I always downshift down significant grades to take advantage of engine braking. In a Toyota hybrid, B mode not only applies max regen braking(but it will backspin one of the electric motors as well), but it will also spin up the ICE as a air compressor.
Using AT to engine brake down mountain...will it hurt AT?
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NO WAY I would make the descent down the west side of Rabbit Ears Pass without putting the A/T into 3rd or even 2nd.
Originally Posted By: CKN
This is what "tow-haul" mode in a truck is good for-even if you don't have a trailer behind you.
Yes-Tow/Haul mode WILL DOWNSHIFT AUTOMATICALLY when going downhill, with a closed throttle. Hard to believe all the manufacturers would include a feature that makes transmissions fail earlier, potentially under warranty. I am guilty of downshifting on the numerous hills around here, the only bad effect I've had has been wearing out a couple AT tailshaft bushings, otherwise it doesn't hurt a thing.
This is what "tow-haul" mode in a truck is good for-even if you don't have a trailer behind you.
Yes-Tow/Haul mode WILL DOWNSHIFT AUTOMATICALLY when going downhill, with a closed throttle. Hard to believe all the manufacturers would include a feature that makes transmissions fail earlier, potentially under warranty. I am guilty of downshifting on the numerous hills around here, the only bad effect I've had has been wearing out a couple AT tailshaft bushings, otherwise it doesn't hurt a thing.
Originally Posted By: nthach
... In a Toyota hybrid, B mode not only applies max regen braking(but it will backspin one of the electric motors as well), but it will also spin up the ICE as a air compressor.
That's partially accurate. When you're coasting with the accelerator released, but not in "B," power from the wheels is "backspinning" MG1. If the speed is over about 45 mph (depending on model), power from the wheels is already spinning the engine slowly. When you shift to "B," the system spins the engine faster and increases regenerative braking. You still must use the brake pedal for "max regen braking."
... In a Toyota hybrid, B mode not only applies max regen braking(but it will backspin one of the electric motors as well), but it will also spin up the ICE as a air compressor.
That's partially accurate. When you're coasting with the accelerator released, but not in "B," power from the wheels is "backspinning" MG1. If the speed is over about 45 mph (depending on model), power from the wheels is already spinning the engine slowly. When you shift to "B," the system spins the engine faster and increases regenerative braking. You still must use the brake pedal for "max regen braking."
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Originally Posted By: bullwinkle
Originally Posted By: CKN
This is what "tow-haul" mode in a truck is good for-even if you don't have a trailer behind you.
Yes-Tow/Haul mode WILL DOWNSHIFT AUTOMATICALLY when going downhill, with a closed throttle. Hard to believe all the manufacturers would include a feature that makes transmissions fail earlier, potentially under warranty. I am guilty of downshifting on the numerous hills around here, the only bad effect I've had has been wearing out a couple AT tailshaft bushings, otherwise it doesn't hurt a thing.
Yep-can't have any new fangled tech stuff on here...No Sir.
Those D.I. motors are going to be blowing up any second!
How about those fuel injectors....can't be any good verses a good old carburetor....No Sir!
OR-how about those CVT's....can't have those either.
Everyone on here would be happy if the clocked stopped in say 1965.......
NOW-let me check Auto Trader for a Crown Vic.
Originally Posted By: CKN
This is what "tow-haul" mode in a truck is good for-even if you don't have a trailer behind you.
Yes-Tow/Haul mode WILL DOWNSHIFT AUTOMATICALLY when going downhill, with a closed throttle. Hard to believe all the manufacturers would include a feature that makes transmissions fail earlier, potentially under warranty. I am guilty of downshifting on the numerous hills around here, the only bad effect I've had has been wearing out a couple AT tailshaft bushings, otherwise it doesn't hurt a thing.
Yep-can't have any new fangled tech stuff on here...No Sir.
Those D.I. motors are going to be blowing up any second!
How about those fuel injectors....can't be any good verses a good old carburetor....No Sir!
OR-how about those CVT's....can't have those either.
Everyone on here would be happy if the clocked stopped in say 1965.......
NOW-let me check Auto Trader for a Crown Vic.
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My C300 will downshift on grades (both up and down) to maintain speed - while it is great during handling actual long uphills and downhills it is obnoxious on this 1/4 mile long slope right outside my condo complex. Going out (down the hill) i am revved up at 3k RPM all the way down the hill because the car thinks I need engine braking, on the way up it will downshift and have me at 3+k RPM all the way up despite the torque of my engine being fine carrying me up at 2.2k RPM. The way up is the most obnoxious as it downshifts very noticeably halfway up the hill, I cast it off as one of those unique scenarios it was never tested in, but I have to say the pause and downshift is maddening - 8 months later I have just gotten used to it and know exactly where it is going to happen.
Other than that it has handled the pass between Chattanooga and Nashville admirably a few times, learned the first trip that the cruise control will stab the brakes (and light up the brake lights) here and there if you are 5+ MPH over the set speed. Set the cruise ~70MPH in the downhill stretch back into Chattanooga, car was engine braking ~3500 RPM and cruise control stabbed the brakes maybe 1-2 times on the steeper stretches.
Love the logic behind it but it is not perfect in every scenario.
Other than that it has handled the pass between Chattanooga and Nashville admirably a few times, learned the first trip that the cruise control will stab the brakes (and light up the brake lights) here and there if you are 5+ MPH over the set speed. Set the cruise ~70MPH in the downhill stretch back into Chattanooga, car was engine braking ~3500 RPM and cruise control stabbed the brakes maybe 1-2 times on the steeper stretches.
Love the logic behind it but it is not perfect in every scenario.
I used 3 for grins in the 528e . It was the best way to drive a 3200lb 128 HP car. The fuel injectors shut off at 5200 Rpm. 5k in 3 was 105 mph. In 2 it was a practically legal at 68 mph. 4th was going 88mph at only 3k RPM. Stock shift points made it poky, perfect for commuting into Boston. On trips I mostly worked the cruise control instead of the gas pedal. Never had any trouble with any of the 4 spd 4HP22 automatics
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Originally Posted By: mrdctaylor
Guys,
My wife and I just got back from a nice trip out west. It look us through parts of Utah and Colorado. When coming down long declines out of a mountain pass, I usually manually kept my automatic transmission in 2 or 3 depending on how fast I was comfortable going. It was never at high or even moderate RPMs. I'd always heard this was safer because if you ride your brakes down a mountain they can overheat and fail.
Anyway, I've had some people tell me that it will wear out my transmission. Obviously, I want to be safe but I'd also rather wear our brakes than a transmission. For those of you that live in mountainous terrain: what is the proper procedure? Should I manually downshift my auto to keep the speed low on a long descent or should I just leave it in D and use the brakes?
Thanks in advance!
PS. This was in my 2012 Highlander. It has a "manual" shift mode where I can control the gear my tapping the gearshift towards the "+" or the "-".
Ski twice a week from mid October to June. Sometimes I put between 18-20,000 miles on BMW in winter just skiing here in CO. I use manual shifting not just to go down but cutting corners. Going down in X5 diesel and manually slowing it down is very efficient bcs of high compression. So far never had issues, and gearbox works as usual.
I was actually considering that 2nd gen. Highlander at one point, and did not like it particularly bcs of slow response when one does manual shifting, because I use it a lot.
So, nothing to worry. Gears are there for a reason.
Guys,
My wife and I just got back from a nice trip out west. It look us through parts of Utah and Colorado. When coming down long declines out of a mountain pass, I usually manually kept my automatic transmission in 2 or 3 depending on how fast I was comfortable going. It was never at high or even moderate RPMs. I'd always heard this was safer because if you ride your brakes down a mountain they can overheat and fail.
Anyway, I've had some people tell me that it will wear out my transmission. Obviously, I want to be safe but I'd also rather wear our brakes than a transmission. For those of you that live in mountainous terrain: what is the proper procedure? Should I manually downshift my auto to keep the speed low on a long descent or should I just leave it in D and use the brakes?
Thanks in advance!
PS. This was in my 2012 Highlander. It has a "manual" shift mode where I can control the gear my tapping the gearshift towards the "+" or the "-".
Ski twice a week from mid October to June. Sometimes I put between 18-20,000 miles on BMW in winter just skiing here in CO. I use manual shifting not just to go down but cutting corners. Going down in X5 diesel and manually slowing it down is very efficient bcs of high compression. So far never had issues, and gearbox works as usual.
I was actually considering that 2nd gen. Highlander at one point, and did not like it particularly bcs of slow response when one does manual shifting, because I use it a lot.
So, nothing to worry. Gears are there for a reason.
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