I learned the trick of turning off Overdrive on this forum to reduce transmission temps while climbing grades. It seems this is still not a well-known fact to many 3rd Gen owners so I figured it was time to make another video. I didn't have my expert video producer/editor @infamounsRNR around but i put together passable product. The lighting while driving washed out some of the trans temp information I was trying to show on my phone but there was enough footage that showed the trans temps when overdrive was off and on that the video worked to document the difference.
Here's the video and Enjoy the Show!
__________________ "My old man is a television repairman, he's got this ultimate set of tools. I can fix it!"
It's a shame that the TCC doesn't lock up earlier than 40-42mph with overdrive disabled. My 04 grand Cherokee will lock up TCC at 30mph with OD turned off. Which is real nice.
Yup, this makes a huge difference. TC locks at 48 MPH in 4th and 42 in 3rd I believe.
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2008 Toyota 4Runner Limited 4x4 - Salsa Red, DD, Mostly Stock, 89k miles 2001 Toyota 4Runner SR5 4x4 - Not Stock, Lifted, Armored, 291k miles 1987 Toyota Supra N/A - Stock, 2nd Owner, 92k miles
I've really not understood what a torque converter even does... as it what benefit it provides. My last vehicle was a manual, so not sure why autos don't just shift through the gears like normal? Is it supposed to be more "smooth" for the driver or something?
I've really not understood what a torque converter even does... as it what benefit it provides. My last vehicle was a manual, so not sure why autos don't just shift through the gears like normal? Is it supposed to be more "smooth" for the driver or something?
It's the same principle as the clutch in a manual transmission, it's just a different way of solving the same problem: Allowing the engine to turn independently of the transmission. Except it does it without driver interaction, as needed in a manual. At least that's how I understand it, lol.
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K82 2000 Limited T4R 4WD V6 auto, factory e-locker, BFG KO2s, Bilstein 5100's all around + 99 talls.
I've really not understood what a torque converter even does... as it what benefit it provides. My last vehicle was a manual, so not sure why autos don't just shift through the gears like normal? Is it supposed to be more "smooth" for the driver or something?
I've really not understood what a torque converter even does... as it what benefit it provides. My last vehicle was a manual, so not sure why autos don't just shift through the gears like normal? Is it supposed to be more "smooth" for the driver or something?
In a manual the clutch sits where the torque converter is on an auto, and when you push the pedal down it physically disconnects the engine from the transmission. The torque converter is a fluid coupling, allowing a permanent connection between the engine and transmission, because it allows the engine to idle while the transmission is stopped. It does this through some nifty fluid dynamics.
Warning, more info than you may want below.
A torque converter has two modes, below and above stall speed. Below stall speed the TC is basically a REALLY tall gear that allows some slip because of the fluid nature of the connection. When you step on the gas the TC very quickly spins up to stall speed, at which point the fluid dynamics inside change and it essentially up-shifts to a new gear. This effectively simulates how a clutch works. Some power is lost through the TC, making it less efficient than a manual. Which is why in top gear it has a lockup feature, which simply means it engages a shaft that creates a physical connection through the TC, eliminating the fluid coupling as if the TC didn't even exist. In a 4 speed auto you will feel a 5th "shift", where the rpms drop a little bit, when the TC locks up. If you disable overdrive, i.e. 4th gear, the TC will lockup in 3rd at a lower speed, which is good for towing because the transmission gets really hot when it's not in lockup and pulling extra weight. You make more power out of lockup because the rpms are a bit higher at any given speed, but it's less stressful on your transmission to stay in lockup as much as possible. Some guys install a switch so they can manually force the TC to lockup whenever they want. Drag racers do it, and some that tow a lot do it.
I got OD off all the time except on freeways. Tim, you has the driver side roof handle. I installed it and find it very useful when you want to readjust the seating position.
In a manual the clutch sits where the torque converter is on an auto, and when you push the pedal down it physically disconnects the engine from the transmission. The torque converter is a fluid coupling, allowing a permanent connection between the engine and transmission, because it allows the engine to idle while the transmission is stopped. It does this through some nifty fluid dynamics.
Warning, more info than you may want below.
A torque converter has two modes, below and above stall speed. Below stall speed the TC is basically a REALLY tall gear that allows some slip because of the fluid nature of the connection. When you step on the gas the TC very quickly spins up to stall speed, at which point the fluid dynamics inside change and it essentially up-shifts to a new gear. This effectively simulates how a clutch works. Some power is lost through the TC, making it less efficient than a manual. Which is why in top gear it has a lockup feature, which simply means it engages a shaft that creates a physical connection through the TC, eliminating the fluid coupling as if the TC didn't even exist. In a 4 speed auto you will feel a 5th "shift", where the rpms drop a little bit, when the TC locks up. If you disable overdrive, i.e. 4th gear, the TC will lockup in 3rd at a lower speed, which is good for towing because the transmission gets really hot when it's not in lockup and pulling extra weight. You make more power out of lockup because the rpms are a bit higher at any given speed, but it's less stressful on your transmission to stay in lockup as much as possible. Some guys install a switch so they can manually force the TC to lockup whenever they want. Drag racers do it, and some that tow a lot do it.
That's actually very helpful. Because my 4Runner puts out a whole lot more power than stock (I've added roughly 100 more HP) it will sometimes peg itself at 3k RPM's and just sit there at about 1/3 throttle, when I want to use more of the powerband. I knew this was because of the torque converter but didn't really know WHY it was doing it. I think I'll try driving with O/D off for a bit and see how that changes things.
I got OD off all the time except on freeways. Tim, you has the driver side roof handle. I installed it and find it very useful when you want to readjust the seating position.
It was a gift from Sean from his many visits to our local Pick and Pulls.
__________________ "My old man is a television repairman, he's got this ultimate set of tools. I can fix it!"
My commute is almost exclusively 30 - 40 mph. I wonder if I could increase fuel economy by disabling overdrive?
Hmm...
In theory yes, if you're not hitting fourth gear anyway the only effect disabling overdrive has is giving you lockup, which should increase mpg.
Quote:
Originally Posted by gamefreakgc
Because my 4Runner puts out a whole lot more power than stock (I've added roughly 100 more HP) it will sometimes peg itself at 3k RPM's and just sit there at about 1/3 throttle, when I want to use more of the powerband.
Not sure I know what you're getting at.
Do you mean you give it some gas and feel like it should downshift for more power but it doesn't? If so, have you tried using the ECT PWR button? I leave that on all the time, it raises the shift points so you hold each gear longer when accelerating, and it will downshift quicker too in the situation I think you're talking about.
You'd think that would impact your gas mileage, but it doesn't seem to. I get 17 - 18 mpg average on my commute, and it's not highway. Plenty of stop and go.
Do you mean you give it some gas and feel like it should downshift for more power but it doesn't? If so, have you tried using the ECT PWR button? I leave that on all the time, it raises the shift points so you hold each gear longer when accelerating, and it will downshift quicker too in the situation I think you're talking about.
You'd think that would impact your gas mileage, but it doesn't seem to. I get 17 - 18 mpg average on my commute, and it's not highway. Plenty of stop and go.
Yes, I also leave the ECT Power on full-time. I even have a shift-kit installed where it modifies the valve body to shift more aggressively and hold gears longer. The issue I think is that it has much more power because of the supercharger and fuel mods, it'll be spinning nicely and scooting along but since the throttle isn't open that much the torque converter won't lock up and sort of saps the power. I think I might just tighten the transmission kick-down cable a bit more to downshift easier, I did that before I had the valve body shift kit installed.