Transmission wear

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I've got a question about wear. If a car has an automatic transmission, and spends 80% on the highway, on top gear, does it translate to the top gear in the transmission getting most of the wear?
 
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Not usually the gears that wear (some do have input shaft issues) but the clutches that wear first , so highway driving would mean reduced low gear shifts resulting in longer clutch life of those gears.
 
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I'd think any convertor wear would come from locking and unlocking. Highway driving should not be doing much of this.
 

MolaKule

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Once you get up to highway speeds the top gear clutch locks up to the associated sun gear and the TC usually remains locked as well, so you should see little wear of clutch and friction plates. Refreshing the ATF fluid and replacing the filter at around 30k miles usually extends the life of an AT.
 
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My personal believe is the clutches or torque converter wear out first if doing lots of stop and go traffic, the next is the gaskets. Gears usually outlast the rest of the system.
 
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I'm thinking most tranny failures are TC clutch related.Shrapnel from that failed lining material clogs screens (Chrysler's 41TE solenoid pack screens for example) and cause immediate fluid starvation to the clutch packs,killing the transmission on the spot.
 
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Originally Posted By: PandaBear
My personal believe is the clutches or torque converter wear out first if doing lots of stop and go traffic, the next is the gaskets. Gears usually outlast the rest of the system.
The friction material wears out with stop and go. Highway travel makes it hard to wear out an automatic transmission.
 
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Originally Posted By: Miller88
Originally Posted By: PandaBear
My personal believe is the clutches or torque converter wear out first if doing lots of stop and go traffic, the next is the gaskets. Gears usually outlast the rest of the system.
The friction material wears out with stop and go. Highway travel makes it hard to wear out an automatic transmission.
No doubt highway driving is easy on an auto, and the car in general. What would be a good run for a primarily city driven auto?
 
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Sometime in the mid-1990's GM designed the TCC with a PWM apply instead of the on-off type of apply in the 4L60E (perhaps they did this to other AT's as well). I don't know why they did this other than for "feel". I would think that this pulsing apply of the TCC would wear it out faster. GM did change the clutch friction material; I haven't read about any more frequent TCC related failures vs. the old on-off TCC apply. When I rebuilt the 4L60E in the Safari, I changed the TCC apply circuit back to the old on-off. The trip computer did reflect a 0.10 MPG decrease in average fuel economy.
 

MolaKule

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Originally Posted By: gregk24
What would be a good run for a primarily city driven auto?
Not sure what you're asking.
 
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Originally Posted By: MolaKule
Originally Posted By: gregk24
What would be a good run for a primarily city driven auto?
Not sure what you're asking.
I am just curious what mileage one should expect out of a stop and go city driven passenger car with an automatic transmission.
 

MolaKule

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Originally Posted By: paulo57509
Sometime in the mid-1990's GM designed the TCC with a PWM apply instead of the on-off type of apply in the 4L60E (perhaps they did this to other AT's as well). I don't know why they did this other than for "feel". I would think that this pulsing apply of the TCC would wear it out faster. GM did change the clutch friction material; I haven't read about any more frequent TCC related failures vs. the old on-off TCC apply. When I rebuilt the 4L60E in the Safari, I changed the TCC apply circuit back to the old on-off. The trip computer did reflect a 0.10 MPG decrease in average fuel economy.
The Pulse Width Modulation system provides a more accurate application of pressure and rate of pressure increase or decrease. The reason this pulsing is not felt is because the fluid "integrates" those pulses into an analog pressure and rate of applied pressure.
 
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My wife has a 2005 Explorer V-8 with the 5 speed auto tranny. She bought it new, it now has around 165,000 on it. I have had the tranny fluid completely exchanged and new filter approximately every 30,000 miles, except for this last time because the shop said the fluid and pan is so clean that they just did a drain and fill with a filter change. It shifts like when it was new. The indie shop drops the pan, cleans it, changes the filter, refills then does a complete exchange of all the ATF. Whimsey
 
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Originally Posted By: MolaKule
The reason this pulsing is not felt is because the fluid "integrates" those pulses into an analog pressure and rate of applied pressure.
I also read about a correct PWM application on a solenoid would make its behavior more analog (gradual movement) than digital (shudder). Do PWM shifted automatic transmissions have any feedback to sense the correct pressure? or do they just go from off to on over a preset period of time?
 
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GM uses a patented algorithm to lock and unlock the converter randomly to avoid driveline vibrations. Almost every slushbox out there uses completely variable pressure throughout their operating envelope. Clutches only wear during shifts. In highway use they should only wear if the unit is slipping, that would quickly degrade the trans. IME the TC usually fails or barfs particles into the downstream components, then the trans fails. This can take a long time or happen in a couple of days.
 
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Originally Posted By: gregk24
Originally Posted By: MolaKule
Originally Posted By: gregk24
What would be a good run for a primarily city driven auto?
Not sure what you're asking.
I am just curious what mileage one should expect out of a stop and go city driven passenger car with an automatic transmission.
That's a tough question to answer. It's like asking how long will a person live? We all know the stories of health nuts dying young, and smokers and drinkers living into their 90's. I junked a beater Aerostar with well over 200,000 miles that spent 90% of its life in NY traffic. My buddy had a transmission fail in a new car in under 5,000 miles. In theory a well maintained transmission that sees lots of highway miles should last a very long time.
 
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