Transmission Fact or Myth
09-06-14, 11:36 AM
#1
Driver
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Transmission Fact or Myth
I recently heard something from a friend of mine about shifting from automatic to manual shifter. He said that doing this over time can mess up the transmission. I normally switch from automatic to manual mode to avoid braking or to slow down going down steep hills. Is this a transission fact or myth?
Last edited by dwayne4lex; 09-06-14 at 11:51 AM. Reason: clarity
09-06-14, 12:01 PM
#2
Downshifting in general is harder on a tranny than rolling in neutral (or neutral mode) but it should be fine.
The manual shifting in the lexus as it's not a real dual clutch tranny and it's an actual auto is just manually setting the shift (and downshift) points electronically on the auto.
The manual shifting in the lexus as it's not a real dual clutch tranny and it's an actual auto is just manually setting the shift (and downshift) points electronically on the auto.
09-06-14, 12:49 PM
#3
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It certainly causes more wear and tear, how much more is debatable, but I look at it like this...
If you need to use engine braking for a safety concern, meaning that you have a loaded vehicle and you're traveling down a hill for an extended period of time and you're afraid of overheating your brakes, then do it. Otherwise, don't. Pads and rotors are a whole lot cheaper to replace than a tranny.
If you need to use engine braking for a safety concern, meaning that you have a loaded vehicle and you're traveling down a hill for an extended period of time and you're afraid of overheating your brakes, then do it. Otherwise, don't. Pads and rotors are a whole lot cheaper to replace than a tranny.
09-06-14, 03:45 PM
#6
Lexus Test Driver
I read this on a manual transmission forum.
I downshift all the time and none of my cars have problems with it. As long as u keep the engine RPM below redline, it should be fine.
Our cars can't go past redline cause the computer won't allow it. Try downshifting when going 70 MPH to 2nd gear, it won't let u, it'll just beep. The car will downshift as far as it is appropriate for the speed and engine RPM.
Most of the time when you drive, you're putting a load (and causing wear) on what I'm going to call the "forward" face of each tooth on each gear in your drivetrain. The front of a tooth on the crankshaft pushes against the back of a tooth on the next gear in line, which pushes the next gear, etc. When you use "engine braking", all you are doing is engaging the teeth in the opposite direction, and putting force and wear on the faces that normally are just along for the ride.
Now, does that mean you're wearing your engine out faster? Marginally... but the parts you're wearing out would normally have to be replaced (if at all) because they'd worn out from the other side; you're wearing surfaces that would usually be thrown out with hardly any wear at all. To borrow a phrase from the medical field, your engine/transmission will die with that wear, not of it.
Now, does that mean you're wearing your engine out faster? Marginally... but the parts you're wearing out would normally have to be replaced (if at all) because they'd worn out from the other side; you're wearing surfaces that would usually be thrown out with hardly any wear at all. To borrow a phrase from the medical field, your engine/transmission will die with that wear, not of it.
Our cars can't go past redline cause the computer won't allow it. Try downshifting when going 70 MPH to 2nd gear, it won't let u, it'll just beep. The car will downshift as far as it is appropriate for the speed and engine RPM.
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09-07-14, 08:39 AM
#8
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For those that think there's no harm in it, can you explain why slowing down using your brakes wears out your pads/rotors over time, but why you think using engine braking by downshifting the tranny is essentially "free"?
This is also an automatic transmission which uses clutch packs (at least auto trannies I've broken down in the past do) and they don't wear out on the "opposite" side when engine breaking. This is true regardless of redlining or not. That's like saying you don' wear out your brakes unless you do panic stops all the time or you don't wear out your tires unless you peal out.
This is also an automatic transmission which uses clutch packs (at least auto trannies I've broken down in the past do) and they don't wear out on the "opposite" side when engine breaking. This is true regardless of redlining or not. That's like saying you don' wear out your brakes unless you do panic stops all the time or you don't wear out your tires unless you peal out.
09-09-14, 06:18 AM
#9
are we talking about using the paddle shifter to downshift or we are talking about switching between auto mode and manual mode by using the auto gear shifter to switch between D to M, M to D? if it is the later, i usually don't do that when the car is moving but only when it is at complete stop. i will never put the gear in neutral for the car to roll. i did that to my dad Merc donkey years ago and i remember it damage the transmission over time.
09-09-14, 07:57 AM
#10
are we talking about using the paddle shifter to downshift or we are talking about switching between auto mode and manual mode by using the auto gear shifter to switch between D to M, M to D? if it is the later, i usually don't do that when the car is moving but only when it is at complete stop. i will never put the gear in neutral for the car to roll. i did that to my dad Merc donkey years ago and i remember it damage the transmission over time.
09-09-14, 09:10 AM
#12
Lexus Champion
are we talking about using the paddle shifter to downshift or we are talking about switching between auto mode and manual mode by using the auto gear shifter to switch between D to M, M to D? if it is the later, i usually don't do that when the car is moving but only when it is at complete stop. i will never put the gear in neutral for the car to roll. i did that to my dad Merc donkey years ago and i remember it damage the transmission over time.
09-09-14, 09:18 AM
#13
Lexus Test Driver
Just don't floor it then shift from N to D.
09-09-14, 10:19 AM
#14
09-09-14, 11:17 AM
#15
Driver
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