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Toyota Motor Corporation Message Board

  • godekw godekw Mar 10, 2010 7:54 AM Flag

    Relative Strength - Brakes VS Engine Power

    Sure, I've had some fun knocking Toyota. However there is one issue that needs to be clarified here... BRAKES will ALWAYS OVERRIDE ENGINE POWER. As any Street racer or Drag racer knows, POWERBRAKING an automatic transmission is the quickest way off the line. LEft foot on the brake, Right foot on the gas FLOORED! THe most powerful Ground Pounding American Muscle Car engines will not override braking FORCE! A shittin' toyota engine certainly will not either. UNLESS ABS and/or other electronics such as stability controls are involved. The myth of runaway cars took hold with AUDI in the '80's. Pedal positioning was different than American brands and people were simply stepping on the gas instead of the brake. In Some cases they killed their relatives and children so the investigators were sympathetic and did not accuse the drivers of what obviously happened.

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    • I doubt automatic gearboxes have an influence on braking systems. Couldn't let all this bool continue so I went for a drive this morning to put an end to all these theories no-one has tried in real life. Here the result of my observations.
      I tried a low speed (30-35mph) test of acceleration and quite hard braking simultaneously, speed slowed down pretty quick and there was some slight skidding probably limited by the ABS system (it's a BMW 318td). Having noticed no dangerous or unusual behaviour during that attempt, I went looking for a wider empty stretch of road and did a higher speed tryout, cruised up to 55-60 and then accelerated fully whilst then testing the brake pedal and you know what, even with full acceleration (at this engine speed we are around maximum torque) you don't even need to press the brakes hard to slow down the car and the car behaves quite as expected, no swerving or stuttering, just a smooth but slow decrease in speed. Cars just don't have the torque or BHP to overcome brake power, the only way a problem could appear is with defective brakes or software (if there is any) malfunctioning on the braking system. And an ABS malfunction does not prevent the mechanical braking process from working. What's more, during unintended acceleration there are two more things to realise, firstly you have no need to press the gas with the right foot whilst experimenting with the left (rarely used) for braking so braking is much easier than in my experiment, only the right foot familiar with braking has to be controlled (braking smoothly with the left without practice is not that easy. Secondly at top speed there is no more acceleration but constant speed meaning initially braking is a less complicated matter than at half speed with full acceleration (the situation during which the Sykes guy was told to switch off his ignition). Anyone still not convinced about braking strength should go try for himself, no-one is asking you to brake or accelerate hard first time round, do it in steps and you'll see there's nothing to it (although maybe rent a car for the more extreme tests as it's probably not so great for the engine but still when it's a choice between engine and life...)

    • george.christoff@sbcglobal.net george.christoff Mar 10, 2010 6:46 PM Flag

      This theory is all wrong. First the old big muscle cars had huge breaks to slow the heavy vehicle from a high speed, second then you floor is while holding the brake at a stop you have no mass moving that needs to be stopped, third, you have a torque that is slipping, fourth, the engine at that rpm hasn't built up enough torque to overcome the breaks.

      How about this, stand in front of a stopped prius and hold it back from someone pushing from the rear, you can probobly keep it from moving. Now jump in front of a coasting prius and try to stop it. And I want to watch.

      • 1 Reply to george.christoff
      • Wow, you're throwing half a dozen theories in a bag and pulling bits of each to make a new one.
        Firstly, it's pointless, energywise a prius running into a 150lb guy standing still is a prius running into somethin with almost no energy. Look at a prius running into a guy just dropping out the hatch of the space shuttle during landing and you should understand. Second, you have no idea how much energy is involved in braking during motion and as you probably will never be able to comprehend the formulae for working it out (think about it anyway, see how much energy it takes to stop a 2000lb car at 75 mph in less than 100 yards and compare with the max energy of an engine, no comparison) just go out and try things a little before posting what you think could be right.

    • Stick shifts still dominate in Europe (probably by a factor of 10:1 or so) - perhaps that's a factor?

    • Disc brakes DO fade and if they get hotter than around 700 degrees (street pads) they can actually cause brake fluid 'boil', which further decreases brake effectiveness. Check the internet under 'brake fade' or something similar. You'll find carbon fiber brakes are the closest to being fade resistant that are made. Too expensive for practical use, though.

    • Imannini is right. You've forgotten inertia and the laws of physics. Try you're theory on a lightly travelled highway sometime. You'll be amazed at how your brakes aren't working...and they will fade unless you have carbon fiber pads.

      • 1 Reply to fliegereins
      • DISK BRAKES dont fade, the disk thickens as it heats and compensates for pad reduction. Drum brakes fade because the drum enlarges and shoes have to reach out farther.

        It takes a long time to wear out disk brake pads often 40 000 miles. If The gas pedal is held fully down and you brake fully the car will be stopped long before the pads are worn much.

        This SIKES guy was pulling a pure con job. He was using the brakes partly, and applying gas, his brake lights were coming on and off as he likely was left foot braking and right on the gas pedal.

        He was trying to set up a lawsuit situation but likely his claim will be easily destroyed if he has the nerve to take it to court.

        What he claims happened over that period of time is technically impossible for an auto to do , against the will of the driver.

        All this focus on the feet of drivers will confuse those who are not skilled in driving and we will see a rash of leaping cars of all makes as gas is hit instead of brakes.

        40000 americans alone die on their highways each year in auto accidents the majority in honda and gm and ford and nissan---not toyotas.
        some of these caused by drivers confusing gas and brake.

        The more we focus on it the more will happen until this hysteria subsides-------and is there ANY DOUBT that detroit is gleefully beating the drum and stirring the pot.

        I still drive a full size gm truck and my wife has an 06 corolla and they both are absolutely safe and dependable.

    • I think these people are doing it intentionally to sue Toyota.

    • Your missing a little of the physics. You forgot about the momentum as a result of 3000 lbs of steel moving at 60-90 mph and a rolling wheel has more friction than a slipping wheel. Power braking is at a standstill and the wheels are usually wet to reduce friction so they don't press the brake all the way to the floor. Why don't you try doing a power brake at 60 MPH and let me know how it goes. No I won't pay your hospital bill!

      • 3 Replies to imaninni
      • Why don't you stop hypothesising on something you've never tried. No need to worry about hospitals, no-one's asking you to test under the worst case scenario first time round. Start on a deserted road at 30mph pressing both pedals full, as you survive that, try 5mph more each time and see how pathetic most people's preconceived ideas are. If you brake hard enough, even at top speed, you'll block the wheels immediately and skid to a halt. No amount of conventional horsepower acceleration will overcome that power, all it can do is lengthen the braking distance, but hey, it took this guy 20 miles to come to a standstill.
        The ONLY question that remains is if this model is equipped with software preventing someone from using their brakes normally and the account already seems to indicate that in the presence of a cop with megaphone, the brakes do work, even at high speed, funny that despite this so many people are now desperately trying to prove braking is impossible.

      • Touche'. I was going to add this. Simple physics KE = 1/2 (MV**2)

      • The car will stop UNLESS there is SOMETHING to interrupt the Dynamic Fluid Pressure between the MASTER CYLINDER(S) which are actuated by the drivers foot pressure and the WHEEL CYLINDER(S) on the Brake Caliper. ABS is one thing that will do this, it "Modulates" the pressure in a form of "pulses" when it senses wheel slippage. I'm not trying to say TOYOTA is not at fault, There MAY be really Crazy circumstances in which the fluid pressure is interrupted by the ABS module or another device such as Stability control, But functionng properly, or without ABS, brakes will ALWAYS STOP a FULL THROTTLE ENGINE.

    • Your point is true for conventional cars. Remember the Prius has regenerative braking that will likely not be functional if the OBC thinks the accelerator is depressed. The standard mechanical brakes are likely no match for the gasoline engine and the electric motors running at full capacity.

    • craigfinch@sbcglobal.net craigfinch Mar 10, 2010 11:08 AM Flag

      Like I said "Where is the gravel runaway Toyota ramp when you need it?"
      Obama needs to cough up some more bucks. The Trucking industry has plenty of those ramps and I see tire tracks on some of them when I drive by! Another Toyodah moment!

    • When you are on the freeway going 50 mph+ the brakes will fade way before you can stop the car if going WOT.

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