. In fact, it’s in the 300zx too, wake up! Can these be interchanged or their parts? Domestics can why not imports? With simple modification (crossmember, drive shaft) I think 240's can see a whole new light. Now this is just speculation because I can’t find a transmission guy who knows what I'm talking about. Also, in theory, since you share the same A/T as a Silvia engine swaps can be easier and cheaper. You can chose one of two things keep your transmission and replace the engine or swap for a beefy SR20DET A/T, either way an aftermarket TCU can adjust for any transmission change.

Motorsports: Drag! And that's it? NO!

I'm not going to make a long spiel about this because I think the point is made. A/Ts can do ANYTHING an M/T can! This means drift, drag, road, circle, and rally. Did you know Formula 1 uses a semi automatic? The gearing and clutch (no clutch pedal) are similar to an M/T but the TCU and hydraulics are like an A/T. It is the perfect fusion of transmissions. Truth of the matter is transmissions are evolving all the time eventually the traditional M/T will be completely outdated and the A/T is not far behind. SM/T is the future!http://www.autoracing1.com/Mar...1.htmh ... ms...pp=15

The Low Down: also known as 2 for us A/T guys.

A/Ts have all the potential of an M/T at twice the cost. That's it!

Who is this, Adonis of Autos? This, Cadillac of men?

Just a guy who thinks transmission are interesting and is about to unleash a bomb on the 240 community. Look out for it in NASA events possibly this summer. Also looking for sponsors.....................AZHitman???............ because lord knows I'm not rich.

Damn that was some shameless pitching.

Links: http://www.levelten.com/store/...n.htm, http://www.importperformancetr...shtml

Modified by moyea at 6:32 AM 4/3/2006

Modified by moyea at 10:21 PM 4/21/2006

Modified by moyea at 7:27 PM 6/5/2006
Modified by moyea at 12:34 AM 8/9/2006

[RazoE]

*stands up and claps*

its about time us auto lovers got some respect..!

[lofapoo]

I hate my auto transmission

[Red coupe]

autos suck ***...cept for drag racing...There is a reason most serious drag cars are automatics...they shift faster then you can, and torque converters increase torque up t 2x when they are slipping.

[VinceSez]

^^ word i hate my auto transmission to... but if my car was ka-t i'd love it.

damn auto transmission is draining all my power from my mods.

[nightkid86]

I dislike my auto transmission too.

It's going bye bye this summer

[SeVa-S13]

Good post. Autos are too underrated in today's "sport compact scene" and I wouldn't mind seeing more high performance Auto cars. Oh, and I wanna see some good Auto drifting too.

[rowlatt]

thanks.............very informative

i guess i will just have to have one of each.............LOL

[rowlatt]

hey nightkid86, my car is in the shop right now, but i quite often drop in at the "Crossroads" coffee shop on a sat or sun.............

[Red coupe]

Oh, and I wanna see some good Auto drifting too.

Meh with all the greatness autos can do for straight line acceleration they still suck at knowing when to downshift into a turn...

[SeVa-S13]

Meh with all the greatness autos can do for straight line acceleration they still suck at knowing when to downshift into a turn...

Read the post.

Shifter is next. I have yet to find aftermarket shifters for the 4RE401A but if you own a domestic your in heaven. http://www.bmracing.com/index....cat=2Three types to work with ratchet, gate, detent. The type in the 4RE401A is a detent/ratchet but don’t quote me on that. The key thing to look for is reverse lock out, preventing you from killing yourself. I prefer a ratchet style because it works like a sequential shifter on M/Ts, every pull of the shifter changes gears then returns the shifter back up. This is very sick! Once again you have now taken away one of the main reason people switch to M/Ts. And yes.....you can downshift.

Not that it's new info, but Auto's have long been able to be controlled manually and driven like a clutchless manual transmission; but it'd be nice to have the right type of shifter first. =\

Oh, and Moyea, I edited your post a bit because a few of the links didn't work. Hope ya don't mind.

[GEO]

lol... i got an auto ka-t..

[240sick]

auto + 75 shot beat most cars with 5x more invested than me. i dont hate my auto, ill race wile sipping my drank, and chewing on my burger lol. dont hate. he is right all the way. only drawback is the price. good post moyea... i applaud you for being one to show the facts as they should be.

[jamesblonde82]

i love my auto, i can talk on my cell phone, and pass people at intersections

[240Knightrider]

Very good post.

Takes the fun factor out of haveing a manual though. Im not looking to be the fastest so a manual for a fun car is good for me

[JesusLikesKFC]

i hated my auto, its only quik if your going in a starit line. mine was slow as hell a year ago. but i do admit i miss it in traffic and wen im eating snickers.

[GEO]

lol, the auto with a turbo can kleep the car sidewyas a LONG time.. :-) Two hands on the wheel is better then one in a drift.

[nvrplzd240]

not to threadjack or anything..but,

GEO- how much power are you making with that IAP kit?and do you have any vids/clips of how your exhaust sounds?

thanks in advance

________END THREADJACK_______

and o ya guys, if you dont get an auto then you cant have the "gangsta lean"

[RazoE]

plus since everyone's swapping, we can pick up beater autos for cheap...

[moyea]

Once again I would like to say this post is to discuss the Nissan automatic transmission, its potential, and application in high performance.

Please don't reply about how you "don't like it". I respect your opinion and each to his own. Keep an open mind and help further the knowledge base of NICO.

In regards to A/Ts only being fast in a straight line....... I guess I didn't clarify things. The following is a paraphrase of another article:

http://www.circletrack.com/techarticles/98598/

<Clarification>

Which TC is for me: Don't want to go straight? Think Brokeback

Reducing slippage is the goal for all trannys weather A/T or M/T. Installing a lower stall converter can have that effect. Wait, didn't I say install a higher stall TC is the way to go? This is where choosing the right TC can get confusing and should be done with care. Using a smaller TC with lower stall will reduce rotational mass and quicken throttle response. Perfect for those not going in a straight line where "bogging" can be felt attacking corners. Put simply, when you modify the car, you shift the torque curve upward into a higher rpm range. If you’re racing circle, auto-X, drifting this is what you want. A smaller low stall TC will keep you high rev'n in and out of corners but remember your increasing direct stress to your transmission. A quality aftermarket TC with strong components is a must. Also keep in mind that your transmission must be supported as well as your engine. The constant flex and vibration of the vehicle's chassis and engine can be hell on any transmission, A/T or M/T. Polyurethane is the best choice here. Direct-drive couplers are not necessary in the 4RE01 transmission as well as most modern A/Ts because the Over Drive facilitates this function. If you wanted to remove to TC in order to reduce mass, I'm sure one could be easily fabricated.

Theories revisited:

Adding clutch drive plates is a good way to increase the strength of your transmission and reduce slippage, at cost though. Once again you are adding more rotational mass to the transmission. Remember what I said about the JDM Silvia having a beefier A/T? Try 7 plates compared to our 5. Could this be a cool little swap for our A/Ts? Imagine a beefier JDM transmission with a OEM lower stall TC, topped with a SR20 monster........ Could this be a recipe for *** kickery? We'll have to see. Also during a transmission rebuild you can request the number of clutches you want. Experiment and have fun! And quit eating and driving you crazy A/Ters!

[PantherRacer]

Well scince my current car only has D,2,& L I had to try and figure it out slightly. My question would be, is there any way to convert the 4RE01 to semi-auto, or is there another Nissan transmission that is/could possibly be converted?

Also, what would be your estimate on the cost of a decent beefed up auto? Not using all the cheapest parts that will break, or the best parts which are out of this world expensive, but rather the ones in the middle, good quality and reasonable price. I think that would be a good addition to this write up

Cheapest built transmission - Middle prices/Mix & Match trannies - Most expensive built transmission.

[moyea]

PantherRacer: Answers to some of your questions

In most GM and older model A/Ts there was only 3 speed gears. D would allow 3rd, 2nd, 1st. 2 would allow 1st and 2nd. L would usually allow 1st only. It sounds like you have a 3 speed but I could be wrong, some GM trannys only have H & L (H=3rd/L=2nd and 1st), either way the principal is the same for all A/Ts that have a manual valve body.

No, there is no way to "convert" an A/T to a semi-auto. The actual transmission is completely different from any other. However, there are ways to facilitate manual function on an A/T, just like there are ways to facilitate automatic function on a M/T. For A/Ts the easiest way is to actually use the shifter as stated above. Level 10 Shiftronic and IPT Electromatic both offer electronic solutions to manually shifting an automatic. These basically control the solenoids for each gear, allowing the user to control which gear to enter and even when to lock the converter. All these functions (and more) can be controlled with an aftermarket TCU but the cost and complexity is twice that of these controllers.

The Tab: Why does everyone keep asking, "Are you going to swap it for a manual"?

Broken down to no, low, mid, high budget build and maintenance. I also included the parts needed and man hours it will take (if your going to a mechanic). I will also include multiple build options within the same budget.

<No Budget> $150Items: transmission filter, fluid, band clamps, mini breather, pan gasket. work time 3 hrs

Yes, you still have to spend some money but almost nothing in comparison. The key here is maintanance, change fluid and filter at least every two years and check for leaks or worn hoses.

Here are some tips from http://www.circletrack.com:

"The plumbing from the transmission to its radiator needs to be heavy-duty. Double and triple clamping all the lines can prevent a disaster."

"A breather coming out of the transmission filler neck can prevent fluid from escaping under hard cornering. This phenomenon is referred to as puking."

This is cheap and easy to do yourself; even though, I recommend using a locking dipstick rather than a breather (mini air filter).

The drop resistor Modification: Drop it like it's hot!To understand what the drop resistor mod does you need to understand the function of the resistor. (Dont quote me on this info) There are several factors that determine shift firmness, a subject I will cover in later posts, accumalator/line pressure is one such factor. Some of the changes in pressure are determined by the throttle posistion sensor (TPS) and vehicle speed, which is governed by other factors itself. In short, these translate into voltage signals which are intercepted by by the resistor. The name in itself gives you a clue to its function, it resists. The voltage input without something retarding it would run constantly at full load; Letting the TCU know it needs to apply full line pressure/shift firmness all the time. With the resistor "on" it modulates the necessary pressure to provide a more comfortable shift. In most cars this involves reducing pressure at the time of shift. Despite the fact that a indicator light might come on this, in certain applications, will not harm a transmission that is in good health to begin with. As you increase the load (more HP) on the transmission you will need to replug the resistor back in. The transmission will need it to regulate the line pressure or you risk "puking" or blown seals. Be sure to take precautions like I stated earlier to ensure the A/T can handle it (i.e. check hoses, leaks, temp gauge, etc.) I'm pretty sure those blown trannys were a result of something else. My recommendation would be to leave it on for daily driving and remove it only when needed (i.e. drag). For road racing, auto-X, or drift it might be better to install a WOT switch like this person:http://jime.homeip.net/DR%20Mod.htmlThis an ideal set-up since in WOT maximum pressure/firmness is most benificial. Be aware that with an aftermarket TCU or Valve body upgrade, you would leave the resistor plugged in because this feature could be configured through the TCU or already is adjusted with an aftermarket VB.

<Low Budget> $300 Items: transmission cooler, tran cooler install kit, temp manifold, temp gauge, gauge mount.

Although not ready for track, with this build you will be ready to play with your A/T car and not worry about it. Everything stateted above with these adittions:

Install a temp gauge of your choosing. This is a must not a option! There are two methods to installing the gauge. 1) Weld a bung into the transmission pan and install the sender there. 2) Use Autometer's temp manifold and intall inline with your fluid hose. I recommend this method because it is easiest and keeps the sender away from the elements. Like stated before a full sweep Oil Psi gauge can be used with the transmission in order to monitor transmission health but its not neccesary. Depending on what kind of gauge you get prices range from $35-300 (that's right $300!)





The transmission cooler is the upgrade that comes in many flavors. Tube & fin, stack plate, w/fan, w/o fan, and what I call tube & plate.

Stack plate: strongest and best cooling without a fan. With a fan it is the best set up.Tube and plate: Doesn't need direct airflow to cool. Worst cooling efficency.Tube & fin w/ fan: Provides cooling at low speeds or idle. Can work with a thermal relay to offer the more cooling efficency.Tube & Fin: Cheapest set-up, easy to damage, average cooling

Adding a stack plate transmission cooler with a thermostatic pusher fan mounted on it is your best option. But like I said before any transmission cooler is better then nothing. Coolers run the price range from $50-250 depending on your choice.

Stay tuned for part two of the A/T Build budget, which will be covering the many options of the Mild A/T Build and the High-end build.
Modified by moyea at 12:29 AM 5/11/2006

[le_ryan]

VERY good thread man! thanx for all the good info, i may have to look into doing some of this.

[pr240sx]

Heat is the AT worst enemy

While back when I had my GN, I installed a B&M supercooler, temp gauge, oil acumulator and bigger oil pan.If you have more oil in your system, the transmission will run cooler and prevent foaming. Now, dont confuse this with overfilling the transmission. AT oil foaming is worst than running without any oil!!

[HashiriyaS14]

This is a fantastic thread.

I just acquired an auto-trans S13 that will be staying that way for quite some time, and I'm just looking to help it go the distance. Lots of useful info here.

A turnkey "tiptronic" solution would be neat, but just not worth it when 5MT's are so cheap and plentiful.

[moyea]

Heat is the AT worst enemy

While back when I had my GN, I installed a B&M supercooler, temp gauge, oil acumulator and bigger oil pan.If you have more oil in your system, the transmission will run cooler and prevent foaming. Now, dont confuse this with overfilling the transmission. AT oil foaming is worst than running without any oil!!

You're very right pr240sx! I just wonder if you're talking about engine oil or ATF? I never heard of using a acumulator for transmission fluid but it could be a interesting idea. If you did use it for your A/T, please share the knowledge because I'm interested on how you did it.

Heat= thermal break down= foaming= RABID 240s!!!

A deeper oil pan could be added to the <Low Budget Build> but there is a reason I left it out. Currently, I am unaware of any supplier of performance Nissan A/T pans. I have contacted many small and big shops about having one custom made but this has been truly disappointing. Companies like TCI and B&M dont even give me the time of day, while smaller shops just dont have the resources to make it happen. I guess I'll just have to make one.

Deep Transmission Pan: Like Barry White deep!2-3hrs $80-300

Adding fluid capacity to your A/T aids in heat transfer and lubrication. Logic dictates that more fluid requires more heat to breakdown than less fluid. This is the principal behind increasing oil capacity for any application(engine, differential, transmission). Pans usually come in two metals: aluminum or steel. Aluminum is lighter and covects heat to ambient air better than steel (best choice). Steel is well.... steel, just make sure it has a rust proof coating of some sort. Also make sure the pan has fins to help disapate heat and a drain plug. There are some other things to consider when looking for a deeper A/T pan:

Will it require modification to my dip stick? Most USDM cars, no. But since we're talking Nissans, who knows.

Will it cause undercarriage clearence problems? Good rule of thumb is that the transmission pan shouldn't be deeper than the engine oil pan or car frame.

Will I need a fluid pick-up extension? As in most cases of deeper pans, most likely. It is unlikely that you will need to modify the filter.

Pan gasket? In some case, yes the gasket will be different.

Cast or Weld? Cast is made from a solid piece, very strong. Depending on the welder's skill, strength varies. A custom welded pan may be the only option for Nissans.

TCI 4 extra quart deep aluminum pan
Modified by moyea at 2:14 AM 6/13/2006

[nightkid86]

hey nightkid86, my car is in the shop right now, but i quite often drop in at the "Crossroads" coffee shop on a sat or sun.............

Cool, I know a guy who works there

[penpen-commander]

why did you have to post a long *** "story"too much for my tiny brain to sustain.

[Red coupe]

very nicely done, you should add a link to this post in your signature....

[Leash]

Amazing post. I might concider trying out a few of these things for fun.