Harsh 2-1 Downshift while in 'S' Mode

[Mistabullet]

Basically the car kicks back when I downshift from 2 --> 1 (while in 'S' mode) @ around 15mph. But it's perfectly smooth while in auto mode.

Is something wrong or is this normal since the car is going slow and there isn't enough force to counter the effects of the downshit? (I say this because the affects aren't as harsh when downshifting @ 25mph as it is @ 15mph)

Also, is this bad for the tranny?

[07XLE]

Just the fact that you used the word "Harsh, kicks back, and perfectly smooth in auto mode" would lead me to think this is not good for the tranny. Why would you shift all the way down to 1 in "S" (Shift limiter) mode? By leaving it on second gear, the car will go into the first gear smoothly when it needs to just like in auto mode. I cannot think of any reason to force the tranny into 1st gear. Also are you saying that the tranny will let you go into 1st gear while traveling 25 mph, I would think the computer would say, "Um, No" and give you the beep reply that the downshift cannot be performed.

Like it's been said before, brakes are for slow, gears are for go!

[onsknht]

FWIW - In all my years driving MANUAL transmissions, I never once downshifted into 1st gear... Why, because it's harsh and erratic just as it is on the S-mode equipped automatic. It is harsh because 1st gear is your "get started gear," it is very tall and allows the engine to work far less to get 3500lbs of steel, plastic and flesh moving.

The Camry will allow you to downshift into 1st gear just as a manual transmission would allow you to... But the point here is, even though you can do it, should you be doing it?

[Yazovets]

In the winter, it is often very useful to shift all the way down to 1 for stopping purposes. When you have ice underneath, using brakes often increases your chance of losing control.

But other than that, going down to 1st isn't necessary.

[onsknht]

Originally Posted by Yazovets

In the winter, it is often very useful to shift all the way down to 1 for stopping purposes. When you have ice underneath, using brakes often increases your chance of losing control.

Sort of.... You need to be going fairly slow before shifting down from 2 to 1. If you do it too soon/fast, the engine braking will actually lock up the wheels and could cause you to lose control.

Downshifting is best used to limit wear and tear on the brakes.

[CamrySExxx]

^what exactly is S mode? if you want to slow down use your brakes. buying new breaks > buying new tranny.

offtopic onsknht when you slow down with out down shifting ... what do you do ? pop it into neutral and hit the breaks ? or do you keep it in gear and hit the brakes, and when you are about to stop then shift into neutral?

[07XLE]

Originally Posted by onsknht

Downshifting is best used to limit wear and tear on the brakes.

I don't understand the logic in that statement, the brakes are make to take the wear and tear, I'd much rather replace the parts that are designed to wear out rather than put that much extra wear and tear on the tranny.

S mode is what the automatic tranny's have, it's supposed to resemble tiptronic shifting but it's really just a top gear limiter, i.e. if you put the tranny in "S" mode (slide the shifter to the left from "D") and select gear 4, the car will accelerate through the gears like normal, however it will not shift beyond 4th gear. It's pretty retarded and is really just a sales feature to think you are getting a tiptronic tranny. Had I known that I would have gotten a VW with DSG tranny.

[CamrySExxx]

^exactly the only time i would downshift is when its needed like going up a hill. sometimes to pass other cars but normally ill just leave it in 5th and wait an extra 1-2 seconds for the car to gain speed

[onsknht]

Originally Posted by 07XLE

I don't understand the logic in that statement, the brakes are make to take the wear and tear, I'd much rather replace the parts that are designed to wear out rather than put that much extra wear and tear on the tranny.

S mode is what the automatic tranny's have, it's supposed to resemble tiptronic shifting but it's really just a top gear limiter, i.e. if you put the tranny in "S" mode (slide the shifter to the left from "D") and select gear 4, the car will accelerate through the gears like normal, however it will not shift beyond 4th gear. It's pretty retarded and is really just a sales feature to think you are getting a tiptronic tranny. Had I known that I would have gotten a VW with DSG tranny.

If the transmission is made to spin the wheels with power from the engine, why would it be any different to have the transmission spin the engine with power from the wheels????

There is no harm done to your engine/transmission as a result of downshifting... Watch/feel your car as you slow down some time, the automatic downshifts on its own. It does this for two reasons, 1. keep you in an appropriate gear should you decide to accellerate 2. use the engine for braking and prolong brake life.

Basically downshifting uses the free compression in your cylinders to brake the car... This has several advantages the most prominent being less wear and tear on the brake components... The engine also dissipates heat faster than the brakes and basically when you slow down you're transferring energy (momentum of the vehicle) into heat... The heat is either absorbed by the brakes or the engine.

Ever hear of a Jake Brake??? Trucks (diesels) have this feature and it basically is used solely to slow the vehicle and is entirely engine based... They need the Jake Brake because a diesel engine operates on entirely different principles than a 4-stroke gasoline engine.

Finally, I agree 100% about the S-Mode, it serves no useful purpose as implemented in the 2007 Camry... My TL while far from the DSG used by VW is light years ahead of the Camry with regards to responsiveness and usefulness.

Here's some more information about downshifting/engine braking.... I should submit an edit to Wiki, it appears this information mixes the dynamics of diesel and gasoline engines somewhat... Also note what it says about engine braking/downshifting on slippery surfaces.

Engine braking

From Wikipedia, the free encyclopedia


Engine braking is the act of using the energy-requiring compression stroke of the internal combustion engine to dissipate energy and slow down a vehicle. Compression braking is a common legal term for the same mechanism. Large trucks use a device called a engine brake to increase the effectiveness of engine braking.

Design
Most four stroke internal combustion engines require compression of the fuel-air mixture before ignition, in order to extract useful mechanical energy from the expansion. Diesel engines are adiabatic and have no spark plugs and use energy transferred to air charge during compression to directly ignite the mixture when the fuel is injected.
Regardless of engine type, compression of gas and vapor requires energy as described by theories in physical chemistry and thermodynamics. Compression in an engine is driven by the flywheel. So the engine ends up converting energy that was formerly kinetic energy of the vehicle into heat in the fuel-air mixture. These hot gases are exhausted from the vehicle and heat is transferred from engine components to the air.

Advantages

The advantage of using the engine to dissipate energy is this immediate ejection of energy. Hot gases are ejected from the vehicle very quickly and the gases also transfer much of their heat directly to engine parts. In addition, friction produced within the engine system also adds heat to the engine parts.
This engine heat is taken away by the engine's integrated cooling system: usually a liquid circulation system and a radiator. Disc or drum brakes have no such energy dissipation mechanisms. They must rely on air flow to remove heat and they use their mass to retain heat without producing temperatures that would deform and damage the brakes.
Placing a vehicle in a low gear causes the engine to have more leverage (mechanical advantage) on the road and the road to have less leverage on the engine. This is what allows cars to slow down using their relatively flimsy engine parts. The engine maintains a high rotational speed to dissipate a lot of power without forcing too much strain on the engine.
The engine brake is used in large diesel vehicles because the rate of conversion of mechanical energy into waste thermal energy is low compared to the mechanical returns to kinetic energy from the air-spring effect in the engine.

Applications

Engine braking is always active in all non-hybrid cars with an internal combustion engine, regardless of transmission type. Engine braking passively reduces wear on brakes and helps a driver maintain control of the car. It is always active when the foot is lifted off the accelerator, the transmission is not in neutral, the clutch is engaged and a freewheel is not engaged. This is often called engine drag.
Active use of engine braking (shifting into a lower gear) is only advantageous when it is necessary to control speed while driving down very steep and long slopes. It should be applied before regular disk or drum brakes have been used, leaving the brakes available to make emergency stops. The desired speed is maintained by using engine braking to counteract the acceleration due to gravity.
Improper engine braking technique can cause the wheels to skid, especially on slippery surfaces such as ice or snow, as a result of too much deceleration. As in a skid caused by over-braking, the car will not regain traction until the wheels are allowed to turn more quickly; the driver must reduce engine braking (shifting back up) to regain traction.

Legal implications

Compression braking, a form of engine braking, produces extreme amounts of noise pollution if there is no muffler on the exhaust system of the engine. Use of a engine brake produces similar effects, due to release of compressed gasses, but the mechanism is distinct from regular car engine braking. Anecdotally, it sounds similar to a jackhammer, however the loudness is between 10-20 times the perceived loudness of a jackhammer. Numerous cities, municipalities, states, and provinces have banned the use of unmuffled compression brakes.
This is often a source of dissatisfaction to professional truck drivers, some of whom believe that municipalities are taking advantage of them due to their transient nature, and thus disregard the law, believing that they will be gone before a complaint can be lodged.

[07XLE]

This comes from the National Auto Sport Association...maybe not as reputable as Wikipedia but anyway..

Downshifting
The first thing to understand is the purpose of the downshift. It is not to slow the car, that is the job of the brakes. The purpose of downshifting is to have the car in the correct gear to accelerate through and out of the corner.
Here is the process:
As you enter the braking zone, apply the brakes, but do not immediately downshift. The downshift should be done after the RPM’s have dropped, but must be complete before you begin the turn-in. Downshifting too early can over-rev the motor, waiting too long means you will be rolling the car through the corner entry, giving up the ability to use the throttle to balance the car.

But either way to each thier own, I am totally comfortable putting all the decelleration load on the brakes, that's how I learned it at Porsche driving school. Two major lessons they taught, don't rest your hand on the shifter (manual) until you are ready to shift because it causes undue stress to the shifter linkage, and never engine brake as the brakes are designed to handle those forces, the engine and tranny are not. I always loved how they announced "this is not a racing school" and right then, some badass GT3 911 racecar would roll by!

[onsknht]

Originally Posted by 07XLE

This comes from the National Auto Sport Association...maybe not as reputable as Wikipedia but anyway..

Downshifting
The first thing to understand is the purpose of the downshift. It is not to slow the car, that is the job of the brakes. The purpose of downshifting is to have the car in the correct gear to accelerate through and out of the corner.
Here is the process:
As you enter the braking zone, apply the brakes, but do not immediately downshift. The downshift should be done after the RPM’s have dropped, but must be complete before you begin the turn-in. Downshifting too early can over-rev the motor, waiting too long means you will be rolling the car through the corner entry, giving up the ability to use the throttle to balance the car.

But either way to each thier own, I am totally comfortable putting all the decelleration load on the brakes, that's how I learned it at Porsche driving school. Two major lessons they taught, don't rest your hand on the shifter (manual) until you are ready to shift because it causes undue stress to the shifter linkage, and never engine brake as the brakes are designed to handle those forces, the engine and tranny are not. I always loved how they announced "this is not a racing school" and right then, some badass GT3 911 racecar would roll by!

There's definitely different opinions between the two methods... But you also need to consider the context under what each method is being used. If I were racing on a road course, I would certainly be more inclined to brake in advance of downshifting, the response is hella faster on the binders than the engine... And as the writeup correctly points out, you risk over-rev which can't happen in the Camry.

Here's a use for down shifting you may not have considered.... I occasionally drive into the city and if I hit the road at the wrong time, I'm greeted with heavy traffic. In stop and go traffic, I'll limit the gear shifting to 2nd or possibly even 3rd gear and I'll drive for 20 miles configured this way. While everyone else is mashing the brakes and lighting up like x-mas trees, I simply stop accellerating and am in total control... Plus I won't wear a hole in the floormat as quickly being on and off the brakes and gas. The car rarely gets over 25-30 MPH in heavy traffic so I trade some RPMs for not dorking around between the brake and the gas pedal.

Finally, yes, you should limit your hand on the shift knob but I can't agree with what they told you about the engine and tranny loads.... C'mon think about it a little bit. There's a helluva lot more load on these components at WOT than there ever is on decelleration, re-read the following.

"Placing a vehicle in a low gear causes the engine to have more leverage (mechanical advantage) on the road and the road to have less leverage on the engine. This is what allows cars to slow down using their relatively flimsy engine parts. The engine maintains a high rotational speed to dissipate a lot of power without forcing too much strain on the engine."

[summerwind]

Down shifting

It is useful to use engine braking when coming down long mountain passes.

When I was in Glacier Park last year a Jammer driver was telling about a park visitor in a rental car that road the brakes to failure coming down Logan Pass. If they had not ran into the back of the Jammer car in front of them they would have probably gone off the road and over the side on the next curve.

S mode. It is not manual shift. It just limits the top gear. The tranny will behave like it is in drive but stop when the top gear is selected. As page 162 of your owners manual states..

Shift into the “3” position. The transmission will downshift to third gear when the vehicle speed drops down to or lower than 141 km/h (76 mph), and stronger engine braking will be enabled.

Shift into the “2” position. The transmission will downshift to second gear when the vehicle speed drops down to or lower than 89 km/h (48 mph), and stronger engine braking will be enabled.

Shift into the “L” position. The transmission will downshift to first gear when the vehicle speed drops down to or lower than 40 km/h (21 mph), and maximum engine braking will be enabled.

Toyota will not allow you to lock the tranny in a specific gear that exceeds the preset speed they have programmed for it. It is not a Tiptronic tranny and does not provide manual shifting capabilities other cars have.

[Old Dood]

Originally Posted by onsknht

FWIW - In all my years driving MANUAL transmissions, I never once downshifted into 1st gear... Why, because it's harsh and erratic just as it is on the S-mode equipped automatic. It is harsh because 1st gear is your "get started gear," it is very tall and allows the engine to work far less to get 3500lbs of steel, plastic and flesh moving.

The Camry will allow you to downshift into 1st gear just as a manual transmission would allow you to... But the point here is, even though you can do it, should you be doing it?

Same here...lowest I ever went was 2nd.

[Virus18]

I have never shifted from 2nd gear to first in a stick. You have to be going much slower than 15mph to downshift to 1 in an auto.

[Streaker]

I didn't even use first gear to start off when I had a manual trans. I started off in second gear cause you had to shift almost immediately into second when you start in 1st gear. 1st gear is good for going slow down enbankments but thats about it. Don't use it to brake your car or you will break your car!