Hard shifting
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rannunziato
- Posts: 45
- Joined: Mon Feb 06, 2012 9:49 am
- Location: Aston, PA
Hard shifting
2006 PF SE V6 Auto 4WD, 129K miles. Trans replaced with rebuilt at 80K by dealer after trans/rad failure. My questions is, when the truck is cold or hasn't been driven for a period of time, the trans shifting from 1st to 2nd is not smooth. It seems to kinda softly slam into 2nd for the first few shifts and after that everything's fine. I did the flush and fill with matic s or j (I forget) last year. Is there something more I can do? ie mechanic in a can? I do tow with it and want to be pro-active in reducing the likelihood of early failure.
Someone else jump in here if I'm way off.
I've had my share of rebuilt transmissions (in other cars) and they're never the same as a new one (despite what the guy who's selling it to you says). Rough or sluggish shifts, the occasional misshift and strange noises are all things you should expect from a rebuilt transmission. There's also a chance you may have received a used transmission rather than a rebuilt one.
I've had my Pathfinder in the shop because of a jumpy transmission a few times and they keep telling me it's normal. Apparently they don't age well.
If you're having issues like this, it's usually because of aged or worn components that were still within spec during the rebuild and, therefore, not replaced. Can you make it go away? Usually not. Does it mean there's something wrong with your transmission? Not necessarily -- especially in the Pathfinder whose transmission uses technology developed by Cavemen and Chimpanzees. Can you add something to help? Sure, though I'm hesitant about adding "Miracle Elixirs." There's usually a tradeoff and transmission fluid is a finicky thing. I have heard from many mechanics that you shouldn't change the fluid in an older transmission unless absolutely necessary and that additives should be a last resort type of thing. When you take your transmission to the dealer and they remove the pan for inspection, they always pour the same transmission fluid back into the valve body.
Mankind can do many things. Building a perfect automatic transmission is not one of them. My parents' brand new Mercedes has been in the shop a few times because of transmission issues related to the computer. What a nightmare! Just be glad the Pathfinder's transmission is as basic as it is.
I've had my share of rebuilt transmissions (in other cars) and they're never the same as a new one (despite what the guy who's selling it to you says). Rough or sluggish shifts, the occasional misshift and strange noises are all things you should expect from a rebuilt transmission. There's also a chance you may have received a used transmission rather than a rebuilt one.
I've had my Pathfinder in the shop because of a jumpy transmission a few times and they keep telling me it's normal. Apparently they don't age well.
If you're having issues like this, it's usually because of aged or worn components that were still within spec during the rebuild and, therefore, not replaced. Can you make it go away? Usually not. Does it mean there's something wrong with your transmission? Not necessarily -- especially in the Pathfinder whose transmission uses technology developed by Cavemen and Chimpanzees. Can you add something to help? Sure, though I'm hesitant about adding "Miracle Elixirs." There's usually a tradeoff and transmission fluid is a finicky thing. I have heard from many mechanics that you shouldn't change the fluid in an older transmission unless absolutely necessary and that additives should be a last resort type of thing. When you take your transmission to the dealer and they remove the pan for inspection, they always pour the same transmission fluid back into the valve body.
Mankind can do many things. Building a perfect automatic transmission is not one of them. My parents' brand new Mercedes has been in the shop a few times because of transmission issues related to the computer. What a nightmare! Just be glad the Pathfinder's transmission is as basic as it is.
Personally, I love the basic-ness of the Pathfinder. It's always the fancy crap that breaks first. My wife's car has a transmission that senses your style of driving and adapts. Yeah, we had to replace the valve body twice. I just wish the gearing wasn't so awkward and stretchy (on the V8).staynlean wrote:I can assure you there are far more "basic" transmissions than the Pathfinders.
I built transmissions for 10+ years, mostly on GM vehicles but I've had my hands in about all makes.
Out of curiosity, since you probably know more about transmissions than me, why is it they say not to change the transmission fluid when you're having transmission problems?
"My wife's car has a transmission that senses your style of driving and adapts."
Nissan has had ECM "self-learning" (which is what you are describing) going all the way back to the 90's; this is nothing new. It'll soften or firm up shift points based on the driver habits over time, among other things.
"...why is it they say not to change the transmission fluid when you're having transmission problems?"
I put that under the category of old wives tales. It's fine to change the fluid if you are having trans problems, but whether is will do any good or not is another thing. The best thing to do is drain and fill the trans at regular intervals, like 30,000 miles, or at least when it shows signs of getting dirty or off-color. ATF is high detergent oil and works in a relatively closed environment, unlike engine oil. The thing that ruins ATF the most is heat, not dirt. So, a vehicle's driving environment and conditions (and type of ATF) play more into when it should be serviced than mileage. The two main contaminants in ATF (excluding coolant from a failed cooler) are metal from the hard parts of the trans and fiber from the clutch plates within the drums of the auto trans; two much of either one indicates an internal failure and an overhaul may be in the not so far off future. As far as the saying, I think that comes from the old days when people would go without any kinds of service to their engine, creating sludge, that would seem to cause the engine to fail right after they finally make the decision to change the oil, at which point the damage has been done. Same for transmissions: by the time they decided to service the ATF, it was too late.
Nissan has had ECM "self-learning" (which is what you are describing) going all the way back to the 90's; this is nothing new. It'll soften or firm up shift points based on the driver habits over time, among other things.
"...why is it they say not to change the transmission fluid when you're having transmission problems?"
I put that under the category of old wives tales. It's fine to change the fluid if you are having trans problems, but whether is will do any good or not is another thing. The best thing to do is drain and fill the trans at regular intervals, like 30,000 miles, or at least when it shows signs of getting dirty or off-color. ATF is high detergent oil and works in a relatively closed environment, unlike engine oil. The thing that ruins ATF the most is heat, not dirt. So, a vehicle's driving environment and conditions (and type of ATF) play more into when it should be serviced than mileage. The two main contaminants in ATF (excluding coolant from a failed cooler) are metal from the hard parts of the trans and fiber from the clutch plates within the drums of the auto trans; two much of either one indicates an internal failure and an overhaul may be in the not so far off future. As far as the saying, I think that comes from the old days when people would go without any kinds of service to their engine, creating sludge, that would seem to cause the engine to fail right after they finally make the decision to change the oil, at which point the damage has been done. Same for transmissions: by the time they decided to service the ATF, it was too late.
Makes sense and great info!smj999smj wrote:I put that under the category of old wives tales. It's fine to change the fluid if you are having trans problems, but whether is will do any good or not is another thing. The best thing to do is drain and fill the trans at regular intervals, like 30,000 miles, or at least when it shows signs of getting dirty or off-color. ATF is high detergent oil and works in a relatively closed environment, unlike engine oil. The thing that ruins ATF the most is heat, not dirt. So, a vehicle's driving environment and conditions (and type of ATF) play more into when it should be serviced than mileage. The two main contaminants in ATF (excluding coolant from a failed cooler) are metal from the hard parts of the trans and fiber from the clutch plates within the drums of the auto trans; two much of either one indicates an internal failure and an overhaul may be in the not so far off future. As far as the saying, I think that comes from the old days when people would go without any kinds of service to their engine, creating sludge, that would seem to cause the engine to fail right after they finally make the decision to change the oil, at which point the damage has been done. Same for transmissions: by the time they decided to service the ATF, it was too late.
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rannunziato
- Posts: 45
- Joined: Mon Feb 06, 2012 9:49 am
- Location: Aston, PA
Hard shifting
Thanks for the info., very helpful...I tow a camper with it and had the fluid replaced once already and it's due to be replaced again. I just want to be as proactive as possible and realize that heated fluid will eventually breakdown and subsequently cause failure. The current fluid has been through several trips and has been heated up pretty good. I'm thinking that replacing it now may prevent problems in the future, maybe wrong IDK. My mechanic is going to do the job and use a product called BG?. He previously used matic s and when I describe the current concern he recommended this BG stuff...says there are conditioners and other things in it that may help to alleviate and prolong wear and tear. I also purchased a road side assist policy from good sam last night. With a wife, 3 kids and a dog, can't afford to be stranded with my ass hanging out there with no protection. Now, if the trans fails, the policy covers towing to the nearest service ctr for repairs. So with the fluid replacement, easy on the pedal, staying within 120 miles of home and the new policy, I feel that I am mostly covered...Thank you all again for the information. I'll check back for responses...
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