Originally Posted By: tom slick
So you've had failures from "poor filtering" in-pan filters? Did the issues clear up when you put an aftermarket filter on? In your experience did the transmission last significantly longer because of the better filter?
It's clear to me that many failures are due to contamination. If you want documented information on failures and contamination, go to SAE.org and research papers by engineers Eleftherakis and Khalil (E & K). I would refer you to three papers (there are others); 2001-01-0867 "Automatic Transmission Hydraulic Cleanliness" (Nieuwland & Droste), 99PC-418 "Optimizing Automatic Transmission Filtration" (Eleftherakis & Khalil), 900561 "Development of a Lab Test Contaminant for Transmissions" (Eleftherakis & Khalil).
It doesn't really matter whether you change the oil or add better filtration, the same end result is achieved... namely the elimination of contaminants and the extension of tranny life. The first change is the most important as, according to the years of testing done by E&K, 75% of the contaminants developed by an automatic in it's lifetime are present in the first 5K miles... either from built-in manufacturing debris or break-in. The difference is that, if you change the oil when the contamination level of the oil reached it's limit, the oils itself is in pretty good shape yet. Additional filtration is a much an oil life extender as a tranny life extender.
After sampling the oil in thousands of automatics in service, they found that the average trans with 70K or more miles that has not had a service contains approximately 263 mg/l (milligrams per liter) of contaminants, 90 percent of which is metallic. Of those metallic particles, 51 percent are ferrous (iron/steel), 21 percent copper, 11 percent aluminum and 7 percent lead. The particles range in size from 5 to 80 microns, about 82 percent of them larger than 5 microns.
Long term, the metallic particles cause wear on the pump vanes/housing and on bearings and bushings, but valves don't like debris either and that's where the shorter term problems can come from. A chunk of debris can score the bore of a valve and cause it to leak, or jam outright. I don't have to tell you what a metallic particle will do to a rubber seal or o-ring. With the advent of electronic valves, a new problem was created. What is an electronically controlled valve? An electromagnet! Magnets attract ferrous particles, so the iron in the trans is gravitating to those areas and causing valve malfunctions to occur even sooner. Once the valves start to malfunction, you get reduced pressures or delayed shifts, all of which cause extra wear on the clutches. Often it's so slow and imperceptible that the driver doesn't feel it until it gets really bad. That might be at 100K miles, so he says, "Oh well" and has the trans rebuilt when with some care, that trans might have outlasted the car. Sometimes there is so much manufacturing grunge (or remanufacturing... rebuilt trans have the same trouble) in the trans that it fails under warranty (very common).
Thing is, if you can keep the contaminants under control, you can greatly extend the reliability of the trans and the life of the oil. I interviewed Abe Khalil for a project and he said the first thing he does with a new car of his own is change the trans oil and filter (within about 5K miles). According to him, that eliminates 90 percent of the potential problems down the road.
So you've had failures from "poor filtering" in-pan filters? Did the issues clear up when you put an aftermarket filter on? In your experience did the transmission last significantly longer because of the better filter?
It's clear to me that many failures are due to contamination. If you want documented information on failures and contamination, go to SAE.org and research papers by engineers Eleftherakis and Khalil (E & K). I would refer you to three papers (there are others); 2001-01-0867 "Automatic Transmission Hydraulic Cleanliness" (Nieuwland & Droste), 99PC-418 "Optimizing Automatic Transmission Filtration" (Eleftherakis & Khalil), 900561 "Development of a Lab Test Contaminant for Transmissions" (Eleftherakis & Khalil).
It doesn't really matter whether you change the oil or add better filtration, the same end result is achieved... namely the elimination of contaminants and the extension of tranny life. The first change is the most important as, according to the years of testing done by E&K, 75% of the contaminants developed by an automatic in it's lifetime are present in the first 5K miles... either from built-in manufacturing debris or break-in. The difference is that, if you change the oil when the contamination level of the oil reached it's limit, the oils itself is in pretty good shape yet. Additional filtration is a much an oil life extender as a tranny life extender.
After sampling the oil in thousands of automatics in service, they found that the average trans with 70K or more miles that has not had a service contains approximately 263 mg/l (milligrams per liter) of contaminants, 90 percent of which is metallic. Of those metallic particles, 51 percent are ferrous (iron/steel), 21 percent copper, 11 percent aluminum and 7 percent lead. The particles range in size from 5 to 80 microns, about 82 percent of them larger than 5 microns.
Long term, the metallic particles cause wear on the pump vanes/housing and on bearings and bushings, but valves don't like debris either and that's where the shorter term problems can come from. A chunk of debris can score the bore of a valve and cause it to leak, or jam outright. I don't have to tell you what a metallic particle will do to a rubber seal or o-ring. With the advent of electronic valves, a new problem was created. What is an electronically controlled valve? An electromagnet! Magnets attract ferrous particles, so the iron in the trans is gravitating to those areas and causing valve malfunctions to occur even sooner. Once the valves start to malfunction, you get reduced pressures or delayed shifts, all of which cause extra wear on the clutches. Often it's so slow and imperceptible that the driver doesn't feel it until it gets really bad. That might be at 100K miles, so he says, "Oh well" and has the trans rebuilt when with some care, that trans might have outlasted the car. Sometimes there is so much manufacturing grunge (or remanufacturing... rebuilt trans have the same trouble) in the trans that it fails under warranty (very common).
Thing is, if you can keep the contaminants under control, you can greatly extend the reliability of the trans and the life of the oil. I interviewed Abe Khalil for a project and he said the first thing he does with a new car of his own is change the trans oil and filter (within about 5K miles). According to him, that eliminates 90 percent of the potential problems down the road.
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