2019 Tundra High ATF Temperature
- Thread starter Whalstib
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Originally Posted by Whalstib
Originally Posted by tundraman
I also have a 2019 Tundra. After the sale I found that Toyota no longer equips the Tundra with an oil cooler. They use the term integrated engine/transmission oil cooling. It appears the warmer is also the cooler. No oil takeoff is present as in previous years so adding a cooler will entail buying the part (p/n Thermostat Unit - Toyota (32970-34030), installation, and cooler/lines. My dealer would not say if it would void warranty. Let us know what you decide.
Regards,
bc
Mine has this part!
I'm pretty sure it's behind the "oil cooler" on side of trans. It's not as big as it looks in the diagram.. maybe 1/2" thick.. Really stuffed up there. You gotta crawl up and look hard and you'll see it.
I think previous years had it on the other side of the trans but if you look at the schematics (I saw somewhere...) there is a common mounting bolt that goes through both..
Whalstib
Can you get a pic? No other 019 I know of has the oil takeoff.
bc
Originally Posted by tundraman
I also have a 2019 Tundra. After the sale I found that Toyota no longer equips the Tundra with an oil cooler. They use the term integrated engine/transmission oil cooling. It appears the warmer is also the cooler. No oil takeoff is present as in previous years so adding a cooler will entail buying the part (p/n Thermostat Unit - Toyota (32970-34030), installation, and cooler/lines. My dealer would not say if it would void warranty. Let us know what you decide.
Regards,
bc
Mine has this part!
I'm pretty sure it's behind the "oil cooler" on side of trans. It's not as big as it looks in the diagram.. maybe 1/2" thick.. Really stuffed up there. You gotta crawl up and look hard and you'll see it.
I think previous years had it on the other side of the trans but if you look at the schematics (I saw somewhere...) there is a common mounting bolt that goes through both..
Whalstib
Can you get a pic? No other 019 I know of has the oil takeoff.
bc
Where are you measuring this temp at? I ask as my 2010 has two sensors, but my SG will only read one of them for some reason, and the speed at which it responds indicates to me that it's convertor outlet (when the TC unlocks, it's a second or two and then temps rise and fast). But there should be one for pan (I think) which I'd expect is cooler and slower to respond.
Anyhow. Convertor outlet, I've seen as high as 230 on hills, once the convertor unlocks and it decides to not bother kicking down. A real broiler. Usually it's at 190 or so on the highway on long drives. But. I don't want to say Aisin transmissions never break, but you have to admit, it's not something they are known for--and the vast majority are used by people who never look at the temperature. Or change the ATF.
You could always just ignore it (that's what most would do, and what Toyota would have you do). If worried, just use the manual selector and kick it down on hills. Keep the rev's up, that will keep TC slippage low, and limit heat generation. Change the ATF to some boutique if you want, or just more often than Toyota says, or whatever it takes to sleep well at night.
Anyhow. Convertor outlet, I've seen as high as 230 on hills, once the convertor unlocks and it decides to not bother kicking down. A real broiler. Usually it's at 190 or so on the highway on long drives. But. I don't want to say Aisin transmissions never break, but you have to admit, it's not something they are known for--and the vast majority are used by people who never look at the temperature. Or change the ATF.
You could always just ignore it (that's what most would do, and what Toyota would have you do). If worried, just use the manual selector and kick it down on hills. Keep the rev's up, that will keep TC slippage low, and limit heat generation. Change the ATF to some boutique if you want, or just more often than Toyota says, or whatever it takes to sleep well at night.
From what I can gather Toyota uses the sensors to adjust performance of the transmission. So there purpose is not over all health of the ATF but using temperature as a signal..
I'm also reading different posts about location of sensors and it all boils down to opinion with out an actual diagram. Some say in pan and TC.
I used my OBD Fusion iPhone app which supports 3 sensors! ( you have to buy an additional package for $10 but plug and play, no PIDs to enter) Two of the sensors read almost exactly the same with one fluctuating 2-5 degrees and the other more steady ~210 in long cross town traffic ~80° ambient T. My readings support the two in the pan theory of location..
The 3rd reads -40° and I think that's Toyota code for either no sensor or broken sensor. Since every report I read says two I'm guessing the generic package of added PID supports some Toyota that has three...
As others have reported they seem to have done away with the take off from a thermostat (I'm sorry I looked closer and mine is just a spacer... I confused other items with ATF lines from a distance). In fact no discernible thermostat of any kind on the outside.
I wonder if a larger heat exchanger may be the simple solution.. Looks like room for 3x the size no problem..
I just can't get my head around the Toyota engineers meeting when it was brought up to delete the transmission cooler.. They should have a good baseline of stats on how long their transmission last as-is and I can't see the new one having any effects on longevity... I guess they just have to get past the 100K warranty and don't care after that..
Sorry if I sound obsessive but mine is brand new sparkling under carriage so for the next few months nice and easy to get under and have a good clean look. So learning what's there before grimed up.
Thanks,
Wh. A.L.S.T.I.B.
I'm also reading different posts about location of sensors and it all boils down to opinion with out an actual diagram. Some say in pan and TC.
I used my OBD Fusion iPhone app which supports 3 sensors! ( you have to buy an additional package for $10 but plug and play, no PIDs to enter) Two of the sensors read almost exactly the same with one fluctuating 2-5 degrees and the other more steady ~210 in long cross town traffic ~80° ambient T. My readings support the two in the pan theory of location..
The 3rd reads -40° and I think that's Toyota code for either no sensor or broken sensor. Since every report I read says two I'm guessing the generic package of added PID supports some Toyota that has three...
As others have reported they seem to have done away with the take off from a thermostat (I'm sorry I looked closer and mine is just a spacer... I confused other items with ATF lines from a distance). In fact no discernible thermostat of any kind on the outside.
I wonder if a larger heat exchanger may be the simple solution.. Looks like room for 3x the size no problem..
I just can't get my head around the Toyota engineers meeting when it was brought up to delete the transmission cooler.. They should have a good baseline of stats on how long their transmission last as-is and I can't see the new one having any effects on longevity... I guess they just have to get past the 100K warranty and don't care after that..
Sorry if I sound obsessive but mine is brand new sparkling under carriage so for the next few months nice and easy to get under and have a good clean look. So learning what's there before grimed up.
Thanks,
Wh. A.L.S.T.I.B.
My dealer has yet to get back to me on what the maximum acceptable long term operating temperature is. While pulling my measly 1350# UTV/trailer rig Saturday at 76 deg. air temp, I was showing a constant 220 on the pan and the TC got up to 250 briefly. I was using higher gears. I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills). The heavy haulers are going to be interesting to hear from.
How about a deep pan?
BC
How about a deep pan?
BC
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
MY Tundra manual doesn't have much to say other than the typical lawyer-ese to explain load limits. No best practices.
If I'm wrong I'd love to hear from others about towing and gearing.
BTW How do you know the sensors are in pan and TC? My readings were exactly the same yesterday and I read elsewhere both sensors in pan....
Oddly today I noticed it did take a while to heat up. It was about 85° here and I had to drive across town on surface streets. 45mph stop and go. It took about 15 minutes to reach 150°.. which seemed a bit odd. Engine hit 193° in less than 5 minutes.... Since most trips of this nature maybe this is why the techs have made warming up a priority. Again further research revealed cold ATF can have negative impacts.....
Wh. A. L. S. T. I. B.
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
MY Tundra manual doesn't have much to say other than the typical lawyer-ese to explain load limits. No best practices.
If I'm wrong I'd love to hear from others about towing and gearing.
BTW How do you know the sensors are in pan and TC? My readings were exactly the same yesterday and I read elsewhere both sensors in pan....
Oddly today I noticed it did take a while to heat up. It was about 85° here and I had to drive across town on surface streets. 45mph stop and go. It took about 15 minutes to reach 150°.. which seemed a bit odd. Engine hit 193° in less than 5 minutes.... Since most trips of this nature maybe this is why the techs have made warming up a priority. Again further research revealed cold ATF can have negative impacts.....
Wh. A. L. S. T. I. B.
Last edited:
Originally Posted by Whalstib
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
MY Tundra manual doesn't have much to say other than the typical lawyer-ese to explain load limits. No best practices.
If I'm wrong I'd love to hear from others about towing and gearing.
BTW How do you know the sensors are in pan and TC? My readings were exactly the same yesterday and I read elsewhere both sensors in pan....
Oddly today I noticed it did take a while to heat up. It was about 85° here and I had to drive across town on surface streets. 45mph stop and go. It took about 15 minutes to reach 150°.. which seemed a bit odd. Engine hit 193° in less than 5 minutes.... Since most trips of this nature maybe this is why the techs have made warming up a priority. Again further research revealed cold ATF can have negative impacts.....
Wh. A. L. S. T. I. B.
Both sensors are in the valve body near the pan. One reads the fluid in pan before pickup (pre converter). The other is coming off the converter going to the works. My fluid takes a while to warm up as well unless going uphill or towing. Converter unlocked equals rapid heat up.
bc
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
MY Tundra manual doesn't have much to say other than the typical lawyer-ese to explain load limits. No best practices.
If I'm wrong I'd love to hear from others about towing and gearing.
BTW How do you know the sensors are in pan and TC? My readings were exactly the same yesterday and I read elsewhere both sensors in pan....
Oddly today I noticed it did take a while to heat up. It was about 85° here and I had to drive across town on surface streets. 45mph stop and go. It took about 15 minutes to reach 150°.. which seemed a bit odd. Engine hit 193° in less than 5 minutes.... Since most trips of this nature maybe this is why the techs have made warming up a priority. Again further research revealed cold ATF can have negative impacts.....
Wh. A. L. S. T. I. B.
Both sensors are in the valve body near the pan. One reads the fluid in pan before pickup (pre converter). The other is coming off the converter going to the works. My fluid takes a while to warm up as well unless going uphill or towing. Converter unlocked equals rapid heat up.
bc
I would press the dealer for an answer on acceptable temperatures, and maybe even bring it in and get it documented. I would also be swapping out the fluid every 25K miles, and never tow in OD.
Originally Posted by Whalstib
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
That's old school thinking. Outside of one possible Ford transmission (AOD?) there isn't a problem with "weak" overdrive gears. The problem is simple: old school programming would first unlock the torque convertor when extra engine power was needed--the engine rpm would rise up a bit. But at the cost of much increased slippage in the convertor. Which made lots of heat. Which, if the trans cooler was undersized, would cook the transmission fluid. It has nothing to do with being in overdrive or not: it has everything to do with the transmission being in a gear ratio that, at this particular vehicle speed, results in the torque convertor being asked to operate in a high slippage region. Technically this problem likely existed back in the days of 3 speed autos and highway gearing (think pushing 2.73's or worse).
I suppose this is still true today--if you let the transmission decide to run with the convertor unlocked, it is apt to make lots of heat. But this is easily combated by forcing a downshift when you sense the TC is unlocked. Even if the TC refuses to lock up, once engine rpm is above 2,000 rpm (give or take), convertor losses go down. [Also the flow of ATF through the transmission cooler goes way up, as it should be roughly proportional to engine rpm, at least once the thermostat opens.]
On flat ground, if the trans is locked up, leave it be. After a few miles you should be able to tell if the trans will hold a hill or not. If you think it won't, proactively kick it down a gear (or two) at the bottom of the hill, that way it won't be asked to shift under power, and it might even take the hill locked up.
My Tundra is "underpowered" so I'd never attempt to tow using 6th gear. 5th is fine on flat ground though, and 4th is required on any hill pretty much. But I'm not interested in listening to the engine drone on flat ground.
And yes, 5&6 are overdrive gears on these Tundra's.
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
That's old school thinking. Outside of one possible Ford transmission (AOD?) there isn't a problem with "weak" overdrive gears. The problem is simple: old school programming would first unlock the torque convertor when extra engine power was needed--the engine rpm would rise up a bit. But at the cost of much increased slippage in the convertor. Which made lots of heat. Which, if the trans cooler was undersized, would cook the transmission fluid. It has nothing to do with being in overdrive or not: it has everything to do with the transmission being in a gear ratio that, at this particular vehicle speed, results in the torque convertor being asked to operate in a high slippage region. Technically this problem likely existed back in the days of 3 speed autos and highway gearing (think pushing 2.73's or worse).
I suppose this is still true today--if you let the transmission decide to run with the convertor unlocked, it is apt to make lots of heat. But this is easily combated by forcing a downshift when you sense the TC is unlocked. Even if the TC refuses to lock up, once engine rpm is above 2,000 rpm (give or take), convertor losses go down. [Also the flow of ATF through the transmission cooler goes way up, as it should be roughly proportional to engine rpm, at least once the thermostat opens.]
On flat ground, if the trans is locked up, leave it be. After a few miles you should be able to tell if the trans will hold a hill or not. If you think it won't, proactively kick it down a gear (or two) at the bottom of the hill, that way it won't be asked to shift under power, and it might even take the hill locked up.
My Tundra is "underpowered" so I'd never attempt to tow using 6th gear. 5th is fine on flat ground though, and 4th is required on any hill pretty much. But I'm not interested in listening to the engine drone on flat ground.
And yes, 5&6 are overdrive gears on these Tundra's.
Originally Posted by tundraman
Originally Posted by Whalstib
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
MY Tundra manual doesn't have much to say other than the typical lawyer-ese to explain load limits. No best practices.
If I'm wrong I'd love to hear from others about towing and gearing.
BTW How do you know the sensors are in pan and TC? My readings were exactly the same yesterday and I read elsewhere both sensors in pan....
Oddly today I noticed it did take a while to heat up. It was about 85° here and I had to drive across town on surface streets. 45mph stop and go. It took about 15 minutes to reach 150°.. which seemed a bit odd. Engine hit 193° in less than 5 minutes.... Since most trips of this nature maybe this is why the techs have made warming up a priority. Again further research revealed cold ATF can have negative impacts.....
Wh. A. L. S. T. I. B.
Both sensors are in the valve body near the pan. One reads the fluid in pan before pickup (pre converter). The other is coming off the converter going to the works. My fluid takes a while to warm up as well unless going uphill or towing. Converter unlocked equals rapid heat up.
bc
In an auto transmission oil circulation system with cooler , torque converter (outlet) temperature is typically 5-10*C higher than sump temperature.
I suspect OP's quoted 210'ish *F by Scangauge is torque converter outlet temperature (if such sensor is provided), which I consider as normal.
However a sump temperature of 210'ish *F is simply too high in a normally operated auto transmission, IMHO.
Originally Posted by Whalstib
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
MY Tundra manual doesn't have much to say other than the typical lawyer-ese to explain load limits. No best practices.
If I'm wrong I'd love to hear from others about towing and gearing.
BTW How do you know the sensors are in pan and TC? My readings were exactly the same yesterday and I read elsewhere both sensors in pan....
Oddly today I noticed it did take a while to heat up. It was about 85° here and I had to drive across town on surface streets. 45mph stop and go. It took about 15 minutes to reach 150°.. which seemed a bit odd. Engine hit 193° in less than 5 minutes.... Since most trips of this nature maybe this is why the techs have made warming up a priority. Again further research revealed cold ATF can have negative impacts.....
Wh. A. L. S. T. I. B.
Both sensors are in the valve body near the pan. One reads the fluid in pan before pickup (pre converter). The other is coming off the converter going to the works. My fluid takes a while to warm up as well unless going uphill or towing. Converter unlocked equals rapid heat up.
bc
In an auto transmission oil circulation system with cooler , torque converter (outlet) temperature is typically 5-10*C higher than sump temperature.
I suspect OP's quoted 210'ish *F by Scangauge is torque converter outlet temperature (if such sensor is provided), which I consider as normal.
However a sump temperature of 210'ish *F is simply too high in a normally operated auto transmission, IMHO.
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I tried the scanguage in my truck first. It was reading the pan. Temperature rose and fell slowly. TQC temps shoot up fast on unlock and drop sharply on lockup. Never could get the guage to read both. Torque Pro reads both.
bc
bc
Originally Posted by Whalstib
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
I was told the same thing, and will continue to do so unless the load is very, very light. The last thing I want is the transmission constantly shifting in and out of OD to maintain speed. My buddy towed a 4,000 lb trailer daily with an 2008 Expedition, always in OD. It didn't take very long for his transmission to die. The guy who rebuilt it told him towing on Long Island's Sunrise Hwy traffic, getting it into OD for 30 seconds or so before slowing down repeatedly is what killed it. I tend to agree.
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
I was told the same thing, and will continue to do so unless the load is very, very light. The last thing I want is the transmission constantly shifting in and out of OD to maintain speed. My buddy towed a 4,000 lb trailer daily with an 2008 Expedition, always in OD. It didn't take very long for his transmission to die. The guy who rebuilt it told him towing on Long Island's Sunrise Hwy traffic, getting it into OD for 30 seconds or so before slowing down repeatedly is what killed it. I tend to agree.
Originally Posted by supton
Originally Posted by Whalstib
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
That's old school thinking. Outside of one possible Ford transmission (AOD?) there isn't a problem with "weak" overdrive gears. The problem is simple: old school programming would first unlock the torque convertor when extra engine power was needed--the engine rpm would rise up a bit. But at the cost of much increased slippage in the convertor. Which made lots of heat. Which, if the trans cooler was undersized, would cook the transmission fluid. It has nothing to do with being in overdrive or not: it has everything to do with the transmission being in a gear ratio that, at this particular vehicle speed, results in the torque convertor being asked to operate in a high slippage region. Technically this problem likely existed back in the days of 3 speed autos and highway gearing (think pushing 2.73's or worse).
I suppose this is still true today--if you let the transmission decide to run with the convertor unlocked, it is apt to make lots of heat. But this is easily combated by forcing a downshift when you sense the TC is unlocked. Even if the TC refuses to lock up, once engine rpm is above 2,000 rpm (give or take), convertor losses go down. [Also the flow of ATF through the transmission cooler goes way up, as it should be roughly proportional to engine rpm, at least once the thermostat opens.]
On flat ground, if the trans is locked up, leave it be. After a few miles you should be able to tell if the trans will hold a hill or not. If you think it won't, proactively kick it down a gear (or two) at the bottom of the hill, that way it won't be asked to shift under power, and it might even take the hill locked up.
My Tundra is "underpowered" so I'd never attempt to tow using 6th gear. 5th is fine on flat ground though, and 4th is required on any hill pretty much. But I'm not interested in listening to the engine drone on flat ground.
And yes, 5&6 are overdrive gears on these Tundra's.
There is additional info to this that isn't being considered. Everything here is correct, but it's not entirely correct. There was a study done years ago looking at true overdrive transmissions that did find that the OD gears develop more heat in the particular model of trans tested (I don't recall the make). I'm going skip the deep explanation and try to say it simply, knowing that the simple answer also has variables that will vary. Picture a large gear turning a smaller gear. There is heat generated in the meshing between the teeth. When the smaller gear is being driven be the larger gear, both of them absorb that heat. The smaller gear has less area with which to dissipate the heat, and ends up running at and exposing fluid to a higher temp. That was an instrumented test with real numbers.
I witnessed this on my 06 tundra. In 4th vs OD, both with the TC locked on even ground at even speed, the trans ran hotter in OD. This was measured at the cooler line leaving the transmission on a gauge.
Adding to that - If I set my 18 F150 in tow mode, it locks out the top two gears, even though the engine has more than enough power to use them, and I'm pretty sure the trans TC stays locked once Im in 3rd and up, not unlocking between shifts.
Anyway, all of that info about slipping at the TC and that heat resulting is true, but there is more to it, based on study I read. It may have been in 4x4 magazine back in the 90s.
-m
Originally Posted by Whalstib
Originally Posted by tundraman
I don't see a reason why I should have to stay in 4th with that load at 68 mph. (rolling hills).
BC
I was always told to avoid towing in over drive... Isn't 4th 1:1 or there abouts? 5th and 6th both over drives?
That's old school thinking. Outside of one possible Ford transmission (AOD?) there isn't a problem with "weak" overdrive gears. The problem is simple: old school programming would first unlock the torque convertor when extra engine power was needed--the engine rpm would rise up a bit. But at the cost of much increased slippage in the convertor. Which made lots of heat. Which, if the trans cooler was undersized, would cook the transmission fluid. It has nothing to do with being in overdrive or not: it has everything to do with the transmission being in a gear ratio that, at this particular vehicle speed, results in the torque convertor being asked to operate in a high slippage region. Technically this problem likely existed back in the days of 3 speed autos and highway gearing (think pushing 2.73's or worse).
I suppose this is still true today--if you let the transmission decide to run with the convertor unlocked, it is apt to make lots of heat. But this is easily combated by forcing a downshift when you sense the TC is unlocked. Even if the TC refuses to lock up, once engine rpm is above 2,000 rpm (give or take), convertor losses go down. [Also the flow of ATF through the transmission cooler goes way up, as it should be roughly proportional to engine rpm, at least once the thermostat opens.]
On flat ground, if the trans is locked up, leave it be. After a few miles you should be able to tell if the trans will hold a hill or not. If you think it won't, proactively kick it down a gear (or two) at the bottom of the hill, that way it won't be asked to shift under power, and it might even take the hill locked up.
My Tundra is "underpowered" so I'd never attempt to tow using 6th gear. 5th is fine on flat ground though, and 4th is required on any hill pretty much. But I'm not interested in listening to the engine drone on flat ground.
And yes, 5&6 are overdrive gears on these Tundra's.
There is additional info to this that isn't being considered. Everything here is correct, but it's not entirely correct. There was a study done years ago looking at true overdrive transmissions that did find that the OD gears develop more heat in the particular model of trans tested (I don't recall the make). I'm going skip the deep explanation and try to say it simply, knowing that the simple answer also has variables that will vary. Picture a large gear turning a smaller gear. There is heat generated in the meshing between the teeth. When the smaller gear is being driven be the larger gear, both of them absorb that heat. The smaller gear has less area with which to dissipate the heat, and ends up running at and exposing fluid to a higher temp. That was an instrumented test with real numbers.
I witnessed this on my 06 tundra. In 4th vs OD, both with the TC locked on even ground at even speed, the trans ran hotter in OD. This was measured at the cooler line leaving the transmission on a gauge.
Adding to that - If I set my 18 F150 in tow mode, it locks out the top two gears, even though the engine has more than enough power to use them, and I'm pretty sure the trans TC stays locked once Im in 3rd and up, not unlocking between shifts.
Anyway, all of that info about slipping at the TC and that heat resulting is true, but there is more to it, based on study I read. It may have been in 4x4 magazine back in the 90s.
-m
I'm trying to picture how heat build up from a larger gear driving a smaller one wouldn't have the same effect going the opposite way--smaller gear driving a larger one. The forces on the teeth are going to be equal? Newton's third law and all. I'm not sure is side load on the bearings--but even that is going to be the same. Maybe there's something there I'm missing, like the forces aren't equal--physics wasn't my strong point.
Any time you step up/down the gears "eat" some amount of power, leading to heating.
Ah: I'm reminded of something I came across recently, that in a planetary gearset, the smaller the gear ratio, the higher the heat buildup. I wonder that is in play here; that was not something I read deeply enough into to understand.
I won't argue with your measurement, I'm just trying to understand it. I do wonder if the amount of fluid going to the trans cooler was a variable, since higher engine rpm will lead to a high rate of fluid going through the cooler.
Unfortunately my Tundra won't lock up in 3rd. I'm not sure why Toyota did that. But AFAIK Aisin transmissions seem to shrug off high heat, going all the way back to AW4's and A340's.
Any time you step up/down the gears "eat" some amount of power, leading to heating.
Ah: I'm reminded of something I came across recently, that in a planetary gearset, the smaller the gear ratio, the higher the heat buildup. I wonder that is in play here; that was not something I read deeply enough into to understand.
I won't argue with your measurement, I'm just trying to understand it. I do wonder if the amount of fluid going to the trans cooler was a variable, since higher engine rpm will lead to a high rate of fluid going through the cooler.
Unfortunately my Tundra won't lock up in 3rd. I'm not sure why Toyota did that. But AFAIK Aisin transmissions seem to shrug off high heat, going all the way back to AW4's and A340's.
so - I wondered the same thing - the best I figure is when going the other way, with the small gear driving a larger gear, the small gear has the advantage of working against a larger level, so less pressure at the mesh. But I can argue that by saying, well, but it then has to turn more to get the same work done.... so I don't have a full understanding either. But the data was there. Seems like IIRC the actual heat development was in the oil film under pressure.
It was a big deal in my tundra. In 4th I could be pulling at 160F which is before the AT thermostat would activate the cooling loop. But if I let it take OD, it'd rapidly rise to 185, then settle back at 180. The t-stat was somewhere around 180. This was a repeatable test, not a one-off. So I accepted it is surprisingly true.
My Tundra only locked in it's top gear. That transmission was solid, bulletproof, probably the best I've owned, under any and all conditions. I had an 06. It was great. So I never had reason to question their design. Great Truck.
It was a big deal in my tundra. In 4th I could be pulling at 160F which is before the AT thermostat would activate the cooling loop. But if I let it take OD, it'd rapidly rise to 185, then settle back at 180. The t-stat was somewhere around 180. This was a repeatable test, not a one-off. So I accepted it is surprisingly true.
My Tundra only locked in it's top gear. That transmission was solid, bulletproof, probably the best I've owned, under any and all conditions. I had an 06. It was great. So I never had reason to question their design. Great Truck.
I wonder if I'm missing the mechanical advantage bit -- the real reason for using gears in the first place! -- force at a distance makes torque. Using step down uses a smaller point force at the teeth but obtains more torque at the shaft. To get the same output torque but in a step up application means there is higher point force at the teeth.
Ok, I can buy higher temps at the teeth, although I'm thinking in terms of standard gears, not planetaries (not sure how to think about those, not without a model in front of me).
Ok, I can buy higher temps at the teeth, although I'm thinking in terms of standard gears, not planetaries (not sure how to think about those, not without a model in front of me).
I never paid attention to TC lock up before towing....
It seems there are after market lock up switches which of course my Tundra does not have...
SO how does one achieve TC lock up? Certain gears at certain RPM....
I was just driving on FWY and could not discern any difference or a lock up. A Couple times letting off accelerator would drop rpm's from 1950 to 1735 with same speed.. But it was an almost feathering of the accelerator to achieve and quickly loss if accelerated or decelerated...
Is there a way to reliably achieve lock up?
Thanks,
Wh. A. L. S. T. I. B.
It seems there are after market lock up switches which of course my Tundra does not have...
SO how does one achieve TC lock up? Certain gears at certain RPM....
I was just driving on FWY and could not discern any difference or a lock up. A Couple times letting off accelerator would drop rpm's from 1950 to 1735 with same speed.. But it was an almost feathering of the accelerator to achieve and quickly loss if accelerated or decelerated...
Is there a way to reliably achieve lock up?
Thanks,
Wh. A. L. S. T. I. B.
IIRC it's a PWM controlled TC. Not sure what the ECU monitors but I'm guessing it'd not be easy for aftermarket solutions.
What I've done is simply listen. A slight feathering of the throttle will tell me if it's locked or not--if no rpm change, then it's locked. If it doesn't want to stay locked, then kick it down a gear.
What I've done is simply listen. A slight feathering of the throttle will tell me if it's locked or not--if no rpm change, then it's locked. If it doesn't want to stay locked, then kick it down a gear.
Put a loud exhaust on it. No doubt then!
bc
bc
It's getting harder to feel the lock up, that's no doubt. In my tundra it just felt like was just grabbing another gear, but with less of an rpm change. It seemed to me that the tundra's TC didn't allow a lot of slip to begin with, but I don't know enough about stall speeds to say anything intelligent. In my 06, it did not feel PWM-variable, but it doesn't mean it wasn't - I just couldn't perceive if it was. For my year, and knowing how toyota is a late adopter, my *assumption* was it was just an on/off device. Maybe it was all along - supton I'd just never thought about it?
In the ford I can barely tell. What I can tell is as I modulate the throttle you can feel the direct engagement, especially coming off the throttle.
@ Whalstib, I recommend you check the OM for directions on towing. See if it suggests locking out OD or if there's a tow mode, then use it and enjoy it. The tundra is no slouch, and is a solid, solid truck. Even going from a toyota to a ford, I learned that Tundras in general just use more metal in every place, where the f150 uses metal for heavy parts then enjoys lots and lots of plastic. Not knocking the 150, I am glad to have it, and it's fuel economy, but the tundra, where metal and the extra work needed to produce metal over plastic molded parts, has more going for it. I had 160,000 miles on mine, as the 3rd owner, and at least one of the previous owners also pulled a trailer with e-brakes, so most likely a TT with it, and the engine and trans drove as brand new when I sold it. I towed right at the weight limit on it also, about 6100 lbs (rated 6900 with the tow package). The body and bearings really weren't up to that capacity, but the driveline was fine. The newer ones are more robust than my gen2 was.
In the ford I can barely tell. What I can tell is as I modulate the throttle you can feel the direct engagement, especially coming off the throttle.
@ Whalstib, I recommend you check the OM for directions on towing. See if it suggests locking out OD or if there's a tow mode, then use it and enjoy it. The tundra is no slouch, and is a solid, solid truck. Even going from a toyota to a ford, I learned that Tundras in general just use more metal in every place, where the f150 uses metal for heavy parts then enjoys lots and lots of plastic. Not knocking the 150, I am glad to have it, and it's fuel economy, but the tundra, where metal and the extra work needed to produce metal over plastic molded parts, has more going for it. I had 160,000 miles on mine, as the 3rd owner, and at least one of the previous owners also pulled a trailer with e-brakes, so most likely a TT with it, and the engine and trans drove as brand new when I sold it. I towed right at the weight limit on it also, about 6100 lbs (rated 6900 with the tow package). The body and bearings really weren't up to that capacity, but the driveline was fine. The newer ones are more robust than my gen2 was.
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