Do you... ummm... go through a lot of transmissions? Differentials?

Scary.

 

Well in this car you really have no choice since you cannot rock all that well. In fact, I thought the car does this for a few reasons one of which is to mimic a rocking?

 

I am no expert but I do have to say I disagree.

During the first major snow fall of the season the roads were horrible. If I tried to apply the breaks, even a little, the moment they touched it slid. I took my foot off, dropped to B and bam -- instant decrease of 20 mph or more.

Yes, I can see B causing a fishtail or yaw if your back tires have no traction but at least it is not locking the tires and putting you into a slide. I used it a few times and it worked perfectly each time.

Just my experience. Time will tell and I will continue to play with it. Could have just been luck.

 

Actually, he may be right.


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Engine braking

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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 an exhaust brake to increase the effectiveness of engine braking.
Contents

[hide]

• 1 Design
• 2 Advantages
• 3 Disadvantages
• 4 Applications
• 5 Legal implications
• 6 See also
• 7 External links

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[edit] Design

Compression of gas and vapor requires energy as described by theories in physical chemistry and thermodynamics. Compression in an engine is driven by the forward momentum of the vehicle as well as the angular momentum of the flywheel. When a driver downshifts to spin the engine at high angular velocity (or RPM) without pressing on the [accelerator pedal], the engine converts energy from the vehicle's speed, which is kinetic energy, into a temperature increase in the fuel-air mixture. These hot gases are exhausted from the vehicle and heat is transferred from engine components to the air.
This energy conversion occurs because 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.

[edit] 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 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 exhaust 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.

[edit] Disadvantages

An engine used for braking will break. Engines are meant to make you go, not stop. If engine braking is used in place of normal braking during everyday driving, your engine and drivetrain will wear faster than usual.[citation needed]

[edit] Applications

Engine braking is always active in all non-hybrid vehicles with an internal combustion engine, regardless of transmission type. Engine braking passively reduces wear on brakes and helps a driver maintain control of the vehicle. 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.
In Hybrid Synergy Drive vehicles like the Toyota Prius, engine braking is simulated by the computer software to match the feel of a traditional automatic transmission. An additional "B" mode is also available that simulates the feel of a lower gear, and which uses the internal combustion engine to waste energy, preventing the battery from becoming overcharged.
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 vehicle 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.

 

The only way this would be possible would be if you could not brake as gently as B mode. That's because B mode cannot slow the car without increasing the frictional force at the tires resisting forward motion. In this sense, it is no different than applying the brakes.

There is no "free" braking or "internal braking" that will not increase frictional force at the tires and thus incur some risk of breaking traction at the tires. From a physics standpoint, if you draw a freebody diagram or otherwise break the system down into simpler components, you'll see that this is true.

It doesn't matter whether you brake at the wheels or far away from them. In fact, you could have the engine or flywheel or motor generator in outer space and it wouldn't help.

When I engage B mode, my car decelerates more than if I was just feathering the brakes. I doubt I have any special ability that allows me to finely apply pressure to the brake pedal that others lack.

 

...and I went it to a skid backing down the steep and icy driveway.
In the 33 years since I got my license, this, unquestionably, is the worst performing car (in winter condition) I've ever driven.
Please don't apologize for the car, it's great under certain conditions, but the same driveway that put my Camry to shame was conquered easily by other cars.
I love the car, but for winter driving, I grade it an "F".

The weather will be the same today and as a test, I will try the 96 Avalon on the same driveway tonight. I will report back on how well it performs.

 

In situations when you're braking ineffectively, it's clearly not the traction control system since you're not giving it gas. It's really just the tires at that point.

My old car, a '95 Camry, was like that. I once was going down a not-so-steep ramp exiting a parking structure. I knew I might I have trouble so I approached the ramp at an idle and applied the brakes firmly before I even hit the ramp. I still slid uncontrollably down the ramp and across several lanes of the street. That was just one of many "exciting" experiences in the snow with that car. A check with Tirerack provided some insight.

Tirerack survey results:

old car's OEM tires:

Light Snow Traction 5.0
Deep Snow Traction 2.9
Ice Traction 3.3

Camry Hybrid OEM tires:

"Michelin Energy MXV4 S8" 5.6, 4.5, 4.6
"Bridgestone Turanza EL400-02" 4.0, 2.9, 3.2

My snow tires:

"Blizzak REVO 1" 8.9, 8.6, 8.6

Wow, the Bridgestone Turanzas really got downgraded since I last checked. They used to be rated slightly better than the Michelins.

Tires really do make a difference. My old car's tires still had plenty of tread and were "all-season," a loose standard that only requires a certain amount of the tread to be evacuated. Snow tires must meet more rigorous requirements to get the snowflake/mountain stamp on the sidewall that will get you waved through chain-up checkpoints unless it's really bad in the mountains.

I think a lot of people underestimate the importance of tires in the snow and blame the vehicle. The car can't do anything if its tires don't have traction. It's not going to shoot out a grappling hook.

 

Sorry to multiquote, but:

Did these significantly affect your gas mileage?

Thats because they really kind of suck A LOT. I wish they'd blow out so i could replace them and not feel guilty about buying new tires to replace "new" tires!


Sometimes I wish it would!!!

 

Surprisingly, no, despite the cold weather that accompanies snow tire season.

I wish my Bridgestones would wear out faster so I can replace them with the Michelins. Coupled with my current snow tires, I would have some of the best winter and summer/spring/fall tires available.

I think most newer cars come with low[er] rolling resistance tires to help boost the fleet average fuel economy (so manufacturers can sell more gas guzzlers). LRR tires are probably never going to be good in the snow because the more deeply treaded a tire is, the higher its rolling resistance will be. The characteristics of LRR tires and snow tires are pretty much at odds with one another.

 

Do the fleet mileage figures account for the spinning of thousands of wheels of cars stuck in the snow and ice?