What really kills ATs ?

[amorrison]

I have had bad experiences with newer automobile ATs (various brands) over the last ~ 15 yrs (1990 -2005).
Previous to that (older ATs) ~1980-1990 I never had any problems and even thought maintenance(fluid changes) was a joke (they never failed).

The vehicles were typically 4 yrs old (50000 miles) when purchased and kept till 80,000 miles.

Has AT quality decreased drastically in the last 15 yrs, have I been statistically unlucky or have I (unknowingly) changed my driving style to cause these problems?

The "books" any overheating is the main AT killer- but what causes the overheating in the first place?

 

[MikeHalloran]

Since they started using FEA on a grand scale, everything has gotten smaller, lighter, cheaper (to make, not replace), and in general, not better.

Not better from the perspective of someone who buys used cars.

But better from the manufacter's perspective, because they weren't providing strength or durability beyond whatever was necessary to get the product through the warranty period. And because they get to sell you more service parts.

I assume some high- paid MBA got a huge bonus for making it happen.




Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[drwebb]

I had the opportunity to survey used ATF oil from several "Big 3" vehicles. They had 70-100K on the factory oil and were all driven by normal joes in south Texas. The pickup trucks were easier on their fluids than the FWD passenger cars, so I think heat may be more important than duty cycle. If your 80-90 cars were RWD that may be a big factor.

Also, the above sample cohorts' fluid condition was significantly better than a similar group surveyed previously of ca. 88-92 cars, which only had 60-90K miles. The better durability over longer service was attributed to higher fluid quality in the later factory fill fluids.

Towing is the main thing that generates AT heat. But a few transmissions have had problems with valve body wear that doesn't have much to do with heat.

 

[Tmoose]

There are lots of different failure modes.

The FORD Taurus transmission fiasco typically involved a piston that broke when made of aluminum. Bad FEA there.

For years the GM lock-up solenoids (buried in the hot transmission, like Honda off road bike ignitions bathed in hot engine oil) died after < 100,000 miles.

We had a Volvo with a ZF HP-something trans used in BMW, Peugeot, Land Rover and Jag that was famous for developing a small internal leak that kept various clutches engaged.If revved up immediately after going from fwd into neutral (like during an emissions test) the clutches smoked in minutes. After a few years ZF modified the trans to include a bleed hole (which was a mod developed by the aftermarket rebuilders, I think). Our trans was murdered by a leaky trans cooler that let coolant into the ATF.

The infamous MOPAR FWD transmissions have at least some failure modes based on sensors, and maybe some outright wear.

My daughter's 100,000 mile INTEGRA has a harsh and hesitant 1-2 shift that has not responded (yet)to SeaFoam or LUCAS snake-oil applications. I think it is a worn valve body, and typical, according to the Internet. Maybe better maintenance by the PO would have helped.

VOLVO has been advocating 20,000 - 30,000 ATF changes since the last millenium

 

[Strider17]

The current AT's have been a great disappointment to
me for the last 9 +/- yrs as well. In 40+ yrs of driving
I always selected cars with manual trans because if anything went wrong they were easy to fix. But now I
have a stop and go commute. AT's are so
complex that unless you are working with them all the
time, you have to refer them to a pro. I have always
purchased used cars, 2 VW and 1 Ford in the last nine
yrs, which were totally unacceptable in service. VW
was the worst, requiring their own proprietary trans
fluid at $18/Pt, and zero information in their service
manuals. Sorry for the rant, but I think the mfrs have
decided to cut costs, reliability, and serviceability
in their AT's
because they are unregulated ( no EPA, OBD II, etc)
and beyond the ability of most to repair in a reasonable
time frame.

(This is anectdotal evidence of course, but I have heard
and read much more)

The more you know, the more you
know you don't know....

 

[patdaly]

One thing that has not been touched upon is the manufacturers need to reduce rotating wieghts, pressures, and pumping losses to help them achieve very stringent EPA mileage requirements. I dont know all the tricks, but the one I do know of is GM cut out the cooler circuit while in OD on the 700R4 to improve CAFE numbers. You pump less, you use less fuel. I would imagine virtually every manufacturer has resorted to the same thing to help them meet CAFE. One of the reasons you dont see this as much in Trucks is because they are not under tha same pressures to shave the line so close.
As with anything else, life is a balance, and to me, this scale has become unbalanced.

And, like most of you, I wish I could still get a car like my 1969 Camaro, 250 six and a 2 speed powerglide. A monkey could work on it, and it still very rarely got less than 23 MPG, even pushed hard.

 

[JayMaechtlen]

Once you get the trans into OD, you should have a pretty good airflow past the car...
Probably have the converter locked up, too- less heat being generated in the converter. Maybe that's a pretty smart move!
The GM 4T60s seem to hold up pretty well, in my limited experience (two vehicles, both >> 100k miles, no problems)
Of course, even a maligned trans like the Ford AOD ('89 Aerostar) <can> hold up well. (160k miles, still works fine)
But, have to look at stats to really evaluate.
You can have the Camaro- I'll take my 231 Buick!
cheers
Jay

Jay Maechtlen

http://home.covad.net/~jmaechtlen/