Why are most AT's less reliable than most engines?

[LouDawg]

With all the talk about what's best for engine lubrication, I read more about automatic transmission failures at earlier mileages than I do engine failures. And usually, like on my Honda, it seems those failures are as much or more to repair or replace than the engine.

Why are they more prone to failing at lower mileages than engines? What can be done to get the absolute most out of the AT, besides changing the fluid (and filter if there is on) on a regular basis?

I drive mine as gently as possible, wait for all shifts to complete before taking my foot off the brake, set parking brake, etc. But I have more concern of tranny failure than engine failure.

Thoughts?

 

[johnd]

I think most ATs are ignored to death. If most people were as careful about AT maintenance as they are about engine oil changes there would be a lot less failures. Manufacturers aren't any help either. My experience has been that transmission coolers are marginal at best at least in the heat where I live and manufacturers recommendations for fluid changes are too far apart. I suspect the mentality of the car manufacturer is as long as the thing stays in one piece for 5yrs/50k mi., who cares. I used to be as guilty as anybody, I just drove the ATs until they quit without any maintenance. I know better now.

 

[1sttruck]

Ever look at an 'exploded diagram' for an auto tranny ? Lots and lots of parts, many little, lots of small passages, actuators, sensors, wriring harnesses, and a design based around some amount of slippage for 'comfort'.

 

[Fatboymoe]

This is exactly the reason I bought my 07 Tacoma with a 6speed manual. I plan on keeping this truck for 10 plus years and didn't want the expence of rebuilding an automatic when I retire in a couple of years. I came to the conclusion that replacing the clutch assy. is far cheaper than paying for a shop to rebuild an auto.

$350 in parts and an afternoon of work will get my clutch replaced. $2500 or more will get an automatic transmission rebuilt in a shop.

 

[NYEngineer]

I'll be picking up my 98 Yukon from the transmission shop this afternoon. It has 190,000 miles on the original engine but it's on it's second 4L60E. I change the fluid and I don't tow with that truck. I would love to swap a 4L80E into that thing. What junk.

 

[ThirdeYe]

The AT on my sister's Firebird Formula costed just a few pennies over $2000 to rebuild. Ouch. My transmission is original and hasn't needed rebuilding yet, however, the fluid has been changed a few times and I plan on doing it again soon.

 

[m2200b]

You seem to get several groups of poorly designed autotrannies - Honda , chrysler and the rest are just more vulernable to poor maintenance. You put a 100K on a toyota MT and the trannie oil look like garbage but you change it and still get to 300K. Try that with a GM 4L60.

 

[tom slick]

on the flip side I've had ATs with 150,000-250,000 miles on them.

they are a complicated machine, much more so then an engine or MT so they require more maintenance.

 

[mstrjon32]

It's pretty simple when you think about it. First of all, an automatic transimssion is a MUCH more complex system of components than an engine, with many, many more potential points of failure. Moreover, when something "fails" in an engine, it can fail in a non-catastrophic way (sticking lifter, leaking valve stem, emissions system, etc.), but more often than not, everything inside the transmission is reliant on everything else in order for it to work.

Add to this the fact that transmissions inherently incur wear every time you shift, regardless of how easy or hard you drive, and inevitably they will all fail.

The best way to care for your automatic transmission is to give it 30-50K fluid changes, add a transmission cooler if you're out of the warranty period (if you add one while you're in, and a fluid line breaks, you'll be totally SOL), and avoid towing.

 

[mstrjon32]

Quote:

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You seem to get several groups of poorly designed autotrannies - Honda , chrysler and the rest are just more vulernable to poor maintenance. You put a 100K on a toyota MT and the trannie oil look like garbage but you change it and still get to 300K. Try that with a GM 4L60.

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Why are you bashing the GM 4L60? It will last a lot longer and withstand a whole more torque than any of the automatics Toyota makes.

 

[Vaca]

It's silly to say that the 4L60E is better than ALL Toyota trannys.

The transmission in my '93 Camry is perfect with zero work other than a fluid change once in a while. The car has almost 200,000 miles. My brother has a '92 Camry with even more miles and even fewer atf changes, zero problems.

BTW, I had a 4L60E in my Suburban from a few years back, and it too was great at 125,000 miles.

 

[mstrjon32]

I'm not saying that all GM Automatics are better than Toyota automatics, but Toyota primarily builds FWD automatics for low torque applications. GM has made some pretty crummy FWD transmissions in its day.

However, he GM longitudinal transmissions are very tough.

 

[unDummy]

Its silly to compare vehicles.

Sorry, but older Camries are underpowered and lightweight compared to most vehicles with a 4l60. I'd love to see a Camry tow 5000lbs for a day, plow snow for a week without breaking, or handle the power of a modded small block.

I've seen 4L60s with 180k miles on decade old OEM fluid. I've also seen plenty of imports puke the transmission before the warranty expires. Why does everyone need to debate or argue which brand is best?

AT's are simply less reliable then engines because they are neglected, and often abused.
If you ignore any maintainable component, you will have issues. Ignore the coolant, radiators will clog. Ignore the engine oil, sludge will form. Ignore the transmission, and threads like this get started.

If you break transmissions, you need to rebuild it better. You should improve the cooling if heat is an issue. You should improve filtration since that is a common point lacking in every transmission. You should incorporate all known OEM and aftermarket upgrades. There isn't a tranny made that doesn't have updates. This is the problem with many generic rebuilds. Causes of failures aren't addressed and will promise the future timely failure.

 

[g20ooh]

Great topic Lou , and very timely . Also an accurate observation of "whats happening" in the world fleet .

From the OEM side - three issues come up almost all the time .

1)Absolutely ridiculous filtration esp in terms of what matters most ie in the .01-10-25-50-100-150-200 micron range for magnetic wear particules and (arbitrary/practical) 2-10-25-50-100-150-200 micron range for everything else . Also ,lack of filtration after the pump but before distribution within the valvebody etc .

2) Inadequate/poorly designed/low standard heat elimination and management .This varies abit in the details from one to another .Sometimes this is an internal issue as well as external - both of which are being hindered in terms of cooling system design choices as well .

3)Material choices/standards/ and engineering/durability standards in general .Lots of too thin ,too soft , and too weak - and its being done eyes wide open .


Most times , no margin for what goes on in the real world .

It would appear to me that the "idea" here is semidisposable units with a 10yr/150K mile life expectancy accompanied by a 2.5-5.0% "early" failure rate is the high end of whats being served up .
This is in my opinion , pure H.S. . At best , a make work program for dealers .


From the owner ;

1)Lack of correct service - both the cooling system and the AT itself .


2) Improper use of the vehicle and necc. the AT ie overstressing the "box" somehow .

These are just the main points - theres more but that starts to get application specific - all of these things interact together so the discussion becomes quite large .
A couple of these not mentioned but "largely universal" would be low grade fluid specs and AT coolers that end up filtering and jammed as a result .
Also , internal "mini screens" that can't be practically speaking , serviced and or backflushed .
Lack of drainplugs (torque converter/pan) and now dipsticks .

Where applicable , inadequate pan capacity/ and "easy partial drain" % .


Bottom line over here as I see it ;

NOT ONE OEM provisions for large numbers of their owners to succeed long/long , cheaply , and easily .

 

[g20ooh]

Quote:

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What can be done to get the absolute most out of the AT, besides changing the fluid (and filter if there is on) on a regular basis?

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Lou , the first key to enlightment for my "brood" on this is to realize that even the "severe" schedule is designed to take you short ie that 10yr/150K design "limit" as outlined above . (Older designs may have had a lower target) .


Soooo - in broad terms you want to upgrade from there .

Lots of choices and trade offs to be made and considered - and as always how much do you you want to spend .
Each situation really is different - I think "snowflakes" .

BTW , the operational consideration that matters most most often on a typical stock system is # of shifts and staying below a certain temp. .

As an example of bare bones-don't want to be complicated approach (definitely not the best and most likely not the most cost efficient) a magnifine filter and a partial drain every 12.5K accompanied with a "full service" every 40-75K sorta works as a baseline for many in "normal" service .
Starting all this as early as possible makes a lot of sense as well .
Personnally , my partial drains are in the 5-10K range (esp Honda) - unless there is a big upgrade on filtration , but really I drive mostly stick .

At this point , on most 1998-2001 or newer , I'd get filtration/cooling in front of super premium fluid but on one I really liked I'd get it all - if you really want to go long-long its really hard to have too much .
YMMV .
It really depends on all the variables as to what works best and even then there are lots of choices to be made .

The key is to do "more better" than the OEM stipulates - unless you are satisfied with the likely outcomes .

 

[LouDawg]

Well I'm definitely not satisfied with the likely (or normal) outcomes. I want the absolute most mileage I can get out of the tranny, like 200K, 300K, or even more. Of course, same goes for the engine.

If that means more frequent drains and more frequent flushes, that's what I'll do. But is it possible to change (or drain) the fluid TOO often?

(As an aside, I would've bought a standard tranny if my wife could drive one.

)

 

[LouDawg]

Quote:

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Ignore the transmission, and threads like this get started.

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I may be misunderstanding what you wrote, but I want to be clear that I haven't ignored this transmission. Indeed I'm trying to do just the opposite, and be proactive and premptive as much as possible.

 

[rpn453]

Quote:

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Well I'm definitely not satisfied with the likely (or normal) outcomes. I want the absolute most mileage I can get out of the tranny, like 200K, 300K, or even more. Of course, same goes for the engine.

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I think that if you drive conservatively, don't abuse the tranny, and change the fluid regularly (I just do a drain-and-replace every 30K on autos), a decent auto tranny should last the life of the vehicle. The only failures I've personally seen were caused by overheating, from inappropriate towing or trying to get unstuck.

 

[Jimbo]

Try the example of the Ford E4OD, a supposedly "heavy duty" unit once even used on turbodiesel trucks. A GM 4L60E will outlast it. Mine certainly did in a Chevy truck. I had the E4OD in a lowly 5.0L gasoline F-150. With no towing or abuse it still wouldnt last. Aluminum parts, where the replacements are steel, complex electrical wiring not protected from heat, oil and road splash, and the list goes on. I changed all the fluid (four gallons) and got absolutely perfect UOA's, so it is NOT lubrication failure.

My plumber went almost 300,000 miles on a 1990 Dodge Ram van with the A-727 Torqueflite. Why do we have complicated, and failure-prone transmissions? The reason, I think, is trying to get more fuel efficiency. Lockup torque converters, another Ford weakness, computer control and extra gears, actuators and clutches crammed into the same space are all responsible.

 

[Jim 5]

I agree with Jimbo. Smaller/lighter/more gears, sensors, servos and other fuel efficiency compromises makes for a weaker transmission. You didn't hear about the good old 3 speed TH350's and TH400 transmissions failing very often.

I will say that my 4L60e in my previous truck went 200k miles with no troubles. It got fluid changes around every 45-50k miles though. Never had a trans filter change either...just t-tech changes.